STORM WATER REPORT ASPHALT AND CONCRETE PLANTS JINKINSON SIDE ROAD, ASHTON CITY OF OTTAWA, ONTARIO PREPARED FOR:

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1 Civil Geotechnical Structural Environmental Industrial Health & Safety (613) Prescott Street P.O. Box 189 Kemptville, Ontario K0G 1J0 FAX: (613) STORM WATER REPORT ASPHALT AND CONCRETE PLANTS JINKINSON SIDE ROAD, ASHTON CITY OF OTTAWA, ONTARIO PREPARED FOR: R.W. Tomlinson Ltd. 891 Jinkinson Road Ashton, Ontario K0A 1B0 PROJECT # DISTRIBUTION: 6 copies R.W. Tomlinson Ltd. 1 copy Kollaard Associates Inc. Revision 0 Issued for Client Review 2012 May 14 Revision 1 - Issued for Distribution to Consultants 2012 Aug 07 Revision 2- Issued for Site Plan Control 2012 Nov 19 Professional Engineers Ontario Authorized by the Association of Professional Engineers of Ontario to offer professional engineering services.

2 2012 Nov 19 Storm Water Report Concrete and Asphalt Plants 891 Jinkinson Road, Ottawa Report STM1 Table of Contents 1 Introduction Pre-development Site Conditions Site Use Storm Water Analysis Purpose Method - Rational Method Results of Rational Method Analysis Pre-Development Baseline Conditions Post-Development Conditions Storage Stormwater Storage Additional potential inlet flows Water Quality Control Wet pond Design for Stormwater Treatment Grey Water from Truck Wash Station Sand Filter Filter Design Calculations Filter Maintenance Related Drawings Drawing # SS Site Servicing Plan # DP - Drainage Control Plan Attachments Figure 1 Key Plan Figure 2 Sub-catchment Areas Appendix A Rational Method Analysis of Pre-development Conditions Appendix B Rational Method Analysis of Post-development Conditions Appendix C Storage Volume Requirements Appendix D Wet Pond Design for Water Quality Control Appendix E Elevation vs Storage Volume in Pond Appendix F Sand Filter Design Appendix G Golder Associates Ltd. Memorandum Project No i

3 2012 Nov 19 Storm Water Report Concrete and Asphalt Plants 891 Jinkinson Road, Ottawa Report STM1 1 INTRODUCTION Kollaard Associates Inc. (Kollaard) was retained by R.W. Tomlinson Ltd. (Tomlinson) to provide a storm water management system design for the R.W. Tomlinson Ltd. concrete plant, asphalt plant, and associated service buildings and site at 891 Jinkinson Side Road, Ashton, Ottawa, Ontario. The site under consideration in the present study consists of the approximately 9.96 hectares ha area indicated in Figure 1, on Lot 15 Concession 11, Geographic Township of Goulbourn, City of Ottawa. The site encompasses areas of the property that are devoted to the production of concrete and asphalt including: buildings and industrial structures; aggregate storage bins; truck wash station; areas used for stockpiling material; roadway and parking areas; landscaped areas and areas used to service the site. It is to be noted that the existing quarry operation, to the west of the site, has an existing approved stormwater management system and is outside the scope of the present study. For the purposes of this study, pre-development conditions are considered to be the conditions that would have existed had the asphalt plant and concrete plant not been constructed. Post development conditions are considered to be conditions arising from the construction of the asphalt and concrete plants. Under pre-development conditions, the site surface consisted in general of a thin soil cover over bedrock with areas of sparse vegetation, coniferous forest and exposed bedrock. It is considered that stormwater runoff from the site generally consisted of uncontrolled sheet flow toward the wetlands to the south and toward areas of standing water to the southeast of the site. The majority of the site is located on land currently zoned ME. A smaller portion, at the southern end, is zoned RU. A wetland area zoned EP3 exists to the south of the site. It is understood that a 120-metre setback line from this wetland limits the southern extent of the site development. In the design of the storm water management system for the site, it has been considered that: The post development runoff rate from the site is to equal the predevelopment runoff rate from the site assuming runoff coefficients based on pre-development conditions; 1

4 2012 Nov 19 Storm Water Report Concrete and Asphalt Plants 891 Jinkinson Road, Ottawa Report STM1 An enhanced level of treatment is required for the site. No additional mitigation for temperature is required; and The receiving body of water for the runoff from the site is the creek to the southeast of the site. In general the proposed stormwater management design consists of directing the flow by means of sheet runoff, swales and ditches to a wet pond at the southern end of the pond. The wet pond is to provide an enhanced level of treatment, as defined by the Ontario Ministry of Environment Stormwater Management, Planning & Design Manual, 2003 (MOE Manual). The outlet of the pond is to be equipped with weirs to limit the discharge rate to that of pre-development conditions. The pond outlet is to discharge to a ditch to be constructed outside of the setback limit to the protected wetland. The outlet ditch is to discharge to an existing creek, flowing generally eastward from the southern end of the site. Existing topography precludes directing all of the runoff into the proposed wet pond. The area between the asphalt plant and Jinkinson Road is to be directed to a grassed swale leading to a sand filter designed to provide a normal level of treatment (as defined by the MOE Manual) before ultimately discharging into the ditch along Jinkinson Road. 2 PRE-DEVELOPMENT SITE CONDITIONS The site is located on the southeast side of Jinkinson Road about 1.8 kilometres southwest of Hazeldean Road, Ottawa, Ontario as shown on the attached Figure 1. The site has an area of about 9.96 hectares. The northern portion of the site is currently zoned for mineral extraction (ME) and the southern portion is zoned rural (RU). For the purposes of this stormwater management design, pre-development conditions are considered to be the conditions that would have existed had the asphalt plant and concrete plant not been constructed. The site is located in an area of high bedrock and in proximity to wetlands. This suggests that infiltration is naturally poor. Accordingly, the predevelopment runoff coefficient was considered to be C = 0.5 for the 5-year and 100-year storm events. It is considered that under predevelopment conditions, stormwater runoff would generally consist of uncontrolled sheet flow to the wetland to the south and the creek/area of standing water to the southeast of the site. The distance of travel for stormwater runoff from the most remote point to the 2

