14201 stormwater report-compiled 150217

STORM WATER MANAGEMENT REPORT

Trinity College

Athletic Field Complex & Site Improvements Hartford, Connecticut

Prepared by:

SMRT, Inc

One Dundee Park, Suite 4

Andover, Massachusetts 01810

Revision of CHA Stormwater Management Report dated September 2011

SMRT Revision 0 - February 2015

SMRT Project Number 14201

TABLE OF CONTENTS

1 PROJECT NARRATIVE............................................................................................................... 3

1.1 Introduction ................................................................................................................... 3

1.2 Historic Flooding ............................................................................................................ 3

1.3 Alterations to Natural Drainageways ............................................................................. 3

1.4 Existing Soils Conditions ................................................................................................. 4

1.5 Methodology and Modeling Assumptions ..................................................................... 4

1.6 Project Impacts .............................................................................................................. 5

2 STORM WATER ANALYSIS ....................................................................................................... 6

2.1 Pre-Development Conditions ......................................................................................... 6

2.2 Post-Development Conditions ....................................................................................... 6

2.3 MDC Peak Flow Stormwater Quantity Requirements ................................................... 7

2.4 CT DEEP General Permit Stormwater Quality Requirements ........................................ 8

3 CONCLUSIONS ......................................................................................................................... 8

4 REFERENCES ............................................................................................................................ 8

FIGURES

Soil Survey Map

FEMA Flood Insurance Rate Map

Synthetic Turf Section

Porous Pavement Section

Pre-Development Watershed Plan

Post-Development Watershed Plan

APPENDICES

Appendix A-1 - Pre-Development Conditions Analysis

Appendix A-2 - Post-Development Conditions Analysis

Appendix A-3 - Water Quality Calcultions

Appendix A-4 - Geotechnical Boring Logs

Appendix A-5 - Stormwater System Maintenance Schedule

Appendix A-6 - CT DEEP Permitting Documents

Trinity College

Athletic Field Complex & Site Improvements

Stormwater Report

February 2015

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1 PROJECT NARRATIVE

1.1 Introduction

The proposed project involves improvements to the athletic field complex located on the Trinity

College campus in Hartford, Connecticut. The existing complex consists of natural grass softball,

baseball, soccer, and lacrosse fields. The proposed project includes the installation of a synthetic

turf softball field, a synthetic turf baseball field, a synthetic turf soccer field as well as discus and

javelin throws. Also included in the improvements are the installation of sidewalks, dugouts at

the softball and baseball fields, permanent grandstand seating at the baseball field, and

associated subsurface utilities.

In 2011 CHA of Rocky Hill, Connecticut permitted this project with the understanding that the

soccer field would remain a natural grass field. At this time, SMRT is re-evaluating the

stormwater analysis based on the soccer field being constructed as synthetic turf. As such,

SMRT has updated the stormwater analysis and report to reflect this new change. The only

change to the proposed ground cover is the addition of the synthetic turf soccer field.

The site is bounded by Broad Street to the east, an existing walk (through Trinity Colleges

campus) to the west, the Ferris Athletic Center to the south, and the synthetic turf football field,

track and synthetic turf field hockey field to the north.

The total drainage area for the project is 13.9 acres. Approximately 12.18 acres will be

disturbed as a result of this project. In an effort to reduce the new impervious area associated

with the project, the proposed sidewalks (approximately 0.49 acres) will be constructed utilizing

porous pavement. The only new impervious areas associated with this project are the dugouts,

the permanent grandstand seating, and the paved throw areas. Total new impervious area for

the project is approximately 0.18 acres.

Based upon the planned development, this report identifies proposed methods of stormwater

management in accordance with the requirements of the Metropolitan District Commission

(MDC) and the State of Connecticut Department of Energy & Environmental Protection (CT

DEEP) General Permit for the Discharge of Stormwater and Dewatering Wastewaters Associated

with Construction Activities (DEP-PED-GP-015). The 2004 Connecticut Stormwater Quality

Manual published by the CT DEEP provided guidance for meeting these requirements.

1.2 Historic Flooding

There have been no reports of historic flooding on the project site, or adjacent to the area of

work. The project area is not identified within a flood area on the FEMA Firm Map No.

09003C0502F panel 502 of 675 dated 09/26/2008. A copy of the FEMA map is included within

this report.

1.3 Alterations to Natural Drainageways

Stormwater runoff from the project area currently conveyed via a series of onsite piping to the

existing storm sewer system located in Broad Street, and will continue to do so. There will be no

alterations to natural drainageways as part of this project.

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1.4 Existing Soils Conditions

The general topography of the athletic complex consists of slopes ranging from 0% to 8%. At the

existing softball field, there is a seating berm that is sloped at approximately 2.5:1.

Based on a review of the USDA National Resources Conservation Service (NRCS) Soil Survey of

the site the soils consist primarily of Udorthents-smoothed, Udorthents-Urban land complex,

Rainbow-Urban land complex and Broadbrook silt loam soils. A summary of the soil composition

is shown in the table below and surficial mapping is included in the appendix.

