implementation process of an iswm construction ordinance · 2012-07-17 · june 26, 2012...

June 26, 2012

Implementation Process of an iSWM Post Construction Ordinance 1

Implementation Process of an iSWM Post Construction Ordinance

Lesley Brooks, P.E., CFM

Ben McWhorter, EIT

North Central TexasCouncil of Governments

Agenda

15 min. Overview of iSWM

5 min.State and Federal Regulations Regarding Water Quality

30 min.Using iSWM to Meet Post Construction Requirements

10 min. iSWM Effect in the Region

June 26, 2012


Overview of iSWM


What is iSWM?

A regional program to assist local governments:

– Manage stormwater impacts– Meet MS4 Permit requirements

Collaborative effort between:– Over 65 local governments– iSWM Committee– Regional Public Works Council

– Consultant team led by Freese and Nichols

June 26, 2012


Where Does iSWM Come From?

Overview of iSWM Program

iSWM Criteria Manual

(For Adoption)

iSWM Technical Manual

(For Reference)

iSWM Tools

(For Reference)

iSWM Program Guidance

(For Reference)

iSWM Program

http://iswm.nctcog.org

June 26, 2012


Criteria Manual

• What’s in the Criteria Manual?

– 84 pages, as is

• Chp. 1: Overview of iSWM Criteria Manual

• Chp. 2: integratedDevelopment Process

• Chp. 3: integrated Design Criteria

• Chp. 4: integrated Construction Criteria

What’s Different?

1. Development Process

• Stormwater ‐ early and often

• Get the right people involved

2. Downstream Assessments

• Detention not always the answer

• See what downstream can handle first

June 26, 2012


What’s Different?

3. Water Quality

• 3 Options to meet TCEQ MS4 Requirements

4. Flooding & Erosion Protection

• 3 Options to reduce problems downstream


Options:1. Use integrated Site Design Practices. Measured with a point system based on the percentage of natural features on a site and the percentage of practice utilized.

2. Treat the runoff resulting from rainfalls of up to 1.5 inches (85th percentile storm).

Water Quality * Streambank Protection * Flood Control

Page 6 of Criteria Manual

3. Assist in implementing off‐site community stormwater pollution prevention programs/activities.

June 26, 2012


Option 1: Site Design

• Requirements Based on Natural Features

Natural Features:• Unfilled floodplain• Stand of trees, forests• Established vegetation

• Steep sloped terrain• Creeks, gullies, and other natural

stormwater features• Wetland areas and ponds

Page 17‐22 of Criteria Manual

Option 1: Site Design

June 26, 2012


Option 2: Treat 1.5” Rainfall

Treating the 1.5 inch (85%) Rainfall Event

• Why 85th Percentile?

– Several entities nation wide chose the 85th

percentile storm.

• How was 1.5” calculated?

– In 2003 precipitation data for North Texas was obtained from NOAA and the 85th percentile was calculated as 1.5 inches.

Page 22‐25 of Criteria Manual

Option 3: Regional Approach

• Not many cities in the state have an organized regional water quality plan.

• Water Quality Master Plans will be required in the future for cities to use this option.

June 26, 2012



Options:1. Reinforce/stabilize downstream conditions.

2. Install stormwater controls to maintain or improve existing downstream conditions.



3. Provide on‐site controlled release of the 1‐year, 24‐hour storm event over a period of 24 hours.


Options:1. Provide adequate downstream conveyance systems.

2. Install stormwater controls on‐site to maintain or improve existing downstream conditions.



3. Maintain existing on‐site runoff conditions in lieu of a downstream assessment.

June 26, 2012



Construction

Chapter 4 of Criteria Manual

State and Federal Regulations Regarding Water Quality


June 26, 2012


TCEQ Permitting Program

TPDES Permitting Program

MS4s(Post Construction

Controls)

Phase I

Phase II

Construction Industrial

Phase I vs. Phase II

Phase I Phase II

Individual Permits

Will trend towards Phase II in the future

Focus areas:• Storm mapping• Construction waste • Public outreach

6 Requirements for all Phase IIs:• Illicit discharge• Public Education• Public Involvement• Good Housekeeping• Post Construction

Controls• Construction Site

Controls

June 26, 2012


Current Phase II MS4 Permit

• Must address runoff from new development and re‐development of 1 acre or more

• Must ensure controls are in place that would prevent or minimize water quality impacts. The permittee shall:

– Develop and implement strategies which include a combination of structural and/or non‐structural BMPs appropriate for the community;

– Use an ordinance or other regulatory mechanism to address post‐construction runoff to the extent allowable by state and local law; and

– Ensure adequate long‐term operation and maintenance of BMPs.

