Hutchinson. Environmental Sciences Ltd. Preliminary Phosphorus Budget for the Proposed Redevelopment of the Canterbury Golf Course

Transcription

1 Hutchinson Environmental Sciences Ltd. Preliminary Phosphorus Budget for the Proposed Redevelopment of the Canterbury Golf Course Prepared for: Canterbury Land Development Corporation Job #: J September Chancery Lane, Bracebridge ON, P1L 2E Suite Krug Street, Kitchener, ON N2B 1L

2 Hutchinson Environmental Sciences Ltd. 1-5 Chancery Lane, Bracebridge ON, P1L 2E Suite Krug Street, Kitchener, ON N2B 1L Farrah Ward Canterbury Land Development Corporation Steeles Avenue Markham, ON L3R 1G9 Dear Ms. Ward: Re: Preliminary Phosphorus Budget for the Proposed Redevelopment of the Canterbury Golf Course The following report describes a preliminary current and post-development phosphorus (P) budget for the proposed redevelopment of the Canterbury Golf Course in Port Perry. A phosphorus (P) budget was requested by Kawartha Conservation as part of this development application. If you have any questions please do not hesitate to contact the undersigned. Sincerely, per: Deborah Sinclair, M.A.Sc. Deborah.sinclair@environmentalsciences.ca _J150033_Scugog Phosphorus Budget ii

3 Signatures Report Prepared by: Deborah Sinclair Senior Aquatic Scientist Brent Parsons Aquatic Scientist Report Reviewed by: Dr. Tammy Karst-Riddoch Senior Aquatic Scientist _J150033_Scugog Phosphorus Budget iii

4 Table of Contents Transmittal Letter Signatures 1. Introduction Methods Project-Specific Input Parameters Land Use Areas Precipitation Stormwater Management Runoff Volumes Results Conclusions and Recommendations References List of Figures Figure 1. Draft Plan, Canterbury Residential Development, Port Perry ON List of Tables Table 1. Phosphorus Export Coefficients Used in the NVCA Tool (HESL 2014a)... 2 Table 2. Recommended Phosphorus Removal Efficiencies of BMP/LID Classes (from HESL, 2014a)... 2 Table 3. Proposed Canterbury Residential Development Pre-Development Land Use Areas... 5 Table 4 Land Use Classifications for the Proposed Canterbury Residential Development... 5 Table 5 Proposed Canterbury Residential Development Post-Development Land Use Areas... 6 Table 6 Runoff and Infiltration Volumes... 8 Table 7 Pre-Development Phosphorus Budget... 8 Table 8 Post-Development Phosphorus Budget... 9 Appendices Appendix A. Land Use Definitions _J150033_Scugog Phosphorus Budget iv

