PRELIMINARY STORMWATER MANAG EMENT …media.zuza.com/.../Preliminary_Stormwater_Management.pdf3.0 STORMWATER MANAGEMENT 3.1 HYDROLOGY 3.1.1 Model Selection Flow calculations for the

1-50 Grant Timmins Drive Kingston, Ontario K7M 8N2 Tel: (343) 266-0002 Fax: (343) 266-0028

PRELIMINARY STORMWATER MANAGEMENT

REPORT

Shorelines Casino Site Plan

1400 Crawford Drive

City of Peterborough

North of Crawford Drive East of Harper Road

Ainley Group Project Number: 16516-1

April 2016

Prepared for: Ontario Gaming East Limited Partnership 95 Schooner St Coquitlam, BC, V3K 6Z1

April 2016 Project No. 16516-1 Preliminary Stormwater Management Report – Shorelines Casino City of Peterborough, ON

i

Table of Contents 1.0 INTRODUCTION ................................................................................................................. 1

2.0 SITE DESCRIPTION ............................................................................................................... 1

2.1 EXISTING CONDITIONS .................................................................................................. 1

2.2 PREVIOUS STUDIES ......................................................................................................... 1

2.3 PROPOSED DEVELOPMENT ............................................................................................ 2

3.0 STORMWATER MANAGEMENT .......................................................................................... 2

3.1 HYDROLOGY ................................................................................................................... 2

3.1.1 Model Selection 2

3.1.2 Rainfall Distribution 2

3.1.3 Model Parameters 3

3.2 PRE-DEVELOPMENT ......................................................................................................... 3

3.3 POST-DEVELOPMENT ...................................................................................................... 4

4.0 QUANTITY CONTROL ......................................................................................................... 5

5.0 QUALITY CONTROL ............................................................................................................ 6

6.0 COLD WATER IMPACTS ...................................................................................................... 7

6.1 BACKGROUND ................................................................................................................ 7

6.2 MITIGATION .................................................................................................................... 7

7.0 EROSION AND SEDIMENT CONTROL ................................................................................ 7

8.0 CONCLUSIONS .................................................................................................................... 7

Appendices Appendix A Figures

Appendix B IDF

Appendix C Hydrology Parameters

Appendix D SWMHYMO model input

Appendix E SWMHYMO model output

Appendix F Stage-Storage-Discharge Curves

Appendix G Permanent Pool Calculations


1.0 INTRODUCTION The services of Ainley Group were retained by Ontario Gaming East Limited Partnership to complete a preliminary stormwater management report to be included with the submission of the Official Plan and Zoning By-Law Amendment applications for a proposed Casino commercial development. The purpose of the report is to summarize the preliminary stormwater management mitigation requirements for the proposed development.

Through the future site plan application process, a Stormwater Management Report will be completed which will detail site-specific stormwater management practices which will consider conclusions of other studies to be undertaken by the developer including a Geotechnical Report, a Hydrogeological Study, and an Environmental Impact Study.

This report has been prepared with consideration of the Ministry of Environment’s Stormwater Management Planning and Design Manual (2003) the City of Peterborough Engineering Design Standards and the Otonabee Conservation Watershed Planning & Regulation Policy Manual (2013).

2.0 SITE DESCRIPTION 2.1 EXISTING CONDITIONS The subject land is bound by Crawford Drive to the south, Harper Road to the north-west, vacant land to the north, existing commercial land to the south east (Tim Hortons and Peterborough and the Kawarthas Tourism) and vacant land to the south-west. It should be noted that the approved Crawford Drive and Harper Road Class Environmental Assessment (EA) proposes the closure of Crawford Drive to the south with its realignment along the east side of the subject lands, and the realignment of Harper Road along the north. The proposed development is based on the approved EA.

The site is generally flat and in its current state is heavily disturbed and has been stripped of most vegetation.

A portion of the Byersville Creek flood plain extends into the subject lands at the northeast limits and an unnamed tributary previously identified as a cold water stream exists within the existing Crawford Drive ROW.

During the Pre-Consultation meeting of March 2016, ORCA and the City agreed that a 15 metre setback from the limit of the existing woody vegetation to the west will be subject to a holding provision until environmental field work can be undertaken during appropriate seasonal conditions, and an EIS is completed.

An overview of the site topography and drainage pattern is provided in Figure 1.

