Table 1 - Infiltration Rates

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Charles Cameron
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Stantec Consulting Ltd. 100-300 Hagey Boulevard, Waterloo ON N2L 0A4 November 14, 2017 File: 161413228/10 Attention: Mr.

1 Stantec Consulting Ltd Hagey Boulevard, Waterloo ON N2L 0A4 November 14, 2017 File: /10 Attention: Mr. Michael Witmer, BES, MPA, MCIP, RPP City of Guelph 1 Carden Street Guelph ON N1H 3A1 Dear Mr. Witmer, Reference: Lowes Road Zoning By-law Amendment (ZC1615) The following letter summarizes the revised infiltration and water balance calculations for the proposed development located at Lowes Road, Guelph. Calculations presented in the Functional Servicing Report (Stantec, May 2017) were revised to reflect the findings of the Guelph permeameter infiltration test completed by Englobe and summarized in a letter to Mr. Alfred Artinger of Reid s Heritage Homes on September 15, 2017 (submitted under separate cover) and subsequently revised in an on October 17, A copy of Table 1 from the letter prepared by Englobe presents the results of the infiltration tests. Test pits were located in proposed areas of infiltration central to the site (please refer to the Englobe letter mentioned above for a location map). Table 1 - Infiltration Rates Infiltration Location Approximate Test Depth (mbgs) Approximate Test Elevation (m) Soil Type Field Saturated K-Value (m/s) Factored Infiltration Rate (mm/hr) GP Sand and Gravel 4.50 x GP Silty Sand 2.99 x GP Silty Sand 2.78 x Infiltration rates are highest further west towards GP while the lower rates are to the east (all central to the site). The lowest factored infiltration rate from the Guelph permeameter test, 45 mm/hr, has been used to update the infiltration sizing calculations and the site water balance. Previously, the assumed infiltration rate was 18 mm/hr from the Geotechnical Investigation Report (Englobe, 2016). The revised calculations are attached.

November 14, 2017 Mr. Michael Witmer Page 2 of 3 Reference: 19-59 Lowes Road Zoning By-law Amendment (ZC1615) Minor changes to the water balance occurred as a result of the infiltration test results.

2 November 14, 2017 Mr. Michael Witmer Page 2 of 3 Reference: Lowes Road Zoning By-law Amendment (ZC1615) Minor changes to the water balance occurred as a result of the infiltration test results. Table 2 presents the changes to the analysis. Table 2 - Revised Water Balance Results Water Balance Distribution Existing Conditions Proposed Conditions May 2017 October 2017 May 2017 October 2017 Precipitation (mm/yr) Total Evapotranspiration (mm/yr) Recharge (mm/yr) Runoff (mm/yr) Recharge Surplus (proposed only) (mm/yr) Runoff Surplus (proposed only) (mm/yr) The infiltration factors used in the water balance methodology were adjusted to reflect the higher infiltration rates obtained in the Guelph permeameter testing. Total annual infiltration volumes increased under existing conditions, affecting the surplus under proposed conditions. In general, changes were minor and no change to the design is recommended as there remains a surplus of groundwater recharge. Design calculations for the proposed infiltration trenches were also revised based on the updated infiltration rates. Table 3 presents the potential changes to the design. Table 3 - Infiltration Trench Design Revisions Depth of Trench (m) Footprint of Trench Drawdown (hrs) (m 2 ) May October The dimensioning in Table 3 is for comparative purposes only; lengths, widths and depths can be adjusted depending on potential design constraints (i.e., high groundwater elevation) and City requirements. It is recommended the functional design remain as-is with minor changes to infiltration trench depths and footprints in order to reduce drawdown times. We trust the above revisions to the water balance and proposed infiltration system are sufficient to address the City of Guelph requirements for the stormwater management design for the proposed Lowes Road residential development.