5 2012 Nov 19 Storm Water Report Concrete and Asphalt Plants 891 Jinkinson Road, Ottawa Report STM1 outlet was approximated as 420 m. The pre-development time of concentration was determined to be 50 minutes. The site is bounded on the northwest by Jinkinson Road, to the west by existing quarry operations and to the north, east and south by undeveloped land. Existing drainage from the undeveloped land is to a wetland southeast of the proposed site. Existing drainage from the site is by means of swales and sheet flow towards the undeveloped land and towards the quarry. Existing drainage from the quarry is towards the wetland southwest of the site. Existing drainage patterns of the properties surrounding the site are such that there is no offsite runoff directed onto the site. 3 SITE USE Facilities used in the production of asphalt are located at the northern end of the site. The asphalt works include an asphalt plant, areas for stockpiling aggregate materials, weigh scales, a service building and parking and roadway areas. Facilities used in the production of concrete are located at the southern portion of the site. The works consist of an 1130 square metre service building, the concrete plant, aggregate storage bins, truck wash station, and parking and roadway areas. The site is occupied by R.W. Tomlinson Ltd. The parking and roadway areas are used by construction vehicles and concrete trucks. The service building is currently serviced by a sewage holding tank, and by drilled cased wells. The holding tank is to be replaced by a Class 4 onsite septic system and a Class 2 grey water septic system. Stormwater runoff from 8.12 ha of the site is to be directed to ditches leading to a wet pond. Runoff from 1.52 hectares is to be directed towards a vegetative filter strip / sand filter along a berm at the northern boundary of the site, adjacent to Jinkinson Road. Runoff from the 0.33 hectare area around the washbay is to be collected in a grey water tank under the pump house (see section below). 4 STORM WATER ANALYSIS Purpose The proposed stormwater management system is designed to limit the post-development runoff from the site to that of pre-development conditions for the 5-year and 100-year design storm events. 3

6 2012 Nov 19 Storm Water Report Concrete and Asphalt Plants 891 Jinkinson Road, Ottawa Report STM1 4.2 Method - Rational Method Pre-development and post development runoff rates were determined based on the Rational method. The rational method is a widely used stormwater runoff model in which runoff is estimated as a fraction of the total rainfall over an area: Q CiA = 360 where Q is the Peak runoff measured in m 3 /s C is the Runoff Coefficient, Dimensionless A is the runoff area in hectares i is the storm intensity measured in mm/hr The Runoff Coefficient, C, represents the estimated proportion of rainfall that will be converted to surface runoff. For example a value of C=1 represents a condition in which all rainwater would leave the area under study as surface runoff. None of the water would infiltrate or evaporate during a rainfall event. A value of C=0.5 is used when it is estimated that only half of the water leaves the area as surface runoff. The other half would infiltrate or evaporate on site. The Time of Concentration, tc is an estimate of the time elapsed before rain falling on the entire area under consideration contributes to runoff. Time of concentration was approximated using the airport formula developed by the U.S. Department of Transportation s Federal Aviation Administration (FAA): t c = 3.26 (1.1 C) (l c ) 0.5 / (S) 0.33 where lc = length of catchement, S = slope of catchment The Storm Intensity, i, is rainfall per unit time. Historical rainfall data for various locations are available in the form of Intensity Duration Frequency (IDF) Curves. For a storm of a given return period (i.e. frequency) and a given duration, the intensity can be read from the IDF curve for the location under consideration. The IDF curves used for this project were those provided by the City of Ottawa for data collected at the Ottawa International airport. Two return periods (i.e. frequencies) were considered: the 5 year and 100 year storm events. For each of these frequencies, storms of various duration, ranging from 10 minutes to 120 minutes, were considered. 4

7 2012 Nov 19 Storm Water Report Concrete and Asphalt Plants 891 Jinkinson Road, Ottawa Report STM1 For storms of duration equal to the time of concentration tc, equations representing the IDF curves for 5-year and 100 year storm events yield: 5-Year Event i = ( ) t c 100-Year Event i = ( ) t c where tc is time of concentraion. 4.3 Results of Rational Method Analysis Results of the rational method analysis are presented in Appendices A and B and described below Pre-Development Baseline Conditions Parameters of the Rational Method analysis of pre-development conditions are presented in Tables A-1, A-2 and A-3. In Table A-1, time of concentration was determined based on length of catchment, slope of catchment and runoff coefficient. The time of concentration was then input into Table A-2 to determine runoff rate versus elapsed time for 5-year storm events of various duration and intensity. Likewise, runoff rate versus elapsed time for 100-year storm events, under pre-development conditions, are presented in Table A-3. Time of concentration, t c It is considered that under predevelopment conditions, stormwater runoff would generally consist of uncontrolled sheet flow to the wetland to the south and the creek and area of standing water to the southeast of the site. The distance of travel for stormwater runoff from the most remote point to the outlet was approximated as 420 m. The pre-development time of concentration was determined to be 50 minutes. 5

