priorities committee meeting jun16 2015 …...2015/06/16 · priorities committee...

Priorities Committee Meeting_Jun16_2015

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Strathcona County Design and Construction Standards Update – Water and Wastewater Report Purpose To present the proposed major changes to the water and sanitary sewer (wastewater) sections of the Design and Construction Standards.

Council History December 13, 2011 – Council approved the “Design and Construction Standards” dated December 2011. Strategic Plan Priority Areas Economy: Priority area: Effective and efficient municipal infrastructure. The objective of the standards review was to identify opportunities to reduce costs for new development while protecting Strathcona County’s residents and customers from performance risk. Governance: Priority area: Cooperative partnerships with community, business, industry and neighboring governments. The standards review process included involvement from the Urban Development Institute (UDI) with the goal of achieving long-term infrastructure performance while balancing current residents’ level of service. Social: Priority area: Helping, caring and safe community. The standards dictate how essential water and wastewater services are provided to residents to ensure their fundamental need for water and sanitation are met. Culture: n/a Environment: n/a Other Impacts Policy: n/a Legislative/Legal: n/a Interdepartmental: Planning & Development Services, Emergency Services Summary Strathcona County Administration, with the technical expertise of the engineering consulting firm Stantec Consulting Ltd., are proposing updates to the current Design & Construction Standards Section 4.2 Sanitary Sewer (Wastewater) System and Section 4.3 Water Distribution System. A summary of the major proposed changes is included in Enclosure 1. Stantec was commissioned to provide a comprehensive review of the design component of the water and wastewater sections. Stantec’s recommended changes are developed using a science-based review of other municipal standards, water billing records, available rainfall data and wastewater flow monitoring data. Stantec submitted an engineering report to support the recommended standards (Enclosure 2). The proposed standards and the Stantec report were provided to the Urban Development Institute of Alberta (UDI) Strathcona Technical Committee for review. UDI responded with a letter supporting the proposed standards, with the exception of four items related to the water and wastewater sections (Enclosure 3).

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Strathcona County Administration and their engineering consultants maintain the position that the proposed standards are appropriate and prudent for Strathcona County. The standards are intended to apply to development globally and be forward looking. The review was not conducted to address specific developments that have servicing challenges. Establishing the minimum design standards for water and wastewater is an issue of the level of service and performance risk (factor of safety) that is acceptable to Strathcona County. Enclosures 1 Strathcona County Design & Construction Standards Update – Summary of Changes

dated January 16, 2015 (Document: 7353984) 2 Design and Construction Standards Update – Water and Wastewater, Stantec

Consulting Ltd. dated May 26, 2015 (Document: 7354207) 3 Urban Development Institute of Alberta Letter to Mr. Rob Coon Re: Strathcona

County – Design and Construction Standards Review 2015 dated April 8, 2015 (Document: 7353762)

4 PowerPoint Presentation (Document: 7327982) Author: Lisa Knorr, Utilities Director: Jeff Hutton, Utilities Associate Commissioner: Kevin Glebe, Infrastructure & Planning Services Lead Department: Utilities

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2001 Sherwood Drive; Sherwood Park, AB T8A 3W7

Strathcona County Design & Construction Standards Update Section 4.2 Wastewater Collection System

Section 4.3 Water Distribution System

Summary of Changes

January 16, 2015

The following is a summary of the major changes incorporated into the 2015 Design &

Construction Standards; Section 4.2 Wastewater Collection System and Section 4.3

Water Distribution System.

Section 4.2 Wastewater Collection System

Section December 2011

Standards

Updated 2015

Standards

Average Residential

Wastewater

Generation Rate

4.2.1.2 (i) 375 L/person/day 300 L/person/day

Commercial /Industrial

Peaking Factor 4.2.1.3 (ii)

The peaking for

commercial/ industrial

development varies

greatly with the type

of development. Each

case must be

considered on an

individual basis.

Each case may be

considered on an

individual basis;

however for planning

purposes 10 xQ-0.45

(min 2.5, max 25)

shall be used.

Inflow and Infiltration

(I/I) Allowance 4.2.1.4 (i) 0.5 L/sec/gross ha 0.4 L/sec/gross ha

Vertical Separation 4.2.1.10

(iii) n/a

Added the allowance

of bridging options if

0.5 m is not

achieved.

Minimum Depth of

Cover

4.2.1.10

(iv) 2.6 m 2.75 m

Manhole Flow Direction 4.2.1.11

(vi)

Shall not exceed 90

degrees.

Added second criteria

of 45 degrees for 600

mm and larger.

Manhole Safety

Platforms

4.2.1.11

(xii)

Did not specify

maximum spacing.

Maximum spacing of

5 m.

Lift Stations and

Wastewater

Forcemains

4.2.1.13 n/a Full section added.

Enclosure 1

Strathcona County Design & Construction Standards Update

Summary of Changes

Page 2 of 3

Pre-cast Manholes 4.2.2.4 (i) n/a

Manufacturers must

possess a current

plant prequalification

certificate.

Manhole connections 4.2.3.5 (ii) n/a

Flexible manhole

connectors are

required when flexible

systems connect to a

concrete manhole.

Section 4.3 Water Distribution System

Section December 2011

Standards

Updated 2015

Standards

Residential Design

Consumption 4.3.1.2

ADD: 375

L/person/day

ADD: 330

L/person/day

Commercial /Industrial

Design Consumption 4.3.1.3 n/a

20,000 L/ha/day

For preliminary

planning purposes.

Each application shall

be reviewed on a

case-by-case basis.

Mid Value Multi-Family

Fire Demand 4.3.1.4 (ii) n/a

180L/s (Applicable

land uses as per Land

Use Bylaw 8-2001 –

R2A, R2B R3)

Casing Requirements

under Arterial Roads

4.3.1.8

(iv) n/a

Casings are required

for all water mains

crossing arterial

roads. At a

minimum, the casing

must span the

extents of the

carriageway.

Blow Off Valves 4.3.1.10

(iii)

Blow off valves need

to be sized to achieve

a minimum flushing

flow of 0.6 m/sec

Blow off valves must

be a minimum of 50

mm in size.

Pressure Control

Valves 4.3.1.11 n/a Full section added.

Service Connections 4.3.1.12

(viii) n/a

Curb stop located in

driveway or hard

surface must be

placed in PVC sleeve.

Interlocking Polyvinyl

Chloride (PVC) Pipe 4.3.2.2

Was listed as an

approved PVC pipe

material

Material removed

Tapping Valve Sleeves 4.3.2.4 n/a Full section added.

Strathcona County Design & Construction Standards Update

Summary of Changes

Page 3 of 3

Hydrants 4.3.2.7 (i) n/a

Hydrant upper barrel

and nozzle section

must be a single cast

unit.

Gate Valves 4.3.2.8 (i) n/a Added 350 mm valve

size.

Air Release Valves 4.3.2.8 (iii) n/a Added full section.

Pressure Control

Valves

4.3.2.8

(iv) n/a Added full section.

Service Saddles 4.3.3.7 (v)

Service saddles must

be used for larger size

copper services

Service saddles must

be used where the

tap diameter is

greater than 25 mm

or where the water

main is greater than

300 mm.

Administrative changes: Changes involving re-formatting, grammar, and other

editorial changes have been made throughout the document, but have not been

included in this list.

Also, please note that the update to Section 7 Standard Drawings is in progress and

will be provided at a later date.

Strathcona County

Water and Wastewater Design

Standards Review

Final Report

Prepared for:

Strathcona County

370 Streambank Avenue

Sherwood Park, AB T8H 1N1

Prepared by:

Stantec Consulting Ltd.

10160 – 112 Street

Edmonton, AB T5K 2L6

Project No. 1101 21016

May 26, 2015

Enclosure 2

Sign-off Sheet

This document entitled Strathcona County Water and Wastewater Design Standards Review was prepared by Stantec Consulting Ltd. for the account of Strathcona County. The material in it reflects Stantec's best judgment in light of the information available to it at the time of preparation. Any use which a third party makes of this report, or any reliance on or decisions made based on it, are the responsibilities of such third parties. Stantec Consulting Ltd. accepts no responsibility for damages, if any, suffered by any third party as a result of decisions made or actions based on this report .

Co-Author: Andreea lrimia, EIT

PERMIT TO PRACTICE STANTEC Y'?Nf'YL TING LTD.

Sig nature JY. M --.... Date i.:1 VY\ vx j 1. 0 l -.;-

• PERMIT NUMBER: P 0258

The Association of Professional Engineers, Geologists and Geophysicists of Alberta

Corporate Permit

(j Stantec

Co-Author: Faruk Kharadi, P.Eng.

Reviewed by: David Krywiak, P. Eng.

STRATHCONA COUNTY

WATER AND WASTEWATER DESIGN STANDARDS REVIEW

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Table of Contents

EXECUTIVE SUMMARY .............................................................................................................. 1

1.0 INTRODUCTION ...........................................................................................................1.1

1.1 REPORT SCOPE ............................................................................................................... 1.1

1.2 METHODOLOGY ............................................................................................................. 1.1

2.0 WATER DISTRIBUTION SYSTEM .....................................................................................2.1

2.1 SYSTEM OPERATING PRESSURES .................................................................................... 2.2 2.1.1 Summary and Recommendation ............................................................. 2.4

2.2 DESIGN WATER CONSUMPTION ................................................................................... 2.4 2.2.1 Water Billing Records ................................................................................... 2.4 2.2.2 Variation in Consumption Based on Neighbourhood Age ................... 2.9 2.2.3 Residential Water Consumption Statistics .............................................. 2.12 2.2.4 Non-Residential Consumption ................................................................. 2.13 2.2.5 Water Consumption Rate Comparison with Other Municipalities ..... 2.14 2.2.6 Summary and Recommendation ........................................................... 2.15

2.3 FIRE FLOW REQUIREMENTS .......................................................................................... 2.16 2.3.1 Summary and Recommendation ........................................................... 2.18

2.4 DISTRIBUTION SYSTEM ................................................................................................... 2.18 2.4.1 Horizontal and Vertical Alignment Requirements ................................. 2.18 2.4.2 Minimum Pipe Sizes .................................................................................... 2.20 2.4.3 Summary and Recommendation ........................................................... 2.21

2.5 HYDRANTS SPACING .................................................................................................... 2.21 2.5.1 Summary and Recommendation ........................................................... 2.22

2.6 SERVICE CONNECTIONS ............................................................................................. 2.22 2.6.1 Summary and Recommendation ........................................................... 2.22

3.0 SANITARY SEWER SYSTEM............................................................................................3.1

3.1 SANITARY SEWAGE GENERATION RATES ..................................................................... 3.2 3.1.1 Residential Sanitary Sewage Generation Rate ....................................... 3.2 3.1.2 Commercial/Industrial/Institutional Sewage Generation Rate ............ 3.7 3.1.3 Population Density ....................................................................................... 3.9 3.1.4 Summary and Recommendation ........................................................... 3.11

3.2 INFLOW AND INFILTRATION ......................................................................................... 3.12 3.2.1 Model Calibration ..................................................................................... 3.13 3.2.2 Simulated Inflow and Infiltration .............................................................. 3.14 3.2.3 Extraneous Flow Allowances by Adjacent Municipalities .................... 3.17 3.2.4 Summary and Recommendation ........................................................... 3.17

3.3 MINIMUM SANITARY SEWER SIZE ................................................................................. 3.18 3.3.1 Summary and Recommendation ........................................................... 3.19

3.4 SANITARY SEWER SLOPE REQUIREMENTS ................................................................... 3.19 3.4.1 Summary and Recommendation ........................................................... 3.21

3.5 SANITARY SEWER ALIGNMENT AND LOCATION ....................................................... 3.21

STRATHCONA COUNTY


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3.5.1 Summary and Recommendation ........................................................... 3.23

3.6 SANITARY MANHOLES .................................................................................................. 3.23 3.6.1 Summary and Recommendation ........................................................... 3.25

3.7 SANITARY SERVICE CONNECTIONS ............................................................................ 3.25 3.7.1 Summary and Recommendation ........................................................... 3.26

4.0 SUMMARY OF RECOMMENDATIONS ..........................................................................4.1

LIST OF TABLES

Table ES.1 – Summary of Water Distribution System Design Standards Review ............... ES.2

Table ES.2 – Summary of Sanitary Sewer System Design Standards Review .................... ES.3

Table 2.1 – Summary of Water System Operation Parameters ........................................... 2.2

Table 2.2 - Residential Annual Average Water Consumption Rates - Method 1 ............. 2.5

Table 2.3 - Residential Average Water Consumption Rates - Method 2 ........................... 2.5

Table 2.4 - Residential Monthly Water Consumption Rates ................................................. 2.6

Table 2.5 - Mean Temperature at the Edmonton International Airport ............................. 2.7

Table 2.6 - Total Precipitation at Edmonton International Airport ...................................... 2.8

Table 2.7 - Residential Density ................................................................................................ 2.10

Table 2.8 - Residential Average Water Consumption Rates in Older Neighbourhoods 2.11

Table 2.9 - Residential Average Water Consumption Rates in New Neighbourhoods . 2.11

Table 2.10 - Non-Residential Water Consumption Rates in 2012 ...................................... 2.13

Table 2.11 – Water Consumption Rates Used by Other Municipalities ............................ 2.14

Table 2.12 - Summary of Residential Water Consumption Rates ...................................... 2.15

Table 2.13 - Fire Flow Requirements in Adjacent Municipalities........................................ 2.17

Table 2.14 - Summary of Water Main Clearance Requirements ...................................... 2.18

Table 2.15 – Minimum Pipe Sizing Requirements ................................................................. 2.20

Table 2.16 - Maximum Allowable Fire Hydrant Spacing .................................................... 2.21

Table 2.17 - Service Connection Requirements in Adjacent Municipalities ................... 2.22

Table 3.1 – Average Wastewater Generation Based on Flow Monitored Data............... 3.4

Table 3.2 - Residential Average Dry Weather Flow ............................................................... 3.6

Table 3.3 - Commercial/Industrial/Institutional Wastewater Generation .......................... 3.8

Table 3.4 - Sherwood Park Population .................................................................................... 3.9

Table 3.5 - Sherwood Park Population Density Based on Water Billing Accounts ............ 3.9

Table 3.6 - Summary of Regional Municipality Servicing Standards ................................. 3.10

STRATHCONA COUNTY


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Table 3.7 - Summary of Residential Sewage Generation Rate ......................................... 3.11

Table 3.8 - Simulated I/I Rates ................................................................................................ 3.15

Table 3.9 - Extraneous Flow Allowances by Adjacent Municipalities ............................... 3.17

Table 3.10 – Sanitary Sewer Size Design Parameters .......................................................... 3.18

Table 3.11 – Sanitary Sewer Required Velocities and Slopes ............................................ 3.20

Table 3.12 – Sanitary Pipe Alignment and Location ........................................................... 3.21

Table 3.13 - Manhole Design Requirements ........................................................................ 3.23

Table 3.14 - Service Connections Design Requirements .................................................... 3.25

LIST OF FIGURES

Figure 3.1 – Wastewater System – Flow Monitoring Location .................. Following Page 3.3

STRATHCONA COUNTY


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Executive Summary

Stantec Consulting Ltd. (Stantec) was retained by Strathcona County (County) to conduct a

review of the County’s water and wastewater design standards for the urban service areas.

The design of water distribution and wastewater collection systems depend on a number of

factors including land uses, population densities, water consumption and sewage generation

rates, service area topography, etc. To provide minimum servicing requirements and to

streamline the design process, each municipality develops a set of design standards based on

historical system performance from servicing s and operation and maintenance perspectives,

risk tolerance and economic factors. With changing trends in the existing system performances,

the County has retained Stantec to perform a science-based review of the current standards,

focusing on Section 4.2.1 (Sanitary Sewer System – System Design) and Section 4.3.1 (Water

Distribution System - System Design) of the Design and Construction Standards, Volume 1

(Strathcona County; December 2011). The review includes a comparison of current standards for

surrounding municipalities.

Water Distribution System Design Standards

One of the key elements in the sizing of water distribution system is water consumption rates.

Water consumption rates include two types of demands: domestic water demand on a daily

basis, and fire flow demand on an occasional emergency situation.

In order to determine the current domestic water consumption rates in the County’s urban

service area, Stantec reviewed water billing records for 2010, 2011 and 2012. The review of the

water billing records examined the variation in consumption rates based on neighbourhood age

and climate data to assess the effect of temperature and precipitation. The water consumption

records were then compared with the County’s current standards and with the standards of the

adjacent municipalities.

Along with the water consumption rates, other design parameters were reviewed and

compared with adjacent municipalities’ standards. Based on these reviews, Table ES.1 provides

a summary of the findings along with recommendations for change where it was deemed

appropriate.

STRATHCONA COUNTY



Table ES.1 – Summary of Water Distribution System Design Standards Review

Design

Parameter Current Standard

Recommended Change

in Standard Justification

Normal

Operating

Pressure Range

350 kPa - 700 kPa

Keep operating pressure

range to 350 kPa - 700 kPa

within distribution system.

Add a requirement for a

maximum pressure control to

550 kPa for water services.

Problems with high pressure

related leakages have not been

widely reported in the County.

However as system ages, the risk

of leakage will increase. Also, the

National Plumbing Code of

Canada specifies that residual

pressures in occupied areas shall

not exceed 550 kPa.

Residential

Water

Consumption

Rate

375 L/person/day

330 L/person/day based on:

15% leakage allowance to

the actual water billing

record.

Design safety factor of 1.5

to account for variability in

consumption rates within

the system.

The actual consumption rate is

200 L/person/day. There is an

overall trend indicating decline in

water consumption rate due to

more efficient fixtures and cost

factors. The proposed water

consumption rate should be

further reviewed after 5 years to

determine if further reduction is

necessary.

Non-Residential

Water

Consumption

Rate

Case-by-case

20,000 L/ha/day for average

day demand for planning

purposes.