4 APPENDIX A Revised Water Balance Analysis Stantec Lowes Road Zoning By-law Amendment (ZC1615)

5 Update cells with red text. See cell comments for additional notes. Monthly Water Balance Analysis Lowes Road Land Cover Descriptions Existing Conditions lawns with some trees fine sand Flat land Main Site Area (ha) 1.64 Impervious 10% Description Factors Land Impervious Perm. Pool Topography Soils Cover Sum (Infiltration Factor) Soil Moisture Capacity (mm) Site Area Percentage of Total Site Area 90% 10% 0% 100% OK Jan Mar Apr Jun Feb May Jul Aug Sep Oct Nov Dec Year Comment Climate Data (Data from Waterloo-Wellington Station - Climate Normals from ) Average Daily Temperature ( C) Daily average temperature in each month Precipitation (mm) Evapotranspiration Analysis Saturation Vapour Pressure (mb) PET (Malstrom, 1969) (mm/month) Expected ET for 916 mm of annual rainfall per unit area of pervious area (zero impervious coverage) Infiltration - PET (mm) Weighted Soil Storage Capacity (mm) Actual Soil Moisture (mm) Assume April soil moisture is at max capacity (i.e., saturated) Change in Soil Moisture (mm) Actual Evapotranspiration (mm) Recharge/Runoff Analysis Surplus Deficit Weighted Infiltration Factor Based on MOE SWM Manual (2003) Runoff (mm) Assume no runoff in sub-zero months Recharge (mm) Volume-Based Balance (m 3 ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year Precipitation 1, ,000 1,222 1,350 1,351 1,617 1,376 1,440 1,105 1,428 1,168 15, mm/year Evapotranspiration ,218 1,415 1, , mm/year Pervious Runoff , , mm/year Impervious Runoff , mm/year Total Runoff , , mm/year Groundwater Recharge , , mm/year Monthly Water Balance Analysis Lowes Road Land Cover Descriptions Post-Development urban lawn fine sand Flat land Main Site Area (ha) 1.64 Impervious Cover 50% Land Description Factors Impervious Perm. Pool Topography Soils Cover Sum (Infiltration Factor) Soil Moisture Capacity (mm) Site Area Percentage of Total Site Area 2 50% 50% 0% 100% OK Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year Comment Climate Data (Data from Waterloo-Wellington Station - Climate Normals from ) Average Daily Temperature ( C) Daily average temperature in each month Precipitation (mm) Evapotranspiration Analysis Saturation Vapour Pressure (mb) PET (Malstrom, 1969) (mm/month) Infiltration - PET (mm) Weighted Soil Storage Capacity (mm) Actual Soil Moisture (mm) Assume April soil moisture is at max capacity (i.e., saturated) Change in Soil Moisture (mm) Actual Evapotranspiration (mm) Recharge/Runoff Analysis - Pervious Areas Surplus Deficit Weighted Infiltration Factor Based on MOE SWM Manual (2003) Runoff (mm) Assume no runoff in sub-zero months Recharge (mm) Pond Pond Evaporation (mm) Runoff (mm) Volume-Based Balance (m 3 ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year Precipitation 1, ,000 1,222 1,350 1,351 1,617 1,376 1,440 1,105 1,428 1,168 15,027 Evapotranspiration ,168 Pond Evaporation Total Evap , mm/year Pervious Runoff mm/year Impervious Runoff , , mm/year Pond Runoff mm/year Total Runoff , , mm/year Groundwater Recharge from Pervious , , mm/year Areas Infiltration Augmentation Rooftop Recharge mm/year - Assuming 80% of roof top runoff is captured and infiltrated and 25 mm of runoff infiltrates from the roof (assume 80% ,742 of the annual rainfall volume) Non-Rooftop Impervious Recharge (to dead storage in SWM facility) , mm/year - Assuming 80% of impervious runoff from catchment to SWM facility is captured and infiltrates in permanent pool of facility (assume 60% of the annual rainfall volume or 15 mm of runoff) Final Recharge mm/year - Sum of groundwater recharge from pervious areas and recharge from rooftops and other impervious , ,702 areas Final Runoff , , mm/year - Assuming infiltration of rooftop areas and non-rooftop areas to SWM facility Final Recharge Surplus , mm/year Final Runoff Surplus , , mm/year Notes: 1. Total ET from site based on total pervious area on-site; i.e., 90% of 1.64 ha site 2. Assumed 50% of site is pervious coverage based on measurements from site plan; includes all lawn areas, rear yards, boulevards, and dry SWM facility coverage 3. Rooftop recharge based on average rooftop area of 110 sq. m; assumes 80% of rooftop reaches infiltration (safety factor); total number of homes to infiltration is Non-rooftop impervious coverage refers to drainage reaching OGS unit for pre-treatment before infiltration in dry facility (includes roadway and driveways) 5. Final recharge a sum of all infiltration from pervious areas on the site, rooftop recharge, and non-rooftop recharge 6. Final runoff is the difference between total runoff volume and rooftop and non-rooftop infiltration volumes 7. Final recharge surplus is the difference between post-development and pre-development annual recharge volumes 8. Final runoff surplus is the difference between post-development and pre-development annual runoff volumes Other: - Existing conditions includes some development; assumed to be approximately 10% of site area - Geotechnical Investigation identifies the majority of the site is sand and gravel, some silt located at south end of site - Site is very flat with little discharge/outlet - Existing ground coverage is lawn - Proposed SWM facility has 0.15 m of permanent pool to promote infiltration of Catchment 49 (0.65 ha) or approximately 40 m 3 - Approximately 0.45 ha of non-rooftop area to SWM facility (including roadway, lawns, boulevard, driveways) - Permanent pool provides sufficient volume to retain the runoff from the 10 mm event from Catchment mm of runoff assumed to represent 85% of annaul rainfall volume while 10 mm rainfall event represents 50% of annual rainfall volume