8 2012 Nov 19 Storm Water Report Concrete and Asphalt Plants 891 Jinkinson Road, Ottawa Report STM1 Intensity, i Values of rainfall intensity corresponding to incremental values of rainfall duration are presented in Appendix A. Intensity was calculated by substituting the corresponding value of duration into the IDF curve equations for 5-year and 100-year storm frequencies. For a storm duration equal to the pre-development time of concentration, substituting, tc= 50 minutes into the IDF equations yields: i = 38 mm/hr for a 5-year storm event; and i =64 mm/hr for a 100 year storm. Runoff coefficients, C: The site is located in an area of high bedrock and in proximity to wetlands and areas of standing water. This suggests that infiltration is naturally poor. Accordingly, the predevelopment runoff coefficient was considered to be C = 0.5 for the 5-year and 100-year storm events. Runoff rates, Q: Estimated pre-development runoff from the site was calculated as follows: Q CiA = 360 For the 5-year Storm event = (0.5 x 38 x 9.96)/360 = 0.52 m 3 /s Q 5year, 50 min = 52 Litres per second For the 100-year Storm event = (0.5 x 64 x 9.96)/360 = 0.88 m 3 /s Q 100year, 15 min = 88 Litres per second These values of pre-development runoff are indicated as Calculated Outflow Restriction in Appendix A and represent the allowable runoff from the site under post-development conditions used in the design of the proposed stormwater management system. 6

9 2012 Nov 19 Storm Water Report Concrete and Asphalt Plants 891 Jinkinson Road, Ottawa Report STM Post-Development Conditions The development consists of an asphalt plant, a concrete plant, service buildings, wash station, areas of aggregate stockpiles, aggregate bins, associated parking, driveway and landscaped areas. For the purposes of the rational method storm water analysis, the site has been divided into subcatchment areas, indicated in Figure 2. Note that runoff from the area labelled C1 is to be directed to the vegetated swale and sand filter; runoff from area C10 is to be collected in a grey water tank; and the remaining areas are to be directed via ditches to a wet pond at the southern end of the site. The vegetative swale/ sand filter has been designed based on water quality requirements only. Attenuation of stormwater runoff rates is to be achieved by the wet pond. The outlet of the wet pond is to be equipped with weirs to limit the discharge rate to that of pre-development conditions for the 5-year and 100 year design storm events. Parameters used in the Rational Method storm water analysis of post-development conditions are included in Appendix B and described below. In Table B-1 of Appendix B, the following parameters are presented for each sub-catchment area: Average runoff coefficient, C (weighted average based on areas of various degrees of imperviousness); Slope of catchment Length of ditch (travel distance in ditch) Length of catchment, Lc (travel distance of overland flow) Tc, time of concentration for overland flow Time of travel in ditch The time of concentration and time of travel in ditch were then input into Table B-2 to determine runoff rate versus elapsed time for 5-year storm events of various duration and intensity. Likewise, runoff rate versus elapsed time for 100-year storm events, under post-development conditions, are presented in Table B-3. These runoff rates represent respectively the 5-year and 100 year inflow hydrographs of the wet pond. Time of Concentration, t c The post-development times of concentration for the overland flow component of each subcatchment were determined using the airport formula. 7

10 2012 Nov 19 Storm Water Report Concrete and Asphalt Plants 891 Jinkinson Road, Ottawa Report STM1 For example, for subcatchment C1: Runoff coefficient, C = Slope of catchment, S = 0.5 Length of catchment, l c = 270 m Time of concentration was therefore calculated as: t c = 3.26 (1.1 C) (l c ) 0.5 / (S) 0.33 = 20 minutes Intensity, i Values of rainfall intensity corresponding to incremental values of rainfall duration are presented in Tables B-2 and B-3 for 5-year and 100-year storm events respectively. Intensity was calculated by substituting the corresponding value of duration into the IDF curve equations for 5-year and 100- year storm frequencies. For example, for a storm duration of 15 minutes (found to produce the maximum discharge at the outlet), substituting, tc= 15 minutes into the IDF equations yields: i = 84 mm/hr for a 5-year storm event; and i =143 mm/hr for a 100 year storm. Runoff Coefficients, C for Controlled and Uncontrolled Areas Average runoff coefficients for post-development conditions, presented in Table B-1, were calculated for each sub-catchment area as a weighted average of areas of different levels of imperviousness. Impervious Ratio The impervious ratio, the total impervious area divided by the total area, represents approximately 26 percent of the site. Post Development Runoff Rates, Q The inflow hydrographs (stormwater runoff rates entering the pond versus time) for storms of various durations are presented for the design 5-year and 100-year storm events in Tables B2 and B3 respectively. Runoff rates for each sub-catchment were calculated by the Rational Method, using appropriate values of C and A from Table B1 and from values of intensity corresponding to duration. Since the length of ditch is different between each sub-catchment and the wet pond, runoff 8