Soil Analysis Summary

Soil Name Range of Slopes % of Area Hydrologic Soil Group

Udorthents-smoothed N/A 85 *C

Udorthents-Urban land complex N/A 6 B

Rainbox-Urban land complex 0-8 6 C

Broadbrook silt loam 3-8 3 C

*Please note that since 2011, when the original stormwater report was submitted, the Natural

Resources Conservation Service (NRCS) has updated their soil mapping. At the time of the

original report, the site soils were classified as Hydrologic Soil Group B soils. The most recent

mapping now classifies the site soils as Hydrologic Soil Group C soils. This change in

classification impacts the runoff calculations for the project. As such, SMRT has updated both

the pre-development and post-development models to reflect the change in the soils types.

1.5 Methodology and Modeling Assumptions

This report and the stormwater modeling analysis have been updated to reflect the change in

ground cover types for the proposed project from a natural grass soccer field to a synthetic turf

soccer field. This change in surfacing has an impact on the peak flow rates generated from the

site.

As previously mentioned a stormwater report was prepared by CHA of Rocky Hill Connecticut

and approved in 2011. The original report was permitted with the assumption that the soccer

field would be constructed with a natural grass surface. At this time Trinity College is

proposing to construct this soccer field with synthetic turf. As such, SMRT, Inc. has revised the

stormwater modeling to reflect this change.

The previously approved report completed by CHA utilized Haestads Methods PondPack

Hydrology Program (Version 10.0) to compute the pre and post development runoff analysis.

SMRT utilizes HydroCAD software to model the pre and post development runoff analysis.

Time of concentration and runoff routing varies somewhat between the two models. SMRT

models the synthetic turf field as a large storage reservoir, detaining rainfall that enters the

structure, before allowing it to infiltrate to underlying soils or be conveyed off-site via the panel

drains (see Section 2.2 for the complete description).

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Stormwater Report

February 2015

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SMRT has confirmed the pre-development land use quantities and time of concentration

calculations from the previous report and utilized them in the pre-development model to

remain consistent with the previous approved CHA report. The post-development conditions

have been updated to reflect the new synthetic turf soccer field and incorporated into the

HydroCad model.

For this report, the runoff and routing calculations have been performed for the watershed

areas impacted by the project in both the pre-development and post-development conditions

using HydroCAD software. Time of concentration and runoff curve number calculations have

been determined using the method described in NRCS Technical Release 55 Urban Hydrology

for Small Watersheds (TR-55). Time of concentration calculations have been amended where

the value given by the TR-55 method is less than five minutes. In these cases a standard

minimum value of five minutes has been used to keep this parameter within the acceptable

working range of the model.

Design rainfall events have been modeled using the SCS Type III hydrograph for 24-hour

duration storms. The rainfall depth for each return period is taken from Table 7-2 2004

Connecticut Stormwater Quality Manual and ConnDOT Drainage Manual (2004). The rainfall

depth values for standard design storm frequencies are given in the table below.

24-Hour Rainfall Depths for Hartford County, Connecticut at Design Storm Frequencies

Table 7-2 2004 Connecticut Stormwater Quality Manual

Frequency 2-Year 10-Year 25-Year 100-Year

Rainfall Depth(in) 3.2 4.7 5.5 6.9

1.6 Project Impacts

The project will result in altered cover conditions at a number of locations. However, the overall

drainage characteristics and patterns will be retained to a high degree. The provision of a large

reservoir of highly porous base stone underneath the new artificial turf field provides significant

detention storage of rainfall and promotes infiltration to the underlying soils, thus reducing the

volume available for surface runoff. Post-development peak rates of runoff, directed to the

storm drainage infrastructure located in Broad Street, remain at, or below existing levels for

each of the analyzed design storm events. The entire WQV is infiltrated to the underlying soils,

providing water quality treatment, groundwater recharge and stream channel protection in

accordance with current State regulations. Additionally, the peak rate of discharge to the

drainage infrastructure in Broad Street is reduced for all storm events, and the overall existing

drainage patterns are maintained to a high degree.

Trinity College


Stormwater Report

February 2015

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2 STORM WATER ANALYSIS

2.1 Pre-Development Conditions

For the purposes of the existing condition analysis, one (1) point of analysis (PA-1) was chosen

to characterize the current drainage patterns of the project site. PA-1 represents the drainage

system in Broad Street.

In the Pre-Development condition the site is broken up into three (3) drainage areas, all of which

are tributary to PA-1.

DA-1 includes a small area at the northwest corner of the site which drains to a catch

basin and then is conveyed through approximately 785 LF of 15 pipe to the MDC storm

sewer in Broad Street.

DA-2 includes the majority of the site and stormwater flows overland to a catch basin

which is conveyed to the MDC storm sewer in Broad Street by approximately 55 LF of

15 pipe.

DA-3 includes a small area to the south of the site adjacent to the Ferris Athletic Center

which is collected by catch basins and assumed to be conveyed to the MDC storm sewer

in Broad Street by approximately 446 LF of 8 pipe, and then conveyed to PA-1 by 552 LF

of the Broad Street storm sewer.

