Storm Water Pollution Prevention
215.1DESCRIPTION
1 This section describes the requirements for control of pollutants and discharges of storm water from construction and industrial activities, including temporary and permanent measures to control erosion.
215.2MATERIALS
1 Provide materials in accordance with the following:
Materials
Subsection Burlap Bag Curbs 806.8 Cover Crop Seed 806.1 Erosion Control Agent 806.5 Mulch, Straw, or Hay 806.2 Silt Fence 805 Wire Staples 806.4 Woven Wire Backing 812.3
2 Provide silt fence posts with a nominal wood size of 2 in × 2 in [50 mm × 50 mm] or steel T-post weighing at least 1.25 lb/ft [2 kg/m]. Tie the silt fence to the post with wire, cord, staples, pockets, or other approved means.
3 Provide erosion bales with approximate external dimensions of 18 in × 18 in × 36 in [450 mm × 450 mm × 900 mm], weighing from 40 lb to 70 lb [20 kg to 35 kg] and tightly bound with wire ties or nylon twine. To secure, use 3-foot [0.9 m] wooden stakes with a nominal dimension of 2 in × 2 in [50 mm × 50 mm].
4 Provide excelsior sediment logs made of excelsior that is encased in a tube of polypropylene netting, having a minimum diameter of 12 in [300 mm], a standard length of 10 ft [3.0 m], and a weight of approximately 4.0 lb/ft [5.95 kg/m]. To secure, use 3-foot [0.9 m] wooden stakes with a nominal dimension of 2 in × 2 in [50 mm × 50 mm].
5 Synthetic triangular silt dikes consist of geotextile-wrapped foam or heavy plastic mesh . Provide foam dikes with a minimum height of 10 in [250 mm], sides of equal length, base of 20 in [500 mm], standard length of 7 ft [2.1 m], and with an outer cover of woven geotextile fabric with flaps extending 24 in [600 mm]. Provide heavy plastic mesh dikes with height of 9 in [230 mm], sides of equal length, base of 11 in [280 mm] base, and standard length of 3.6 ft [1.1 m]. To secure, use U-pin wire staples.
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6 Provide plastic liner, wooden flumes, metal pipe, plastic pipe, half-round pipe, or erosion control blanket for slope drains.
7 Use non-toxic chemical settling agents for water treatment as necessary.
215.3EQUIPMENT
1 Where practical, use a spreader truck with a pressurized spray bar to apply the erosion control agent and ensure a continuous, uniform application. Use other equipment in areas not accessible to the pressurized spray bar.
2 Set seed drills to produce uniform rows no more than 8 in [200 mm] apart, and equip them with a positive means for calibration to ensure seed distribution at the specified rate.
215.4CONSTRUCTION
215.4.1 General
1 Coordinate temporary and permanent soil erosion work. Stage permanent erosion control work to minimize the need for temporary work —the purpose of which is to supplement the permanent work and provide effective control throughout the construction period. Protect locations of exposed, erodible earth with functional erosion control measures installed correctly. Maintain measures to ensure maximum sediment reduction.
2 Complete erosion control work, temporary and permanent, as soon as practical and in conjunction with other construction work and subject to seeding date restrictions. Restore and seed haul roads, material sources, staging areas, and othe r disturbed areas as work is completed and subject to seeding date restrictions.
3 When permanent soil erosion control is established, remove the temporary measures, spread the accumulated sediment, and seed the disturbed area caused by the removal of the temporary measure as specified for the project reclamation.
215.4.2 Storm Water Control
215.4.2.1 Contractor Storm Water Control
1 Apply and secure approval for an EPA or WDEQ General Permit to Discharge Storm Water Associated with Construction Activities and, where necessary, Industrial Activities, for work within the construction limits . When obtaining a WDEQ General Permit to Discharge Storm Water Associated with Construction Activities, secure the permit for one year beyond the contract completion date. Develop, implement, and monitor the Storm Water Pollution Prevention Plan for the project, including temporary erosion control measures necessary, in addition to those specified, and associated labor, materials, equipment, and incidentals needed to fully implement the plan and comply with all rules,
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regulations, and restrictions imposed by EPA or WDEQ as a part of the General Permit Program.