11 2012 Nov 19 Storm Water Report Concrete and Asphalt Plants 891 Jinkinson Road, Ottawa Report STM1 contributed by each sub-catchment would arrive at the pond inlet at different times. Tables B2 and B3 indicate the rate of stormwater inflow to the wet pond from each sub-catchment as a function of time, accounting for ditch travel time. The summation of the flow rates for each time increment is indicated for controlled areas and uncontrolled areas. Note that the uncontrolled area consists of subcatchment C1, which is directed to the vegetative swale and sand filter. The values of flow rate versus time for controlled areas represent inflow hydrographs of the wet pond (for corresponding frequency and duration). For example, for a five-year storm of duration of fifteen minutes, corresponding to an intensity of i = 84 mm/hr as calculated above, the maximum possible runoff from subcatchment area C1 would be: Q CiA = 360 = (0.78)(84)(0.52)/360 = m 3 /s Since the time of concentration is 20 minutes (as calculated above), not all of the area would contribute simultaneously to runoff for a storm of duration 15 minutes (runoff from the most remote point of the catchment would not arrive at the outlet before the end of the storm). Peak runoff was therefore approximated as: Q peak = D/tc Q = 15/20 (0.275) = m 3 /s Since the travel time in the ditch for sub-catchment C1 = 15 minutes, the peak flow contributed by this area would not arrive at the inlet to the wet pond until 30 minutes from the start of the storm event. In Table B-2, this corresponds to the value for runoff for sub-catchment C1 for storm duration of 15 minutes and 30 minutes of elapsed time. Allowable Controlled Area Release Rate The allowable controlled area release rates, presented in Tables C1 and C2 for 5-year and 100 year storms respectively, were calculated as the calculated outflow restriction (i.e. the peak predevelopment runoff rate) less the uncontrolled peak runoff. For a 5-year storm event, the peak pre-development runoff rate was found to be m 3 /s, corresponding to a storm duration of 50 minutes (Table A2). Maximum post-development runoff was found to occur for a storm of 15 min duration (Table B2). The maximum uncontrolled runoff for this design storm event was found to be m 3 /s. The allowable discharge for a 5-year storm was therefore calculated as (Table C1): Q5 year allowable = m3 /s m3/s = 0.31 m3 /s = 31 L/s 9

12 2012 Nov 19 Storm Water Report Concrete and Asphalt Plants 891 Jinkinson Road, Ottawa Report STM1 Similarly, the allowable discharge rate for a 100-year event was calculated as 0.53 m 3 /s (Table C2). Q100year allowable = m3 /s m3/s = 0.53 m3 /s = 53 L/s 5 STORAGE 5.1 Stormwater Storage The wet pond indicated in the site servicing drawings has been designed for attenuation of discharge flowrate as well as for water quality control. Stormwater is to be directed to the pond via ditches. Weirs are to be provided at the pond outlet to limit the discharge to the allowable controlled area release rates for the 5-year and 100-year storm events. Calculations of required volume of on-site stormwater storage to attenuate discharge flowrate are presented in Appendix C, Tables C1 and C2. The pond was designed for water quality control according to the requirements of the MOE Manual; associated calculations are included as Appendix D. Calculation of the storage volume in the pond and ditches, as a function of elevation, are included as Appendix E. The calculation of required storage is an iterative process: the required storage is related to the release rate, the release rate is dependent on the head of water above the control structure (in this case two outlet weirs), which is in turn dependent on the storage volume. The calculation of required storage for the design 5-year storm event is presented in Table C1. The runoff rate entering the pond was set equal to the inflow hydrograph for a 5-year storm of 15-minute duration, from Table B2, since this event was found to produce maximum runoff. Volume entering the pond over time was then calculated based on this inflow rate. In the first iteration, the discharge rate (outflow hydrograph from storage) was set to arbitrary values less than the allowable controlled area release rate of 31 L/s. The required storage was then calculated based on this release rate. The calculated required storage volume was input into Table E1 (Appendix E) to determine the corresponding head of water and discharge rate over the outlet weir of the wet pond. The discharge rate calculated in Table E was then re-entered as the discharge rate in Table B2, and a new corresponding value of required storage volume was calculated. Further iterations were calculated, with adjustments made to the shapes of the wet pond and outlet weirs, until convergence was achieved. 10

13 2012 Nov 19 Storm Water Report Concrete and Asphalt Plants 891 Jinkinson Road, Ottawa Report STM1 For the design 5-year storm event, a 0.4 m long rectangular weir at elevation m was found to produce a maximum discharge rate of 24.5 L/s resulting in a storage volume of about 1040 m 3. Similarly, for the design 100-year storm event, the addition of a second weir 0.6 m in length set at elevation m (the high water mark of the 5-year storm), was found to produce a total discharge rate of 45 L/s resulting in a storage volume of about 1520 m 3, corresponding to a high water elevation of m. The storage requirements and weir design are reflected in the design of the wet pond indicated in the site servicing drawings. 5.2 Additional potential inlet flows There is an existing sump in the structure under the aggregate bins, (to the north of the wash station). This sump is equipped with two pumps, one capable of delivering 17.4 L/s, the other 7.9 L/s. It is planned to use ground water from this sump in the production of concrete, and as dilution water for the grey water from the truck wash station (discussed in section 6.2). There is an additional sump in the office/garage which is equipped with a pump capable of delivering 15 U.S. G.P.M. (1 L/s). It is proposed to route water pumped from these sumps through the stormwater pond, rather than constructing a separate ditch network. The maximum flow rate associated with the groundwater pumps is 26.3 L/s or m 3 /s. The calculated maximum inflow to the stormwater pond associated with a design storm of 5-year return period is m 3 /s. The maximum flow from groundwater sumps would therefore represent about 2% of the peak flow associated with the 5-year design storm. The contribution of groundwater pumped from the sumps is considered negligible with regard to storage volume. 6 WATER QUALITY CONTROL Stormwater runoff quality control is to be provided primarily by a wet pond to be constructed south of the parking area for the concrete plant. In addition, a vegetated swale/ sand filter system has been designed to treat the runoff from the area between the asphalt plant and the berm along Jinkinson Road. 11