Detailed descriptions of the subcatchment areas can be found in the HydroCAD runoff reports

and on the pre-development watershed plan.

2.2 Post-Development Conditions

The project includes the construction of new artificial turf playing fields, a new grandstand

seating area, and some minor re-configuration of the access to the field areas.

The largest change to the pre-development cover conditions is the addition of the new artificial

turf fields. The fields are included in the model as Direct Entry (CN 98) since there is no

depression storage, or evapotranspiration loss of rainfall that lands on the structure. Rainfall

will drain directly through the surface of the fields to the underlying base layer of highly porous

crushed stone. The stone base will act as a large storage reservoir, detaining rainfall that enters

the structure, before allowing it to infiltrate to underlying soils. The stone base layer is modeled

as a pond with 35% voids. A conservative value of 0.15 in/hr has been utilized to represent

infiltration to underlying soils below the new field. This rate is consistent with Hydrologic Type C

soils with limited permeability, as indicated in 2004 Connecticut Stormwater quality manual.

The piped underdrain system is designed to convey excess rainfall to outlet points at each field.

The underdrains are modeled as multiple vertical orifices that discharge to the larger collector

pipes that collect and convey stormwater around the perimeter of the proposed turf fields.

The post-development conditions analysis has been broken out into eight subcatchment areas.

The development of the site discharging to PA-1 consists of the following land use changes and

improvements

DA-1A: Includes the area around the synthetic turf soccer field, porous pavement

sidewalk, dugouts, softball seating berm and open grass area. Stormwater is collected

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Stormwater Report

February 2015

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by a series of catch basins and underdrain trenches which are conveyed via

approximately 492 LF of 15 pipe to the MDC storm sewer in Broad Street.

DA-1B: Includes the synthetic turf soccer field. Stormwater is collected by underdrains

beneath the field of play and conveyed to the MDC storm sewer by approximately 692

LF of 15 pipe to the MDC storm sewer in Broad Street.

DA-2: Includes the synthetic turf softball field. Stormwater is collected by underdrains

beneath the field of play and conveyed to the MDC storm sewer by approximately 1047

LF of 15 pipe to the MDC storm sewer in Broad Street.

DA-3: Includes the half of the synthetic turf baseball field that drains to the north via

underdrains and then to the MDC storm sewer by approximately 692 LF of pipe.

DA-4: Includes the half of the synthetic turf baseball field that drains to the south via

underdrains and then to the MDC storm sewer by approximately 428 LF of pipe.

DA-5: Includes primarily open space area north of the baseball field which sheet flows to

a catch basin and then conveyed to the MCD storm sewer by approximately 57 LF of

pipe.

DA-6: Includes open space area, the baseball grandstand, dugout and porous pavement

sidewalk. Stormwater is collected by various catch basins, then conveyed to the MDC

storm sewer by approximately 787 LF of pipe.

DA-7: Includes open space and existing paved sidewalks that drain to catch basins and

then conveyed to the MDC storm sewer by 998 LF of pipe.

Detailed descriptions of the subcatchment areas can be found in the HydroCAD runoff reports

and on the post-development watershed plan.

The analyzed post-development subcatchment areas described above drain to the existing MDC

storm sewer in Broad Street. The runoff and routing analysis shows that there will be no

increase in peak rate of runoff into the system under any design storm conditions. The table

below compares the peak rates of runoff from the pre-development to the post-development

conditions for this project. As shown in the table, there is no increase in post-development peak

rate of runoff in the 2-year, 10-year, 25-year and 100-year storms.

Runoff Summary- Peak Flow (cfs)

Analysis Point Design Storm Event Return Period

2-Year 10-Year 25-Year 100-Year

Pre-Dev Design Point 1 12.48 27.03 35.48 50.90

Post-Dev Design Point 1 10.58 21.32 27.15 36.94

Change -1.90 -5.71 -8.33 -13.96

2.3 MDC Peak Flow Stormwater Quantity Requirements

Because of the installation of the three synthetic turf fields, the post-development flow has

been reduced from the pre-development condition as shown in the Runoff Summary Table. The

MDC specifies that the 10-year storm must be reduced in the post-development condition. As

the Table indicates, the 2-yr, 25-yr and 100-yr storms are also reduced.

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February 2015

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The proposed stormwater conveyance systems throughout the site has been designed for the

10-year, 24-hour event, in accordance with the 2004 Connecticut Stormwater Quality Manual.

2.4 CT DEEP General Permit Stormwater Quality Requirements

The CT General Permit requires the removal of suspended solids and floatables (i.e. oil and

grease, other floatable liquids, floatable solids, trash, etc.) from stormwater. A goal of 80

percent removal of total sediment load from the stormwater discharge shall be used in

designing and installing stormwater management measures.