The recommendation for

specifying a consumption rate is

based on review of other

municipalities. The

recommended rate is based on

County’s wastewater generation

rate with approximately 10%

allowance to account for water

that is consumed but not

returned into the sewer system.

Fire Flow

Requirements

Low density

residential: as per

Fire Underwriters

document.

High value

properties: 250 L/s.

Low density residential: as per

Fire Underwriters document.

High value properties: 250 L/s

Include a definition for high

value properties: commercial,

institutional, industrial sites and

apartment buildings.

Design standards are reasonable

based on comparison with other

municipalities.

Distribution

System Sizing

and Alignment

Varies

All design standards pertaining

to the distribution system sizing

and alignment to remain as

per the current County

standards.

Design standards are

reasonable. There is insufficient

information available to propose

any changes at this time.

STRATHCONA COUNTY



Design

Parameter Current Standard

Recommended Change


Hydrant

Spacing

Single Family:

150 m

Multi- Family: 90 m

Non-Residential:

90 m

County Specifications with

reference to hydrant spacing

to remain unchanged.

The hydrant spacing

requirements are reasonable

based on comparison with other

municipalities.

Service

Connections

20 mm if length of

the service is less

than 20 m

25 mm if length of

the service is

greater than 20 m

The minimum diameter of the

water service to remain

unchanged for the single

family residential properties.

The current specifications are

reasonable and in agreement

with the standards used by other

municipalities

Sanitary Sewer System Design Standards

For wastewater collection system design standards review, the available flow monitoring data

from 2010 to 2012 were reviewed to determine average sewage generation rates, peaking

factors, and inflow/infiltration rates. Other sanitary sewer system sizing related parameters, i.e.

minimum pipe diameter, required sewer capacity, minimum slope etc. were also reviewed

based on practices by other municipalities. Based on these reviews, Table ES.2 provides a

summary of the findings along with recommendations for change where it was deemed

appropriate.

Table ES.2 – Summary of Sanitary Sewer System Design Standards Review

Design

Parameter Current Standards

Recommended Change


Residential

Sewage

Generation

Rate

375 L/person/day 300 L/person/day

The reduction is to account for

trend in lower water consumption

rate and therefore in sewage

generation rate.

Non-Residential

Sewage

Generation

Rate

18,000 L/ha/day 18,000 L/ha/day No change.

Peaking Factor

Residential:

Greater of 3 or

1 +14

(4 + P0.5)

Non-Residential:

Consider on an

individual basis

Residential:

Greater of 3 or

1 +14

(4 + P0.5)

Non-Residential:

P = 10 ∗ Q−0.45

(min. 2.5; max. 25)

Residential

No change

Non-Residential:

Need to provide guidance for

consistency

STRATHCONA COUNTY



Design

Parameter Current Standards

Recommended Change


Population

Density 3.5 people/unit

3.5 people/unit for low

density residential

2.5 people/unit for multi-

family residential

The design population density

accounts for demographic

variation over a long period of time

due to varying economic and

social factors.

Inflow/

Infiltration

Extraneous flow

allowance: 0.5 L/s/ha

Sag manhole flow

allowance: 0.4 L/s/MH

Extraneous flow allowance:

0.4 L/s/ha

Sag manhole flow

allowance: 0.4 L/s/MH

Reduction in extraneous flow is

proposed based on

observed/modeled values for new

service areas. For older service

area, the observed/modeled

values are significantly higher. The

I/I rates needs to be monitored and

reviewed on an ongoing basis and

adjust design allowance, if

necessary.

Pipe Sizing

Minimum pipe size:

200 mm

(residential)

250 mm (non-

residential)

Capacity:

𝐸𝑠𝑡𝑖𝑚𝑎𝑡𝑒𝑑 𝐷𝑒𝑠𝑖𝑔𝑛 𝐹𝑙𝑜𝑤

0.86

Minimum pipe size:

200 mm

(residential)

250 mm (non-

residential)

Capacity:


0.86

To minimize the high social and

financial risk of undersized

wastewater mains, it is

recommended that the sewer

mains in Strathcona County

continue to be designed to carry

the design flow at a flow depth of

80% of the sewer diameter.

Pipe Slope

Varies based on

diameter,

Flow velocity:

0.6 m/s (min)

3.0 m/s (max)

All sewer system

configuration design

standards to remain as per

the current County

standards

The current specifications are

reasonable and in agreement with

the standards for other adjacent

municipalities.

If the County wishes to specify a

minimum vertical separation for

watermains crossing above the

sewer pipe, it is recommended that

a minimum of 300 mm of

separation is used to allow for

adequate bedding.

Sewer Main

Alignments

Minimum depth of

cover: 2.6 to obvert

Manholes

Maximum spacing:

150 m

Drops though straight

run sewers: 12 mm

Drops through sewers

that change

directions: 50 mm

Service

Connection

Minimum size

required: 150 mm

Minimum grade: 2%

Minimum depth of

cover: 2.6 m.

STRATHCONA COUNTY


Introduction

May 26, 2015

1.1

1.0 Introduction

Engineering design standards are known to change periodically in light of new technologies,

change in social trends, change in climate factors and system performance observations.

Stantec Consulting Ltd. (Stantec) was retained by the Strathcona County to conduct a review of

the County’s water and wastewater design standards as it pertains to servicing urban areas and

to provide recommendations as applicable for the updating of the current design standards.

The focus of this report is on Section 4.2.1 and Section 4.3.1 of the Design and Construction

Standards, Volume 1 (Strathcona County; December 2011).

1.1 REPORT SCOPE

The study scope for the review of the County’s design standards for water and wastewater

servicing in the urban servicing area includes:

Project management services

Collection and review of existing, applicable information (i.e. reports, water billing

records, reservoir supply rates, wastewater flow monitoring records, etc.)

Research of industry trends with respect to design standards and practices for water and

wastewater systems as they pertain to urban service areas

Comparison of design standards and practices for urban water and wastewater systems

utilized by selected municipalities in Alberta

Document findings of the above

1.2 METHODOLOGY

The methodology for the review of the County’s standards consisted of the following sequence

of tasks:

Reviewed Sections 4.2.1 and 4.3.1 of the Design and Construction Standards, Volume 1

(Strathcona County; December 2011).

Reviewed and compared numerous other design standards and practices for

surrounding municipalities as well as Alberta Environment and Sustainable Resource

Development (AESRD) Standards and Guidelines for Municipal Waterworks, Wastewater

and Storm Drainage Systems.

Reviewed last three years of monthly water billing records within the Urban Services Area

and computed the average and maximum water consumption rates for existing County

residential and non-residential service areas. Assessed variations in consumption rates

STRATHCONA COUNTY


Introduction

May 26, 2015

1.2

between older and newer service areas to identify effect of new fixture efficiencies,

population demographic trends, and home sizes.

Reviewed available rainfall and sanitary sewer flow monitoring records for last three

years to determine the residential and non-residential wastewater flow generation rates;

peaking factors and inflow/infiltration rates.

STRATHCONA COUNTY


Water Distribution System

May 26, 2015

2.1

2.0 Water Distribution System

The design of water distribution systems depends on a variety of factors including, land uses,

population densities, water consumption rates, fire flow requirements and topography of the

serviced area, among other factors. To provide minimum servicing requirements and to

streamline the design process, each municipality develops a set of design standards based on

historical system performances, risk tolerance and economic factors.

According to the Potable Water Regulation (277/2003), Strathcona County is required to meet,

as a minimum, the performance standards and design requirements set out in the Standards

and Guidelines for Municipal Waterworks, Wastewater and Storm Drainage Systems, published

by AESRD.

The water distribution system design standards for the Strathcona County have been provided in

Section 4.3.1 of the Design and Construction Standards. This section of the design standards

provides design parameters such as water consumption rates, normal operating pressure range,

fire flow requirements, etc. These standards were reviewed and compared with the recent

water consumption data as well as standards used by other adjacent municipalities. The

recommendations based on this review process for the water distribution system design

parameters are provided in this section.

The key design parameters included in Section 4.3.1 and reviewed as part of this study are as

follows:

Normal operating pressures

Water consumption rates

Normal operating velocities

Fire flow requirements

Minimum pipe sizes

Minimum depth of cover

Minimum vertical and horizontal separation distance between water mains and sewers

Maximum spacing of hydrants

Water services

The review of each of the above parameter is discussed in subsequent sections.

STRATHCONA COUNTY



May 26, 2015

2.2

2.1 SYSTEM OPERATING PRESSURES

Section 4.3.1 of the Design and Construction Standards, Volume 1 (Strathcona County;

December 2011), lists the normal operating pressures range for the water distribution system as:

Operating pressure: between 350 kPa and 700 kPa

Maximum velocity: 3 m/s

Minimum residual peak hour pressure: 350 kPa at ground level at any node in the system

Minimum residual pressure during fire flow: 140 kPa at ground level at any node in the

system

The AESRD standards require the minimum pressure to be 150 kPa at the property line during

peak demand design flow. The guidelines indicate the water distribution system should be

designed to handle a normal operating pressure between 350 kPa and 550 kPa under a

condition of maximum hourly design flow and distribution system pressures above 550 kPa should

be reviewed against the Canadian Plumbing code to determine specific building/household

requirements to avoid damage to internal building/household piping.

Table 2.1 lists the design pressure requirements and velocities in the system for various

surrounding municipalities. The municipalities in Table 2.1 were chosen based on two factors: the

proximity to Strathcona County and the availability of urban design and construction standards.

Table 2.1 – Summary of Water System Operation Parameters

Municipality

Minimum Peak

Hour Pressure

(kPa)

Maximum

Allowable

Pressure (kPa)

Minimum

Pressure in

MDD + Fire

Flow (kPa)

Normal

Operating

Pressure

Range (kPa)

Velocity (m/s)

Strathcona

County 350 700 140 350-700 3

City of St. Albert 280 700 140 350-700 3

City of Leduc 280 - 140 - 3

City of Fort

Saskatchewan 275 - 140 - 3

City of Edmonton 280 550 140 - 3

City of Red Deer 300 - 150 - 1.5 (PHD)

2.5 (MDD+FF)

Table 2.1 indicates that most of the other municipalities do not specify the preferred normal

operating pressure range (NOPR). Strathcona County and City of St. Albert do specify the NOPR

in the design standards, and the NOPRs are the similar for both municipalities. A low pressure in

the water distribution system is set to provide sufficient pressure to operate fixtures without the

STRATHCONA COUNTY



May 26, 2015

2.3

aid of pumping in common height properties, as well as for the operation of automatic sprinkler

systems. A high pressure system can increase the possibility of wastage in tap flow and increase

the likeliness of minor leaks in plumbing. The upper limit of the NOPR must be much lower than

the rating of the pipe, however sufficiently high to minimize the potential for inflow of

contaminants in a distribution system in case of a watermain break as well as to reduce number

of pressure zones for simplifying operation of the distribution system. Specifying ranges for NOPR

ensures that the system works effectively.

Other jurisdictions in Canada recommend NOPR upper limits that are less than 700 kPa –

including the Ministry of Environment in Ontario (480 kPa), the City of Ottawa (550 kPa), and the

City of Toronto (550 kPa).

The National Plumbing Code of Canada specifies that residual pressures in occupied areas shall

not exceed 550 kPa.

The County’s current normal operating range appears reasonable since problems with high

pressures and leakages have not been widely reported; however it is recommended that the

requirement for pressure control measures be added to the County’s specifications for areas

with pressures between 550 kPa and 700 kPa to reduce the risks associated with high pressures.

Pressure control measures to be considered are as follows in order of preference:

If possible, systems to be designed to residual pressures of 350 to 550 kPa in all occupied

areas outside of the public right-of-way without special pressure control equipment.

If the above is not possible then the next preferred measure is a pressure reducing valve,

as a central unit, to be located in a chamber or vault.

As a last resort, pressure reducing valves to be installed immediately downstream of the

isolation valve in the home/building, located downstream of the meter so it is owner

maintained.

The minimum residual pressure in the system in case of a fire flow situation is consistent among

every municipality in Table 2.1. This minimum residual pressure assures that in the case of a fire

emergency, the system can still supply water with a reasonable pressure required for routine

uses.

The maximum velocity of water in a distribution system is consistent among most municipalities

with the exception of the City of Red Deer. A maximum flow velocity is set to minimize damage

to pipes and fittings during transient conditions. Based on the desktop review, the maximum

velocity of 3 m/s is considered reasonable.

STRATHCONA COUNTY



May 26, 2015

2.4

2.1.1 Summary and Recommendation

Based on the discussion above, it is recommended that the water distribution system operating

pressure range should remain same as currently listed in the County Standards with the addition

of a requirement for pressure control measures where the system pressure is between 550 kPa

and 700 kPa.

2.2 DESIGN WATER CONSUMPTION

Section 4.3.1 of the Design and Construction Standards, Volume 1 (Strathcona County;

December 2011) lists the water consumption used to design the water network as follows:

Average Day Demand: 375 L/person/day

Maximum Day Demand: 750 L/person/day

Peak Hour Demand: 1,125 L/person/day

The County Standards currently do not state a consumption rate for non-residential (i.e.,

commercial, industrial, or institutional) service area.

With the above water consumption rates, for computing the water demands, an estimate of

population is required for a given residential service area. Population estimates could be

determined based on a lot count and population per unit or an average density per unit area.

The County standards currently do not specify population densities for different types of

residential units. The current County practice is to use the ultimate design population estimate

for the area based on planning documents. Other municipalities specify average population

densities to be used based on unit type. Both methods are considered to be reasonable, and

therefore it is recommended that the County keep the method for estimating population as is.

Further analysis could be done in future if differences in opinion/requirements arise.

To determine whether the current design consumption rates are reasonable, water billing

records provided by the County within Sherwood Park for the last three years were reviewed.

The design standards of other municipalities were also reviewed and compared to the County’s

standards. In addition, two statistical reports that were readily available were reviewed for

overall water consumption trends. The findings are presented in the subsequent sections.

2.2.1 Water Billing Records

The residential monthly water billing records provided by the County from 2010 to 2012 were

reviewed and analyzed to determine actual consumption rates. The residential average water

consumption rates were computed using the following two methods:

Method 1: Total annual residential water consumption divided by the total population

according to the census data.

STRATHCONA COUNTY



May 26, 2015

2.5

Method 2: Total monthly consumption divided by the number of accounts and

converted to average liters/account/day. The per capita consumption rates

(liters/capita/day) were computed based on a population density of 3 people/unit for

low density residential and 2.2 people/unit for apartment units for each month and then

averaged over each year.

The results are summarized in Tables 2.2 and 2.3.

Table 2.2 - Residential Annual Average Water Consumption Rates - Method 1

Year Annual Average Day Demand (L/cap/day)

2010 194

2011 194

2012 184

Table 2.3 - Residential Average Water Consumption Rates - Method 2

Year Average Day Demand

Low Density Residential (L/cap/day)

Average Day Demand

Apartment Units Residential (L/cap/day)

2010 198 191

2011 193 189

2012 184 188

Based on the information presented in Tables 2.2 and 2.3, the average consumption rate is

approximately 200 L/cap/day.

Table 2.4 presents a graphical illustration of the monthly residential water consumption rates

based on the customer group. Based on the information presented in Table 2.4, the largest

monthly average consumption for the low residential development was in June 2010 and was

computed to be 299 L/cap/day. The largest monthly average consumption for the apartment

units was also in June 2010, and was computed to be 276 L/cap/day.

STRATHCONA COUNTY



May 26, 2015

2.6

Table 2.4 - Residential Monthly Water Consumption Rates

Residential Water Consumption

for Customer Group 1 (Residential)

Residential Water Consumption

for Customer Group 1b & 1c (Residential Condo)

2.2.1.1 Climate Factors

To determine whether the lower water consumption rates can be attributed in part to climate

factors, the climate data for 2010 to 2012 were obtained from Environment Canada. The climate

data used in this study was recorded at the Edmonton International Airport location. Although

there are stations that are closer to Strathcona County, most of these stations do not have

complete set of metrological data.

TEMPERATURE FACTORS

Table 2.5 summarizes on the mean monthly temperatures for 2010 to 2012. The normal

temperatures averaged over a period of 30 years were also provided for comparison purposes.

0

50

100

150

200

250

300

350

1 2 3 4 5 6 7 8 9 10 11 12

L/c

apita/d

ay @

3ppl/account

Month

2010

2011

2012

0

50

100

150

200

250

300

350

1 2 3 4 5 6 7 8 9 10 11 12

L/c

apita/d

ay @

3ppl/account

Month

2010

2011

2012

STRATHCONA COUNTY



May 26, 2015

2.7

Table 2.5 - Mean Temperature at the Edmonton International Airport

Month Year Average

(1981-2010) Graph

2010 2011 2012

January -12.1 ºC -13.1 ºC -9.3 ºC -12.05

February -9.1 ºC -13.9 ºC -8.3 ºC -9.85

March -0.9 ºC -10.6 ºC -2.4 ºC -4.42

April 5.6 ºC 1.2 ºC 3.7 ºC 4.17

May 8.1 ºC 11.2 ºC 9.6 ºC 10.22

June 13.9 ºC 13.6 ºC 14.2 ºC 14.14

July 15.6 ºC 15.3 ºC 17.6 ºC 16.2

August 14.4 ºC 14.6 ºC 16.1 ºC 15.15

September 8.2 ºC 11.9 ºC 12 ºC 10.23

October 5.8 ºC 4.1 ºC 0.6 ºC 3.78

November -7 ºC -6.3 ºC -8.4 ºC -5.36

December -15.3 ºC -5.6 ºC -16.5 ºC -11.02

The observations of the mean monthly temperature versus the monthly average water

consumption rates are as follows for the past three years:

Year 2010 - The monthly temperatures recorded in 2010 are similar to the average monthly

temperatures recorded over the 30 year period. The higher average water consumption

recorded in June and September of 2010 cannot be directly attributed to high temperatures

based on the above information.