14 2012 Nov 19 Storm Water Report Concrete and Asphalt Plants 891 Jinkinson Road, Ottawa Report STM1 6.1 Wet pond Design for Stormwater Treatment The receiving body for the treated storm water discharged from the wet pond is the creek at the south end of the property, which flows in a general eastward direction toward wetland areas to the south-east of the site. An enhanced level of stormwater treatment is to be provided. The Ministry of Environment s Stormwater Management Planning and Design Manual (MOE Manual) details the requirements for storm water quality based on the receiving body of water. Enhanced treatment corresponds to a long-term average removal of 80% of total suspended solids (TSS). In the MOE Manual, Table 3.2 Water Quality Storage Requirements Based on Receiving Waters outlines the storm water storage requirements for quality purposes required to achieve the desired level of protection. In Part 4, the MOE Manual details the design requirements of several types of end of pipe storm water management facilities. The proposed wet pond has been designed according to the criteria set out in the MOE Manual for ponds proportioned for enhanced treatment. Calculations related to the water quality control design of the wet pond are presented in Table D1 of Appendix D. Note that the active storage volume of 1520 m 3 was governed by the 100-year storm storage rather than by water quality storage requirement Grey Water from Truck Wash Station Used wash water from the truck wash station is collected in a grey water tank under the pump house (refer to Drawing #4 Total Site and Grading Details). Stormwater runoff from the area identified as Catchment Area 10 in Fig 2 of this report is also collected in this tank. Based on information from R.W. Tomlinson Limited, it is our understanding that this grey water is to be used in the production of concrete, but that from time to time, grey water is to be discharged. A feasibility study conducted by Golder Associates Ltd. (Golder) for R.W. Tomlinson (Golder report , Appendix G) determined that grey water from the wash station tank, mixed with groundwater at a ratio of 1:19 (one in twenty), could be discharged to the stormwater management pond without resulting in a ph outside the Provincial Water Quality Objective. The report suggests that a suitable mixing ratio may be achieved by reducing the grey water pump rate to 1.2L/s while maintaining the existing total discharge rate of 25.2L/s from the groundwater sump. 12

15 2012 Nov 19 Storm Water Report Concrete and Asphalt Plants 891 Jinkinson Road, Ottawa Report STM1 Grey water diluted as per the Golder report would contribute a maximum of 26.4 L/s to the proposed stormwater management pond, over a period of 18.5 hours. Note that the proposed dilution water is the groundwater sump mentioned in section 5.2 above. The inflow rate associated with the design 100-year storm and 5-year storm events and the allowable discharge are an order of magnitude greater than the grey water flow. The grey water flow rate is considered negligible with regard to storage requirements. However, grey water flow has been considered in proportioning of the pond with regard to treatment. 6.2 Sand Filter The receiving body for the vegetated swale/ sand filter is the ditch along Jinkinson Road. The system has been designed in accordance with Part 4 section of the MOE Manual to provide a Normal level of treatment, defined as 70% TSS removal. The sand filter system is to provide water quality control only; it has not been designed for flow attenuation. The sub-catchment area served by the filter has been considered as an uncontrolled area for the purposes of stormwater quantity control (i.e. flow attenuation). As indicated in the site servicing drawings, runoff from the area between the asphalt plant and the berm along Jinkinson Road is to be collected in a grassed swale. A sand filter is to be constructed within the swale, near its outlet. Discharge from the sand filter is to be directed via a swale to the existing ditch along Jinkinson Road. The filter is to treat the water quality storage volume prescribed by the MOE Manual. The purpose of the filter is to treat the first flush of runoff (represented by the water quality storage volume), which is considered to carry the greatest proportion of the suspended solids. According to section of the MOE Manual, Volumetric Sizing Water Quality volumes to be used in the design of a filter are to be as indicated in Table 3.2 under the infiltration heading. The impervious ratio for the sub-catchment area is about 58 percent. From Table 3.2 of the MOE Manual, the water quality storage requirement at a normal level of treatment was determined to be 20 cubic metres per hectare. Since the area to be treated by the filter is 1.5 hectares, the total water quality storage requirement is 30 cubic metres. Part 4 section states that pre-treatment is recommended for all filters. The pre-treatment storage should have a volume equal to 25% of the design water quality control volume. This is equal to 0.25*30 = 7.5 m 3. 13

16 2012 Nov 19 Storm Water Report Concrete and Asphalt Plants 891 Jinkinson Road, Ottawa Report STM1 The treatment and pre-treatment storage volumes are to be provided within the grassed swale. Plan and cross section drawings of the swale are included on the site-servicing plan. The bottom of the swale is to be about 1 m in width and is to slope at 0.3% toward the filter. The elevation of the bottom of the swale at the location of the filter is to be m. A ponding elevation of m was determined to correspond to a volume of about 8.79 m 3 of storage in the swale. This volume has been considered as the design pre-treatment storage volume. An overflow swale is to be provided at elevation m so that water ponding above this level will be diverted from the filter. An elevation of m corresponds to a total storage volume of m 3, which is m 3 in excess of the pre-treatment volume. The design water quality storage volume that would be treated is therefore m Filter Design Calculations Calculations associated with the filter design are included as Appendix F. The sand filter is to be constructed with a relatively uniformly graded sand commonly used in the construction of onsite septic systems. The filter sand is to have a percolation rate of T = 4 to 6 min/cm with less than 2% silt/clay content. A percolation rate of T = 4 to 6 min/cm corresponds to a permeability of 180 mm/h to 360 mm/h or a k of 1 x 10-2 cm/sec to 5 x 10-3 cm/sec. It is acknowledged that a permeability of 360 mm/h is greater than the suggested value for sand of 45 mm/hr as found in the MOE Manual Equation The selected sand was chosen for the following reason. A permeability of 45 mm/hr corresponds to sand with a percolation rate of 8 min/cm. Commercially available sand with a percolation rate of 8 min/cm is much less well controlled during production than sand with a percolation rate of 4 to 6 min/cm. Using the selected filter sand will ensure a better product is used within the filter than had a sand with a higher percolation rate been specified. The MOE Manual states that the size of the filter may be determined using the Darcy Equation, which is equation 4.12 in the MOE Manual: A = 1000Vd k( h + d) t Where: A = surface area of the filter in m 2 V = design volume (m 3 ) to be outlet through filter d = depth (m) of the controlling filter medium (sand) 14