2 Authority to issue permits for lands on the Wind River Indian Reservation resides with the EPA; the Water Quality Division of WDEQ maintains authority elsewhere.
3 Give a copy of the approved General Permit and Storm Water Pollution Prevention Plan to the engineer before starting work on the project . Provide the engineer copies of required monitoring reports and necessary Storm Water Pollution Prevention Plan revisions. This information is not for approval but will be used to document the Contractor Storm Water Prevention pay item.
4 Throughout the work, implement the Storm Water Pollution Prevention Plan, modifying as necessary. The engineer may make periodic inspections of the storm water pollution prevention devices and will notify the contractor when any of the following conditions are not being met:
Make modifications; perform maintenance or repairs upon notification. If the modifications, maintenance or repairs are not started within 2 working days, liquidated damages in the amount of $1000 per calendar day will be assessed until completed. If the modifications, maintenance or repairs have not been started within the 2 working day period, the engineer may proceed to repair, rebuild, or otherwise restore the devices. The engineer will deduct the cost to repair, rebuild, or otherwise restore the devices from the next monthly progress payment in addition to liquidated damages.
5 Temporary soil erosion control details and specified information in Subsection 215.4.3, Temporary Soil Erosion Measures, may be used in developing and implementing a Storm Water Pollution Prevention Plan. Other methods are available that may be more appropriate depending on the circumstances.
6 Upon project completion, remove and dispose of temporary soil erosion control measures not specified or designated by the engineer to remain as permanent erosion control measures.
7 Upon final acceptance of the project in accordance with Subsection 1 13.4, Final Acceptance, submit to the WDEQ or EPA a Notice of Termination or request a permit transfer to the department or other specified entity. After approval of the termination or transfer, the department or other entity will accept responsibility for storm water control on the project.
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215.4.2.2 Department Storm Water Control
1 When specified, the department will secure, modify, and terminate the WYPDES/NPDES Permit and Storm Water Pollution Prevention Plan for the project, material sources, or both. The engineer will perform monitoring and reporting requirements.
2 Implement, modify, and remove storm water control measures for the Storm Water Pollution Prevention Plan, as specified or directed by the engineer.
215.4.3 Temporary Soil Erosion Measures
215.4.3.1 Burlap Bag Curbs
1 Install burlap bag curbs at specified locations and elsewhere as needed to control slope erosion.
2 Use burlap tubes 25 ft [7.5 m] long and filled with sand or suitable excavation material from the project. After filling, sew or tie the tube ends to form a closed unit. Tightly adjoin the tubes to form a watertight curb. Direct drainage from the curb into embankment protectors or drainage structures.
3 Inspect the burlap bag curbs frequently to ensure that there are no breaks or underwashing.
215.4.3.2 Silt Fence
1 Install silt fences at specified locations and elsewhere as needed to prevent erosion of ditch channels and sheet flows.
2 Use a wire-reinforced silt fence (woven wire) above WDEQ class I waters and in severe snowfall or high wind areas.
3 Build fences and grade fence locations so that water is spread uniformly along the fence. Taper the ends of the fence uphill. Drive posts to a minimum depth of 18 in [450 mm] at a maximum spacing of 8 ft [2.4 m]. Where it is impossible to drive the posts to a depth of 18 in [450 mm], adequately secure the fence to prevent overturning. Attach geotextile fabric to each post using at least two ties through the top 8 in [200 mm] of fabric . Embed a minimum of 6 in [150 mm] of the geotextile fabric at the bottom of the fence in a trench. Backfill the trench with soil and compact. Construct the fence to handle the stress of the sediment loading.
4 Maintain the silt fence until the fence is removed or until the final acceptance of the project in accordance with Subsection 113.4, Final Acceptance. Check the geotextile fabric after each rainfall event to ensure it is free of rips, tears, and other types of deterioration, and replace as needed. Remove sediment deposits when the deposit depth reaches one half of the height of the silt fence.