With the sidewalks being porous pavement, the proposed site adds a minimal amount of new

impervious surface area (approximately 0.18 acres). The only impervious areas that are being

added to the site are dugouts, permanent grandstand, and the paved throw areas. These areas

are disconnected from each other and either sheet flow across vegetated areas or flow onto the

porous pavement before entering the storm system. The vegetative flow path will provide

absorption of pollutants and the porous pavement will provide filtration and infiltration of the

stormwater. Also, the sediment load at these impervious areas will be minimal since there will

be no vehicular use. However to combat any pollutants, the conveyance system will include the

installation of deep sump catch basins and hoods for control of any suspended solids or oils and

grease pollutant loads.

3 CONCLUSIONS

The project will not result in any increase in surface runoff to downstream receiving waters. The

inclusion of a large, porous stone reservoir beneath the fields will effectively capture and detain

rainfall entering the turf field, promoting groundwater recharge and attenuating peak discharge

to the piped system from this area. The runoff and routing calculations demonstrate that the

development will not result in any increase in the peak rate of runoff from the site during design

storm events of, 2-year, 10-year, 25-year and 100-year return periods.

The proposed improvements have been designed to fit the existing topography of the site and

minimize proposed disturbed areas of the property to the maximum extent practical. The

existing drainage patterns will be maintained to a high degree.

4 REFERENCES

CT Stormwater Manual (2004 and as amended)

Connecticut Guidelines for Soil Erosion and Sediment Control (2002)

NRCS Technical Release 378

NRCS Web Soil Survey


Figures

Hydrologic Soil GroupState of Connecticut(Trinity College)

Natural ResourcesConservation Service

Web Soil SurveyNational Cooperative Soil Survey

1/9/2015Page 1 of 4

4624

260

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691950 691990 692030 692070 692110 692150 692190 692230 692270 692310 692350

691950 691990 692030 692070 692110 692150 692190 692230 692270 692310 692350

41 44' 57'' N72

41' 2

9'' W

41 44' 57'' N

72 4

1' 11''

W

41 44' 48'' N

72 4

1' 29''

W

41 44' 48'' N

72 4

1' 11''

W

N

Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 18N WGS840 50 100 200 300

Feet0 25 50 100 150

MetersMap Scale: 1:1,890 if printed on A landscape (11" x 8.5") sheet.

MAP LEGEND MAP INFORMATIONArea of Interest (AOI)

Area of Interest (AOI)Soils

Soil Rating PolygonsAA/DBB/DCC/DDNot rated or not available

Soil Rating LinesAA/DBB/DCC/DDNot rated or not available

Soil Rating PointsAA/DBB/D

CC/DDNot rated or not available

Water FeaturesStreams and Canals

TransportationRailsInterstate HighwaysUS RoutesMajor RoadsLocal Roads

BackgroundAerial Photography

The soil surveys that comprise your AOI were mapped at 1:12,000.

Warning: Soil Map may not be valid at this scale.Enlargement of maps beyond the scale of mapping can causemisunderstanding of the detail of mapping and accuracy of soil lineplacement. The maps do not show the small areas of contrastingsoils that could have been shown at a more detailed scale.

Please rely on the bar scale on each map sheet for mapmeasurements.Source of Map: Natural Resources Conservation ServiceWeb Soil Survey URL: http://websoilsurvey.nrcs.usda.govCoordinate System: Web Mercator (EPSG:3857)Maps from the Web Soil Survey are based on the Web Mercatorprojection, which preserves direction and shape but distortsdistance and area. A projection that preserves area, such as theAlbers equal-area conic projection, should be used if more accuratecalculations of distance or area are required.This product is generated from the USDA-NRCS certified data as ofthe version date(s) listed below.Soil Survey Area: State of ConnecticutSurvey Area Data: Version 13, Oct 28, 2014Soil map units are labeled (as space allows) for map scales 1:50,000or larger.Date(s) aerial images were photographed: Mar 28, 2011May12, 2011The orthophoto or other base map on which the soil lines werecompiled and digitized probably differs from the backgroundimagery displayed on these maps. As a result, some minor shiftingof map unit boundaries may be evident.

Hydrologic Soil GroupState of Connecticut(Trinity College)



1/9/2015Page 2 of 4

Hydrologic Soil Group

Hydrologic Soil Group Summary by Map Unit State of Connecticut (CT600)Map unit symbol Map unit name Rating Acres in AOI Percent of AOI

82B Broadbrook silt loam, 3 to8 percent slopes

C 0.4 2.8%

243B Rainbow-Urban landcomplex, 0 to 8percent slopes

C 0.8 6.0%

306 Udorthents-Urban landcomplex

B 0.8 6.1%

308 Udorthents, smoothed C 11.7 85.1%Totals for Area of Interest 13.7 100.0%

DescriptionHydrologic soil groups are based on estimates of runoff potential. Soils areassigned to one of four groups according to the rate of water infiltration when thesoils are not protected by vegetation, are thoroughly wet, and receive precipitationfrom long-duration storms.

The soils in the United States are assigned to four groups (A, B, C, and D) andthree dual classes (A/D, B/D, and C/D). The groups are defined as follows:

Group A. Soils having a high infiltration rate (low runoff potential) when thoroughlywet. These consist mainly of deep, well drained to excessively drained sands orgravelly sands. These soils have a high rate of water transmission.