17 2012 Nov 19 Storm Water Report Concrete and Asphalt Plants 891 Jinkinson Road, Ottawa Report STM1 k = soil percolation rate in mm/hr h = average operating head of water on the filter (m) t = design drawdown time in hours A depth (i.e. thickness) of 0.5 m of sand has been specified. For the design water quality storage volume of V = m 3, the elevation of the top of the water stored in the ditch would be m. This would result in a contact surface area of A = 1.6 m 2 of sand through which the runoff would be filtered. The average head on the filter at this ponding elevation would be h = 0.2 m. For the sand specified, the resulting drawdown time would be 48.5 hrs, which is greater than the minimum 24 hours recommended. The storage will outlet either completely through the sand filter or through the overflow swale (elevation m) and ultimately discharge into the roadside ditch Filter Maintenance. Silt/sediment may be removed from the surface of the sand filter if the flow rate through the filter is observed to slow, causing excessive water back up in the swale during storm events. The upstream layer of the filter material (e.g., 0.1 to 0.15 m) should be removed and replaced with clear material when accumulated sediment is removed from the filter. 15

18 2012 Nov 19 Storm Water Report Concrete and Asphalt Plants 891 Jinkinson Road, Ottawa Report STM1 We trust that this report provides sufficient information for your present purposes. If you have any questions concerning this report or if we can be of any further assistance to you on this project, please do not hesitate to contact our office. Sincerely, Ian Malcolm, P.Eng. Kollaard Associates, Inc. Related Drawings: Drawing # SS Site Servicing Plan # DP Drainage Control Plan Attachments: Figure 1 Key Plan Figure 2 - Controlled and Uncontrolled areas Appendix A Rational Method Analysis of Pre-development Conditions Appendix B Rational Method Analysis of Post-development Conditions Appendix C Storage Volume Requirements Appendix D Wet Pond Design for Water Quality Control Appendix E Elevation vs Storage Volume in Pond Appendix F Sand Filter Design Appendix G - Golders Associates Ltd. Memorandum Project No

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21 Appendix A Rational Method Analysis of Pre-development Conditions

22 Table A-1 Pre Develoment - C & tc Tributary Area Total Area (m2) Building Area/asphalt Septic Bed Grass, Shrubs, trees over shallow bedrock C Slope (%) velocity (m/s) Length of Catchment (m) tc - catch (min) Label C= FAA

23 Table A-2 Pre Development - Storm Runoff Rates for 5-year Event Summary - Storm Duration vs Maximum Runoff Duration (min) Max Intensity (mm/hr) Controlled m 3 /s Uncontrolled m 3 /s Total m 3 /s Time (min) vs Runoff (m 3 /s) Calculated Outflow Restriction 0.52 m 3 /s Max RO (m3/s) Area (ha) C tc ditch (min) Tc catch(min) Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s

24 Table A-2 Pre Development - Storm Runoff Rates for 5-year Event Summary - Storm Duration vs Maximum Runoff Duration (min) Max Intensity (mm/hr) Controlled m 3 /s Uncontrolled m 3 /s Total m 3 /s Time (min) vs Runoff (m 3 /s) Calculated Outflow Restriction 0.52 m 3 /s Max RO (m3/s) Area (ha) C tc ditch (min) Tc catch(min) Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s

25 Table A-3 Pre Development (100 Year) - Storm Runoff Event Summary - Storm Duration vs Maximum Runoff Duration (min) Max Intensity (mm/hr) Controlled m 3 /s Time (min) vs Runoff (m 3 /s) Uncontrolled m 3 /s Total m 3 /s Calculated Outflow Restriction 0.88 m 3 /s Max RO (m3/s) Area (ha) C tc ditch (min) Tc catch(min) Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s

26 Table A-3 Pre Development (100 Year) - Storm Runoff Event Summary - Storm Duration vs Maximum Runoff Duration (min) Max Intensity (mm/hr) Controlled m 3 /s Time (min) vs Runoff (m 3 /s) Uncontrolled m 3 /s Total m 3 /s Calculated Outflow Restriction 0.88 m 3 /s Max RO (m3/s) Area (ha) C tc ditch (min) Tc catch(min) Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s

27 Appendix B Rational Method Analysis of Post-development Conditions

28 Table B-1 Post Develoment - C & tc Tributary Area Total Area (m2) Building or Impervious Area Grass and Shrubs Gravel Surface Septic bed Label C = C1 (uncontrolled) C C C C C C C C C10 (recycled) Total C Pond Weighted Average C Slope (%) Length of Ditch (m) velocity (m/s) Length of Catchment (m) tc - catch (min) Time of travel in ditch (min) Tc for catchment area rounded (min) Time of travel in ditch round(min) Area contributing to pond weighted average C Impervious ratio 0.26

29 Table B-2 Post Development (5 Year) - Storm Runoff Event Summary - Storm Duration vs Maximum Runoff Duration vs Intensity Max Duration (min) Max Controlled m 3 /s Intensity (mm/hr) Max Uncontrolled m 3 /s Max Combined Areas m 3 /s Time (min) vs Runoff (m 3 /s) Max RO (m3/s) Area (ha) C tc ditch (min) Tc catch(min) MIN Storm (uncontrolled) C C C C C C C C C10 (recycled) Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s MIN Storm (uncontrolled) C C C C C C C C C10 (recycled) Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s MIN Storm (uncontrolled) C C C C C C C C C10 (recycled) Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s