5 1. Introduction Perry Pines Development Inc. is proposing to develop 124 residential units on Canterbury Golf Course, Port Perry in the Township of Scugog, Region of Durham. A phosphorus (P) budget was requested by Kawartha Conservation as part of the development application process. Lake Scugog is a very shallow (mean depth = 1.4 m), nutrient-rich lake that is a primary source of drinking water for the residents of Lindsay (Kawartha Conservation, 2010, 2013). Water depth, area and volume of Lake Scugog are controlled by the Trent Severn Waterway via the Lindsay Dam on the Scugog River. There are two dissimilar lake basins, the western and eastern basins, which have different hydrographic features and hydrological regimes. The western basin of Lake Scugog, which is adjacent to the proposed development site, contains the highest concentrations of total phosphorus and most abundant growth of aquatic vegetation. Kawartha Conservation has recommended that a reduction of the total phosphorus load to Lake Scugog from the current 9,400 kg to ~6,000 kg a year is required to improve water quality (Kawartha Conservation, 2013). Urban runoff is a significant source of phosphorus to the lake representing 18.2% of the total annual load, ~7-11% (630 kg) of which is exported per year from the developed areas of Port Perry (5.16 km 2 ). Kawartha Conservation has targeted a reduction in phosphorus loads to the lake from urban lands of kg in the Lake Scugog Environmental Management Plan (Kawartha Conservation, 2013). This preliminary phosphorus budget was completed to estimate loadings to Lake Scugog from the proposed development site under existing and post-development conditions and to determine the potential for phosphorus load reduction with implementation of mitigation measures (i.e., Low Impact Development (LID) techniques and Best Management Practices (BMPs)). 2. Methods The phosphorus budget was developed using the approach described in the Phosphorus Budget Tool and Guidance for Managing New Urban Development in Phosphorus-Sensitive Watersheds (HESL, 2014a). This Tool was adapted from the Lake Simcoe Phosphorus Budget Tool (HESL, 2012) for estimating phosphorus loads and phosphorus reduction with implementation of BMPs and LID in Ontario outside of the Lake Simcoe watershed. The Tool uses a combination of established phosphorus export coefficients for natural heritage land uses in Ontario and new derivation techniques for estimating phosphorus loads from urban and agricultural lands based on site-specific soil and runoff characteristics (Table 1). Phosphorus load reduction efficiencies for major classes of BMPs and LID are recommended in the Tool based on efficiencies documented in the scientific literature and their applicability for use in Ontario (Table 2). Definitions of the land uses for the Tool are provided in Appendix A _J150033_Scugog Phosphorus Budget 1

6 Table 1. Phosphorus Export Coefficients Used in the NVCA Tool (HESL 2014a) Land Use Export Coefficient (kg/ha/yr) Notes Forest 0.06 Transition 0.07 Wetland 0.05 Turf/Sod 0.11 Hay/Pasture 0.08 Mean phosphorus export for all monitored Lake Simcoe subwatersheds (n = 7) derived using phosphorus loads from CANWET modeling. Monitored subwatersheds are those with sufficient measured data to validate and calibrate the model. Low Intensity Residential 0.13 Unpaved Roads 0.83 Open Water 0.26 Calculated from the mean measured atmospheric load of 19 tonnes/yr averaged over 5 years from 2002 to 2007 to the surface of Lake Simcoe (surface area = 722 km 2 ) (Scott et al., 2006; LSRCA, 2009). Developed from the relationship between CANWET derived phosphorus export for Lake Simcoe subwatersheds and soil loss. Cropland 0.16 x A Where: A = soil loss determined using the Universal Soil Loss Equation (USLE) Residential Where: Commercial Industrial TP i x Precip x P j x R V x 10-2 TP i is total phosphorus concentration (mg/l) in runoff measured from urban land uses: 0.41 mg/l for residential, 0.20 mg/l for commercial, 0.41 mg/l for industrial and 0.50 mg/l for transportation, Precip is the annual precipitation (mm/yr), Transportation P j is the fraction of Precip that produces runoff, and R V is the runoff coefficient. Table 2. Recommended Phosphorus Removal Efficiencies of BMP/LID Classes (from HESL, 2014a) BMP/LID Class % Phosphorus Removal Efficiency Bioretention Systems 100* Constructed Wetlands 77 Dry Detention Ponds 10 Dry Swales none _J150033_Scugog Phosphorus Budget 2