2.2 PREVIOUS STUDIES The subject lands have been the focus of several Stormwater Management Reports in the past in support of the existing developments within the boundaries. The following is a brief summary of these reports;

Stormwater Management Report Peterborough Visitor Centre Phase 1 (D.M. Wills Rev 2 September 2006)


The report recommended that stormwater mitigation be provided by infiltration methods with pre-treatment provided by forebays. The infiltration reduced peak discharge rates but not to pre-development levels, a review of downstream hydraulics was completed and deemed suitable to allow increased peak discharge rates from the site without additional on-site retention.

Letter: Proposed Tim Hortons Development Peterborough Visitor Centre, Phase 1B (D.M. Wills, June 18, 2008)

The letter outlined a modification of the previous catchment areas from the September 2006 SWM report to accommodate the proposed additional developments within the subject lands. No change in the overall SWM approach was made.

For the purposes of this SWM review (2016) the previous studies have been considered as background information only. The overall approach recommended in the historic documents of infiltration with uncontrolled release is not recommended for the future development of the site, but rather a post-pre control should be considered and level 1 (enhanced) quality treatment.

2.3 PROPOSED DEVELOPMENT The proposed development will incorporate a total area of approximately 5.3ha. This area includes the future redevelopment of the tourism building, the Tim Horton’s site to remain, as well as the City of Peterborough’s lands to the north, also forming part of the Official Plan and Zoning By-Law Amendment applications.

The proposed development plan is outlined on Figure 2.

An overview of the site topography and proposed drainage pattern is provided in Figure 3.

3.0 STORMWATER MANAGEMENT 3.1 HYDROLOGY

3.1.1 Model Selection Flow calculations for the pre-development and post development conditions were carried out using the SWMHYMO computer program. This program is a complex hydrologic model used for the simulation and management of stormwater runoff in either small or large rural and urban areas.

3.1.2 Rainfall Distribution The quantity rainfall design storm hyetograph was developed in accordance with the City of Peterborough Engineering Design Standards (March 2015); which requires at a minimum the 2, 5 and 100 year storms to be evaluated using the 2002 Peterborough Airport IDF for either the Chicago distribution or the SCS Type II distribution.

For this report the following distributions have been considered to evaluate the scenario that generated the greatest storage volume requirements;

• Chicago 1 hr • Chicago 3 hr • Chicago 6 hr


For this report the current Peterborough Airport IDF (2014) has been applied, a copy of the IDF is enclosed in Appendix B.

3.1.3 Model Parameters The SWMHYMO model has been developed with consideration of the parameters interpreted from air photos, Ontario Soils Mapping, topographic information background reports and the designer’s knowledge of the site based on visual observations. Supporting documentation to support the model parameters is enclosed in Appendix C.

3.2 PRE-DEVELOPMENT The following tables outline the pre-development discharge rates anticipated to be generated from the development site. Figure 1 outlines the catchment areas.

Chicago 1 Hour

2yr 5yr 100yr

Area Pre Pre Pre

NE 0.009 0.018 0.053

E 0.08 0.105 0.177

SE 0.019 0.036 0.105

SW - - -

E(total) 0.081 0.107 0.182

Site (total) 0.081 0.107 0.188

Chicago 3 Hour

2yr 5yr 100yr

Area Pre Pre Pre

NE 0.012 0.022 0.066

E 0.08 0.106 0.178

SE 0.024 0.045 0.128

SW - - -

E(total) 0.082 0.109 0.192

Site (total) 0.082 0.11 0.226

Chicago 6 Hour

2yr 5yr 100yr

Area Pre Pre Pre

NE 0.014 0.025 0.073

E 0.08 0.106 0.18

SE 0.027 0.051 0.142

SW - - -

E(total) 0.083 0.112 0.201

Site (total) 0.084 0.113 0.25


A copy of the SWMHYMO input and output file is enclosed in Appendix D. 3.3 POST-DEVELOPMENT The subject property has been separated into sub-catchments based on the anticipated detailed grading, Figure 3 outlines the catchments.

An estimate of the contributing site impervious cover has been prepared for use in the SWMHYMO modeling, supporting Calculations for the estimate of impervious cover are included in Appendix C.

The development areas have been routed through proposed facilities (outlined further in Section 4.0) to generate anticipated controlled discharge rates. The following tables outline the post development discharge rates anticipated to be generated from the overall site and upstream catchment area. The tables also provide a comparison of the anticipated post development rates versus the pre-development rates.

