Low Impact Industrial Development

Transcription

1 Low Impact Industrial Development CREDIT VALLEY CONSERVATION Low Impact Development in Action Conference October 4 th & 5 th, 2012 Presented by: Tim Gallagher, P.Eng., P.E. (Water Resources Engineer)

2 next 15 minutes Case Study Site Location Background Drainage Conditions/Constraints SWM Criteria SWM Alternatives Preferred LID Alternatives Incentives for Considering LID

3 Functional Servicing Report Draft Plan of Subdivision, Alliston, ON Existing Status 62.7 ha (155 acre) Site South/Central Alliston Agricultural Land Use (soy bean, rye, and/or potatoes) Designated as Employment Area 2 within Town of New Tecumseth Official Plan (2010) Industrial Zoning No aquatic or terrestrial features or species that are rare, threatened or endangered FSR Scope of Services Grading Road Works Municipal Servicing Approach Water Sanitary Drainage/SWM Utilities Additional Stantec Services Traffic Impact Study Geotechnical Investigation 3

4 Site Location Boyne River N Alliston Honda Plant Site Outlet into Spring Creek Nottawasaga River 4

5 Nottawasaga Valley Conservation Authority (Boyne River Watershed) 2007 Subwatershed Report Card Overall Surface Water Quality Grade of B Benthics Score = C Baseflow TP (22 ug/l) = C Baseflow TSS (3.6 mg/l) = A E.coli (219 cfu/100 ml) = C Spring Creek indicated to have a Poor Surface Water Quality Condition but improving due to recent efforts by industry Outlet to Spring Creek (from Honda Site) Walton Site

6 Existing SWM/Drainage NE SWM Pond Product Storage Yard Spring Creek Outlet Honda Plant Culvert PIT Industrial Pkwy Simcoe Parts Plant Walton Site Southern External Drainage NW SWM Pond Rail Spur Site Outlet Test Track CN Railroad (Abandoned) EX. CP Railroad 6

7 Honda Drainage Product Storage Yard Honda Plant Industrial Pkwy Culvert PIT NW SWM Pond Rail Spur Employee Parking PIT WEIR CONTROL Test Track 7

8 Onsite Drainage 8

9 Onsite Drainage Characteristics 62.7 ha (onsite) and 51.8 ha (external) Gently Sloping Terrain (0.25% to 0.65%) from south to north Agricultural Use (Soy Bean, Rye and/or Potatoes) Sheet and Shallow Concentrated Flow (no swales) Four (4) Existing DICBs along Industrial Pkwy Shallow ponding on south side of Industrial Pkwy at DICBs during infrequent events Storm sewer discharges to Honda PIT 270 mm of Topsoil (Average) Underlain by fine sands (60 mm/hr to 240 mm/hr) 9

10 Existing VO2 Schematic Walton Site Honda Site Other External through Honda

11 Unmitigated Runoff Summary Storm Regional (Timmins) Ex. Q (m 3 /s) Ex. Volume (mm) Pr. Q (m 3 /s) Pr. Volume (mm) Q % Increase Volume % Increase % 39% 100yr 4hr Chic % 105% 100yr 24 hr SCS % 74% 25yr 4hr Chic % 136% 25yr 24 hr SCS % 97% 10yr 4hr Chic % 168% 10yr 24hr SCS % 116% 5yr 4hr Chic % 210% 5yr 24hr SCS % 136% 2yr 4hr Chic % 318% 2yr 24hr SCS % 187% 25 mm 4hr Chic % 510%

12 Drainage Alternatives Assessment Major constraints associated with draining through Honda lands Recognized by Town & NVCA Open to alternative drainage strategies including the following: Option 1: Drain through Honda (match post to pre runoff rate and volume 25 mm through Timmins) Option 2: Drain northwest along abandoned RR to Spring Creek (match post to pre runoff rate up to 100yr; safely convey Timmins) Option 3: Drain southeast along abandoned RR to Nottawasaga River (match post to pre runoff rate up to 100yr; safely convey Timmins)