Year 2011 - Year 2011 exhibit slightly lower temperatures than normal in the first part of the

year, and slightly higher temperatures than normal in the last month of the year. The summer

temperatures are also slightly lower than normal. The data provided in Table 2.4 indicate the

highest residential water consumption rate was recorded in June. The average temperature

recorded in June 2011 was slightly lower than the normal for the month. Hence, the higher

water consumption recorded in June cannot be directly correlated to temperature data.

Year 2012 - Compared to the average monthly temperatures recorded over the 30 year

period, the monthly temperatures recorded in 2012 are higher in the beginning of the year

and also during summer. Later month of the year were significantly colder. The highest water

consumption recorded in this year was in the month of August. The month of August had a

slightly higher average temperature than the previous years and the average for the 30 year

period, which could have contributed to higher water usage. Based on the information

provided in Table 2.4, the water consumption in the month of June was significantly lower

than in the previous two years. Therefore there is no direct correlation with temperatures for

-20

-15

-10

-5

0

5

10

15

20

Te

mpera

ture

(D

egre

e C

els

ius)

2010

2011

2012

Normals

STRATHCONA COUNTY



May 26, 2015

2.8

the month of June as the temperature data indicates marginally higher average

temperatures in June 2012.

Based on the temperature data presented in Table 2.5, the significant decrease in average

water consumption rates from 2010 to 2012 cannot be attributed to extreme temperature

variation as there was no significant difference in temperatures between 2010 and 2012.

PRECIPITATION FACTORS

Table 2.6 summarizes the monthly total precipitation data recorded at the Edmonton

International Airport for 2010 to 2012. In addition, the average monthly precipitation computed

over a 30 year period is also summarized for comparison purposes.

Table 2.6 - Total Precipitation at Edmonton International Airport

Month

Year

(Precipitation in mm) Average

mm

(1981-2010)

Graph

2010 2011 2012

January 8.6 58.7 2.6 20.79

February 1.2 20.6 4 11.89

March 4.2 16.8 6.6 16.47

April 41 19.2 44.7 28.67

May 105.9 15.6 34.4 49.39

June 79.4 123.4 69.8 72.65

July 146.7 150.2 72.6 95.56

August 38.8 10.8 73.4 54.91

September 40.5 5.2 21 41.34

October 7.8 8.8 19.1 22.62

November 15.8 22 17.2 17.34

December 21.1 10 14.2 14.45

Total Yearly 511 461 380 446

The observations of the monthly precipitation versus the monthly average water consumption

rates are as follows for the past three years:

Year 2010 – The data in Table 2.6 indicates that in 2010, there was approximately 15% more

precipitation than the average yearly precipitation computed over 30 years. The month of

May experienced more than twice the precipitation than normal for this month. As indicated

in Table 2.4, the average residential water consumption in May was lower than in 2011 and

2012 which could be correlated with a wetter month requiring less lawn watering. The month

0

20

40

60

80

100

120

140

160

To

tal

Mo

nth

ly P

recip

itati

on

(m

m)

2010

2011

2012

Normals

STRATHCONA COUNTY



May 26, 2015

2.9

of June had average precipitation; however the average low density residential water

consumption rate reached 300 L/cap/d. The high water consumption rate for June cannot

be directly correlated to precipitation.

Year 2011 - The total annual precipitation in 2011 is very close to the yearly normal; however,

approximately 60% of the precipitation occurred during June and July. While May, August

and September were abnormally dry. The highest water consumption in 2011 was in June

which cannot be directly correlated to lawn watering as the amount of precipitation during

this month was significantly high.

Year 2012 – 2012 was a dry year. In 2012, the highest residential water consumption was

recorded in February, May and August. Table 2.6 indicates that there was very low

precipitation during winter months as well as during May which may indicate a correlation

between the water consumption data and the precipitation data.

Based on the above review of the temperature and precipitation records, it is difficult to

determine direct correlation with water consumption rates from monthly recorded data. The

lawn watering and other outdoor water usage activities are highly dependent on daily climate

variations as well as seasonal factors. Generally May and early parts of June are dry and the

temperatures start to be warm enough for the outdoor water usage activities. July and August

are relatively wet and the lawn watering is reduced during these months and then it appears to

pick up in September when rainfall amount is reduced while the temperatures are still warm. This

general trend does seem to exist although the trend towards reduced consumption appears to

be taking hold due to environmental and cost considerations will need to be monitored on an

ongoing basis and should be evaluated based on daily County water consumption and climate

records. The monthly record tends to average out consumption and climate variation and

makes it difficult to discern implication on consumption rates. The precipitation distribution

pattern tends varies significantly from month to month and the consumption rates would vary

accordingly in response to climate factors.

2.2.2 Variation in Consumption Based on Neighbourhood Age

The data provided by the County were analyzed to identify whether there is any significant

variation in residential water consumption between older neighborhoods and newer

neighborhoods. The information on older neighborhoods was provided by the County and was

defined as being greater than 25 years of age. ‘Newer neighborhoods’ are defined by County

as those constructed in the past 10 years.

The new and old areas used in this analysis were identified by the County and listed below:

Older Areas (25 years+):

Residential Neighborhoods: Millshaven, Sherwood Heights, Glen Allan

STRATHCONA COUNTY



May 26, 2015

2.10

Newer Areas (< 10 years):

Residential Neighborhoods: Aspen Trails, Emerald Hills, Summerwood, Foxboro, The Ridge

The annual average residential consumption was computed based on the available

consumption information for each account in the neighbourhood indicated above. The

following steps were followed in computing the annual average consumption rates:

The water consumption for all accounts was added for each year and then divided by

the number of accounts to obtain an average demand per account.

The average demand per account was then divided by the residential population

density in each neighbourhood to determine the average daily water consumption rate

per capita. The population density obtained through the 2009 census was used in

computing the 2010 water consumption rates, the population density computed from

the 2012 census data was used in computing the 2012 water consumption rates and an

average density of these two values were used to compute the 2011 water consumption

rates.

Table 2.7 indicates the calculated densities for each neighbourhood as per the 2009 census

information and as per 2012 census information. The average calculated density is less than 3

people per dwelling in all cases.

Table 2.7 - Residential Density

Neighbourhood

Densities Based on 2009 Census Densities Based on 2012 Census

Population Number

Dwellings Density Population

Number of

Dwellings Density

Older Areas (25 years+)

Mills Haven 3272 1211 2.70 3272 1215 2.69

Sherwood Heights 2727 1073 2.54 2563 1007 2.55

Glen Allan 5044 1876 2.69 4912 1875 2.62

Average Density 2.64 2.62

Newer Areas (< 10 years)

Aspen Trails 647 256 2.53 2106 1075 1.96

Emerald Hills 657 256 2.57 2106 1075 1.96

Summerwood 2404 1118 2.15 3113 1127 2.76

Foxboro 2518 815 3.09 4124 1422 2.90

The Ridge** Not

Available

Not

Available 2.58

Not

Available

Not

Available 2.40

Average Density 2.58 2.40

Note: The population densities in The Ridge is an average of the population densities in Aspen Trails,

Emerald Hills, Summerwood and Foxboro

STRATHCONA COUNTY



May 26, 2015

2.11

Tables 2.8 and 2.9 summarizes the computed water consumption rates for older and newer

neighbourhoods, respectively.

The older neighbourhoods as indicated in Table 2.8 indicate a downward trend in in water

consumption rates. This downward trend could be primarily attributed to home improvements

resulting in more efficient fixtures and customers’ changing habits to conserve water due to cost

of water and corresponding wastewater services and possibly environmental consciousness due

to consumer education on the importance of water preservation.

Table 2.8 - Residential Average Water Consumption Rates in Older Neighbourhoods

Area L/capita/day Average

2010 2011 2012 L/capita/day

Mills Haven 213 205 195 204

Sherwood Heights 211 208 190 205

Glen Allan 202 193 182 197

Average 209 202 196 202

The consumption rates for newer neighbourhoods, presented in Table 2.9, indicate a relatively

constant water consumption rate. This trend may be due to the fact that the newer

neighbourhoods have been built with the latest fixtures and other factors (i.e., cost of water and

wastewater services and environmental consciousness) are not affecting the customer habits.

Table 2.9 - Residential Average Water Consumption Rates in New Neighbourhoods

Area L/capita/day Average

2010 2011 2012 L/capita/day

Aspen Trails 193 200 218 204

Emerald Hills 182 185 210 192

Summerwood 228 188 159 192

Foxboro 171 177 177 175

The Ridge** 209 213 218 211

Average 197 193 195 195

In general, the average water consumption rates indicated in Tables 2.8 and 2.9 indicates that

slightly higher consumption rate in the older neighbourhoods than in the newer neighbourhoods.

This is most likely due to newer neighbourhoods having more efficient fixtures than in the older

neighbourhoods. There are however cases where the average daily water consumption in older

neighbourhoods is less than in some of the new neighborhoods, i.e. Aspen Trails and Emerald Hills

having significantly higher consumption in 2012 than in Mills Haven, Sherwood Heights or Glen

Allen. This could be due to higher initial landscape watering requirements for newer properties.

STRATHCONA COUNTY



May 26, 2015

2.12

2.2.3 Residential Water Consumption Statistics

The 2011 Municipal Water Use report prepared by Environment Canada was reviewed in order

to gain a better understanding of current trends in residential water consumption. The Municipal

Water Use report provides information on overall water consumption trends in Canada.

In addition, the 2011 EPCOR Waterworks Statistics were reviewed to identify the overall regional

water consumption rates.

2011 MUNICIPAL WATER USE REPORT – ENVIRONMENT CANADA

This report is based on a survey sent out to all municipalities in Canada with a population greater

than 1,000 and to a sample of municipalities with population less than 1,000. The 2009 census

information was used to determine the population in each municipality.

Overall in Canada, 1,590 municipalities responded to this survey. Based on the survey

information, the 2009 Canadian average residential water use per person was 274 L/cap/day

versus 327 L/cap/day in 2006. These water consumption rates appear to include non-residential

consumption volume.

The drop in water consumption rate is attributed to various factors. Some of these factors

include: a potential increase in the sustainable use of water resources, lower temperatures in

June and July 2009 versus 2006 and higher rainfall in July and August, 2009 versus 2006. The

climatic factors could influence lawn watering and recreational usage in residential

neighborhoods.

The average leakage and system maintenance in Canada is higher in 2009 than in 2006. The

average leakage rate rose from 12.8% to 13.3%.

2011 EPCOR WATERWORKS STATISTICS

The EPCOR Waterworks Statistics are based on the EPCOR’s report to Alberta Environment and

are published on the EPCOR’s website. EPCOR served over 812,201 people in Edmonton and

approximately 347,668 people in the Capital Region in 2011.

In Edmonton, the average domestic day demand (includes residential and multi-residential) is

202 L/cap/day. Based on the three years of water consumption data that was analyzed as part

of this study, the annual average residential demand in Sherwood Park is consistent with the

EPCOR findings.

The average day demand in Edmonton including commercial sites is 311 L/cap/day.

STRATHCONA COUNTY



May 26, 2015

2.13

2.2.4 Non-Residential Consumption

Currently, the County standards do not indicate specific water consumption rate that could be

used to determine the water demand for a non-residential service area. The County standards

indicate that the consumption in a non-residential area should be considered on an individual

basis. There are municipalities that provide an average consumption rate in L/ha/day that can

be used based on zoning for sizing of the distribution system as specific land use information is

generally not available during a neighbourhood design stage.

A preliminary analysis was completed on water billing data provided by the County to

determine whether a typical consumption rate can be established based on customer land

parcel zoning. Table 2.10 summarizes the average daily consumption rates per hectare for

various zoning of non-residential customers in 2012. The consumption rates are summarized for

the following zonings:

C1 Community Commercial

C2 Arterial Commercial

C3 Highway Commercial

C4 Major Commercial

C5 Service Commercial

IH Heavy Industrial

IM Medium Industrial

ILT Light Industrial

DR Direct Control

Table 2.10 - Non-Residential Water Consumption Rates in 2012

Month Consumption Rates (L/ha/day)

C1 C2 C3 C4 C5 DC1 IH ILT IM

Jan-12 8,413 4,072 10,031 14,087 4,294 4,964 2,039 1,626 3,086

Feb-12 7,193 5,516 18,794 9,559 2,982 4,259 249 1,046 1,500

Mar-12 6,178 5,190 25,463 15,184 3,530 3,784 266 1,853 1,265

Apr-12 5,977 4,082 14,671 7,696 2,305 3,321 517 859 1,008

May-12 7,888 5,208 - 15,953 3,262 4,536 294 1,210 1,619

Jun-12 5,583 5,624 20,811 11,915 3,528 3,595 302 1,328 1,693

Jul-12 6,829 6,542 12,886 11,393 3,295 4,210 334 6,314 2,045

Aug-12 3,733 6,997 23,149 14,822 4,215 5,205 381 2,193 2,193

Sep-12 5,452 6,088 6,140 11,352 3,182 3,924 675 1,250 1,858

STRATHCONA COUNTY



May 26, 2015

2.14

Month Consumption Rates (L/ha/day)

C1 C2 C3 C4 C5 DC1 IH ILT IM

Oct-12 4,792 5,377 15,047 11,080 2,823 4,098 566 1,550 1,481

Nov-12 4,001 4,955 3,349 9,437 2,461 1,871 696 2,031 1,265

Dec-12 2,778 4,490 11,729 8,554 2,249 2,206 505 1,399 1,474

Average 5,735 5,345 14,734 11,753 3,177 3,831 569 1,888 1,707

Table 2.10 does not include approximately 67,000 m3 of water as over 400 non-residential sites

could not be matched with the GIS data. In addition, the high water consumers have been

removed from the data set before computing averages as it significantly affected the average

consumption rates. It is recommended that the water consumption of high users be identified

separately at the planning level, i.e. for breweries or meat processing/packing plant, etc.

The information in Table 2.10 indicates that the water consumption varies significantly from one

non-residential site to another based on many factors such as type of development, time of the

year, economic factors, etc. There is no apparent pattern in non-residential development. It is

recommended that the standards continue to indicate that the consumption in a non-

residential area should be considered on an individual basis.

2.2.5 Water Consumption Rate Comparison with Other Municipalities

As part of this project, an urban servicing standards review of adjacent communities was

completed. Table 2.11 summarizes the water consumption rates utilized by the adjacent

municipalities.

Table 2.11 – Water Consumption Rates Used by Other Municipalities

Municipality Residential ADD

(L/cap/day)

Residential MDD

(L/cap/day)

Residential PHD

(L/cap/day)

Commercial

(L/ha/day)

Strathcona

County 375 750 1,125

Considered on an

individual basis

City of St. Albert 350 700 1,400 25,000

City of Leduc 360 720 1,440 22,500

City of Fort

Saskatchewan 360 720 1,080 N/A

City of Edmonton 250 425 750 N/A

City of Red Deer - 750 1,500 0.15 L/s/ha

Or 12,960 L/day/ha

STRATHCONA COUNTY



May 26, 2015

2.15

The review of the water consumption rates used by other adjacent municipalities indicates that

Strathcona County has the highest residential average day demand specified among the

regional municipalities. The City of Edmonton specifies the lowest residential water consumption

rate of 250 L/cap/day. The water consumption rates were recently reduced by the City in their

updated 2013 standards. The City previously had specified a residential MDD of 725 L/cap/day

and a PHD of 1,100 L/cap/day. In 2013, the City updated the water consumption rates and now

specifies the ADD, MDD and PHD as indicated in Table 2.11.


Based on the information presented in the above sections, Table 2.12 summarizes the various

residential water consumption rates.

Table 2.12 - Summary of Residential Water Consumption Rates

Current County Standard

ADD

Annual County ADD

Water Billing Data

Standard Review ADD

rates

Recommendation for

ADD

375 L/cap/day 200 L/cap/day 250 to 360 L/cap/day 330 L/cap/day

It is recommended that the existing 375 L/cap/day ADD be reduced to 330 L/cap/day. The

proposed reduction in the water consumption rate is justifiable due to a significantly lower

actual annual average consumption rate of 200 L/cap/day, an overall trend indicating

reduction in consumption rate due to more efficient fixtures and based on the standards review

of other municipalities. The proposed 330 L/cap/day is established based on the following:

15% leakage allowance to the actual billing record

Design safety factor of 1.5 to account for risk mitigation

The design safety factor primarily accounts for variation in monthly consumption rate such as

that noted for month of June in 2010 and 2011 where the average monthly consumption rates

were approximately 299 and 272 L/cap/day, respectively. The maximum average monthly

consumption for 2012 was in August at 225 L/cap/day.

The maximum day water consumption rate generally occurs during dry summer period and can

last from couple days to couple weeks. The maximum peak hour demands occur during these

maximum day demand period and system has to be designed to perform adequately. Daily

Countywide data would need to be established determine these parameters. In absence of

such data, it is recommended to maintain the current multiplier of 2.0 and 3.0 for maximum day

and peak hour demand conditions.

It should be noted that it is the maximum day demand period when the overall water distribution

is challenged. During such demand period water supply rate can be curtailed to the County

STRATHCONA COUNTY



May 26, 2015

2.16

due to high regional demand and making necessary to build adequate storage to meet high

demands requirement while reserving adequate fire supply storage to meet emergency

requirements. The distribution system and pumping system is utilized to maximum making

presenting danger for system failure especially during a fire flow situation making it necessary to

have some redundancy to maintain adequate level of service to customers.

The non-residential water consumption rates in Table 2.10 vary significantly from approximately

250 L/d/ha to 25,500 L/d/ha depending on the current site usage. As non-residential area zoning

permit verity of businesses on a given site, the actual usage is expected change and demand

will likely increase and sites that currently house low intensity development will eventually

increase in development intensity. Therefore, it is recommended that the commercial water

consumption is determined on a case-by-case basis as currently indicated in the County

standards. For planning purposes, it is recommended that an average day demand of 20,000

L/ha/day be used for non-residential developments. This is based on the County’s wastewater

generation date with a 10% allowance to account for water that is consumed and not returned

into the sewers. It is also suggested to the keep the peaking factors of 2.0 and 3.0 for maximum

day and peak hour demand conditions as per the current standards as there are no data to

support modification of these factors.