30 Table B-2 Post Development (5 Year) - Storm Runoff Event Summary - Storm Duration vs Maximum Runoff Duration vs Intensity Max Duration (min) Max Controlled m 3 /s Intensity (mm/hr) Max Uncontrolled m 3 /s Max Combined Areas m 3 /s Time (min) vs Runoff (m 3 /s) Max RO (m3/s) Area (ha) C tc ditch (min) Tc catch(min) MIN Storm (uncontrolled) C C C C C C C C C10 (recycled) Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s MIN Storm (uncontrolled) C C C C C C C C C10 (recycled) Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s MIN Storm (uncontrolled) C C C C C C C C C10 (recycled) Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s

31 Table B-2 Post Development (5 Year) - Storm Runoff Event Summary - Storm Duration vs Maximum Runoff Duration vs Intensity Max Duration (min) Max Controlled m 3 /s Intensity (mm/hr) Max Uncontrolled m 3 /s Max Combined Areas m 3 /s Time (min) vs Runoff (m 3 /s) Max RO (m3/s) Area (ha) C tc ditch (min) Tc catch(min) MIN Storm (uncontrolled) C C C C C C C C C10 (recycled) Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s MIN Storm (uncontrolled) C C C C C C C C C10 (recycled) Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s (uncontrolled) C C C C C C C C C10 (recycled) Controlled Max m 3 /s Uncontrolled Max m 3 /s Total Max m 3 /s

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36 Appendix C Storage Volume Requirements

37 n Outflow restriction year storm event Uncontrolled peak runoff minute duration Allowable Discharge Max Discharge post development Storage req'd Cummulative Total Active Time Runoff Rate Volume Cumulative Actual Discharge Discharge Storage Entering Pond per interval Volume Discharge Volume Volume Requirement min m 3 /sec m 3 m 3 m 3 /sec m 3 m 3 m Column 1 Column 2 Column 3 Column 4 Column 5 Column 6 Column 7 Column 8 Column 1 Elapsed time from start of storm (min) Column 2 Runoff rates corresponding to elapsed time for 5 year storm of 15 minute duration, Table B-2 Column 3 Column 2 x (Column 1 n - Column 1 n-1 ) x 60 s/min Column 4 Column 3 n + Column 4 n-1 Column 5 Discharge from Table E1 corresponding to volume in Column 4 Column 6 Column 5 x (Column 1 n - Column 1 n-1 ) x 60 s/min Column 7 Column 3 n + Column 4 n-1 Column 8 Column 4- Column 7 Table C1: Quantity Storage Volume Requirement Calculation

38 Table C2 Quantity Storage Volume Requirement Calculation Outflow restriction m3/s Uncontrolled peak runoff m3/s 100 year storm event Allowable Discharge 0.53 m 3 /sec 15 minute duration Max Discharge 0.45 m 3 /sec post development Storage req'd 1521 m 3 Cummulative Total Active Time Runoff Rate Volume Cumulative Actual Discharge Discharge Storage Entering Pond per interval Volume Discharge Volume Volume Requirement min m 3 /sec m 3 m 3 m 3 /sec m 3 m 3 m 3 n Column 1 Column 2 Column 3 Column 4 Column 5 Column 6 Column 7 Column 8 Column 1 Elapsed time from start of storm (min) Column 2 Runoff rates corresponding to elapsed time for 100 year storm of 15 minute duration, Table B-3 Column 3 Column 2 x (Column 1 n - Column 1 n-1 ) x 60 s/min Column 4 Column 3 n + Column 4 n-1 Column 5 Discharge from Table E1 corresponding to volume in Column 4 Column 6 Column 5 x (Column 1 n - Column 1 n-1 ) x 60 s/min Column 7 Column 3 n + Column 4 n-1 Column 8 Column 4- Column 7

39 Appendix D Wet Pond Design for Water Quality Control

40 Table D1: Wet Pond Design Based on Water Quality Sizing Criteria Required Volume Area to be treated = ha Table B1 Impervious Ratio = 0.17 Table B1 Impervious Ratio vs Storage Required for Enhanced Treatment Impervious Ratio (MOE Table) Storage Required (m 3 /ha) Total Quality Storage Volume = m 3 95 m 3 /ha MOE Req'd Permanent Pool Storage Volume = m 3 m 3 /ha MOE Extended Detention Quality StorageVolume = m 3 40 m 3 /ha MOE 100 year Storage Volume = m 3 Table C2 Total Required Active Storage Volume = m 3 (greater of extended detention or 100 year) Total Required Volume = m 3 (active + permanent) Design Quality Storm A = area contributing to pond (Table B1) C = 0.71 avg C of areas contributing to pond (sheet 'C') Peak Flow Rate of water quality storm i = 43*C+ 5.9 eqn 4.9 (MOE) = Qwq= CiA/360 eq'n 4.8 (MOE - flow rate associated with design water quality storm) = m 3 /s Grey Water flow rate diluted grey water discharged into pond Qgw = Q= Forebay Length greater of a) Dist = (rq p /V s ) 0.5 b) Dist = 8Q/dV f Dist = length of dispersion Q p = peak flow rate from pond during design quality storm V s = settling velocity; recommended value m/s r = length-to-width ratio of forebay min 2:1 Q = inlet flowrate (m 3 /s) d = depth of the permannent pool in the forebay (m) V f = desired velocity in the forebay (m/s) 0.1 to 0.15 m/s S S = Side Slope Angle H:1V A CF = Cross section Area Forebay Minimum Forebay Deep Zone Bottom Width c) Width = Dist/8