6 APPENDIX B Revised Infiltration Trench Design Spreadsheet Stantec Lowes Road Zoning By-law Amendment (ZC1615)

7 19-59 Lowes Road, Guelph ON mm From Rooftop Areas Infiltration Trench Sizing Calculation Volume-Based Water Balance Spreadsheet Lawn Rock Trench Month # Month Days Monthly Evap (mm) Impervious Area To Lawn 0 sq.m Impervious Area 0 sq.m 1 Jan 31 0 Lawn Area 0 sq.m Lawn over RT 0 sq.m 2 Feb 28 0 Directly to Tench 2970 sq.m Summary Lawns Trench Total 3 Mar 31 0 Total area: 0 sq.m Total area: 2970 sq.m Trench/Rooftop footprint Total evaporation *Assumes no evaporation for conservative estimate 4 Apr 30 0 Trench surf. area: 245 sq.m Safety Factor 25% Total exfiltration May 31 0 Trench depth: 0.5 m Actual footprint 306 sq m Total drainflow Jun 30 0 Trench porosity: 0.35 Total runoff Jul 31 0 Trench full: cu.m Total Reused 8 Aug 31 0 Trench initial vol: 0 cu.m 9 Sep 30 0 Subsoil exfil. rate: 45 mm/hr Subsoil exfil. rate: 45 mm/hr Sum Oct 31 0 Soil depth: 150 mm Soil depth: 0 mm Total rainfall Nov 30 0 Soil porosity: 0.35 Soil porosity: 0.35 % Treated 100% 100% 12 Dec 31 0 Soil field cap: 0.15 Soil field cap: 0.15 % untreated 0% 0% Soil wilt point: 0.1 Soil wilt point: 0.1 % Captured 100% 100% Soil infil. rate 3.5 mm/hr Soil infil. rate 3.5 mm/hr EIA 0% 0% Soil wilt point vol: 0.0 cu.m Soil wilt point vol: 0.0 cu.m Soil porosity vol: 0.0 cu.m Soil porosity vol: 0.0 cu.m Soil field cap vol: 0.0 cu.m Soil field cap vol: 0.0 cu.m Soil initial vol: 0.0 cu.m Soil initial vol: 0.0 cu.m Ponding 0 m *No contribution from lawn area to infiltration trench Lawns Rock Trench - Multi block roof area to trench All in cubic metres All in cubic metres beginning Water that beginning Total Beginning Beginning Beginning Rain Water Unsaturated Rain into Soil Water Water from Soil does not Water that water that Runoff Rain Water Rain Water Rain into Ponding Vol out Unsaturated Rain into Soil Water Water from Soil Water that Trench Water Trench Underdrain onto pervious Runoff Soil Volume to GW exfiltrate Stays in Soil runsoff Evaporation into Swale Directly to trench Ponding ponding Runoff Soil Volume to Trench Stays in Soil Volume Exfiltration Drainflow Evaporation Month 30/06/ :55 Precip (mm) ETO Precip (mm/hr) /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : /07/ : Page 1 November 13, 2017

Chiang Rai Province CC Threat overview AAS1109 Mekong ARCC

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