It is recommended that the proposed water consumption rates be reviewed after 5 years to

determine if further reduction is necessary. Future reduction should be considered carefully due

to a wide variety of factors which include demographic variations, climate fluctuations, cost of

water and wastewater treatment, and socio-economic variables which affect consumption

rates. The consumption rate review should also consider maximum monthly average as the 2010

to 2012 rates were fairly high over relatively extended period over the whole month.

2.3 FIRE FLOW REQUIREMENTS

Strathcona County currently requires fire flows to be determined as using the procedure outlined

in “Water Supply for Public Fire Protection, A Guide to Recommended Practice” published by

the Fire Underwriters Survey, the most recent version of which was published in 1999. AESRD

indicates that the provision of fire protection is solely the decision of the Local Authority. Based

on these requirements, each development must determine the fire flow requirements based on

proposed development.

For high value properties, the County standards specify a minimum fire flow rate of 15,000 liters

per minute (or 250 L/s) must be provided; high value properties include schools.

Table 2.13 summarizes the fire flow requirements by the adjacent municipalities.

STRATHCONA COUNTY



May 26, 2015

2.17

Table 2.13 - Fire Flow Requirements in Adjacent Municipalities

Municipality Fire Flow for Single Family

Residential

Fire Flow for Mid-Value,

Multi-Family Residential

Fire Flow for High Value

Properties

Strathcona County As per Fire Underwriters

document - 250 L/s

City of St. Albert As per Fire Underwriters

document -

As per Fire Underwriters

document

City of Leduc 115 L/s 227 L/s 227 L/s

City of Fort

Saskatchewan 76 L/s 114 - 227 L/s

Industrial: 227 L/s

Commercial: 265 L/s

City of Edmonton 100 L/s 180 L/s

High Value

Residential/High Value

Properties: 300 L/s

City of Red Deer

As per Fire Underwriters

document

Minimum: 75 L/s

In accordance with Fire

Flow Requirements set out

by the architect

In accordance with Fire

Flow Requirements set out

by the architect

A number of municipalities define the minimum fire flow requirements based on the type of

development such as single family residential, mid-value/multi-family residential, and high value

properties. The zonings are typically defined in the standards. The fire flow requirements for the

County are based on the Fire Underwriters document which requires details on the type of

development that is to be protected. Details such as zoning, type of house, type of roof used

and spacing between buildings may not be known until much later in the design process. It

would be useful for the county to have minimum fire flow requirements specified for three groups

of typical zonings, similar to that used by other municipalities. This would simplify planning of the

distribution system design at much earlier stage and the system would be designed based on

consistent parameters.

There are also alternative methods for fire flow calculations. These include:

National Building Code

ISO method

NFPA13 – sprinkler requirements

NFPA 1142 – Standard on Water Supplies for Suburban and Rural Fire Fighting

These standards were not reviewed in detailed for the purpose of this study; however, they have

been identified as potential references that may be used in future.

STRATHCONA COUNTY



May 26, 2015

2.18


To clarify the requirements for each type of zoning, it is recommended that the County

Standards keep specifying the use of “Water Supply for Public Fire Protection, A Guide to

Recommended Practice” by FUS for determining the fire flow requirements.

It is also recommended that the standards include a definition of high value properties to

include commercial, institutional, industrial land uses.

2.4 DISTRIBUTION SYSTEM

2.4.1 Horizontal and Vertical Alignment Requirements

Section 4.3.1 of the Design and Construction Standards lists the following horizontal and vertical

clearance requirements between water distribution system and sewer collection systems:

Minimum clearance of 1.5 m horizontally between water mains and any catch basins

(CBs) or storm manholes (MHs)

3 m separation distance between water and sanitary mains

Water mains must cross above sewers with sufficient separation to allow for proper

bedding

Where water mains cross below sewers, a vertical separation of at least 0.5 m from the

water main crown to the sewer invert is required, along with structural support of the

sewer to avoid joint deflection and settling, and a centering of the length of the water

main at the point of crossing so that the joints are equidistant from the sewer.

In addition, the minimum cover from finished grade to top of pipe is provided in the

Design and Construction Standards, Volume 1 as 2.75 m.

AESRD standards specify a minimum horizontal separation distance of 2.5 m between a

watermain and a storm or sanitary sewer or manhole. The vertical separation requirements are

the same, while the minimum frost cover requirement is set to 2.5 m above the crown. These

standards are considered to be similar to the County standards.

To determine whether these standards are adequate, a standard review of the adjacent

municipalities was completed and the findings are summarized in Table 2.14.

Table 2.14 - Summary of Water Main Clearance Requirements

Municipality Horizontal

Clearance

Vertical Clearance

when a Water Main

Crosses above a

Sewer

Vertical Clearance

when a Water Main

Crosses below a

Sewer (m)

Minimum

Depth of

Cover (m)

Strathcona 3 m – from sewer mains sufficient separation to 0.5 m 2.75

STRATHCONA COUNTY



May 26, 2015

2.19

Municipality Horizontal

Clearance

Vertical Clearance

when a Water Main

Crosses above a

Sewer

Vertical Clearance

when a Water Main

Crosses below a

Sewer (m)

Minimum

Depth of

Cover (m)

County 1.5 m – from CB and

MH

allow for proper

bedding

AESRD 2.5 m – from sewer

mains and MH

sufficient separation to

allow for proper

bedding

0.5 m 2.50

City of St.

Albert

3 m – from sewer mains

1.8 m – from gas lines

1.5 m – from CBs and

MHs

sufficient separation to

allow for proper

bedding

0.5 m 2.65

City of Leduc 3 m – from sewer mains - - 2.70

City of Fort

Saskatchewan

3 m – from any sewer

main 0.5 m 0.5 m 2.75

City of

Edmonton

Min 2.5 m from any

sewer main (3 m is

preferred)

0.3 m 0.5 m

Varies based

on diameter:

min 2.59 m

for 150 mm

City of Red

Deer 2.5 m in all instances - - 2.70

As indicated in Table 2.14, the horizontal clearance between water mains and sewer mains are

similar in all cases except for the City of Red Deer which meets the AESRD standards. For the

municipalities that provide a minimum requirement for a vertical clearance, it is, in every case

where a water main crosses below a sewer pipe, 0.5 m as measured between the nearest pipe

walls of the two sewer mains. This is to provide proper bedding and to minimize the risk of

contamination of water in case of a leak. The risk of contamination is minimized also by the

requirement for the centering of the water main length and supporting the wastewater main.

Based on this comparison of standards, the County’s design standards are reasonable.

The minimum depth of cover varies slightly from one municipality to another. Most of the above

mentioned municipalities have a standard minimum depth of cover between 2.65 m to 2.75 m,

all which meet the AESRD’s 2.5 m cover specification. The City of Edmonton standards provide

minimum depth of cover for most pipe diameters. The minimum depth of covers depends on

many factors such as the change in the frost line on a yearly basis in various areas, the soil

characteristics, and climate among other factors. Based on the standards review of surrounding

municipalities, the County’s minimum cover is reasonable.

STRATHCONA COUNTY



May 26, 2015

2.20

2.4.2 Minimum Pipe Sizes

All design standards for typically include minimum requirements for water sizing for the

distribution system. Table 2.15 provides a summary of minimum pipe size requirements for

Strathcona County and for other adjacent municipalities and AESRD.

Table 2.15 – Minimum Pipe Sizing Requirements

Municipality Residential Developments Commercial/Industrial Developments

Strathcona

County

150 mm – no hydrants

200 mm – with hydrants 300 mm

AESRD 150 mm -

City of St.

Albert 150 mm 300 mm

City of Leduc 150 mm – serving 12 lots

200 mm – serving > 12 lots. 250 mm

City of Fort

Saskatchewan

200 mm – single family residential

200 mm – multi-family residential 250 mm

City of

Edmonton

150 mm – no hydrants

200 mm – with hydrants -

City of Red

Deer 150 mm 200 mm

The minimum pipe sizing requirements are similar among the different municipalities. A minimum

pipe size of 200 mm is typically used for residential developments with the exception of small cul-

de-sacs where the hydrant is located at the entrance into the cul-de-sac, where 150 mm

diameter pipes are typically used.

The minimum pipe sizing requirements for commercial and industrial developments differ among

various municipalities. However, the minimum pipe size is generally dictated by the fire flow and

maximum velocity requirements for both residential and non-residential service areas. The City of

Leduc and the City of Fort Saskatchewan require a minimum fire flow of 227 L/s for non-

residential service areas. In order to meet the maximum velocity requirement of 3 m/s, a

minimum 250 mm diameter pipe loop would be required, as specified in their respective

standards.

Strathcona County’s minimum fire flow requirement for high value properties is 250 L/s. To meet

the minimum velocity requirements, a 250 mm pipe loop would be adequate in isolated service

areas. However for a larger network system, the head losses would accumulate significantly due

to additional base demand. It is therefore concluded that the County’s current standard with

reference to minimum pipe size is adequate.

STRATHCONA COUNTY



May 26, 2015

2.21


The County’s design standards pertaining to the alignment of the watermain and minimum

cover requirements should be kept as per current standards. The current standards are close to

or slightly above the minimum standards specified by AESRD and there is insufficient information

available to propose a change at this time.

Pipe sizes should be determined based on hydraulic network analysis. The network analysis

determined sizes should not be less than the minimum required pipe sizes in the County

Standards.

The minimum pipe size of 150 mm in a water system is considered reasonable for a line that does

not have a fire hydrant. The minimum pipe size of 200 mm for a residential line with a hydrant

and a 300 mm for a non-residential line are considered to be reasonable standards. In addition,

these minimum pipe sizes are in agreement with some of the other municipalities. It is therefore

recommended that the County keep the standards as they are currently detailed in

Section 4.3.1 of the current design standards.

2.5 HYDRANTS SPACING

Design guidelines typically include minimum hydrant spacing requirements for the distribution

system. Table 2.16 summarizes the Strathcona County’s and adjacent municipalities’ current

hydrant spacing standards. AESRD does not state specific hydrant spacing requirements either in

their specifications or guidelines.

Table 2.16 - Maximum Allowable Fire Hydrant Spacing

Municipality Single Family

Residential

Multi-Family

Residential Industrial/Commercial/Schools

Strathcona County 150 m 90 m 90 m

City of St. Albert 150 m 120 m 120 m

City of Leduc 150 m – residential 150 m – residential 90 m

City of Fort

Saskatchewan 150 m 120 m 90 m

City of Edmonton 150 m 90 m 90 m

City of Red Deer 180 m 120 m 120 m

The maximum hydrant spacing for the County matches that of the City of Edmonton for single

family residential, multifamily residential and commercial/industrial/institutional developments.

The standards also closely matches the hydrant spacing with other municipalities for residential

and non-residential service area, however most other municipalities uses slightly longer spacing

for multifamily residential development. The hydrant spacing is dependent on the fire flow

STRATHCONA COUNTY



May 26, 2015

2.22

requirements and firefighting equipment, and therefore, any changes to current standards

would need to be consulted with the County’s Fire Marshall. However, based on the information

presented in Table 2.16, the maximum allowable fire hydrant spacing in Strathcona County is

reasonable and does not need to be changed.


In light of the discussion above, the spacing requirements are reasonable. It is recommended

that the County specifications with reference to hydrant spacing remain unchanged.

2.6 SERVICE CONNECTIONS

As per Section 4.3.1 of the County’s Design and Construction Standards, the services to the

single family dwellings or multi-family units shall be a minimum of 20 mm in diameter unless the

total length of the service is greater than 20 m, in which case the size of the service provided is

to be 25 mm in diameter. AESRD does not specify specific sizes for services to individual

properties; however, the guidelines indicate that pipe sizes should be sufficient to sustain the

minimum operating pressure. Table 2.17 summarizes the minimum sizes specified by other

adjacent municipalities for services.

Table 2.17 - Service Connection Requirements in Adjacent Municipalities

Municipality Service Connection Diameter

Strathcona County 20 mm if length of the service is less than 20 m

25 mm if length of the service is greater than 20 m

City of St. Albert 20 mm if length of the service is less than 20 m


City of Leduc 19 mm if length of the service is less than 20 m


City of Fort Saskatchewan -

City of Edmonton 20 mm if peak hour pressure is > 350 kPa

25 mm if peak hour pressure is < 350 kPa

City of Red Deer -

As per the information presented in Table 2.17, the service connection size specifications are

similar among neighbor municipalities. The County’s service connection specifications are

reasonable based on this desktop review.


Based on the discussion above, it is recommended that the County’s standards with reference

to the minimum diameter of the water service remain unchanged as the current specifications

are reasonable and in agreement with the standards used by other municipalities. The only

STRATHCONA COUNTY



May 26, 2015

2.23

deviation is in the City of Edmonton design standards where different sizes are proposed based

on available peak hour demand pressure. As the County’s current minimum peak hour pressure

requirement is 350 kPa, such requirement would be redundant. However, the County could

specify such requirement where the minimum 350 kPa will not be due to special circumstances.

STRATHCONA COUNTY


Sanitary Sewer System

May 26, 2015

3.1

3.0 Sanitary Sewer System

The main purpose of a sanitary sewer system is to collect the sewage generated by residential

and non-residential developments and convey it to appropriate wastewater treatment facilities

for treatment and disposal. Generally all municipalities have design standards in place so that

the new sewer systems can be constructed with sufficient capacity to allow orderly

development of new service areas without impacting the level of service for the existing

customers.

The wastewater collection system design standards for Strathcona County have been provided

in Section 4.2.1 of the Design and Construction Standards, Volume 1, dated December 2011. The

design standards provide parameters for computing design flows based on average sewage

generation rates, peaking factors and inflow/infiltration rate. The design flow is then used to size

the required conveyance system to an appropriate outlet system eventually conveying the flow

to the treatment facilities.

This section provides Stantec’s findings on the review of the current County standards along with

a comparison of standards used by other adjacent municipalities. Where available, the Alberta

Environment and Sustainable Resource Development (AESRD) standards and guidelines has

been included as the AESRD has the regulatory mandate, in accordance with the

Environmental Protection and Enhancement Act (EPEA) and Regulations (119/1993), for the

Drinking Water and Wastewater Programs serving large public systems in Alberta. AESRD

considers the establishment of standards and guidelines for municipal wastewater facilities an

integral part of it’s regulatory program directed at ensuring public health and environmental

protection. According to AESRD, it objective is “to develop comprehensive and scientifically

defensible standards and guidelines that are effective, reliable, achievable and economically

affordable.”

One of the main factors affecting the sanitary sewer system design is the sewage loading which

consists of three main components: domestic flow, ground water inflow and rainfall induced

inflow infiltration. In order to establish appropriate design parameters, available sanitary sewer

flow monitoring data were obtained and analyzed. The data was then used to calibrate the

County’s sanitary sewer system model, so that anticipated hydrologic loading can be

determined under a design rainfall event representing the County’s desired level of service for

the urban service areas. The simulated loading is then used to determine design parameters that

could be used to size future sanitary sewer system to service new growth areas. The findings of

this process are discussed in subsequent sections along with other physical aspect of sanitary

sewer design parameters.

STRATHCONA COUNTY



May 26, 2015

3.2

The design parameters that have been addressed in the following sections are as follows:

Wastewater Generation Rates and Peaking Factor

Inflow/Infiltration Allowances

Pipe Sizing (Including minimum pipe size, required sewer capacity, minimum flow

velocity, minimum slope)

Sanitary Sewer Alignments and Location

Manhole Spacing and Configuration

Service Connection Configuration

3.1 SANITARY SEWAGE GENERATION RATES

Strathcona County’s Design and Construction Standards, lists the following parameters for

computing the average sewage flows:

Average residential sewage flow to be used in design is 375 L/person/day

Commercial/light industrial sewage flow to be used in design is 18 m3/ha/day

Minimum population density of 3.5 persons per household must be used in determining

residential flows

This section of the report addresses these items as follows:

Average residential sewage generation and peaking factor addressed in Section 3.1.1.

Commercial/light industrial sewage generation addressed in Section 3.1.2.

Residential population density addressed in Section 3.1.3.

3.1.1 Residential Sanitary Sewage Generation Rate

The residential sanitary sewage generation rate in Sherwood Park was evaluated based on the

following:

Review of available flow monitoring data during dry weather flow (DWF) periods

Calibration of sanitary system model for DWF

Review of servicing standards used by adjacent municipalities

A comparison of water consumption rates to sewage generation rates

STRATHCONA COUNTY



May 26, 2015

3.3

3.1.1.1 Flow Monitoring Data

Flow monitoring data was provided by Strathcona County at various locations within Sherwood

Park. Data for Flow Monitoring Sites 17, 39, 40, 42, 49, 50, 51, 66, 85 and 96 were reviewed. The

location of these flow monitors and their associated catchment areas are shown on Figure 3.1.

The DWF generation patterns were reviewed for 2012, 2011 and 2010. Flow Monitor Sites 39, 40,

42, 49, 66 and 85 monitor flows from areas that are mostly residential and therefore were used to

determine average residential sewage generation rates. Site 49 measures flow from older parts

of Sherwood Park; however, there is a parallel 900 mm diameter pipe where some flow splitting

occurs which is currently not measured. The monitored data at this site were used to compare

modelled flow for calibration purposes. For more detailed analysis of this catchment area, the

900 mm diameter parallel pipe should also be monitored in future along with the monitoring of

Site 49.

A set of flow monitoring data with an approximately one month period was selected from each

flow monitoring site for each year to determine the average sewage generation rate during

DWF period. The data sets were selected with consistent flow patterns and without any negative

flows to avoid suspect monitoring data.

The average DWF sewage generation rate was computed by averaging the measured flow

over the selected period and dividing the average by the total service population for flow

monitoring site.

The service populations within each flow monitor site basin area were established based on total

lot counts within service area multiplied by average population density and are assumed to be

constant over the three year period as these service areas are fully developed and any minor

variation in population in the flow monitor catchment area is not expected to have significant

effect on the computed sewage generation rates.