7 BMP/LID Class % Phosphorus Removal Efficiency Enhanced Grass/Water Quality Swales 100* Flow Balancing Systems 77 Green Roofs 100* Hydrodynamic Devices none Perforated Pipe Infiltration/Exfiltration Systems 87 Permeable Pavement 100* Sand or Media Filters 45 Soakaways - Infiltration Trenches 60 (100*) Sorbtive Media Interceptors 79 Underground Storage 25 Vegetated Filter Strips/Stream Buffers 65 Wet Detention Ponds 63 * infiltration techniques are credited with 100% removal efficiency if their effectiveness is verified in the SWM plan. 2.1 Project-Specific Input Parameters The Tool requires input parameters specific to the project and site. For urban land uses the Tool requires the total annual precipitation and fraction of precipitation that produces runoff (Pj) for the site, and impervious areas for each type of urban land use (e.g commercial, residential, industrial, and transportation). Land use areas and storm water management/lid and BMP practices are also required Land Use Areas The entire study area is ha, of which Perry Pines Development Inc. is planning on redeveloping ha (Figure 1). The balance (7.4 ha) of the study area would be subject to a separate application and therefore has not been included in the phosphorus budget calculations. A preliminary estimate of the pre-development (i.e., current) land use areas of the redeveloped area were determined using the following methods: Delineation of the different land uses using satellite imagery by Malone Given Parsons (MGP). Cross-check of the identified land uses with available Ecological Land Classification mapping (Beacon 2015); and A site visit in September 2015 to ground-truth land uses. The predominant land use is golf course (10.07 ha), golf course, with two ponds and maintenance building and yard forming the balance of the ha area (Table 3). The maintenance area was classified as commercial land use based on the land use description of the Tool _J150033_Scugog Phosphorus Budget 3

8

9 Table 3. Proposed Canterbury Residential Development Pre-Development Land Use Areas Land Use Area (ha) Golf Course Commercial (Maintenance Shed) 0.40 Open Water (three on-site ponds) 0.57 Total Notes: Land use areas are approximate, and are subject to change. In the post-development scenario all of the golf course, the two ponds, and the maintenance shed will be re-developed (Figure 1). The post-development areas for these lands were determined from the Schedule of Land Use in the Draft Plan of Subdivision prepared by MGP (dated September 23, 2015) and categorized into land uses as defined by the Tool (Table 4). Table 4 Land Use Classifications for the Proposed Canterbury Residential Development Draft Plan of Subdivision Land Use Class Area (ha) Single Family Homes Residential 7.7 Environmental Protection Transition 0.22 Servicing Block Residential 0.12 Open Space Vistas Residential 0.14 Walkways Residential m buffer Residential 0.01 Roads Residential 2.62 Total Total Residential Notes: Land use areas are approximate, and are subject to change. For the purposes of the phosphorus budget, all land uses were categorized as Residential (10.82 ha) with the exception of Environmental Protection. The Environmental Protection area (0.22 ha) was classified as Transition, as these areas will contain the 30 m wetland buffer. The area for all land uses used in the post-development phosphorus budget are provided in Table _J150033_Scugog Phosphorus Budget 5

10 Table 5 Proposed Canterbury Residential Development Post-Development Land Use Areas Post-Development Land Use Area (ha) Residential Transition 0.22 Total Notes: Land use areas are approximate, and are subject to change Precipitation The closest Environment Canada climate station to the subject property is Burketon McLaughlin Station (Climate ID ). The total precipitation for Burketon is 909 mm/yr ( normals). The fraction of precipitation that produces runoff (P j ) was estimated as 0.9. This is the default value for the Tool Stormwater Management The following is a summary of site runoff and stormwater management under current and proposed conditions. Details are provided in the Functional Servicing and Stormwater Management Report (SCS Consulting Group Ltd., 2015) and the Hydrological Investigation Report (Golder Associates, 2015) Pre-Development Runoff from the subject lands currently drain either directly to Lake Scugog, or via an existing storm sewer system and SWM pond within the subdivision. The two golf course ponds overflow to the mainline storm sewer system on Waterbury Crescent (SCS Consultants Ltd., 2015). The SWM pond discharges to Lake Scugog. The condition of the pond to treat stormwater runoff is not known. SWM ponds have a recommended phosphorus removal efficiency of 63% (HESL 2014a), however, for the purposes of this study, it was assumed that the pond does not provide any phosphorus removal under the current scenario because, to our knowledge, they have not been maintained to retain their function. The maintenance of the ponds will be confirmed with Township staff. Currently the northern and north-eastern part of the subject property is bound by riparian vegetation. Riparian vegetation (buffer strips) have been proven to be effective in reducing phosphorus loadings from adjacent land uses (SNC 2003). Effectiveness of vegetative buffers depends on the uniformity of the surface flow intercepted by the buffer and the width, slope and vegetation of the buffer. The width of the buffer around the site is approximately 10 to 20 m. Buffer strips that are a minimum of three metres wide have been estimated to reduce phosphorus loadings by approximately 70% (SNC 2003). The Tool uses a conservative reduction efficiency of 65%, which was used to determine the phosphorus load reduction achieved by the buffer strips. This was applied to the south-east (2.39 ha) and a parcel of the north-west portion of the golf course that drain to Lake Scugog through a buffer (SCS Consulting Group Ltd., 2015) _J150033_Scugog Phosphorus Budget 6