Group B. Soils having a moderate infiltration rate when thoroughly wet. Theseconsist chiefly of moderately deep or deep, moderately well drained or well drainedsoils that have moderately fine texture to moderately coarse texture. These soilshave a moderate rate of water transmission.

Group C. Soils having a slow infiltration rate when thoroughly wet. These consistchiefly of soils having a layer that impedes the downward movement of water orsoils of moderately fine texture or fine texture. These soils have a slow rate of watertransmission.

Group D. Soils having a very slow infiltration rate (high runoff potential) whenthoroughly wet. These consist chiefly of clays that have a high shrink-swellpotential, soils that have a high water table, soils that have a claypan or clay layerat or near the surface, and soils that are shallow over nearly impervious material.These soils have a very slow rate of water transmission.

If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter isfor drained areas and the second is for undrained areas. Only the soils that in theirnatural condition are in group D are assigned to dual classes.

Hydrologic Soil GroupState of Connecticut Trinity College



1/9/2015Page 3 of 4

Rating OptionsAggregation Method: Dominant ConditionComponent Percent Cutoff: None SpecifiedTie-break Rule: Higher

Hydrologic Soil GroupState of Connecticut Trinity College



1/9/2015Page 4 of 4


Pre-Development Conditions Analysis Appendix A-1

CONTENTS:

1. Pre-development HydroCAD Runoff and Routing Calculations

DA-1

DA-2

DA-3

PA-1

PA-1

Routing Diagram for 14201-PREPrepared by SMRT, Inc., Printed 2/17/2015

HydroCAD 10.00 s/n 08778 2012 HydroCAD Software Solutions LLC

Subcat Reach Pond Link

Type III 24-hr 2-Year Storm Rainfall=3.20"14201-PRE Printed 2/17/2015Prepared by SMRT, Inc.

Page 2HydroCAD 10.00 s/n 08778 2012 HydroCAD Software Solutions LLC

Time span=0.00-40.00 hrs, dt=0.02 hrs, 2001 pointsRunoff by SCS TR-20 method, UH=SCS

Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method

Runoff Area=2.406 ac 0.12% Impervious Runoff Depth=1.04"Subcatchment DA-1: Tc=6.8 min CN=74 Runoff=2.69 cfs 0.208 af



Inflow=12.48 cfs 1.196 afLink PA-1: PA-1 Primary=12.48 cfs 1.196 af

Total Runoff Area = 13.941 ac Runoff Volume = 1.196 af Average Runoff Depth = 1.03"97.83% Pervious = 13.638 ac 2.17% Impervious = 0.303 ac



Summary for Subcatchment DA-1:

Runoff = 2.69 cfs @ 12.11 hrs, Volume= 0.208 af, Depth= 1.04"

Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-40.00 hrs, dt= 0.02 hrsType III 24-hr 2-Year Storm Rainfall=3.20"

Area (ac) CN Description* 2.403 74 >75% Grass cover, Good, HSG C

0.003 98 Paved roads w/curbs & sewers, HSG C2.406 74 Weighted Average2.403 99.88% Pervious Area0.003 0.12% Impervious Area

Tc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)

6.8 Direct Entry, Previous Report

Subcatchment DA-1:

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

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)

3

2

1

0

Type III 24-hr2-Year Storm Rainfall=3.20"

Runoff Area=2.406 acRunoff Volume=0.208 af

Runoff Depth=1.04"Tc=6.8 min

CN=74

2.69 cfs






Area (ac) CN Description0.090 61 >75% Grass cover, Good, HSG B

* 10.460 74 >75% Grass cover, Good, HSG C0.194 98 Paved roads w/curbs & sewers, HSG C0.092 89 Gravel roads, HSG C

10.836 74 Weighted Average10.642 98.21% Pervious Area0.194 1.79% Impervious Area

Tc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)12.5 Direct Entry, Previous Report

Subcatchment DA-2:

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

11

10

9

8

7

6

5

4

3

2

1

0




CN=74

10.03 cfs







* 0.230 74 >75% Grass cover, Good, HSG C0.106 98 Paved roads w/curbs & sewers, HSG C0.699 71 Weighted Average0.593 84.84% Pervious Area0.106 15.16% Impervious Area


Subcatchment DA-3:

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

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0.480.460.440.420.4

0.380.360.340.320.3

0.280.260.240.220.2

0.180.160.140.120.1

0.080.060.040.02

0




CN=71

0.44 cfs



Summary for Link PA-1: PA-1

Inflow Area = 13.941 ac, 2.17% Impervious, Inflow Depth = 1.03" for 2-Year Storm eventInflow = 12.48 cfs @ 12.17 hrs, Volume= 1.196 afPrimary = 12.48 cfs @ 12.17 hrs, Volume= 1.196 af, Atten= 0%, Lag= 0.0 min