The sewage generation rate for Site 85 was determined to be unsuitable for this analysis due to a

relatively small service population, which resulted in a low flow rate. Although variations in the

monitored flow rates appear to be within the measurement accuracy of the flow monitor, the

measured flow rates fluctuates significantly making data unusable. Site 42 was also monitored

for 2010 to 2012; however, it was moved in 2012 to slightly different location and data for 2012

were not available. For 2010 and 2011, the data are significantly different and were not used

due to inconsistencies.

The flow monitoring data at Site 66 for 2010 appears to be much higher than in 2011 and 2012,

possibly due to spring snowmelt, and the 2010 data was subsequently excluded in the final

analysis. In general, this area generates higher sewage flows than other parts of Sherwood Park.

It is believed this area has a higher groundwater table, resulting in a higher base flow in the

system.

39

51

50

49

85

17

40

42

66

Sher

wood

Dr.

Broa

dmoo

r Blvd

.

Clov

erbar

Road

Trans Canada Highway Yellowhead Highway

Baseline Rd

Wye Rd

Clov

erba

r Roa

d

Clov

erba

r Roa

d

Bren

twoo

d Bl

vd.

Broa

dmoo

r Blvd

.

Sher

wood

Dr.

Granada Blvd.

High

way 2

1

Lakeland Dr.

96

99

3.1

N

66

DESIGN STANDARDS REVIEW

STRATHCONA COUNTY



May 26, 2015

3.4

Table 3.1 provides a summary of the average sewage generation rate and associated peaking

factors for the DWF condition. The peaking factors were computed by dividing the maximum

flow rate by the average flow rate for the selected DWF period. The sewage generation rates in

Table 3.1 include some minor non-residential areas flows as the non-residential flow could not be

easily separated; however, the flow monitoring sites 66, 40 and 39 have minimal amount of non-

residential contributing areas and represent relatively new service areas (post 1990

development).

Table 3.1 – Average Wastewater Generation Based on Flow Monitored Data

Flow

Monitor

Site

Year Selected DWF Period Population

Average Wastewater

Generation

(L/cap/day)

Peaking

Factor

66

2012

Apr. 21 to May 8, 2012 933 176

312

2.54

Sep. 1 to 21, 2012 933 372 2.37

Nov. 1 to 30, 2012 933 378 2.30

Dec. 1 to 31, 2012 933 351 2.57

2011 Sep. 5 to Oct. 5, 2011 933 282 2.66

2010 Apr. 5 to May 4, 2010 A 933 600 A Suspect 2.64

40

2012 Sep. 22 to Oct. 20, 2012 3,408 256

269

2.18

Nov. 17 to Dec. 14, 2012 3,408 244 2.14

2011 Aug. 13 to Aug. 27, 2011 3,408 266 2.00

Sep. 30 to Oct. 13, 2011 3,408 250 2.33

2010 Apr. 10 to May 8, 2010 3,408 329 2.08

39

2012

Aug. 1 to 19, 2012 32,640 263

236

1.73

Sep. 1 to Sep. 18, 2012 32,640 254 1.94

Nov. 1 to Nov. 26, 2012 32,640 245 1.93

2011 Sep. 1 to Oct. 17, 2011 32,640 215 2.13

2010 Mar. 10 to Mar. 31, 2010 32,640 201 2.30

49 B

2012 Sep. 4 to 21, 2012 20,501 163

159

1.66

Dec. 1 to Dec. 31, 2012 20,501 155 1.98

2011 Sep. 1 to Sep. 30, 2011 20,501 184 1.90

2010 Mar. 23 to Apr. 12, 2010 20,501 134 1.64

Average (with FM 49) 248 2.15

Average (without FM 49) 272 2.24

Note: A - Suspect data - not included in the calculation of average wastewater generation rates.

B – The sewage generation rate does not include flow in 900 mm parallel pipe and is excluded

from overall average.

STRATHCONA COUNTY



May 26, 2015

3.5

Based on the results presented in Table 3.1, the wastewater generation rate varies from

176 L/cap/day to 378 L/cap/day, resulting in an average of 272 L/cap/day. The large variability

observed in the wastewater generation rate could be attributed to the estimated populations

within each area, some inflow/infiltration (I/I) due to snow melt or minor rainfall, variation in

groundwater inflow and some inaccuracy of flow monitoring data as well as some actual

occasional significant flow variation. It is very difficult to determine if the occasional large

fluctuation in flow monitoring data is real or due to flow monitor malfunction. For the purpose of

this study, the occasional high, non-wet weather related data have not been utilized.

In addition, the variation in wastewater generation rate could be attributed to house and lot size

as well as water consumption patterns during different months (see Table 2.4 for monthly

average water consumption rates). Flow monitor 66 is located downstream of the Estates of

Sherwood Park, a residential development with estate lot type homes. This neighbourhood also

experiences consistently high groundwater table and could be contributing higher base flow.

This may explain the higher than average wastewater generation from this neighbourhood as

recorded by FM66.

The wastewater generation flows observed at Site 49 is low due to flow splitting resulting in the

parallel 900 mm pipe in the service area that is not currently included in computation of

average sewage generation rate.

The computed peaking factor ranges from 1.73 to 2.66. The peaking factors are a function of

service area population as indicated in Section 3.1.1.3.

3.1.1.2 Calibrated Model - DWF

The sanitary system model was calibrated in two steps: dry weather flow calibration and wet

weather flow calibration.

DWF calibration was completed for a time period between September 20 and September 24,

2011. Based on the rain gauge data, there was no rainfall recorded during this time period.

The residential DWF in the sanitary sewer system model is represented by an average per capita

sewage generation rate (L/d/person) and population in each catchment. Diurnal patterns (unit

hydrographs) are used to simulate the daily variation in flow.

Based on the calibration, the average residential sewage generation rate was estimated to be

approximately 220 L/cap/day with the exception for Flow Monitors 66, 96 and 39 where the per

capita sewage generation rate of 250, 280 and 210 L/cap/d, respectively, were used. For non-

residential areas, a sewage generation rate of 4,500 L/d/ha was used. These dry weather flow

parameters were calibrated to a specific set of recorded data during September 20 to 24, 2011

period. The difference in sewage generation rate between the flow monitoring data summary

provided in Section 3.1.1.1 and the calibrated DWF model is primarily due to the dry weather

STRATHCONA COUNTY



May 26, 2015

3.6

period selected for the two analyses and splitting of DWF for residential and non-residential

contributing areas.

3.1.1.3 Sewage Generation Rate Comparison with Other Municipalities

A servicing standards review of adjacent municipalities was completed to compare residential

sewage generation rates used by other municipalities, the findings of this review is summarized in

Table 3.2. As indicated in Table 3.2, the sewage generation rates used by the adjacent

municipalities are lower than that specified by the Strathcona County. As indicated in Table 3.2

the sewage generation rate used by the adjacent municipalities range from 300 L/cap/day to

360 L/cap/day.

Stantec also contacted these municipalities to inquire on factor of safety used to determine

these standards. Responding municipalities indicated that a factor of safety of 1.3 to 1.5 was

typically utilized. Based on the average monitored sewage generation rate of 272 L/cap/day,

and the subsequent application of a 1.3 factor of safety, the resulting wastewater generation

rate corresponds closely to Strathcona County’s current design standard of 375 L/cap/day.

Table 3.2 - Residential Average Dry Weather Flow

Municipality Residential Average DWF

(L/cap/day) Residential Peaking Factor **

Strathcona County 375

Greater of 3 or

1 +14

(4 + P0.5)

City of St. Albert 320

Greater of 3 or

1 +14

(4 + P0.5)

City of Leduc 360 Greater of 1.5 or

2.6 𝑃−0.1

City of Fort Saskatchewan 360 Greater of 1.5 or

2.6 𝑃−0.1

City of Edmonton 300 Greater of 1.5 or

2.6 𝑃−0.1

City of Red Deer 320 1 +14

(4 + P0.5)

Note: * Equivalent population based 37 people/ha

** P = Population in thousands

It is Stantec’s opinion that the average monitored sewage generation rate for Sherwood Park, at

272 L/cap/day, is higher than several of its neighboring municipalities due to the presence of

significant base flow from higher groundwater table in the Sherwood Park area. This is evident by

known problems in the adjacent Estates of Sherwood Park development and is reflected in their

flow monitoring results (see Flow Monitor Site 66).

STRATHCONA COUNTY



May 26, 2015

3.7

Table 3.2 lists methods used for computing residential peak flow by various municipalities. In

comparison to the formula used by City of Edmonton, City of Leduc and City of Fort

Saskatchewan, the formula used by Strathcona County provides a more conservative peaking

factor for smaller populations. The peaking factor formula used by the City of Edmonton was

developed by the City based on actual flow monitoring records within the City. The Harmon’s

peaking factor formula currently used by Strathcona County is used by most municipalities in

North America. The following table shows peaking factors based on monitored data versus

computed peaking factors based on the two formulas.

FM Population Average/ Range of

Monitored PF

Strathcona County

PF

City of Edmonton

PF

66 933 2.49

(2.30 – 2.66) 3.82 2.62

40 3,408 2.15

(2.00 – 2.33) 3.39 2.30

39 32,640 2.01

(1.73 – 2.30) 2.44 1.83

Note: Site 49 was not used due to flow splitting in a 900 mm diameter parallel line.

The above monitored peaking factor rates are lower compared to that computed using the

County formula and closer to that computed using the City of Edmonton formula. The variation

in computed peaking factor is greater (50% higher) for smaller population (Site 66 and 40) and

not as significant (20% higher) for larger population (Site 39).

The peaking factors computed using the current County formula provides slightly more

conservative design flow rate and is recommended not to be changed until further analysis

future flow monitoring record. The monitored peaking factors in Table 3.1 are based on selected

periods, as the monitoring data fluctuates very significantly throughout the year with significant

variation in flow rates and peaking factors and it is not clear whether the fluctuations are due to

actual variation in flow rates or due to accuracy of flow monitoring equipment, the current

method of computing peaking factors should be maintained. This conservative approach allows

to build some excess capacity in primarily new local sanitary system.

3.1.2 Commercial/Industrial/Institutional Sewage Generation Rate

Section 4.2.1.2 of the Design and Construction Standards provides guidelines for computing the

average sewage flow for commercial/industrial areas. The County standards indicate that each

case must be considered on an individual basis as the flow typically varies with the type of

development. For preliminary planning purposes, the 18 m3/ha/day sewage generation rate

may be used for Commercial/Light Industrial developments.

To determine whether this sewage generation rate is reasonable, non-residential sewage

generation rates used by the adjacent municipalities were reviewed, the findings of this review

are summarized in Table 3.3.

STRATHCONA COUNTY



May 26, 2015

3.8

Table 3.3 - Commercial/Industrial/Institutional Wastewater Generation

Municipality Average DWF (L/ha/day) Peaking Factor

Strathcona County 18,000 Considered on an Individual Basis

City of St. Albert 6,170 3.0

City of Leduc 17,280 3.0

City of Fort Saskatchewan 17,280 P = 10 ∗ Q−0.45

(min. 2.5; max. 25)

City of Edmonton 20,000 P = 10 ∗ Q−0.45

(min. 2.5; max. 25)

City of Red Deer 0.15 l/sec/ha

12,960

P = 10 ∗ Q−0.45

(min. 2.5; max. 25)

Note: Q = Average Flow in L/s.

The average DWF specified in the County’s standards is similar to what most of the neighboring

municipalities use, with the exception of the City of St. Albert and City of Red Deer. Based on the

water billing data which indicates high variability in water consumption among different

businesses, it is expected that the wastewater generation rate may vary significantly. It is

therefore recommended that the County continue to specify the average sewage flow

computed on an individual basis. For planning purposes, the 18 m3/ha/day sewage generate is

reasonable for commercial/light industrial developments with a note that higher intensity

commercial and industrial will likely generate more than 18 m3/ha/day.

The County standards do not specify peaking factor computation method for non-residential

service area. Other municipalities specify either a specific peaking factor value or provide a

formula for computing the peaking factor. It is recommended that the County specify the

following peaking factor formula that is being used by other municipalities to compute the non-

residential peak flow for the planning purpose: P=10∗ Q−0.45, (min 2.5, max 25). This formula was

developed by the City of Edmonton based on available flow monitoring data from non-

residential areas in late 1990s. The wide range in peaking factor allows for significant variation in

peak flow rates from small sites (individual lot or business) for sizing local collection system, while

the lower peaking factor allows to compute peak flows for large contributing areas for sizing of

off-site trunk systems.

STRATHCONA COUNTY



May 26, 2015

3.9

3.1.3 Population Density

Sherwood Park census information is summarized in Table 3.4. The populations summarized

below do not include any rural developments.

Table 3.4 - Sherwood Park Population

Year Sherwood Park Population Census Type

2010 64,000 Extrapolated Based on 2011 and 2012

2011 64,733 Federal Census

2012 65,465 Municipal Census

Note: Population indicated on Strathcona County’s website accessed on May 28, 2013

(http://www.strathcona.ab.ca/departments/Legislative_and_Legal_Services/Municipal-Census-2012.aspx)

The population density in Sherwood Park was computed based on lot counts estimated from the

following two sources:

The Sherwood Park MikeUrban sanitary sewer system model was calibrated based on

actual lot counts and the total urban service area population based on census data. The

population density and wastewater generation rates were adjusted to match the total

urban service area population and monitored dry weather flow (DWF). Based on this

calibration process, the 2011 development scenario resulted in a population density of

approximately 2.75 people/unit. The population density for the estates neighborhood

serviced through Sherwood Park is estimated to be approximately 3.0 people/unit, which

is slightly higher due to larger homes in the neighborhood. As the occupancy in newer

areas could not be confirmed, the population density may be slightly under estimated.

The second method used the number of water billing accounts and corresponding

census data for computing population density. Table 3.5 provides a summary of water

billing accounts and estimated population densities for the last three years.

Table 3.5 - Sherwood Park Population Density Based on Water Billing Accounts

Year

Sherwood

Park

Population

Number of

Low Density

Residences

Number of

Condo Units

Total Number of

Residential Units

Population

Density

(ppl/unit)

2010 64,000 20,146 2,177 22,323 2.87

2011 64,733 20,469 2,053 22,522 2.87

2012 65,465 20,613 1,903 22,516 2.91

Note: The number of billing accounts provided by the County for condos varied from month to month

and thus the average annual account numbers are slightly different.

Based on the information presented in Table 3.5, the population density in the urban service

area appears to have increased by approximately 1.4% from 2011 to 2012.

http://www.strathcona.ab.ca/departments/Legislative_and_Legal_Services/Municipal-Census-2012.aspx

STRATHCONA COUNTY



May 26, 2015

3.10

3.1.3.1 Design Population Density Comparison with Adjacent Municipalities

A servicing standards review of the adjacent municipalities was completed to determine the

design population densities used by each municipality. The population densities used by the

adjacent municipalities are summarized in Table 3.6.

Table 3.6 - Summary of Regional Municipality Servicing Standards

Municipality

Single Family Residential

Density Multi-Family Residential Density

Strathcona County 3.5 people/unit 3.5 people/unit

City of St. Albert 40 people/ha 40 people/ha

Sturgeon County 3.5 people/res 3.5 people/res

City of Leduc 40 people/ha Greater of subdivision population or

40 people/ha

City of Fort Saskatchewan 50 people/ha 90 people/ha – medium density

150 people/ha – high density

City of Edmonton 3.46 people/unit

96 people/ha (net)

1.89 to 2.81 people/unit

614 to 170 people/ha

City of Red Deer 45 people/ha 45 people/ha

Parkland County 3.0 people/unit 3.0 people/unit

Town of Stony Plain Greater of 3.5 people/unit

or 42 people/ha

44 units/ha at 2.4 people/unit

to 296 units/ha at 2.4 people/unit

Town of Beaumont 40 people/ha Greater of subdivision population or

40 people/ha

As indicated in Table 3.6, a population of density of 3.5 people/unit is generally used for single

family residential units by other municipalities. For multi-family residential a lower population

density is typically used depending on the types of multi-family units. It is recommended that the

County consider lower population densities for multi-family land uses through the formal

variance process.

STRATHCONA COUNTY



May 26, 2015

3.11


Table 3.7 provides a summary of findings for the residential sewage generation rates discussed in

previous sections.

Table 3.7 - Summary of Residential Sewage Generation Rate

Sewage

Generation Rate in

County Standards

Sewage

Generation Rate

based on Flow

Monitoring Data

Sewage

Generation Rate

Used by Adjacent

Municipalities

Calibrated Model

Sewage

Generation Rate Recommendation

375 L/cap/day

236 to 312

L/cap/day

Average 272

L/cap/d

300 to 360

L/cap/day

220 to 280

L/cap/day 300 L/cap/day

Based on the above presented data, it is our recommendation that the sewage generation rate

be reduced to 300 L/cap/day. During neighbourhood design stage, a hydrogeotechnical

investigation should be completed, and for areas with high ground water table, the sewage

generation rate could be increased to 375 L/d/ha to account for extra base flow. The

recommended reduction is based on the recommended reduction in water consumption rate,

as well as the actual flow monitoring data variation. The proposed water consumption rate is 330

L/cap/d and with the assumption of 90% of the consumed water returns to the sewers.

The calibrated model sewage generation of 220 to 280 L/cap/day represents monitored flow

during specific time period; however as summarized in Table 3.1, the actual monitored flow

varies significantly due to variety of factors such as variation in ground water table at different

time of the year affecting the amount of base flow contribution and variation in monthly water

consumption rates. The day to day fluctuation in flow monitoring data is considered to be due to

actual fluctuation in generation rates as well as inaccuracies in data collection equipment due

to probe fouling in hostile environment of the sewer system. In order to gain higher confidence in

the flow monitoring records, a more consistent and frequent equipment cleaning/maintenance

is required.It is also recommended that the residential peaking factor computation formula

remain unchanged. This formula does provide slightly conservative peaking factors compared

to the monitoring data peaking factors. However, the monitored data does indicate significant

variation in peak flow on a day to day basis.