13 Option 1 (through Honda)

14 Option 2 (to Spring Creek) Spring Creek Spring Creek confluence with Boyne River

15 Option 3 (to Nottawasaga River) Upper Nottawasaga River

16 Preferred Alternative (Option 1) Already an existing municipal drainage easement through Honda to Spring Creek Follows existing drainage pattern Would need to acquire easements for Options 2 and 3 on RR, Town, and private lands Extensive shallow sloping large storm sewers required for both Options 2 and 3 at significant depths in places (costly and challenging to construct) Option 3 would divert drainage from Boyne River to Nottawasaga River (not a recommended practice)

17 Proposed Draft Plan of Subdivision (January 2012) Design Plan Services Inc. Plan Statistics Industrial = ha Roads = 5.99 ha SWM = 4.32 ha Total = ha

18 SWM Design Criteria (Applicable to Preferred Option 1) Water Quality: MOE Level 1 (Enhanced) to achieve 80% TSS removal efficiency Water Quantity: Post-development to Pre-development rate controls for the 25 mm 4hr Chicago through Regional (Timmins) storm; consider both 24 hr SCS and 4hr Chicago Water Balance: Post-development to Pre-development runoff volume controls for the 25 mm 4hr Chicago through Regional (Timmins) storm; consider both 24 hr SCS and 4hr Chicago

19 Unmitigated Runoff Summary Storm Regional (Timmins) Ex. Q (m 3 /s) Ex. Volume (mm) Pr. Q (m 3 /s) Pr. Volume (mm) Q % Increase Volume % Increase % 39% 100yr 4hr Chic % 105% 100yr 24 hr SCS % 74% 25yr 4hr Chic % 136% 25yr 24 hr SCS % 97% 10yr 4hr Chic % 168% 10yr 24hr SCS % 116% 5yr 4hr Chic % 210% 5yr 24hr SCS % 136% 2yr 4hr Chic % 318% 2yr 24hr SCS % 187% 25 mm 4hr Chic % 510%

20 Water Balance Critical to be able to utilize the underlying (highly permeable) fine sandy soils to meet strict water balance requirements. but you can t infiltrate water from industrial areas?!!! Actually per the MOE, infiltration facilities MUST NOT receive runoff from pollution hot spots, such as vehicle fuelling, servicing or demolition areas, outdoor storage or material handling areas for hazardous materials or from heavy industrial use areas. Needed to focus on low risk areas to source for clean water runoff for infiltration.

21 Overall SWM Approach Onsite Controls: Infiltrate as much runoff as possible at the source (ie. 100-yr storm) Source runoff for infiltration from low risk areas such as building rooftop, employee parking, and landscaped areas Separate runoff from all Other Industrial Areas and convey to end-of-pipe MOE Level 1 treatment for all onsite areas Conveyance Controls: Utilize lined vegetated swale system to assist with water quality (filtering) and water quantity (to reduce pond active storage requirement) End-of-Pipe Controls: Size SWM pond to satisfy MOE Level 1 treatment for Roads and Other Industrial Areas Size active storage to meet overall quantity controls in tandem with onsite infiltration Provide infiltration cell in SWM Block to infiltrate remaining required volume to meet overall site requirements

22 Onsite Controls Clean Water Sources: Rooftop Landscaped Areas Employee Parking but how can we quantify the lot area coverage for 12 separate development blocks with potentially 12 separate industrial users at the Draft Plan stage? Need to make some reasonable assumptions. Zoning By-Law for Industrial: Minimum 10% lot coverage to be landscaped Maximum 60% building coverage of the lot Employee parking must be 25% of the gross floor area Lot Coverage Assumptions: In collaboration with the Town and upon review of various industrial and commercial uses a 35% building coverage of the lot was established 8.75% Employee Parking (25% of building) 10% landscaping 46.25% of remaining lot considered to be higher risk uses termed Other Industrial Areas

23 Onsite Summary Lot Breakdown Percentage of Gross Lot Area Treatment Prior to Discharge Discharge Location of Stormwater Rooftops 35 No Infiltration basin located within Block Employee Parking Lots 8.75 Stormceptor or other oil/grit separator Infiltration basin located within Block Landscape Buffer 10 No Infiltration within Landscape buffer or directed to centralized SWM Facility End Discharge Point In Ground In Ground In Ground or Centralized SWM Facility Other Industrial Areas (OIA) Total Stormceptor or other oil/grit separator Swale Centralized SWM Facility