Primary outflow = Inflow, Time Span= 0.00-40.00 hrs, dt= 0.02 hrs

Link PA-1: PA-1

InflowPrimary

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

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13

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1

0

Inflow Area=13.941 ac12.48 cfs

12.48 cfs



















Subcatchment DA-1:

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

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(

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6

5

4

3

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1

0




CN=74

5.78 cfs










Subcatchment DA-2:

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

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w

(

c

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2423222120191817161514131211109876543210




CN=74

21.64 cfs









Subcatchment DA-3:

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

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1

0




CN=71

1.03 cfs






Link PA-1: PA-1

InflowPrimary

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

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30

28

26

24

22

20

18

16

14

12

10

8

6

4

2

0


27.03 cfs



















Subcatchment DA-1:

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

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(

c

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8

7

6

5

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3

2

1

0




CN=74

7.57 cfs










Subcatchment DA-2:

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

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w

(

c

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)

30

28

26

24

22

20

18

16

14

12

10

8

6

4

2

0




CN=74

28.38 cfs









Subcatchment DA-3:

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

1

0




CN=71

1.38 cfs






Link PA-1: PA-1

InflowPrimary

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

38363432302826242220181614121086420


35.48 cfs



















Subcatchment DA-1:

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

12

11

10

9

8

7

6

5

4

3

2

1

0




CN=74

10.83 cfs










Subcatchment DA-2:

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

44424038363432302826242220181614121086420




CN=74

40.66 cfs









Subcatchment DA-3:

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

2

1

0




CN=71

2.03 cfs






Link PA-1: PA-1

InflowPrimary

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

55

50

45

40

35

30

25

20

15

10

5

0


50.90 cfs


Post-Development Conditions Analysis Appendix A-2

CONTENTS:

1. Post-development HydroCAD Runoff and Routing Calculations

DA-1A

DA-1B

Soccer Turf

DA-2

Softball Turf

DA-3

Baseball Turf-Split

DA-4

Baseball Turf-Split

DA-5

DA-6

DA-7

TF1

Soccer Turf

TF2

Softball Turf

TF3

Baseball Turf

TF4

Baseball Turf

1L

Link

PA-1

PA-1

Routing Diagram for 14201-POSTPrepared by SMRT, Inc., Printed 2/17/2015

HydroCAD 10.00 s/n 08778 2012 HydroCAD Software Solutions LLC

Subcat Reach Pond Link

Type III 24-hr 2-Year Storm Rainfall=3.20"14201-POST Printed 2/17/2015Prepared by SMRT, Inc.




Runoff Area=3.155 ac 6.53% Impervious Runoff Depth=1.09"Subcatchment DA-1A: Tc=11.2 min CN=75 Runoff=3.24 cfs 0.288 af

Runoff Area=2.194 ac 100.00% Impervious Runoff Depth=2.97"Subcatchment DA-1B: Soccer Turf Tc=5.0 min CN=98 Runoff=7.04 cfs 0.543 af

Runoff Area=1.135 ac 100.00% Impervious Runoff Depth=2.97"Subcatchment DA-2: Softball Turf Tc=5.0 min CN=98 Runoff=3.64 cfs 0.281 af

Runoff Area=1.589 ac 100.00% Impervious Runoff Depth=2.97"Subcatchment DA-3: Baseball Turf-Split Tc=5.0 min CN=98 Runoff=5.10 cfs 0.393 af





Peak Elev=104.48' Storage=7,302 cf Inflow=7.04 cfs 0.543 afPond TF1: Soccer Turf Discarded=0.33 cfs 0.331 af Primary=1.54 cfs 0.211 af Outflow=1.87 cfs 0.543 af

Peak Elev=110.18' Storage=3,400 cf Inflow=3.64 cfs 0.281 afPond TF2: Softball Turf Discarded=0.17 cfs 0.166 af Primary=1.03 cfs 0.115 af Outflow=1.20 cfs 0.281 af

Peak Elev=97.50' Storage=5,722 cf Inflow=5.10 cfs 0.393 afPond TF3: Baseball Turf Discarded=0.24 cfs 0.235 af Primary=0.64 cfs 0.158 af Outflow=0.88 cfs 0.393 af


Inflow=2.85 cfs 0.372 afLink 1L: Link Primary=2.85 cfs 0.372 af





Summary for Subcatchment DA-1A:




0.177 98 Paved roads w/curbs & sewers, HSG C0.023 89 Gravel roads, HSG C

* 0.231 68 Porous Pavement* 0.029 98 Dugouts



Subcatchment DA-1A:

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

3

2

1

0




CN=75

3.24 cfs



Summary for Subcatchment DA-1B: Soccer Turf



Area (ac) CN Description* 2.194 98 Synthetic Turf

2.194 100.00% Impervious Area


5.0 Direct Entry,

Subcatchment DA-1B: Soccer Turf

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

7

6

5

4

3

2

1

0




CN=98

7.04 cfs



Summary for Subcatchment DA-2: Softball Turf






5.0 Direct Entry,

Subcatchment DA-2: Softball Turf

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

4

3

2

1

0




CN=98

3.64 cfs



Summary for Subcatchment DA-3: Baseball Turf-Split






5.0 Direct Entry,

Subcatchment DA-3: Baseball Turf-Split

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

5

4

3

2

1

0




CN=98

5.10 cfs









5.0 Direct Entry,


Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

6

5

4

3

2

1

0




CN=98

5.54 cfs








* 0.027 68 Porous Pavement1.751 75 Weighted Average1.747 99.77% Pervious Area0.004 0.23% Impervious Area