For design population density, it is also recommended that the current standards of 3.5

people/unit for a single family residential unit be maintained. The current average population

density in Sherwood Park is slightly less than 3 people/unit. The adjacent municipalities standards

review indicates use of a 3.5 people/unit population density by most municipalities for single

family residential units. This design population density accounts for demographic variation over a

long period of time due to economic and social factors.

STRATHCONA COUNTY



May 26, 2015

3.12

A lower population density of 2.5 people/unit can be used for multi-family residential units for

planning purposes and is proposed that the County consider lower population densities for multi-

family land uses through the formal variance process for more detailed design purposes.

It is also recommended that the County standards continue to require that the average sewage

flow be computed on an individual basis due wide variety of uses being developed in the

County. For the planning purposes, 18 m3/ha/day is reasonable sewage generation rate for

commercial/light industrial developments. It is recommended that a note be added indicating

that higher intensity commercial and industrial will likely generate more than 18 m3/ha/day.

There is currently no minimum value or formula mentioned for computing peaking factors for

non-residential areas. It is recommended that a note be added to the County standards

indicating peaking factors are to be computed on an individual land use basis; however for the

planning purposes, peaking factors can be computed based on this formula being used by

other municipalities: P = 10 ∗ Q−0.45, (min 2.5, max 25). As indicated in Section 3.1.2, this formula

was developed by the City of Edmonton and has been adopted by Fort Saskatchewan and

Red Deer. It has a large peaking factor range to accommodate various sizes of catchment

areas to account for the anticipated range peak flow variations.

3.2 INFLOW AND INFILTRATION

Section 4.2.1.4 of the County’s standards provides a description of how to compute extraneous

flow allowances. The extraneous flows consist of an infiltration allowance of 0.5 L/s/gross area

and an allowance of 0.4 L/s per each manhole located in a sag.

The inflow/infiltration allowance is a wet weather flow contribution to sanitary sewer system that

enters through a variety of means such as manhole and pipe walls, weeping tiles, manhole

covers, illicit and cross-connections, etc. New sewer systems are now being design with more

stringent control measures, however inflow/infiltrations contribution continues to be observed in

all jurisdictions. In addition, gradual increase in inflow/infiltration is expected due to deterioration

of the new system as more cracks in manholes and pipe joints (at manhole and service

connection locations) and road surface deterioration at manhole locations are developed over

time. Further system deterioration is also expected to occur at lot level when lot grading is

impacted by foundation backfill settlement. Although, the seepage is collected by foundation

drain and directed to sump pump or storm system, some of the seepage ends up running along

the service pipe through sand bedding and collects in the main pipe bedding. This seepage

eventually enters into the sanitary system through service connection joints and/or pipe joint at

manholes. The amount of seepage through this mechanism is not consistent as much of the

water is supplied by the roof leader when the extension is left in folded up positing during lawn

mowing process.

The specified inflow/infiltration allowance is slightly different from one municipality to another as

it depends on the variety of factors indicated above and soil types and ground water table

STRATHCONA COUNTY



May 26, 2015

3.13

levels as well as a municipality’s existing system performance experience and its risk tolerance

level.

The extraneous flow allowance is meant to account for rainfall induced inflows to sanitary sewer

system which increases with the increase in rainfall amount and duration. For sanitary sewer

system design purposes, a specific design rainfall event is generally not specified in terms of the

desired level of service and only an allowance amount is specified.

To determine whether the extraneous flow allowance is indicative of what the sanitary sewer

system experiences under a given rainfall event, Stantec calibrated the existing sanitary sewer

system model based on recorded rainfall and flow monitoring data. The calibrated model was

then run for the 1:25 year 24 hour Huff design rainfall event to determine anticipated

inflow/infiltration response from various basin areas. This response is then compared with the

current inflow/infiltration rate allowance in the County’s design standards. It should be noted

that the County may experience larger than the 1:25 year design rainfall event and in such case

the inflow/infiltration response will be higher and may overload the system.

In addition, a desktop review of the design standards for surrounding municipalities was

completed to compare with the County standards.

3.2.1 Model Calibration

The wet weather calibration was completed using continuous rain gauge and flow monitoring

data for five significant rainfall events that occurred in 2011, 2012 and 2014, as measured at Rain

Gauge 60 in Sherwood Park. The five rainfall events used for wet weather flow calibration are:

July 21 to 22, 2011 – A long duration storm with a return frequency of 1:5 years. This was a

continuous rainfall event with a spatially wide distribution.

August 6, 2011 – A short duration, high intensity storm event with a 1:10 year return

frequency.

July 12, 2012 - A short duration, high intensity storm event with a 1:10 year return

frequency.

July 14 to 15, 2012 – A long duration storm with a return frequency of 1:2 years. This was a

continuous rainfall with a widespread distribution.

July 25, 2014 – A long duration and moderate intensity storm event with approximately

1:25 year return frequency.

Originally, the model was calibrated using the Runoff Module in XPSWMM, which primarily

involves altering the percent imperviousness in order to match the simulated flows to the

measured flows. However, it was difficult to match the simulated flows to the measured flows for

different rainfall events (e.g. short duration, high intensity events and long duration, lower

intensity events) using the same I/I model parameters. Therefore, it was decided to convert the

STRATHCONA COUNTY



May 26, 2015

3.14

model to DHI Mike Urban software and use the “Model B and RDII” engine to calibrate the

model. This engine contains two components that enable more effective calibration of the

model to various types of rainfall events because there are two primary parameters that are

varied until an acceptable match between simulated and measured flows is achieved. These

components include:

Fast Response (Model B): The fast inflow to the sanitary sewer is through manhole covers

or weeping tile/roof leader connections to the sanitary sewer, and typically only occurs

during and immediately following a rainfall event (i.e. inflows to the sanitary system drop

off quickly after the rain ends). Percent imperviousness is the primary model calibration

parameter.

Slow Response (RDII or Rainfall-induced Inflow and Infiltration): The slow infiltration into the

sanitary sewer through cracks or poor pipe joints that may occur during the rainfall event

and last for a significant period of time (sometimes several days or longer) after the

rainfall ends (as long as the ground remains wet). “Percentage RDII Area” is the primary

model calibration parameter.

Typically, the peak flow in the sanitary sewer system is governed primarily by the percent

imperviousness (Model B) while the total volume of I/I into the sanitary system during the rainfall

event is largely governed by the RDII Area parameter (RDII component). Using two distinct

parameters for model calibration allows for better model correlation with both short duration,

high intensity events and long duration, lower intensity events using the same set of model

parameters. In general, simulation of short duration, high intensity events is governed by the

imperviousness percentage (RDII area has little effect) and simulation of long duration, lower

intensity events is governed more by RDII Area (percentage imperviousness has less influence).

As a result, good correlation between the simulated and measured flows was achieved using

the Mike Urban model.

3.2.2 Simulated Inflow and Infiltration

The calibrated model was used to estimate the I/I from at various flow monitoring locations in

Sherwood Park during the 1:25 year 24 hour rainfall event. These locations were selected to

assess variation in I/I rate due to timing of when the service areas were constructed (i.e. in

general older neighborhoods constructed prior to ~1990 had weeping tile drains connected to

sanitary system while newer neighborhoods constructed in 1990 and later had more stringent

design criteria prohibiting weeping tile connections to sanitary system and defined overland

drainage system). The I/I rate is also impacted ground conditions (soil type, water table

elevation, etc.) and type of development (residential or non-residential). For example, the

“Review of LOS Criteria” (AECOM, 2009) study found that I/I during a 1:25 year 24 hour rainfall

event varied between approximately 0.024 L/s/ha in a relatively new Edmonton neighborhood

(built in 1990s and 2000s) and 0.397 L/s/ha in a slightly older Edmonton neighborhood (built in the

1980s and 1990s). Measured I/I rates during several rainfall events supported this finding. The

large difference in I/I between the neighborhoods was attributed to the possibility of weeping

STRATHCONA COUNTY



May 26, 2015

3.15

tile connections to the sanitary sewer system in the older neighborhood built in the 1980s and

earlier.

Table 3.8 summarizes the simulated I/I rates (using the Mike Urban model) during the five

calibration rainfall events and also during the 1:25 year 4 hour and 24 hour rainfall events at

various locations in Sherwood Park. I/I rates were determined for each catchment by removing

the DWF and dividing the remaining peak flow rate by the catchment area. The older area is

considered to be built prior 1990 when major changes to servicing standards adopted.

Table 3.8 - Simulated I/I Rates

Location Description

Simulated Inflow and Infiltration (L/s/ha)

July 21-

22, 2011

(~1:5

Year)

August

6, 2011

(~1:10

year)

July 12,

2012

(~1:10

Year)

July 14

to 15,

2012

(~1:2

Year)

July 25,

2014

(~1:25

Year)

1:25

Year 24

Hour

1:25

Year 4

Hour

Flow Monitor

49

Older

Residential

Area

0.727 1.149 1.170 0.405 1.864 1.409 1.678

Flow Monitor

96

Newer

Residential

Area

0.265 0.450 0.489 0.189 0.557 0.589 0.829

Flow Monitor

39

Newer

Residential

Area

0.109 0.212 0.239 0.104 0.249 0.275 0.393

Flow Monitor

50

West

Sherwood

Park Including

Non-

Residential

Area

0.704 1.089 1.119 0.402 1.613 1.354 1.607

Flow Monitor

40

Newer

Residential

Area

0.145 0.333 0.293 0.160 0.370 0.265 0.505

Flow Monitor

42

Newer

Residential

Area

0.071 0.153 0.120 0.112 0.122 0.098 0.224

Flow Monitor

85

Newer

Residential

Area

0.085 0.210 0.157 0.142 0.128 0.121 0.310

Flow Monitor

17

Newer

Residential

Area

0.148 0.349 0.313 0.122 0.254 0.264 0.558

STRATHCONA COUNTY



May 26, 2015

3.16

Location Description

Simulated Inflow and Infiltration (L/s/ha)

July 21-

22, 2011

(~1:5

Year)

August

6, 2011

(~1:10

year)

July 12,

2012

(~1:10

Year)

July 14

to 15,

2012

(~1:2

Year)

July 25,

2014

(~1:25

Year)

1:25

Year 24

Hour

1:25

Year 4

Hour

Flow Monitor

66

Older

Residential

Area

0.260 0.371 0.320 0.198 0.373 0.345 0.304

Flow Monitor

99

Newer

Residential

Area

0.128 0.234 0.208 0.111 0.320 0.188 0.357

Non-

Residential

Throughout

Sherwood

Park

0.305 0.493 0.482 0.167 0.805 0.544 0.735

Entire System All Model

Service Area 0.352 0.461 0.483 0.232 0.633 0.609 0.576

Notes: FM49 - Simulated flow is computed by combining flow in 1,050 mm and 900 mm pipes at this

location.

FM96 - Simulated flow is reduced by the amount of diverted flow at Baseline Road and Bremner

Drive.

FM50 - Simulated flow is computed by combining flow in 1,200 mm and 600 mm diameter pipes at

this location and adding the amount of diverted flow at Baseline Road and Bremner Drive.

Non-Residential – I/I flow rates were estimated by adding all non-residential catchment area peak

flows and subtracting the peak dry weather flow rates within the model.

As indicated in Table 3.8, the simulated I/I in Sherwood Park varies from approximately

0.098 L/s/ha to 1.409 L/s/ha during the 1:25 year 24 hour rainfall event. Weeping tile connections

to the sanitary system in the older areas of Sherwood Park are the likely cause for the high I/I

values. The simulated I/I rates, for the 25 year 4 hour event range from 0.224 L/s/ha to 1.678

L/s/ha.

The total flow leaving Sherwood Park through the Southeast Regional Trunk Sewer (SERTS sewer

was also used to estimate the overall I/I from Sherwood Park. The average DWF was subtracted

from the peak flow during the 1:25 year 24 hour rainfall event to estimate the overall I/I (note

that the flows used in this calculation are subject to pipe routing effects). This computation

yielded an average I/I rate of approximately 0.609 L/s/ha in Sherwood Park. As indicated in

Table 3.8, the I/I generation rates in new and old areas vary significantly. The reduction in I/I rates

new service area due to the following factors:

Prohibition of weeping tile connections to sanitary system

Utilization of PVC pipes with tighter joints and sealed MHs at sag locations

Enforcement of proper lot grading

Prevention/enforcement of illicit connections

STRATHCONA COUNTY



May 26, 2015

3.17

More stringent construction practices

Construction of defined dual storm drainage system

3.2.3 Extraneous Flow Allowances by Adjacent Municipalities

Table 3.9 summarizes the extraneous flow allowance requirements by the neighboring

municipalities. As indicated in Table 3.9, most of these municipalities, including Strathcona

County, require additional inflow allowance for manholes located within roadway sags. In

general, the inflow/infiltration allowance is lower in all other adjacent municipalities included in

this servicing standards review. Also none of the municipality defines a level of service

associated with the design extraneous flow rate requirements.

Table 3.9 - Extraneous Flow Allowances by Adjacent Municipalities

Municipality Inflow/Infiltration Allowance

(l/s/ha)

Sag Manhole Flow Allowance

(L/s/MH)

Strathcona County 0.5 0.4

City of St. Albert 0.28 0.4

City of Leduc 0.20 - res

0.05 - com 0.4

City of Fort Saskatchewan 0.28 – res

0.05 - com 0.4

City of Edmonton 0.28 0.4

City of Red Deer 0.20 n/a


Based on the wet weather flow analysis within Strathcona County and servicing standards

review of adjacent municipalities, it is recommended that the I/I rate allowance be reduced to

0.4 L/s/ha from the current 0.5 L/s/ha based on the recorded flow monitoring data and the

simulated flows using the calibrated model for the 1:25 year 4 hour and 24 hour design rainfall

events.

The simulated I/I rate for newer area (FM39) of Sherwood Park has I/I rate that is approximately

0.28 L/s/ha and 0.39 L/s/ha for the 1:25 year 24 hour and 4 hour design rainfall events,

respectively. Although the 25 year 24 hour I/I rate is same as the I/I allowance used by other

neighboring municipalities, the I/I rate increases significantly for the short duration higher intensity

event. Although smaller I/I is simulated for more newer service areas such Site 42, this service

area is not calibrated to larger rainfall event such as July 2014 rainfall event. Also the older parts

of the County service area is experiencing significantly higher I/I rate than the other

municipalities. Therefore, it is possible that as the sanitary sewer system ages in the newer parts

STRATHCONA COUNTY



May 26, 2015

3.18

of the County, the I/I rate will likely increase in future from the new service areas due to sewer

system and lot grading deterioration.

In addition to potential increase in I/I due to aging, I/I rate allowance needs to include some

factor of safety to account for rainfall events greater than 1:25 year event. The City of

Edmonton experienced rainfall events significantly greater 1:25 year in 2004, 2010 and 2012. The

major events during years resulted in thousands of basement flooding due to sanitary sewer

system backup which resulted in significant social and financial costs to the residents and the

City. In response to these frequent nature of the significant rainfall events (possibly could be

attributed to climate change), the City of Edmonton has developed new design rainfall

hyetographs which has significantly higher rainfall volumes and intensities for 1:50 and 1:100 year

rainfall events. These new design rainfall events are currently being tested for their implication on

infrastructure requirements and depending on these findings, the City’s servicing standards may

be updated.

For these reasons, it is prudent to use a more conservative I/I rate in the design of new sanitary

sewer system. There could be significant economic and social cost in the future if the sanitary

sewer system is undersized for wet weather events as a larger than the design rainfall event will

be exceeded in time.

In order to develop better confidence in the simulated results, flow monitoring should be

continued with goal achieve more accurate and reliable monitoring data. As significant events

are recorded, further verification/refinement of the model should be carried out on an ongoing

basis. In addition, more detailed monitoring of the older service area is required to identify

opportunities to reduce I/I contribution to meet ACRWC’s Level of Service requirement.

3.3 MINIMUM SANITARY SEWER SIZE

A minimum pipe diameter for sanitary sewer is generally specified in all servicing standards to

facilitate pipe maintenance and cleaning, and to minimize potential for clogging. Table 3.10 lists

the parameters that are used by various municipalities in sizing the wastewater piping.

Table 3.10 – Sanitary Sewer Size Design Parameters

Municipality Minimum Pipe Size (mm) Manning

Coefficient “n” Design Sewer Capacity

Residential Non-Residential

Strathcona

County 200 250 0.013


0.86

AESRD 200 𝐸𝑠𝑡𝑖𝑚𝑎𝑡𝑒𝑑 𝐷𝑒𝑠𝑖𝑔𝑛 𝐹𝑙𝑜𝑤

0.86

City of St. Albert 200 200 0.013 𝐸𝑠𝑡𝑖𝑚𝑎𝑡𝑒𝑑 𝐷𝑒𝑠𝑖𝑔𝑛 𝐹𝑙𝑜𝑤

0.86

STRATHCONA COUNTY



May 26, 2015

3.19

Municipality Minimum Pipe Size (mm) Manning

Coefficient “n” Design Sewer Capacity

Residential Non-Residential

City of Leduc

200 for first 2

pipes

250 mm for the

remaining

250 0.013 𝐸𝑠𝑡𝑖𝑚𝑎𝑡𝑒𝑑 𝑇𝑜𝑡𝑎𝑙 𝑃𝑒𝑎𝑘 𝐹𝑙𝑜𝑤

0.86

City of Fort

Saskatchewan 200 250 0.013

𝐸𝑠𝑡𝑖𝑚𝑎𝑡𝑒𝑑 𝑇𝑜𝑡𝑎𝑙 𝑃𝑒𝑎𝑘 𝐹𝑙𝑜𝑤

0.86

City of Edmonton 200 200 0.013 or as

approved

𝐸𝑠𝑡𝑖𝑚𝑎𝑡𝑒𝑑 𝑇𝑜𝑡𝑎𝑙 𝑃𝑒𝑎𝑘 𝐹𝑙𝑜𝑤

0.86

City of Red Deer Not stated Not stated Not stated

Based on slope, pipe

material, actual in-service

flows, projected in-service

roughness coefficient.