24 Block 4 Example for Onsite SWM

25 Block 4 (Lot Concept)

26 Conveyance Controls (Conceptual Grading Plan)

27 End-of-Pipe Controls Water Quality: Permanent pool must satisfy MOE Level 1 Applying minimum depth (1.0 m) yields a permanent pool volume of 20,200 m 3 (7,125 m 3 required for Level 1) Pond geometry/volume dictated by having to provide Regional storm detention (active storage) Water Quantity: Active storage sized to meet balance of overall quantity control requirements (accounting for onsite controls) 2.0 m max. active storage fluctuation in accordance with MOE Storage in conveyance system (veg swales) considered as active storage to minimize SWM pond size Water Balance: Infiltration basin sized to meet balance of overall volume control requirements (13,300 m 3 over 48 hrs) SWM pond used for more efficient retention storage Sized assuming the lowest onsite percolation and with a Fs=1.5 Physical Geometry: Designed in accordance with MOE and Municipal standards

28 End-of-Pipe Controls

29 Overall Proposed Conditions VO2 Schematic Walton Site Honda Site

30 Water Quality Summary Treatment Train!! Development Blocks broken down based on SWM approach Other Industrial Areas (to SWM pond) Rooftop and Parking Lot (to onsite infiltration) OGS to pre-treat both areas to satisfy MOE Level 1 Lined Vegetated Swale to further filter runoff and capture sediments prior to discharging to SWM pond SWM pond significantly exceeds MOE Level 1

31 Site Outlet Water Quantity Summary Storm Existing Conditions Peak Flow Rate (m 3 /s) Proposed Conditions Peak Flow Rate (m 3 /s) Percent Reduction (%) Regional (Timmins) 100yr 4-hr Chicago 100yr 24-hr SCS 25yr 4-hr Chicago 25yr 24-hr SCS 10yr 4-hr Chicago 10yr 24-hr SCS 5yr 4-hr Chicago 5yr 24-hr SCS 2yr 4-hr Chicago 2yr 24-hr SCS 25 mm 4-hr Chicago % % % % % % % % % % % %

32 Water Balance Summary Storm Existing Conditions Runoff Volume (mm) Proposed Conditions Runoff Volume (mm) Percent Reduction (%) Regional (Timmins) 100yr 4-hr Chicago 100yr 24-hr SCS 25yr 4-hr Chicago 25yr 24-hr SCS 10yr 4-hr Chicago 10yr 24-hr SCS 5yr 4-hr Chicago 5yr 24-hr SCS 2yr 4-hr Chicago 2yr 24-hr SCS 25 mm 4-hr Chicago % % % % % % % % % % % %

33 SWM Detailed Design Complex SWM Strategy for the overall Subdivision Important to establish universal criteria for end user at detailed design to simplify Level 1 Onsite WQ Control (2x) Unit-Rates for Runoff Volume (mm) for overall Block Unit-Rates for Uncontrolled Runoff (L/s/ha) Onsite Percolation Tests to confirm site specific conditions

34 Rate & Volume Targets Storm Event Site Release Rate (L/s/ha) Allowable Runoff Volume (mm) Regional (Timmins) Storm year 4-hr Chicago year 24-hr SCS year 4-hr Chicago year 24-hr SCS year 4-hr Chicago year 24-hr SCS year 4-hr Chicago year 24-hr SCS year 4-hr Chicago year 24-hr SCS mm 4-hr Chicago

35 Conclusions Just because a Site is Zoned and Designated doesn t necessarily mean supporting civil engineering investigations were undertaken; risk of grading/servicing constraints to developers purchasing a property FSR was circulated to Honda and they provided a letter to the Town indicating that they have no objection to the proposed SWM approach Draft Plan of Subdivision Approved; subject to further groundwater level monitoring and confirmation in the SWM Block Low Impact Development techniques can be applied for Industrial Areas provided that proper SWM criteria/constraints are clearly identified LID Approach and Innovative SWM Strategy helped to minimize SWM Block and maximize developable land (ie. SWM Block ~ 7% of Subdivision Area and achieves full Regional storm detention)

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