Chicago 1 Hour

2yr 5yr 100yr

Area Pre Post Pre Post Pre Post NE 0.009 0.005 -44.4% 0.018 0.01 -44.4% 0.053 0.034 -35.8% E 0.08 0.08 0.0% 0.105 0.105 0.0% 0.177 0.176 -0.6%

SE 0.019 0.016 -15.8% 0.036 0.019 -47.2% 0.105 0.025 -76.2% SW - 0.016 - - 0.019 - - 0.009 -

E(total) 0.081 0.093 14.8% 0.107 0.121 13.1% 0.182 0.195 7.1% Site (total) 0.081 0.095 17.3% 0.107 0.123 15.0% 0.188 0.199 5.9%

Chicago 3 Hour

2yr 5yr 100yr

Area Pre Post Pre Post Pre Post NE 0.012 0.008 -33.3% 0.022 0.022 0.0% 0.066 0.041 -37.9% E 0.08 0.08 0.0% 0.106 0.105 -0.9% 0.178 0.177 -0.6%

SE 0.024 0.016 -33.3% 0.045 0.02 -55.6% 0.128 0.029 -77.3% SW - 0.017 - - 0.021 - - 0.029 -

E(total) 0.082 0.096 17.1% 0.109 0.125 14.7% 0.192 0.208 8.3% Site (total) 0.082 0.099 20.7% 0.11 0.129 17.3% 0.226 0.212 -6.2%

Chicago 6 Hour

2yr 5yr 100yr Area Pre Post Pre Post Pre Post NE 0.014 0.011 -21.4% 0.025 0.024 -4.0% 0.073 0.043 -41.1% E 0.08 0.08 0.0% 0.106 0.106 0.0% 0.18 0.177 -1.7%

SE 0.027 0.016 -40.7% 0.051 0.02 -60.8% 0.142 0.029 -79.6% SW - 0.018 - - 0.021 - - 0.03 -

E(total) 0.083 0.098 18.1% 0.112 0.127 13.4% 0.201 0.209 4.0% Site (total) 0.084 0.101 20.2% 0.113 0.131 15.9% 0.25 0.215 -14.0%


It can be seen in the above tables that the anticipated discharge rates from the site is decreased under most scenarios. Several events do exceed the pre-development level; however these exceedances are all lower that the anticipated highest pre-development peak generated from the 6hr 100 year event.

A copy of the SWMHYMO input file is enclosed in Appendix D and the output in Appendix E.

4.0 QUANTITY CONTROL The proposed development is proposed to be controlled to pre-development rates as follows;

North East Section

This area consists primarily of parking lot and will drain to the north east corner of the development site. Quantity control is proposed to be provided in a wet pond facility (more discussion on the wet pond facility is provided in Section 5.0). A stage-storage-discharge curve has been created for this facility and included in Appendix F. The facility will over control discharge to less than the pre-development rates to offset portions of the site that will discharge higher than the pre-development rates.

East Section

This area consists of the existing Tim Horton’s development. The area considered in this report is comparable to the previous design (D.M. Wills, 2008). An existing dry pond facility exists in this catchment and is recommended to continue to be the quantity mitigation for the area.

South West Section

This area consists of the main building and a portion of parking lot and will drain to the south-west. Quantity control is proposed to be provided in a wet pond facility (more discussion on the wet pond facility is provided in Section 5.0). A stage-storage-discharge curve has been created for this facility and included in Appendix F. The facility is proposed to utilize a portion of the existing facility in place The existing facility is located within the environmental setback however in accordance with The ORCA Watershed Planning & Regulation Policy Manual (May 17, 2012) section 4.1.2(1) this is a permitted activity. The ponds footprint and volume will not be enlarged within the limits of the setback.

South East Section

This area consists of the proposed hotel, associated parking and the sites main entrance. Quantity control is proposed to be provided by a combination of underground storage, oversized storm sewers in series and parking lot storage (maximum depth of 0.3m). A stage-storage-discharge curve has been created for this facility and included in Appendix F.

The combination of the potential storage components will reduce the post-development discharge rates from the subject site to the pre-development levels.


5.0 QUALITY CONTROL The development site is required to provide Level 1 (enhanced) treatment of stormwater discharge. The following outlines how the individual catchments are proposed to achieve this target;

North East Section

Quality control is proposed to be provided in a wet pond facility in accordance with section 4.6.2 of the MOE SWM Manual (2003). For this catchment area the required permanent pool volume is 500m3, supporting calculations included in Appendix F. This storage can be accommodated within the proposed SWM block (Figure 4). The storage will be divided between two cells (forebay and main pond).