Subcatchment DA-5:

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

1

0




CN=75

1.76 cfs







* 1.382 74 >75% Grass cover, Good, HSG C0.080 98 Paved roads w/curbs & sewers, HSG C




Subcatchment DA-6:

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

2

1

0




CN=74

2.10 cfs






Area (ac) CN Description0.184 61 >75% Grass cover, Good, HSG B0.068 98 Paved roads w/curbs & sewers, HSG C0.252 71 Weighted Average0.184 73.02% Pervious Area0.068 26.98% Impervious Area



Subcatchment DA-7:

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

0.230.220.210.2

0.190.180.170.160.150.140.130.120.110.1

0.090.080.070.060.050.040.030.020.01

0




CN=71

0.21 cfs



Summary for Pond TF1: Soccer Turf

Inflow Area = 2.194 ac,100.00% Impervious, Inflow Depth = 2.97" for 2-Year Storm eventInflow = 7.04 cfs @ 12.07 hrs, Volume= 0.543 afOutflow = 1.87 cfs @ 12.41 hrs, Volume= 0.543 af, Atten= 73%, Lag= 20.3 minDiscarded = 0.33 cfs @ 10.32 hrs, Volume= 0.331 afPrimary = 1.54 cfs @ 12.41 hrs, Volume= 0.211 af

Routing by Stor-Ind method, Time Span= 0.00-40.00 hrs, dt= 0.02 hrsPeak Elev= 104.48' @ 12.41 hrs Surf.Area= 95,550 sf Storage= 7,302 cf

Plug-Flow detention time= 51.0 min calculated for 0.542 af (100% of inflow)Center-of-Mass det. time= 51.0 min ( 806.5 - 755.5 )Volume Invert Avail.Storage Storage Description

#1 104.26' 22,406 cf Custom Stage Data (Prismatic) Listed below (Recalc)Elevation Surf.Area Voids Inc.Store Cum.Store

(feet) (sq-ft) (%) (cubic-feet) (cubic-feet)104.26 95,550 0.0 0 0104.93 95,550 35.0 22,406 22,406

Device Routing Invert Outlet Devices#1 Primary 102.18' 12.0" Round Culvert L= 360.0' Ke= 0.500

Inlet / Outlet Invert= 102.18' / 99.51' S= 0.0074 '/' Cc= 0.900 n= 0.012, Flow Area= 0.79 sf

#2 Discarded 104.26' 0.150 in/hr Exfiltration over Surface area #3 Device 1 104.26' 4.0" Vert. Orifice/Grate X 16.00 C= 0.600

Discarded OutFlow Max=0.33 cfs @ 10.32 hrs HW=104.27' (Free Discharge)2=Exfiltration (Exfiltration Controls 0.33 cfs)

Primary OutFlow Max=1.54 cfs @ 12.41 hrs HW=104.48' (Free Discharge)1=Culvert (Passes 1.54 cfs of 3.76 cfs potential flow)

3=Orifice/Grate (Orifice Controls 1.54 cfs @ 1.59 fps)



Pond TF1: Soccer Turf

InflowOutflowDiscardedPrimary

Hydrograph

Time (hours)4038363432302826242220181614121086420

F

l

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)

7

6

5

4

3

2

1

0

Inflow Area=2.194 acPeak Elev=104.48'

Storage=7,302 cf

7.04 cfs

1.87 cfs

0.33 cfs

1.54 cfs



Summary for Pond TF2: Softball Turf














Pond TF2: Softball Turf


Hydrograph

Time (hours)4038363432302826242220181614121086420

F

l

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w

(

c

f

s

)

4

3

2

1

0

Inflow Area=1.135 acPeak Elev=110.18'

Storage=3,400 cf

3.64 cfs

1.20 cfs

0.17 cfs

1.03 cfs



Summary for Pond TF3: Baseball Turf






Device Routing Invert Outlet Devices#1 Primary 97.00' 10.0" Round Culvert

L= 365.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 97.00' / 94.80' S= 0.0060 '/' Cc= 0.900 n= 0.012, Flow Area= 0.55 sf



Primary OutFlow Max=0.64 cfs @ 12.52 hrs HW=97.50' (Free Discharge)1=Culvert (Inlet Controls 0.64 cfs @ 1.89 fps)

3=Orifice/Grate (Passes 0.64 cfs of 2.73 cfs potential flow)



Pond TF3: Baseball Turf


Hydrograph

Time (hours)4038363432302826242220181614121086420

F

l

o

w

(

c

f

s

)