11 Post-Development The post development stormwater management plan for the proposed development includes: reduced lot grading, increased topsoil depth, direction of roof leaders to soakaway pits, infiltration trenches, and storm sewers with oil and grit separators (OGS). The OGS which will reduce TSS in the stormwater and direct it to Lake Scugog. The increased soil depth will promote infiltration and reduce runoff. The soakaway pits and infiltration trenches will infiltrate runoff from the site. Runoff from all hardened surfaces in catchments 212, 222a, 232, and 235 will be collected and infiltrated, leaving an area of 1.88 ha of lawn. Runoff from catchment 222 will be directed to an OGS equipped with a sorptive media filter which has a P removal efficiency of 89% in the Tool. Catchments 226 and 225, will drain to the existing SWMP via the existing storm sewers. The SWMP will be improved to ensure it s function to mitigate water quality. Runoff from catchment 231 (0.79 ha) will drain directly to Lake Scugog via a buffer, which will reduce the P load by 65%. The remaining catchment areas will drain offsite and intro grassed roadside ditches no reduction in P load was applied to the runoff from these areas. Oil grit separators are mostly known for reducing TSS, metal and oil and grease content of stormwater, whereas phosphorus removal efficiencies are seldom reported and often considered negligible. Some particulate phosphorus associated with the sediments is likely being removed from the stormwater, which has been demonstrated in a few field studies. One of the studies reviewed by the Stormwater Management Monitoring and Performance (SWAMP) program reported a 31%TP removal efficiency (SWAMP 2004) at a TSS removal efficiency of 51%. Two other Stormceptor field studies reported TP removal efficiencies of 18 and 32 %, at TSS removal efficiencies of ca. 30% and 76 %, respectively (Rinker Materials 2012). Based on the SWAMP studies, a 30% reduction in efficiency was applied to areas treated by the OGS Runoff Volumes Pre-Development For the pre-development scenario, urban lands included the maintenance shed, which is considered commercial land use by the Tool. The volume of runoff volume from this area was calculated using the Tool assuming a fraction of impervious area of 0.50, estimated by inspection of the aerial photography Post-Development For the post-development scenarios, runoff volumes were provided by Golder Associates for all of the redeveloped lands (Table 6). For the base scenario (no LID or SWM), the runoff was 51,199 m 3 /yr. With mitigation (i.e., increased topsoil depth) the volume of runoff from the site was reduced to 40,050 m 3 /yr. Runoff was further reduced by infiltration by soakaway pits and infiltration trenches for a final site runoff of 13,258 m 3 /yr _J150033_Scugog Phosphorus Budget 7