The required sewer capacity is similar among the different municipalities with the exception of

City of Red Deer where the required sewer capacity is based on actual in-service flows. All other

municipalities listed in Table 3.10 size the wastewater mains based on design flow depth at an

80% of the sewer diameter. The sanitary sewers are sized to carry approximately 14% more flow

than the design flow. This method includes a safety factor for the potential increase in the

friction factor over life of a sewer due to deposition, joint displacement, etc. to ensure that the

sewers have a reliable conveyance capacity.


Based on above review, it is recommended that the County maintain the current minimum pipe

requirements as well as the design capacity requirement at 80% flow depth. The 80% flow depth

requirement is to ensure sufficient capacity in between cleaning cycle to account for deposits

and clogging from oil and grease.

3.4 SANITARY SEWER SLOPE REQUIREMENTS

Section 4.2.1.5 of the Design and Construction Standards, Volume 1, for Strathcona County

provides information on minimum and maximum flow velocity and minimum required grade

sanitary sewers depending on the pipe size and location in the system. A minimum flow velocity

of 0.6 m/s is required to provide self-cleansing and therefore reduces the need for periodic

flushing. A limit on the maximum flow velocity is specified to prevent turbulence and minimize

erosion and odours due to sulphide generation. The minimum slope for various sanitary pipe sizes

are provided to ensure the minimum flow velocity is achieved. Table 3.11 lists the acceptable

sanitary sewer flow velocities and minimum slope requirements for adjacent municipalities.

STRATHCONA COUNTY



May 26, 2015

3.20

Table 3.11 – Sanitary Sewer Required Velocities and Slopes

Municipality

Flow Velocity (m/s) Minimum

Grade of Most

Upstream Pipe

Minimum Slopes

on Straight

Stretches of Pipes

Minimum Slopes on

Curved Stretches

of Pipe Minimum Maximum

Strathcona

County 0.6 3.0 1.0%

200mm – 0.40%

250mm – 0.28%

300mm – 0.22 %

≥375mm – 0.15%

Minimum slopes

shall be increased

by 50%

AESRD 0.6 3.0 Not stated

200mm - 0.40%

250mm - 0.28%

300mm - 0.22%

375mm - 0.15%

450mm - 0.12%

525mm - 0.10%

600mm - 0.08%

Minimum slopes

shall be increased

by 50%

City of St.

Albert 0.6 3.0 0.6%

200mm – 0.40%

250mm – 0.28%

300mm – 0.22%

375mm – 0.15%

≥525mm – 0.10%

Increase of the

minimum pipe

slope is based on

sewer radius

City of Leduc ≤300mm -0.6

>300mm -0.65 3.0 0.6%

200mm – 0.40%

250mm – 0.28%

300mm – 0.22%

375mm – 0.15%

≥525mm – 0.10%

200mm – 0.60%

250mm – 0.42%

300mm – 0.33%

375mm – 0.22%

525mm – 0.14%

600mm – 0.12%

≥675mm – 0.10%

City of Fort

Saskatchewan 0.6 3.0 1.0%

200mm – 0.40%

250mm – 0.28%

300mm – 0.22%

375mm – 0.15%

≥525mm – 0.10%

Minimum slopes

shall be increased

by 50%

City of

Edmonton 0.6 3.0 Not stated

200mm – 0.40%

250mm – 0.28%

300mm – 0.22%

375mm – 0.15%

450mm – 0.10%

≥525mm – 0.10%

200mm – 0.40%

250mm – 0.31%

300mm – 0.25%

375mm – 0.18%

450mm – 0.15%

525mm – 0.13%

600mm – 0.10%

City of Red

Deer 0.6 Not stated Not stated

200mm – 0.40%

250mm – 0.28%

300mm – 0.22%

375mm – 0.15%

450mm – 0.12%

525mm – 0.10%

600mm – 0.08%

Minimum slopes

shall be increased

by 50%

The AESRD and the neighboring municipalities to the County have very similar specifications in

terms of minimum and maximum flow velocities in the system. The County specifies a higher

STRATHCONA COUNTY



May 26, 2015

3.21

minimum grade of 1.0% on the first upstream sanitary system pipe which is steeper grade than

some of the surrounding municipalities specify. However, the steeper slope allows generating

higher velocity to cleanse the pipe as there is generally insufficient flow to achieve the required

cleansing velocity.

The County has minimum pipe slope for larger pipes which is set at 0.15% while other

municipalities have the minimum slope set to 0.1% except for Red Deer which is set to 0.08%.

Although the steeper slope requirement allows use of smaller pipe diameter, the slope

requirement may need to be relaxed to allow connections to existing downstream systems

without excessive fill and/or lift station requirements. Such variance should be should granted

based on formal County variance process on a site specific requirement basis.


Based on the discussion above, it is recommended that the minimum and maximum allowable

flow velocity range and the minimum acceptable pipe slope specifications that are currently

stated in the Strathcona County Design Standards remain unchanged. Minimum slope

requirement for larger pipes should be relaxed on a case by case basis, if the current slope

requirement results in need for excessive fill and/or a lift station.

3.5 SANITARY SEWER ALIGNMENT AND LOCATION

Section 4.2.1.7 of the Design and Construction Standards, Volume 1 of Strathcona County

provides information on the alignment, depth of cover and separation distances between

sewers and water mains. Table 3.12 below provides summary of the standards used by the

County and other adjacent municipalities.

Table 3.12 – Sanitary Pipe Alignment and Location

Municipality Depth of

Cover (m)

Horizontal Pipe Separation (m) Vertical Pipe Clearance (m)

Sanitary

Sewers and

Water Mains

Sanitary and

Stormwater

Sewers

Water Main

Crossing above

Sewer

Water Main

Crossing below

Sewer

Strathcona

County

2.6 to

obvert 3.0 -

sufficient

separation to

allow for proper

bedding

0.5

AESRD 2.5 to

obvert 2.5

sufficient

separation to

allow for proper

bedding

0.5

STRATHCONA COUNTY



May 26, 2015

3.22

Municipality Depth of

Cover (m)

Horizontal Pipe Separation (m) Vertical Pipe Clearance (m)

Sanitary

Sewers and

Water Mains

Sanitary and

Stormwater

Sewers

Water Main

Crossing above

Sewer

Water Main

Crossing below

Sewer

City of St.

Albert

2.6 to

obvert 3.0 1.8

sufficient

separation to

allow for proper

bedding

0.5

City of Leduc 1.8 to

obvert - - - -

City of Fort

Saskatchewan

2.8 to

obvert - - - -

City of

Edmonton

2.6 to

obvert - -

300 mm between

top of sewer and

bottom of water

line

500 mm

between

bottom of

sewer and top

of water line

City of Red

Deer

2.7 to

obvert 2.5 - - -

The design standards of all neighboring municipalities typically include a minimum depth of

cover for wastewater pipes. This is meant to ensure that the pipes are designed to be buried

sufficiently deep to prevent freezing in wintertime and creating back-up. Compared to water

line, the sewer line generally has a smaller depth of cover specified by some municipalities due

to the nature of the substance being conveyed and its ability to generate heat. The standard

depth of cover is similar in most municipalities (except Leduc) and ranges from 1.8 to 2.8 m. The

minimum required depth of cover in Strathcona County is 2.6 m. Without conducting an

investigation on the variation of frost depth within Sherwood Park, the depth of cover appears to

be reasonable.

The minimum clearance requirements between the wastewater line and the water or storm lines

are provided in Table 3.12 above. Providing a minimum clearance requirement ensures that

there is sufficient space to allow for adequate bedding, minimizes the risk of cross-contamination

in the case of a leak and allows space for maintenance in case of need for repairs. The

County’s specifications appear to be reasonable and in line with other municipalities and AESRD

requirements.

The County may wish to consider specifying minimum vertical separation for watermains crossing

above the sewer pipes of 300 mm.

STRATHCONA COUNTY



May 26, 2015

3.23


Based on the discussion above, it is recommended that the specifications on the sanitary sewer

alignments and location that are currently stated in the Strathcona County Design Standards

remain unchanged.

If the County wishes to specify minimum vertical separation for watermains crossing above the

sewer pipe, it is recommended that 300 mm clearance is specified to allow for adequate

bedding.

3.6 SANITARY MANHOLES

Section 4.2.1.8 of the Strathcona County Design and Construction Standards, Volume 1 provides

information on maximum spacing of manholes to provide access points for maintenance of the

line, maximum change in flow direction, the requirements for drops in the manholes, and

requirements where pipe size changes occur. Table 3.13 summarizes the requirements for

Strathcona County, AESRD and the neighbor municipalities.

Table 3.13 - Manhole Design Requirements

Municipality Maximum Spacing of

Manholes

Drops Pipes connecting

through MHs Straight Run

Sewers

Sewers that Change

Directions

Strathcona

County 150 m 12 mm 50 mm

the crowns

(obverts) of the

incoming mains

shall be designed

to match or be

higher than the

outgoing main

AESRD

120 m for up to 375 mm

150 m for 450 to 750 mm

>150 for pipes larger

than 750 mm

- - Match 80% Flow

depth

City of St.

Albert

135 m

92 m – curved sewer 12 mm 50 mm

the crowns, or

obverts, of the

mains shall be

placed at the

same elevation

STRATHCONA COUNTY



May 26, 2015

3.24

Municipality Maximum Spacing of

Manholes

Drops Pipes connecting

through MHs Straight Run

Sewers

Sewers that Change

Directions

City of Leduc 120 m

10 mm for a bend

in the pipe

alignment

between 0 and 10

degrees;

10 mm for a bend in

the pipe alignment

between 0 and 10

degrees; 30 mm for

a bend in the pipe

alignment between

10 and 45 degrees;

50 mm for a bend in

the pipe alignment

between 45 and 90

degrees.

The obvert

elevation of a

sanitary sewer

entering a

manhole shall not

be lower than the

obvert elevation

of the outlet

sewer

City of Fort

Saskatchewan

250 m for pipes that are

less than 600 mm in dia.;

150 m for pipes than

range from 675 mm to

1200 mm in dia.;

- 60 mm -

City of

Edmonton

150 m for sewers less

than 1200 mm in dia.;

500 m for sewers 1200 to

1650 mm in dia.; 800 m

for sewers larger than

1800 mm.

-

deflections less than

45° require a 30 mm

drop; deflections of

45° to 90° require a

60 mm drop.

The obvert

elevation of a

sewer entering a

manhole shall not

be lower than the

obvert elevation

of the outlet

sewer.

City of Red

Deer 150 m - 50 mm

the obvert

(crown) elevation

of the lowest

upstream pipe

shall be equal to,

or higher than the

obvert of the

downstream pipe

The design considerations for manhole spacing and drops are different among different

municipalities. A maximum manholes spacing is set to facilitate maintenance. With each

municipality having its own maintenance program, the requirements for maximum spacing are

also different. Strathcona County’s maximum spacing of manholes is reasonable based on the

review of other municipalities’ standards.

The drops across the manholes account for head loss as water passes through manholes. The

minimum required drop for a curved sewer is similar among municipalities and ranges from

50 mm to 60 mm. The requirement for 50 mm drop in the County Standards is reasonable based

on the desktop review of the various standards, as is the 12 mm drop for straight run sewers.

STRATHCONA COUNTY



May 26, 2015

3.25

In addition, for pipes connecting to manholes, all municipalities have the same requirement for

the elevation of the incoming pipe overt to be above or equal to the obvert elevation of the

downstream pipe. AESRD guidelines indicate matching 0.8 depth point of both sewers where

the difference in elevation is less than 600 mm.


Based on the discussion above, it is recommended that the design standards for manhole

spacing and drops not to be changed at this time.

3.7 SANITARY SERVICE CONNECTIONS

Section 4.2.1.9 of the County’s design standards has specifications on the minimum service main

size, minimum slope, and minimum depth of cover for service connections. In addition, this

section provides provisions for a sampling manhole and the conditions that trigger the need for

a manhole connection.

Table 3.14 below lists the minimum design requirements for Strathcona County in addition to the

requirements set by other municipalities. AESRD does not provide specific standards or guidelines

for the sanitary service connections.

Table 3.14 - Service Connections Design Requirements

Municipalities Minimum Size Required

Minimum

Grade

Required

Minimum Depth

of Cover

Requirement for a

Sampling MH

Strathcona County 150 mm 2% 2.6 m Yes

AESRD Not stated Not stated Not stated Not stated

City of St. Albert

100 mm – single family

150 mm – commercial,

multi-family.

2% 2.9 m

Yes, for commercial,

institutional and

multi-family.

City of Leduc 150 mm – single family 2% - Yes, for commercial

and industrial lot.

City of Fort

Saskatchewan 100 mm - - -

City of Edmonton 150 mm 1% 2.75 m -

The service connection must be designed to service the anticipated flow. The minimum pipe size

is specified to reduce the possibility of a blockage and therefore reduce the risk of back-flow.

The minimum service connection size varies slightly among different municipalities from 100 mm

diameter to 150 mm diameter. The County specification of a minimum size required for service

connections of 150 mm is reasonable based on the above desktop review.

STRATHCONA COUNTY



May 26, 2015

3.26

Minimum slope on the service connection is typically 2%, which is meant to provide a self-

cleansing flow velocity. Strathcona County’s minimum slope requirement is 2%, which is similar to

that specified by most of the other municipalities and is considered to be reasonable.

The minimum depth of cover is set to minimize the risk of pipe freezing and preventing to convey

the flow. The minimum depth of covers depends on the frost line in various areas. The County’s

minimum required depth of cover is slightly less than what other municipalities specify, however it

appears to be reasonable.

Most municipalities require a sampling manhole, especially for the commercial and industrial

lots. A sampling manhole is used to periodically sample and determine the composition of the

sewage, and to identify the type of chemicals that it contains. The County requires a sampling

manhole to be provided within the road ROW or frontage easement for each service to an

industrial or commercial lot.


The current County Standards for this section are considered to be adequate and it is

recommended that the current standards not be changed. Compared to the design standards

in other municipalities, the County’s design standards are reasonable.

STRATHCONA COUNTY


Summary of Recommendations

May 26, 2015

4.1

4.0 Summary of Recommendations

The following conclusions and recommendations are drawn from this standard review:

Section 4.3.1 – Water Distribution System

It is recommended that the water system operation parameters remains as currently

listed in the County Standards with the addition of a requirement for pressure control

measures where the system pressure is between 550 kPa and 700 kPa.

It is recommended that the existing 375 L/cap/day ADD be reduced to 330 L/cap/day.

It is recommended that the non-residential water consumption is determined on a case-

by-case basis as currently indicated in the County standards.

Proposed water consumption rate be reviewed after 5 years to determine if further

reduction is necessary.

To clarify the fire flow requirements for each type of zoning, it is recommended that the

County Standards keep the reference to the “Water Supply for Public Fire Protection, A

Guide to Recommended Practice” by the FUS for determining fire flow requirements.

It is recommended that the County standards include a definition of high value

properties: commercial, institutional, industrial sites.

Water distribution system pipe sizes should be determined based on hydraulic network

analysis. Pipe sizes determined based on hydraulic network modeling should not be

smaller than the minimum pipe sizes listed in the County Standards.

It is recommended that the County standards with reference to the minimum diameter

of the water service remain unchanged as the current specifications are reasonable and

in agreement with the standards used by other municipalities with an addition of the

service connection diameter based on system pressure, similar to the City of Edmonton

standards.

No changes are proposed at this time to the County design standards pertaining to

minimum pipe sizes and hydrant spacing requirements.

Section 4.2.1 – Sanitary Sewer System

It is recommended that the sewage generation rate be reduced to 300 L/cap/day,

however the peaking factor should remain unchanged.

It is our recommendation that Strathcona County continue to maintain a design

population density of 3.5 people/unit. A lower population density of approximately

2.5 people/unit is used for multi-family residential units by adjacent municipalities and the

use of such a population density should be considered by Strathcona County as

applicable.

STRATHCONA COUNTY


Summary of Recommendations

May 26, 2015

4.2

It is recommended that the County specifications continue to stipulate that the average

sewage flow must be computed on an individual basis. For planning purposes,

18 m3/ha/day is reasonable amount to be used for commercial/light industrial

developments.

It is recommended that a note be added to the County standards where the peaking

factor for non-residential flow can be computed on an individual basis; however at the

planning level it can be computed based on this peaking factor formula used by some

of the other municipalities: P = 10 ∗ Q−0.45, (min 2.5, max 25).

Based on the sanitary sewer system model simulation results for the 1:25 year 24 hour

design rainfall events, the County’s current I/I allowance rate of 0.5 L/s/ha be reduced to

0.4 L/s ha.

No changes are proposed at this time to the County design standards pertaining to

minimum and maximum allowable flow velocity range and the minimum acceptable

pipe slope specifications, pipe alignments and location, manhole spacing and drops,

and service connection design.

THE URBAN DEVELOPMENT INSTITUTE OF ALBERTA

GREATER EDMONTON CHAPTER

#324 Birks Building, 10113 - 104 Street Jasper Avenue, Edmonton, AB T5J 1A1 Ph. 780-428-6146 Fax 780-425-9548

Email: [email protected] Web: www.udiedmonton.com

April 8, 2015 (sent via e-mail)

Strathcona County 2001 Sherwood Drive Sherwood Park, AB T8A 3W7

Attention: Mr. Rob Coon – CAO and Co-Chair Strathcona County Developer Committee

Re: Strathcona County - Design and Construction Standards Review 2015

The UDI Strathcona Technical Committee has reviewed the proposed revisions to

the referenced standards and is pleased to advise that UDI supports the proposed

standards excepting those items outlined below.