41 Q p = 0.31 V s = r = 4 (r >=2) Q = d = 1 V f = 0.15 S S = 4 Min Forebay Length a) = b) = Design Forebay Length 64.3 Forebay width (at elevation m) Min Forebay deep zone width c) = Actual Forebay deep zone width (at bottom) Min Length of Main Bay Design length of Main Bay Total length Actual Ave Forebay Velocity m 129 m m V f = Q/A CF A CF =depth 2 x sideslopes + depth x width A CF = m 2 V f = < 0.15 m/s ok elev width m m elevation of permanent bottom = m weir elevation of permanent pool = m weir elevation of 5-year storage = elevation of 100-year storage = min elevation of top of storage = m m m

42 Appendix E Elevation vs Storage Volume in Pond

43 Table E-1: Elevation versus Storage Volume permanent pool volume 1479 (m 3 ) Weir 1 2 Cw = L = g = weir elevation Cumulative Cumulative Total Volume Head Head Discharge Discharge Total Volume Volume Cumulative above Over Over Through Through Discharge Elevation in Pond in Ditch Volume permanent Weir 1 Weir 2 Weir 1 Weir 2 Pool Q=CwLh 3/2 Q=CwLh 3/2 (m) (m 3 ) (m 3 ) (m 3 ) (m 3 ) (m) (m) (m 3 /s) (m 3 /s) (m 3 /s) Bottom NA NA NA NA NA NA NA NA permanent pool NA 0 NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA 0.047

44 Table E-1: Elevation versus Storage Volume permanent pool volume 1479 (m 3 ) Weir 1 2 Cw = L = g = weir elevation Cumulative Cumulative Total Volume Head Head Discharge Discharge Total Volume Volume Cumulative above Over Over Through Through Discharge Elevation in Pond in Ditch Volume permanent Weir 1 Weir 2 Weir 1 Weir 2 Pool Q=CwLh 3/2 Q=CwLh 3/2 (m) (m 3 ) (m 3 ) (m 3 ) (m 3 ) (m) (m) (m 3 /s) (m 3 /s) (m 3 /s) NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA 0.193

45 Table E-1: Elevation versus Storage Volume permanent pool volume 1479 (m 3 ) Weir 1 2 Cw = L = g = weir elevation Cumulative Cumulative Total Volume Head Head Discharge Discharge Total Volume Volume Cumulative above Over Over Through Through Discharge Elevation in Pond in Ditch Volume permanent Weir 1 Weir 2 Weir 1 Weir 2 Pool Q=CwLh 3/2 Q=CwLh 3/2 (m) (m 3 ) (m 3 ) (m 3 ) (m 3 ) (m) (m) (m 3 /s) (m 3 /s) (m 3 /s) NA NA NA NA NA NA NA NA NA NA NA NA year storage NA NA year storage

46 Table E-1: Elevation versus Storage Volume permanent pool volume 1479 (m 3 ) Weir 1 2 Cw = L = g = weir elevation Cumulative Cumulative Total Volume Head Head Discharge Discharge Total Volume Volume Cumulative above Over Over Through Through Discharge Elevation in Pond in Ditch Volume permanent Weir 1 Weir 2 Weir 1 Weir 2 Pool Q=CwLh 3/2 Q=CwLh 3/2 (m) (m 3 ) (m 3 ) (m 3 ) (m 3 ) (m) (m) (m 3 /s) (m 3 /s) (m 3 /s)

47 Appendix F Sand Filter Design

48 TABLE F1 : SAND FILTER WATER QUALITY VOLUME AND DISCHARGE RATE side slope 3 width (b) 1 sand filter media depth 0.5 m filter width 6 permeability of filter sand, k 360 mm/hr m/s swale slope overflow invert Water Layer Cumulative Pond Ave Head Surface Discharge Drawdown Total Layer Elevation Surface Volume Volume Depth On Sand Area of through Time Drawdown Area Filter Filter Filter per layer Time n m m 2 m 3 m 3 m m m 2 m3/sec Hours Hours Column 1 Column 2 Column 3 Column 4 Column 5 Column 6 Column 7 Column 8 Column 9 Column 10 Column 11 Column 1 Layer of water in storage under consideration Column 2 Elevation (at top of layer) in metres Column 3 Surface area of the ponded water in storage at a ponding level corresponding to the elevation in Column 1 Column 4 Volume of the layer under consideration (i.e. volume in storage between the corresponding elevation n and elevation n-1). Column 5 Sum of layer volumes (1 to n) Column 6 Elevation in column 2 less the elevation of the bottom of the pond Column 7 Half depth of water adjacent to filter. (Column 6 / 2) Column 8 Surface area of sand filter in contact with ponding water Column 9 Discharge calculated using Darcy's Law. Surface area (Column 8) x Permeability x ((media depth + average head on filter (Column 7)/media depth) Column 10 Time for water in layer n to discharge: Column 4 / Column 9 /360 Column 11 Time for water in layers 1 to n to discharge: sum of Column 10 from 1 to n

49 Table F2: Design Summary - Sand Filter Requirements of MOE Manual Provided in design Catchment area to be treated 1.52 ha Water Quality Volume 20 m 3 /ha Volume to be treated m 3 Treatment volume provided, V = m 3 Pretreatment Storage 25% of water quality volume Pretreatment Storage volume 7.58 m 3 Pre-treatment volume provided = 8.79 m 3 (pre-treatment storage is below elevation m) Filter area required: where 1000Vd A = V = volume to be treated= m 3 k ( h + d ) t d = depth of media = 0.5 m k = permeability = 360 mm/hr Total surface area of sand provided 3.0 m 2 h = head on filter = 0.20 m Area beneath pretreatment storage = 1.4 m 2 t = drawdown time = 48.5 hr Effective area of filter for treatment= 1.6 m 2 A REQ'D= 1.59 m 2

50 Appendix G Golder Associates Ltd. Memorandum Project No

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