Based on observed water levels from historic reports of the area groundwater is known to be high within the property. As such the SWM facility will be required to be lined to prevent connection to the groundwater to both protect it from contamination and adverse lowering. Due to high groundwater levels on the site the pond lining may need to be completed using a synthetic geomembrane; this should be reviewed further in combination with the pending geotechnical site review.

Alternatively quality treatment could be provided by way of a combined approach utilizing an OG unit and dry pond facility. This may be reviewed further during detailed design.

East Section

This area consists of the existing Tim Horton’s development. The area considered in this report is comparable to the previous design (D.M. Wills, 2008). An existing forebay and dry pond (infiltration) facility exists in this catchment and is recommended to continue to be the quality mitigation for the area.

South West Section

Quality control is proposed to be provided in a wet pond facility in accordance with section 4.6.2 of the MOE SWM Manual (2003). For this catchment the required permanent pool volume is 275m3, supporting calculations included in Appendix F. This storage can be accommodated within the proposed SWM block (Figure 4). The storage will be divided between two cells (forebay and main pond).

Based on historic reports of the area groundwater is known to be high within the property. As such the SWM facility will be required to be lined to prevent connection to the groundwater to both protect it from contamination and adverse lowering.

Alternatively quality treatment could be provided by way of a combined approach utilizing an OG unit and dry pond facility. This may be reviewed further during detailed design.

South East Section

Quality control is proposed to be provided by an OG unit (possibly in series to achieve target quality treatment levels.) The unit(s) will be specified during detailed design).


6.0 COLD WATER IMPACTS 6.1 BACKGROUND The watercourse within the Crawford Drive ROW has been identified as a cold water system and as such the proposed development should attempt to offset the adverse impacts associated with discharge from developed areas.

6.2 MITIGATION Utilizing the direction outlined in the Credit Valley Conservation Study Report: Thermal Impacts of Urbanization including Preventative and Mitigation Techniques (January 2011) the following measures are recommended to be incorporated into the detailed design of the various SWM facilities;

• Roof Colour recommendation • Cooling trench inlets • Permanent pool ponds (wet pond) • Reverse slope outlets combined with cooling towers • Maximize Length to width ratio • Pond orientation (as feasible) • Planting strategy • Cooling trench outlets

If the above measures are appropriately implemented the impacts of the proposed development on the thermal regime of the surrounding water course will be significantly reduced.

7.0 EROSION AND SEDIMENT CONTROL An erosion and sediment control strategy should be implemented as part of the engineering drawing package in order to minimize the transfer of silt off site during construction. The following measures are recommended to be included in the strategy as required:

• Silt fencing around the limits of the development; • Straw bale barriers within any permanent or temporary swales; • Regular inspection of the erosion and sediment control devices; • Removal and disposal of the erosion and sediment control devices after the site has been

stabilized; • All exposed earth is to be re-vegetated within thirty days.

8.0 CONCLUSIONS

• The proposed development will be required to provide quantity and quality mitigation measures of stormwater runoff,


• Quantity control is proposed to be provided in combination of 2 extended detention ponds and underground/parking lot storage, the resulting post development total discharge from the site will be less that the peak 6hr 100 year pre-development flows.

• Quality control is proposed to be provided by combination of wet pond facilities and OG units.

o Alternatively at detailed design the use of OG units and dry pond facilities could be considered.

• The site has a high groundwater level, accordingly all mitigation measures should be lined to prevent cross connection.

• Cold water impact mitigation is recommended to be provided through combination of various measures including roof colour, cooling trenches, permanent pool facilities and reverse slope outlets.

• A detailed maintenance plan should be incorporated into the detailed design.

We trust the above information meets your needs at this time and should you have any questions or concerns, please do not hesitate to contact the undersigned.

Yours very truly,

AINLEY GRAHAM AND ASSOCIATES LIMITED Prepared by:

Adam Wilson, P.Eng. Senior Engineer


Appendix A Figures

LIMIT OF PROPERTY

EASEMENT

LIM

IT O

F P

RO

PE

RTY

EASEMENT

EASEMENT

EASEMENT

2.18

NE

2.55

SE

0.60

E

5 0 5 10 15 20 25 30 35 m

1:1000

Date: CONTRACT No. 16516-1 2016/04/29

X

X= DRAINAGE AREA IDENTIFIER

Y= DRAINAGE AREA (HECTARES)