Deadlines and New Permits

• MS4’s required to fully implement Stormwater Master Plan by end of August 2012.

• New Phase II Permits

– Draft new permit to be issued

– Key proposed changes

• Focus on volume control, impervious area

• Emphasize LID

June 26, 2012


Using iSWM to Meet Post Construction Requirements


Where to Start

1. Create a committee of decision makers

2. Discuss main goals and responsibilities

3. Review existing materials

4. Develop new City specific materials

5. Fix conflicts in existing documents

6. Public involvement

7. Staff training

June 26, 2012


1. Create a Committee

1. Create a Committee

• Every committee needs a champion

–Point of contact

–Organizes meetings

–Compiles comments

–Good working relationship with all departments

June 26, 2012


2. Discuss goals

• Do you want to call it iSWM?

–Requires a licensing agreement with NCTCOG

–Payment based on City population

COG Policy on Implementation

iSWM Element Points for Element

City Points

3 – Step Review Process (Concept, Preliminary, Final) 15

Water Quality Option 1: integrated Site Design Practices 10

Water Quality Option 2: Treat the Water Quality Protection Volume 10

Water Quality Option 3: Off‐Site Pollution Programs/Controls 10

Downstream Assessment for 3‐Storm Events (Streambank Protection, Conveyance, Flood Mitigation) 15

Streambank Protection* (Require Options 1, 2 and/or 3) 15

Flood Mitigation** (Require Options 1, 2 and/or 3) 15

integrated Construction Criteria 10

Points Available 100 100

Minimum Points Required 70 70

City Score

* Requires Downstream Assessment**Requires Downstream Assessment if using iSWM Criteria. As an alternative, Community qualifies for Flood Mitigation points if a community‐wide drainage study / master plan has been developed and no development is allowed in the fully developed 100‐year floodplain.

• Community must be a current participant of the Regional Public Works Program.

• Community must adopt the iSWM Criteria Manual for Site Development and Construction (Manual) with Local Provisions as desired – OR – the Community must incorporate or reference portions of the Manual into codes, ordinances, drainage manual, etc.

• Community’s adoption or incorporation of elements of the iSWM Criteria Manual for Site Development and Construction must meet a minimum of 70 points in accordance with the table.

• Note that no License Agreement is required for use of the iSWM Technical Manual.

June 26, 2012


2. Discuss goals

• What kind of development does your community want to attract?

– LID design is harder to regulate but results in aesthetic and sustainable development

2. Discuss goals

• Is meeting the minimum MS4 requirements priority or can more be done?

–How do you want to handle redevelopment? Are there additional standards you want to include?

June 26, 2012


3. Review Existing Materials

• Gather all existing materials and become familiar with where they are located

–Development Process

–Development checklists

– Existing manuals

–Ordinances related to stormwater and landscaping. Are they in Zoning or Subdivision Ordinances?

3. Review Existing Materials

Reviewing the Development Process

• iSWM has 3 development review stages

• What are your steps?

• What is the earliest stormwater is discussed?

• Could that discussion be moved earlier?

June 26, 2012


4. Develop New Materials

Two Main Option to Incorporate iSWM

1. Use the Criteria Manual


Two Main Option to Incorporate iSWM

2. Create separate materials to adopt a Post Construction Ordinance

– Add a chapter to your existing drainage manual and adopt through an ordinance

– Add language to an ordinance detailing requirements

June 26, 2012



• Possible Downstream Assessment Changes/Additions

– Identify the point of influence downstream. 10% rule or confluence?

10 acres

40 acres80 acres

120 acres

190 acres

Site A

Site B


• Possible Water Quality Changes/Additions

–Update Option 1 point system, define natural features

– Set treatment removal rates to Option 2 based on TSS removal rates or average removal rates

–Provide alternatives to Option 3 are eliminate

June 26, 2012



• Possible Stormwater Controls Changes/Additions

–Do you want to specify materials?

–Are there stormwater controls that will not be allowed?

–Do you want to develop details and specifications?


• Additional Changes/Additions

–Are there to be any technical changes regarding hydrology and hydraulics?

–Review applicability requirements.

–Add ordinance language for maintenance, inspection, and enforcement of structural controls.

June 26, 2012


5. Review for Conflicts

• Review ordinances to determine if there are any conflicts with new language.