Water Distribution Proposed By County UDI Would Accept

Average daily consumption

330 L/person/day 300 L/person/Day

Minimum Residual Pressure At peak hour consumption

330 L/person/day 300 kPa, but require 25mm services where less than 350 kPa

Wastewater Criteria Proposed By County UDI Would Accept

Peaking Factor Harmon Formula 2.6 X P - 0.1, but provision in new lines for 40 % more than design capacity.

Enclosure 3

mailto:[email protected]

http://www.udiedmonton.com/

Wastewater Criteria (continued)

Proposed By County UDI Would Accept

I/I Rate 0.40 L /sec/ ha 0.28 L/sec/ha where weeping tile is not connected to sanitary. Implementation of watertite technology must be enforced.

Storm Drainage Proposed By County UDI Would Accept 45o bends on all pipe 600

mm and up Require justification, and If justified, allow bend without extra manhole.

Building Permit Requirements

Proposed By County UDI Would Accept

All infrastructure, except landscape

Water, drainage, wastewater, curb and gutter, and first lift paving, except if weather shuts down paving by or before Oct 25, proper sub grade and gravel to gutter lip would be acceptable.

As discussed at our meeting, the developers and builders would provide information to home purchasers regarding a schedule of improvements not in place at the time of their purchase and reinforce that concerns/complaints are to be made to the builder/developer and not Administration or Council.

The revisions UDI is requesting are representative of standards in other major municipalities in the Capital Region with some added factor of safety in some cases. We believe our proposal does not detract from reasonable level of service.

UDI would like the opportunity to make representation directly to County Council if UDI’s counterproposals, as indicated above, are found to be unacceptable.

We thank you for the opportunity to review the standards and work with Administration to make Strathcona County a better place to do business.

Sincerely,

R.F. (Bob) Horton, P. Eng. Co-Chair Strathcona County Developer Committee Copied by e-mail: Kevin Glebe – Strathcona County

Stacy Fedechko – Strathcona County Jessica Jones – Strathcona County Rick Preston - Executive Director, UDI UDI Members – Strathcona County Developer Committee

Strathcona CountyDesign and Construction Standards Update

Section 4.2 - Sanitary Sewer (Wastewater) SystemSection 4.3 - Water Distribution System

Priorities Committee Meeting Date: June 16, 2015Presented by: UtilitiesDocument: 7327982

Enclosure 4

Purpose for Review

• Strathcona County Design and Construction Standards– Current version is December 2011– Last major edits to the Water and Wastewater Sections was in 1998/1999

• 2015 Update included a review of:– Customer demographics and behaviors– State of current infrastructure– Performance risk– Climate impact– New technologies, materials, construction practices, etc.– Cost to construct

2

Design and Construction Standards

• Each municipality develops minimum servicing requirements (design standards) based on historical system performance, operation / maintenance perspectives, level of service, risk tolerance and economic factors.

• Strathcona County is responsible to ensure the design and construction of infrastructure holds paramount health, safety and welfare of the community.

• Standards are science-based and are intended to balance current conditions with future system resiliency.

3

Engineering Consulting Firm

• Administration commissioned Stantec Consulting Ltd. to review:– Volume 1 – Design Standards

• Section 4 – Urban Service Area Standards– 4.2 Sanitary Sewer (Wastewater) System, and– 4.3 Water Distribution System

• Stantec performed a science-based review including review of:– Alberta Environment and Sustainable Resource Development (AESRD)

Standards and Guidelines for Municipal Waterworks, Wastewater and Storm Drainage Systems

– Other municipal standards• Reviewed nine (9) surrounding municipal standards

4

SECTION 4.2 SANITARY SEWER (WASTEWATER) SYSTEM

Design and Construction Standards Update

5

Doc #7327982

Sanitary Sewer (Wastewater) System– Flow Monitoring Data

• Ten flow monitoring locations within the Urban Services Area• Dry weather flow generation for 2010, 2011 and 2012• Five significant rainfall events that occurred in 2011, 2012 and 2014

– Rainfall Data• Three rainfall gauges within the Urban Services Area• Five significant rainfall events that occurred in 2011, 2012 and 2014

– Hydraulic Wastewater Model• Original model software was XP-SWMM, however converted to MIKE URBAN for more effective

calibration results• Used census data to determine actual sewage generation rates• Current land uses

– Neighbourhood Age• Analyzed to identify flow variation between older and newer neighbourhoods (e.g. weeping tile vs.

sump pumps)

– Adjacent Municipal Standards6

Summary of ChangesSection 4.2 Sanitary Sewer (Wastewater) System

Section December 2011 Standards Updated 2015 Standards

Average Residential Wastewater Generation Rate 4.2.1.2 (i) 375 L/person/day 300 L/person/day

Commercial /Industrial Peaking Factor 4.2.1.3 (ii)The peaking for commercial/ industrial development varies greatly with the type of development. Each case must be considered on an individual basis.

Each case may be considered on an individual basis; however for planning purposes 10 xQ-0.45

(min 2.5, max 25) shall be used.

Inflow and Infiltration (I/I) Allowance 4.2.1.4 (i) 0.5 L/sec/gross ha 0.4 L/sec/gross ha

Vertical Separation 4.2.1.10 (iii) n/a Added the allowance of bridging options if 0.5 m is not achieved.

Minimum Depth of Cover 4.2.1.10 (iv) 2.6 m 2.75 m

Manhole Flow Direction 4.2.1.11 (vi) Shall not exceed 90 degrees. Added second criteria of 45 degrees for 600 mm and larger.

Manhole Safety Platforms 4.2.1.11 (xii) Did not specify maximum spacing. Maximum spacing of 5 m.

7

Summary of ChangesSection 4.2 Sanitary Sewer (Wastewater) System

(Continued)Section December 2011 Standards Updated 2015 Standards

Lift Stations and Wastewater Forcemains 4.2.1.13 n/a Full section added.

Pre-cast Manholes 4.2.2.4 (i) n/a Manufacturers must possess a current plant prequalification certificate.

Manhole connections 4.2.3.5 (ii) n/a Flexible manhole connectors are required when flexible systems connect to a concrete manhole.

8

UDI Proposed Wastewater Revisions

Wastewater Criteria Proposed by County UDI Would AcceptPeaking Factor Harmon Formula 2.6 X P -0.1, but provision in

new lines for 40% more than design capacity.

Inflow/Infiltration Rate 0.40 L/sec/ha 0.28 L/sec/ha where weeping tile is not connected to sanitary. Implementation of watertight technology must be enforced.

9

Sewage Generation Rate

• Stantec recommends 300 L/person/day (reduced from 375 L/person/day) based on:

– Average sewage generation rate is 272 L/person/day (flow monitoring)– Variability in data attributed to I/I from snow melt or minor rainfall, variation in groundwater inflow and

accuracy of flow monitoring data

• Adjacent Municipality comparison:

City of Edmonton 300 L/person/dayCity of St. Albert 320 L/person/dayCity of Leduc 360 L/person/dayCity of Fort Saskatchewan 360 L/person/day

10

Peaking Factor• What is a Peaking Factor?

– It is a multiplier that is applied to the average sewage generation rates to determine the maximum wastewater rate

• Strathcona County Standard– Harmon formula with a minimum value of 3

• City of Edmonton Standard– Introduced in 1997 based on several years of flow monitoring records from the City of Edmonton– The City of Edmonton’s standard has a minimum value of 1.5

0

0.5

1

1.5

2

2.5

0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00

Flow

Time

11

Peaking Factor (Continued)

• Stantec recommends using the Harmon Formula (no change from current standard) based on:

– The average computed peaking factor was 2.2 – Harmon Formula provides a more conservative peaking factors for smaller populations– Flow monitoring data fluctuates very significantly throughout the year

• Fluctuations may be due to actual variation in flow rates or the accuracy of the flow monitoring equipment

– AESRD Standards and Guidelines for Municipal Waterworks, Wastewater and Storm Drainage Systems uses Harmon Formula

– Harmon Formula is used by most municipalities in North America


City of Edmonton 2.6 x P-0.1

City of St. Albert Harmon FormulaCity of Leduc 2.6 x P-0.1

City of Fort Saskatchewan 2.6 x P-0.1

12

Peaking Factor (Continued)

Flow MonitorArea*

Population Average/Range of Monitored PF

HarmonFormula

City ofEdmonton2.6 x P-0.1

UDI2.6 x P-0.1

plus 40%Estates of

Sherwood Park933 2.49

(2.3 – 2.66)3.82 2.62 3.67

Nottingham 3,408 2.15(2.00 – 2.33)

3.39 2.30 3.22

Northeast Trunk 32,640 2.01(1.73 – 2.30)

2.44(min. of 3)

1.83 2.56

* These flow monitoring areas were chosen because they have a minimal amount of non-residential contributing areas and represent relatively new service areas.

• The variation between Harmon and the City of Edmonton is greater (50% higher) for smaller populations (Estates and Nottingham) and not as significant (20% higher) for larger populations (Northeast Trunk).

13

Inflow / Infiltration• What is Inflow and Infiltration (I/I)?

– Inflow: extraneous water that enters the sewer system from rainfall directly through manhole covers and weeping tile connections

– Infiltration: extraneous water that enters the sewer system through pipe joints, deteriorated pipes (cracks), sewer pipe connections to manholes, deteriorated manhole barrels (joints and cracks) and improperly installed / defective service connections

• Strathcona County Existing I/I ProgramsManhole plugging / sealing Manhole lid replacementsSump pump retrofit Step fill in older areasLot grading improvements Manhole re-habilitation program (mortaring) Catch basin / manhole inspection program Mainline CCTV and reliningLeak detection / repair

14

Inflow / Infiltration Rate• Stantec recommends 0.4 L/sec/ha (reduced from 0.5 L/sec/ha) based on:

– The simulated calibrated model results (with a focus on newer areas)– I/I rate in new areas will likely increase in the future as sewer system ages and lot

grading deteriorates– Need more accurate and reliable flow monitoring data (of magnitude rainfall events)

to verify / refine the model– I/I standard should account for rainfall events greater than a 1:25 year

• The City of Edmonton has experienced rainfall events greater than 1:25 year resulting in numerous sewer back ups. They are developing new design rainfall hyetographs with significantly higher rainfall volumes and intensities.

15

Inflow / Infiltration Rate (Continued)

City of Edmonton 0.28 L/sec/haCity of St. Albert 0.28 L/sec/haCity of Leduc 0.28 L/sec/haCity of Fort Saskatchewan 0.28 L/sec/ha

16

– Sewer back-ups result in significant social and financial cost to homeowners– The cost to construct an additional pipe size during development (greenfield

construction) has far less economic impact than retrofitting a fully developed area


Inflow / Infiltration Rate (Continued)Flow Monitor

Description EventJuly 25, 2014

(~1:25 Year 12 hr)1: 25 Year24 Hour

1:25 Year4 Hour

Simulated FS* Simulated FS* Simulated FS*50 West Sherwood Park 1.61 0.3 1.35 0.3 1.61 0.3

49 Older Residential Area 1.86 0.2 1.4 0.3 1.68 0.2

66 Older Residential Area 0.37 1.1 0.35 1.2 0.30 1.3

96 Newer Residential Area 0.56 0.7 0.59 0.7 0.83 0.5







Entire System

All model Service Area 0.63 0.6 0.61 0.7 0.58 0.7

17

*FS: Factor of Safety in relation to proposed standard.

Comparison of Design Standards in the Edmonton RegionPEAK DRY WEATHER FLOW

0.40

0.330.35

0.40

0.52 0.52

0.57 0.59 0.590.61

0.490.46

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

Litres/sec for Peak Dry Weather FlowPopulation of 2400

Peak Dry W

eather Flow

Litres/sec

CurrentDesign

Standards

ProposedDesign

StandardsUDI

RequestedStandards

18

Comparison of Design Standards in the Edmonton RegionPEAK TOTAL WASTEWATER FLOW

Dry Weather Peak Flow

Wet Weather Flow (I/I)

0.400.33 0.35

0.40

0.52 0.520.57 0.59 0.59 0.61

0.49 0.46

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

Litres/sec/ha for Peak Total Wastewater FlowBased on 40 persons/ha and Population of 2400

Peak Total W

astewater Flow

Litres/sec/ha

CurrentDesign

Standards

ProposedDesign

StandardsUDI

RequestedStandards

0.680.61 0.63

0.68

0.80 0.800.85 0.87 0.87

1.11

0.89

0.74

19

Section Summary4.2 Sanitary Sewer System

• The standards where positions diverge serve to protect residents from peaks generated in the wastewater system– Peaks are generated on a daily basis by resident usage patterns– Peaks are generated by inflow and infiltration during rainfall events– The municipality has the responsibility to determine an appropriate safety factor or

level of protection it wishes to provide to its residents– The cost of retrofit is much greater than the cost of adding capacity at time of

development

20

SECTION 4.3 WATER DISTRIBUTION SYSTEM

Design and Construction Standards Update

21

Doc #7327982

Water Distribution System– Water Consumption

• Monthly billing records from 2010 to 2012• Used census data to determine actual consumption rates• Current land uses

– Climate Factors (Temperature and Precipitation)• Metrological Data for 2010 to 2012 from Environment Canada• Data recorded at the Edmonton International Airport

– Neighbourhood Age• Analyzed to identify any significant variation in residential consumption between older and newer

neighbourhoods

– 2011 Municipal Water Use Report – Environment Canada• In Canada, 1,590 municipalities responded to a survey about residential water use

– 2011 EPCOR Waterworks Statistics– Adjacent Municipal Standards

22

Summary of ChangesSection 4.3 Water Distribution System


Residential Design Consumption 4.3.1.2 Average Day Demand375 L/person/day

Average Day Demand330 L/person/day

Commercial /Industrial Design Consumption 4.3.1.3 n/a

20,000 L/ha/dayFor preliminary planning purposes. Each

application shall be reviewed on a case-by-case basis.

Mid Value Multi-Family Fire Demand 4.3.1.4 (ii) n/a 180L/s (Applicable land uses as per Land Use Bylaw 8-2001 – R2A, R2B R3)

Casing Requirements under Arterial Roads 4.3.1.8 (iv) n/aCasings are required for all water mains crossing arterial roads. At a minimum, the casing must

span the extents of the carriageway.

Blow Off Valves 4.3.1.10 (iii) Blow off valves need to be sized to achieve a minimum flushing flow of 0.6 m/sec

Blow off valves must be a minimum of 50 mm in size.

Pressure Control Valves 4.3.1.11 n/a Full section added.

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Summary of ChangesSection 4.3 Water Distribution System (Continued)


Service Connections 4.3.1.12 (viii) n/a Curb stop located in driveway or hard surface must be placed in PVC sleeve

Interlocking Polyvinyl Chloride (PVC) Pipe 4.3.2.2 Was listed as an approved PVC pipe material Material removed

Tapping Valve Sleeves 4.3.2.4 n/a Full section added

Hydrants 4.3.2.7 (i) n/a Hydrant upper barrel and nozzle section must be a single cast unit

Gate Valves 4.3.2.8 (i) n/a Added 350 mm valve size

Air Release Valves 4.3.2.8 (iii) n/a Full section added

Pressure Control Valves 4.3.2.8 (iv) n/a Full section added

Service Saddles 4.3.3.7 (v) Service saddles must be used for larger size copper services

Service saddles must be used where the tap diameter is greater than 25 mm or where the

water main is greater than 300 mm

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UDI Proposed Water Revisions

Water Distribution Proposed by County UDI Would AcceptAverage daily consumption

330 L/person/day 300 L/person/day

Minimum Residual Pressure at Peak Hour Consumption

350 kPa 300 kPa, but require 25 mm services where less than 350 kPa

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Average Day Demand• Stantec recommends 330 L/person/day (reduced from 375 L/person/day) based

on:– Actual annual average consumption rate is ~ 200 L/person/day (billing records)– Overall trend indicating reduction in consumption rate due to more efficient fixtures– Added leakage allowance to the actual billing record– Design safety factor of 1.5 to account for risk mitigation

• Accounts for variation in monthly consumption rate such as for June in 2010 and 2011 where the average monthly consumption rates were ~ 299 and 272 L/person/day respectively


City of Edmonton 250 L/person/dayCity of St. Albert 350 L/person/dayCity of Leduc 360 L/person/dayCity of Fort Saskatchewan 360 L/person/day

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Average Day Demand (Continued)

• Stantec also recommends that the average day demand be reviewed after five years to determine if further reduction is necessary.– Future reduction should be considered carefully due to a wide variety of

factors including:• Demographic variations• Climate fluctuations• Socio-economic variables• More comprehensive monitoring

• From a design perspective, fire flow requirements govern the required pipe sizing. The average day demand is mainly important in reservoir (storage) design.

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Minimum Residual Pressure at Peak Hour Consumption

• Standards update recommends a minimum residual peak hour pressure of 350 kPa (no change from current standard) based on:– Maintaining a level of service to urban residents

• Minimum pressures are provided to sufficiently operate fixtures without the aid of homeowner pumping

• Administration has received resident complaints in areas within the Urban Services Area that are at or slightly below the minimum 350 kPa residual pressure


City of Edmonton 280 kPaCity of St. Albert 280 kPaCity of Leduc 280 kPaCity of Fort Saskatchewan 275 kPa

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Section Summary4.3 Water Distribution System

• The standards where positions diverge are level of service considerations– Average day demand drives reservoir design; storage is a critical tool in regards to

water demand management– Minimum residual pressure is a service level that residents experience frequently– The municipality has the responsibility to determine a level of service that aligns with

resident expectations

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Other Feedback

• UDI provided comment on storm drainage and building permit requirements

• This feedback will be incorporated into reviews of other sections of the design and construction guidelines

• This work will follow the completion of the update to the water and wastewater standards

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SUMMARYDesign and Construction Standards Update

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Doc #7327982

Summary

• Stantec Consulting Ltd. performed a science-based review

• Where prudent, standards were lowered

• In other cases, standards were maintained to ensure an adequate level of service for residents

• Balance between cost for development and protection for residents– Immediate costs are often less in cost and community impact than future

costs

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priorities committee meeting jun16 2015 …...2015/06/16 · priorities committee...

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