5

4

3

2

1

0

Inflow Area=1.589 acPeak Elev=97.50'Storage=5,722 cf

5.10 cfs

0.88 cfs

0.24 cfs0.64 cfs



Summary for Pond TF4: Baseball Turf






Device Routing Invert Outlet Devices#1 Primary 97.00' 10.0" Round Culvert

L= 365.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 97.00' / 94.80' S= 0.0060 '/' Cc= 0.900 n= 0.012, Flow Area= 0.55 sf



Primary OutFlow Max=0.65 cfs @ 12.53 hrs HW=97.50' (Free Discharge)1=Culvert (Inlet Controls 0.65 cfs @ 1.90 fps)

3=Orifice/Grate (Passes 0.65 cfs of 2.81 cfs potential flow)



Pond TF4: Baseball Turf


Hydrograph

Time (hours)4038363432302826242220181614121086420

F

l

o

w

(

c

f

s

)

6

5

4

3

2

1

0


5.54 cfs

0.91 cfs

0.26 cfs0.65 cfs



Summary for Link 1L: Link



Link 1L: Link

InflowPrimary

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

3

2

1

0


2.85 cfs






Link PA-1: PA-1

InflowPrimary

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

11

10

9

8

7

6

5

4

3

2

1

0


10.58 cfs





Runoff Area=3.155 ac 6.53% Impervious Runoff Depth=2.21"Subcatchment DA-1A: Tc=11.2 min CN=75 Runoff=6.82 cfs 0.581 af

Runoff Area=2.194 ac 100.00% Impervious Runoff Depth=4.46"Subcatchment DA-1B: Soccer Turf Tc=5.0 min CN=98 Runoff=10.41 cfs 0.816 af

Runoff Area=1.135 ac 100.00% Impervious Runoff Depth=4.46"Subcatchment DA-2: Softball Turf Tc=5.0 min CN=98 Runoff=5.38 cfs 0.422 af






Peak Elev=104.59' Storage=10,978 cf Inflow=10.41 cfs 0.816 afPond TF1: Soccer Turf Discarded=0.33 cfs 0.410 af Primary=2.72 cfs 0.406 af Outflow=3.05 cfs 0.816 af

Peak Elev=110.27' Storage=4,953 cf Inflow=5.38 cfs 0.422 afPond TF2: Softball Turf Discarded=0.17 cfs 0.208 af Primary=1.86 cfs 0.215 af Outflow=2.03 cfs 0.422 af



Inflow=5.79 cfs 0.735 afLink 1L: Link Primary=5.79 cfs 0.735 af





Summary for Subcatchment DA-1A:








Subcatchment DA-1A:

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

7

6

5

4

3

2

1

0




CN=75

6.82 cfs



Summary for Subcatchment DA-1B: Soccer Turf






5.0 Direct Entry,

Subcatchment DA-1B: Soccer Turf

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

11

10

9

8

7

6

5

4

3

2

1

0




CN=98

10.41 cfs



Summary for Subcatchment DA-2: Softball Turf






5.0 Direct Entry,

Subcatchment DA-2: Softball Turf

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

6

5

4

3

2

1

0




CN=98

5.38 cfs









5.0 Direct Entry,


Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

8

7

6

5

4

3

2

1

0




CN=98

7.54 cfs









5.0 Direct Entry,


Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

9

8

7

6

5

4

3

2

1

0




CN=98

8.19 cfs








* 0.027 68 Porous Pavement1.751 75 Weighted Average1.747 99.77% Pervious Area0.004 0.23% Impervious Area


Subcatchment DA-5:

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

4

3

2

1

0




CN=75

3.72 cfs







* 1.382 74 >75% Grass cover, Good, HSG C0.080 98 Paved roads w/curbs & sewers, HSG C




Subcatchment DA-6:

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

5

4

3

2

1

0




CN=74

4.52 cfs






Area (ac) CN Description0.184 61 >75% Grass cover, Good, HSG B0.068 98 Paved roads w/curbs & sewers, HSG C0.252 71 Weighted Average0.184 73.02% Pervious Area0.068 26.98% Impervious Area



Subcatchment DA-7:

Runoff

Hydrograph

Time (hours)403938373635343332313029282726252423222120191817161514131211109876543210

F

l

o

w

(

c

f

s

)

0.5

0.45

0.4

0.35

0.3

0.25

0.2

0.15

0.1

0.05

0




CN=71

0.48 cfs



Summary for Pond TF1: Soccer Turf














Pond TF1: Soccer Turf


Hydrograph

Time (hours)4038363432302826242220181614121086420

F

l

o

w

(

c

f

s

)

11

10

9

8

7

6

5

4

3

2

1

0


10.41 cfs

3.05 cfs

0.33 cfs

2.72 cfs



Summary for Pond TF2: Softball Turf




#1 109.99' 11,729 cf Custom Stage Data (Prismatic) Listed below (Recalc)Elevation Surf.Area Void

14201 stormwater report-compiled 150217

Documents

project narrative

proposed project

smrt project number

synthetic turf baseball

synthetic turf softball

synthetic turf soccer

project impacts

existing complex