• Make changes in the ordinance or to remove conflicts.

• Conflicts addressed by variance may inhibit some developers.

6. Public Involvement

• Inform outside stakeholders

–Council members

–Developers

–HOAs

–Consulting FIRMs

• Emphasize options

June 26, 2012


7. Staff Training

• What to look for in the review process

• How to check technical data

• How to oversee construction

• Maintenance and inspection efforts

iSWM Effect in the Region


June 26, 2012


City Status with iSWM

1. Cities that have implemented an iSWM license

• Azle, Benbrook, Dallas, Duncanville, Fort Worth, Glenn Heights, Grand Prairie, Mansfield, Roanoke, Seagoville

2. Cities that may implement in the future

• Allen, Bedford, Coppell, Denton, Frisco, McKinney, Murphy, Terrell, Lakeside, Southlake

3. Cities that have adopted a post construction ordinance

• The Colony, Garland, Arlington

4. Untold cities who are referencing through Fort Worth or Dallas

Feedback from City Leaders

• Why adopt iSWM? – We were referencing another City’s manual who adopted iSWM so

followed suit. Made a few changes based on local needs.

– Trying to move towards more open space and more natural sites. More about aesthetics than water quality. iSWM gave us the opportunity to put “encouragements” into writing.

– It was in our SWMP and all the existing standards made it easier than starting from scratch.

• What difference has it made? – One development has had significant drainage issues.

Used iSWM to design a detention pond that will serve as sediment basin during construction and retention pond after construction.

– We think about water quality impacts earlier rather than after the fact

June 26, 2012



• What do you hope it will accomplish? – Hope it will set a standard that developers and designers can

reference that will increase the quality of stormwater management in the region, as well as within the City limits.

– We would all benefit from cities having the same codes. We should all use iSWM as closely as possible to the way it is written for drainage design as well as water quality design. This will benefit the development and consulting industry in making for an easier transition to these requirements, and it will shorten the learning curve for all of us. We also reduce drainage related lawsuits if all cities have the same standards. Texas drainage law is vague, protection from liability depends on all engineering experts having agreement on acceptable industry practices.

– Improve quality of creeks, reduce volume of material removed from storm sewer maintenance, reduce sediment build up in ditches, and standardize drainage design.


• Who was involved in implementation? – Environmental Services and Engineering Department.

Future updates will involve the Planning Department and City Management.

– Public works staff and City Attorney.

• What was your path of implementation? – Based on another City’s adoption. Reviewed their local

criteria and made changes where necessary.

• What advice do you have for other communities? – Provide plenty of education to Public Works officials, work with

them to add local provisions, and be flexible.

– Seems overwhelming in the beginning. But, once you get into the nuts and bolts and compare that to your current drainage requirements there are not that many differences.

June 26, 2012


Corgan Assoc. Building, Dallas

• Downtown at the corner of Houston and Ross• Retrofits to historic building made in February 2007• Certified LEED Silver• Rain harvesting cistern measuring 10’ in diameter and 10’ tall• Cistern used for irrigation of property landscaping

Rayzor Ranch, Denton

• Designed using iSWM Criteria

• 410 acre Mixed Use Development

June 26, 2012




June 26, 2012



Denton, TX

Recently received a Section 319 Grant to proceed with a number of other BMP projects

• Swales and dry detention at firehouse

• Bioretention system at treatment plant

BMPs at Dog Park

Bioretention at Denton Municipal Airport

June 26, 2012


University of Texas ‐ Dallas

• Updated entrance way as part of a central campus redesign

• Entrance includes a larger filter strip between two roads on University Parkway from Campbell Road

• Alternative cul‐de‐sac design

Elm Fork, Dallas

June 26, 2012


Elm Fork, Dallas

Merritt Road, Rowlett

• Approx. 9,070 foot roadway project

• Approx. 3,600 feet of bioretention swales

• Between Liberty Grove Road and Pleasant Valley Road

• To be constructed Fall 2011 to Spring 2013

June 26, 2012


Merritt Road, Rowlett

LID Design Competition

June 26, 2012


Lesley Brooks, PE, [email protected]‐217‐2248

Ben McWhorter, [email protected]‐217‐2273

Mike Wayts, PE, CFM [email protected]‐217‐2222

QUESTIONS?

Jeff [email protected]‐695‐9212

Jack [email protected]‐695‐9220

implementation process of an iswm construction ordinance · 2012-07-17 · june 26, 2012...

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