12 Table 6 Runoff and Infiltration Volumes Scenario Runoff Volume Base: No mitigation 51,199 Mitigation: increased topsoil and disconnected roof leaders 40,050 Infiltration Volume Less volume of runoff infiltrated from rooftops 8,937 Less volume of runoff infiltrated by trenches 7,855 Total annual site runoff after mitigation and infiltration 13,258 Notes volumes in m 3 /yr 3. Results The pre-development phosphorus load was compared to the post-development load to estimate the net annual phosphorus load to Lake Scugog from the proposed Canterbury Residential Development relative to existing conditions. The phosphorus load from the pre-development scenario was estimated to be 1.6 kg/yr from the subject lands (Table 6). The buffer was estimated to remove 0.2 kg/yr, allowing 1.4 kg/yr to reach Lake Scugog. Most of the phosphorus load was from the golf course (1.1 kg/yr). Table 7 Pre-Development Phosphorus Budget Land Use Load Open Water 0.1 Buffer Strip Removal Golf Course Commercial 0.3 Final Load Total Notes: values in kg/yr The phosphorus load from the post-development scenario without any mitigation (i.e., increased topsoil depth or infiltration) was estimated to be 21 kg/yr. Phosphorus load is reduced by 4.6 kg/yr with the addition of topsoils to promote infiltration, and by an additional 13.4 kg/yr with the addition of infiltration to the soakaway pits and infiltration trenches. Phosphorus removal from runoff treated by the OGS fitted with an absorptive membrane filter and the existing SWM pond (with improvements) further reduces the P load from the site by 2.2 kg/yr. With all stormwater mitigative measures, the total phosphorus load from the site is 0.8 kg/yr for a net reduction in loading over existing conditions of 0.5 kg/yr _J150033_Scugog Phosphorus Budget 8

13 Table 8 Post-Development Phosphorus Budget Area (ha) P coeff (kg/ha/yr) Load Load Removed by BMP/LID Final Load Residential - lawns to OGS Residential lawns to grassed swales Residential - to OGS + filter Residential - to existing SWM Residential to L. Scugog buffer Transition Net Change in Load from Pre- Development Total Area infiltrated 3.2 Total Area Notes: values in kg/yr except where noted. 4. Conclusions and Recommendations The draft phosphorus budget provided the following estimates of phosphorus loading from the proposed Canterbury Residential Development: 1.6 kg/yr from current land uses with no BMPs/LIDS 1.4 kg/yr from current land uses with BMPs (buffer strip) 21 kg/yr from proposed land use changes with no BMPs/LIDs 16.4 kg/yr from proposed land use changes with the addition of topsoil 3 kg/yr from proposed land use changes with the addition of topsoil and infiltration 0.8 kg/yr from proposed land use changes with the addition of topsoil and infiltration and BMPs/LIDs Net decrease of 0.5 kg/yr of phosphorus to Lake Scugog over existing conditions. The no net increase in phosphorus loadings to Lake Scugog from the proposed Canterbury Residential development is a conservatively value as there is potential for phosphorus reduction from infiltration in the roadside ditches. Improvements to the existing stormwater pond would further reduce phosphorus loadings to Lake Scugog from existing residential lands outside of the study area. The proposed _J150033_Scugog Phosphorus Budget 9

14 redevelopment of the Canterbury Golf Course would meet Kawartha Conservation s mandate to reduce of phosphorus loadings to Lake Scugog _J150033_Scugog Phosphorus Budget 10

15 5. References Berger Estimation of Phosphorus Loadings to Lake Simcoe. Prepared for the Lake Simcoe Region Conservation Authority by the Louis Berger Group. September Golder Associates, 2015 Hydrological Investigation Report, Canterbury Redevlopment, September 2015 (HESL) Phosphorus Budget Tool in Support of Sustainable Development for the Lake Simcoe Watershed. Report prepared for the Ontario Ministry of the Environment. 2014a. Managing New Urban Development in Phosphorus- Sensitive Watersheds Final Report and Database Tool. Prepared for Nottawasaga Valley Conservation Authority. October pp. 2014b. Proposed Keswick Business Park - Phosphorus Budget. Prepared for Glenwoods Gateway Investments Inc. December pp. Kawartha Conservation Lake Scugog Environmental Management Plan. May Kawartha Conservation Port Perry Stormwater Management Plan. December Kawartha Conservation, 2013: Port Perry Stormwater Management Plan, Final Report. December 10, Paterson, A.M., Dillon, P.J., Hutchinson, N.J., Futter, M.N., Clark, B.J., Mills, R.B., Reid, R.A. and Scheider, W.A A Review of the Components, Coefficients and Technical Assumptions of Ontario s Lakeshore Capacity Model. Lake and Reservoir Management, 22:7-18. Rinker Materials Como Park Field Monitoring, Wisconsin Field Monitoring. SCS Consulting Group Ltd., 2015 Functional Servicing and Stormwater Management Report, Canterbury Redevlopment, September 2015 South Nation Conservation (SNC), Updated Phosphorus Source Accounting Methodology for the Rural Water Quality Program. Prepared by Chris Allaway, University of Ottawa. Stormwater Management Monitoring and Performance (SWAMP) Program, Performance assessment of two types of Oil & Grit Separator for stormwater management in parking lot applications - Markham & Toronto, Ontario. Report prepared for Ontario Ministry of the Environment, Toronto and Region Conservation Authority, Municipal Engineers Association of Ontario, The City of Toronto. July Winter, J.G. and P.J. Dillon Export of nutrients from golf courses on the Precambrian Shield. Environmental Pollution 141: _J150033_Scugog Phosphorus Budget 11