DRAINAGE BOUNDARY

FIGURE 1

PRE DEVELOPMENT DRAINAGE

DIRECTION OF MAJOR FLOW

Y

LIMIT OF PROPERTY

EASEMENT

LIM

IT O

F P

RO

PE

RTY

EASEMENT

EASEMENT

EASEMENT

PROPOSEDCASINO

BUILDINGFUTUREHOTEL

COVEREDENTRYPLAZA

PREL

IMIN

ARY

CRAW

FORD

DRI

VE R

EALI

GNM

ENT

PRELIMINARY HARPER ROAD REALIGNMENT

HARPE

R ROAD

15m ENVIRONMENTALSETBACK (SUBJECT TO

HOLDING PROVISIONUNTIL COMPLETION OF

ENVIRONMENTALIMPACT STUDY)

EXISTINGTIM HORTON'S

TO REMAIN




SWM POND

SWM POND

SWM POND

5 0 5 10 15 20 25 30 35 m

1:1000

Date: CONTRACT No. 16516-1 2016/04/29

FIGURE 2

PROPOSED DEVELOPMENT

LIMIT OF PROPERTY

EASEMENT

LIM

IT O

F P

RO

PE

RTY

EASEMENT

EASEMENT

EASEMENT

PROPOSEDCASINO

BUILDINGFUTUREHOTEL

COVEREDENTRYPLAZA

PREL

IMIN

ARY

CRAW

FORD

DRI

VE R

EALI

GNM

ENT


HARPE

R ROAD





TO REMAIN




3.3%

3.3%

1.5%

1.8%

ROAD ELEV.

197.00 ±

ROAD ELEV.

193.50±

ROAD ELEV.

195.25±

ROAD ELEV.

196.00±

1.4%1.

6%

ROAD ELEV.

197.00 ±

ROAD ELEV.

194.00 +/-

1.5%

2.3%

0.9%

1.1%

1.1%

5.0:

1

5.0:1

5.0:1

5.0:

1

5.0:1

5.0:1

5.0:1

5.0:1

5.0:1

5.0:1

5.0:1

0.9%

0.9%

0.5%

0.8%

1.2%

1.2%

0.1%

2.38

NE

1.485

SW

0.865

SE

0.60

E

5 0 5 10 15 20 25 30 35 m

1:1000

Date: CONTRACT No. 16516-1 2016/04/29

X



DRAINAGE BOUNDARY

FIGURE 3

POST DEVELOPMENT DRAINAGE

DIRECTION OF MAJOR FLOW

Y

LIMIT OF PROPERTY

EASEMENT

LIM

IT O

F P

RO

PE

RTY

EASEMENT

EASEMENT

EASEMENT

PROPOSEDCASINO

BUILDINGFUTUREHOTEL

COVEREDENTRYPLAZA

PREL

IMIN

ARY

CRAW

FORD

DRI

VE R

EALI

GNM

ENT


HARPE

R ROAD





TO REMAIN




3.3%

3.3%

1.5%

1.8%

ROAD ELEV.

197.00 ±

ROAD ELEV.

193.50±

ROAD ELEV.

195.25±

ROAD ELEV.

196.00±

1.4%1.

6%

ROAD ELEV.

197.00 ±

ROAD ELEV.

194.00 +/-

1.5%

2.3%

0.9%

1.1%

1.1%

5.0:

1

5.0:1

5.0:1

5.0:

1

5.0:1

5.0:1

5.0:1

5.0:1

5.0:1

5.0:1

5.0:1

0.9%

0.9%

0.5%

0.8%

1.2%

1.2%

0.1%

2.38

NE

1.485

SW

0.60

E

WET POND FACILITY

WET POND FACILITY(MAINCELL)

COMBINED UNDERGROUNDAND PARKING STORAGEINCLUDING OIL GRIT SEPARATOR (OGS)

5 0 5 10 15 20 25 30 35 m

1:1000

Date: CONTRACT No. 16516-1 2016/04/29

FIGURE 4

MITIGATION MEASURES

X



DRAINAGE BOUNDARY

Y


Appendix B IDF


Appendix C Hydrology Parameters


Appendix D SWMHYMO Model Input


Appendix E SWMHYMO Model Output


Appendix F Stage-Storage-Discharge Curves


Appendix G Quality Calculations

Documents

PRELIMINARY STORMWATER MANAG EMENT …media.zuza.com/.../Preliminary_Stormwater_Management.pdf3.0 STORMWATER MANAGEMENT 3.1 HYDROLOGY 3.1.1 Model Selection Flow calculations for the