16 Appendix A. Land Use Definitions _J150033_Scugog Phosphorus Budget

17 Table A1. Description of Land Uses for the NVCA Tool (HESL 2015) Land Use Forest Transition Wetland Turf/Sod Hay/Pasture Low Intensity Residential Unpaved Roads Open Water Cropland Residential Commercial Industrial Transportation Description Tree cover >60% of the land area. Includes ELC Forest (FO) and Cultural Plantation (CUP) classes. Also includes ELC Cultural Woodland (CUW) classes with tree cover between 35% and 60%). Tree cover generally <60% and often with a large proportion of non-native plant species. Includes ELC Cultural Meadow (CUM), Cutltural Thicket (CUT), Open Alvar (ALO) and Open Tallgrass Prairie (TPO) classes. Water generally <2 m deep, with variable flooding regimes, standing water or saturated soils. Includes ELC Swamp (SW), Fen (FE), Bog (BO), Marsh (MA) and Shallow Water (SA) classes. Turf/sod farms. Includes Golf courses, including lane ways, but not the isolated woodlots within, unless the area of the woodlots is < 0.5 ha. Hay and pasture fields, including the related agricultural buildings such as barns, silos and the farm residence. Fields are dominated with herbaceous vegetation and grasses with an understory of similar material in a state of decay. Weedy hay and/or pasture covers more than 50% of the area. Cleared areas with a low density of trees, including lawns and landscaping. Land use is dominated by gardens, parkland and lawns, e.g., cemeteries, urban parks, ski hills and residential estate properties with a minimum size of 2 ha or with <5% impervious area. Includes rail lines and associated cleared adjacent areas and rural development properties not directly associated with an agricultural operation. On developed portions, these properties are under intensive use. Based on canopy cover, these areas will often appear as Cultural Savannah or Cultural Woodland in aerial photographs or satellite imagery. However, the presence of buildings and manicured lands identify the properties as Rural Development. Unpaved roads and associated shoulders. Excludes driveways and unpaved parking lots. Water generally >2 m deep, with no tree or shrub cover, as per ELC Open Water (OW) class. Also includes streams and rivers. Cultivated row crops, including the related agricultural buildings (e.g., barns, silos and the farm residence), producing crops in varying degrees (e.g., corn and wheat) and includes specialty agriculture (i.e., orchards, market gardens, Christmas tree plantations and nurseries). Urban related land uses with >10% impervious area. Includes residential properties (single, semidetached and strip dwellings, apartment buildings and associated out-buildings, driveways, parking lots and paved roadways). Excludes green land areas such as parks or river valleys. Impervious properties that contain a building and an adjacent parking lot (e.g., shopping and strip malls, power centres, scrap yards). Excludes green land areas such as parks or river valleys. Exludes roadways. Impervious properties that are not commercial and include industrial operations e.g., factories, manufacturing facilities, processing facilities, bulk fuel storage. Excludes green land areas such as parks or river valleys. Excludes roadways. Includes major transportation corridors (highways) and paved roadways that are not considered in other land use designations. Excludes driveways. Notes: ELC is the provincial Ecological Land Classification for Southern Ontario _J150033_Scugog Phosphorus Budget