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215.4.3.3 Ditch Checks
1 Install ditch checks to control ditch, channel, and inlet erosion. Install ditch checks to ensure that water does not flow around, between, or under the devices.
2 Construct ditch checks of either of the following devices:
Bury bales at least 6 in [150 mm] deep.
[600 mm]. Bury logs at least 3 in [75 mm] deep.
3 Tightly butt the devices together. Stake and backfill devices, driving stakes into the ground at least 6 in [150 mm].
4 Inspect ditch checks frequently, and replace deteriorated or damaged devices that are not functioning properly.
5 Use removed devices to mulch areas of sediment disposal in accordance with Subsection 215.4.1, Storm Water Pollution Prevention, Construction, General.
215.4.3.4 Triangular Silt Dike
1 Place synthetic triangular silt dikes to reduce ditch and channel erosion.
2 Attach foam dikes to the ground with wire staples.
3 Prior to installation of the mesh dikes, place erosion blankets or ditch liner as specified. Place plastic panels next, with the upstream panel folded into and pinned to the underlying blanket (liner). Attach to the ground with wire staples spaced at 6 in [150 mm] intervals along the panel lips.
215.4.3.5 Rock Check Dikes
1 Install rock check dikes to control ditch and channel erosion, as specified. Use rock with diameters from 3 in to 6 in [75 mm to 150 mm] intermixed with gravel. To maintain filtering capability, do not use larger rock. Establish the flow line from 6 in to12 in [150 mm to 300 mm] below the side elevations.
2 Do not install rock check dikes within the specified clear zone.
215.4.3.6 Sediment Traps
1 Construct sediment traps to reduce sediment in runoff. Construct sediment traps as close to the source of the sediment as possible. Construct the sediment trap by excavation of
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a basin, by using a natural terrain depression, or by building a low dam. Determine the size of the sediment trap based on the inflow and as specified.
2 Remove accumulated sediment as necessary to maintain proper sediment trap operation.
215.4.3.7 Contour Diversion Ditches
1 To prevent erosion of construction areas, surface runoff may be diverted to permanent or temporary cross ditches.
2 Use triangular contour diversion ditches as specified for low volume runoff. Use parabolic or trapezoidal contour diversion ditches as specified and when necessitated by higher volume runoff. If high velocities are expected or if runoff is causing erosion to the ditch, line the ditch with erosion control blankets.
3 When using ditches, divert water from a slope by one of the described ditches and then water may be redistributed with a level spreader as specified. Cover the level spreader with geotextile fabric, erosion control blanket, or rock.
4 Inspect ditches frequently for breaks. Remove accumulated sediment as necessary.
215.4.3.8 Slope Drains
1 Use slope drains to convey runoff down unprotected fill slopes. Use slope drains in conjunction with temporary diversion features at the edges of newly constructed slopes.
2 Construct slope drains so that the water funnels into it and does not wash around the drain. Stake or weigh down drains. Compact the soil around the inlet.
3 As the construction progresses, modify slope drains as necessary. Inspect slope drains after each storm for structural integrity, blockage, and stability at the inlet.
215.4.3.9 Erosion Control Agent
1 Apply erosion control agent to specified non-traffic areas of exposed, erodible soils.
2 Before applying, give two copies of the manufacturer’s published material specifications and recommended application procedures to the engineer. Before proceeding with the full application, verify agent’s performance characteristics at the recommended application rate by testing on a small area designated by the engineer . Unless approved by the engineer, only one product will be used on the project.
3 Before applying the agent, and to ensure penetration, prepare treatment areas by loosening hard-packed soil to a depth of from ½ in to 1 in [13 to 25 mm] . Smooth areas to prevent runoff and puddling.
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4 Mix, store, and apply the agent in accordance with the manufacturer’s recommendations.
5 Protect slopes left unfinished and without vegetation before suspension of work by one of the two following methods:
Temporary Cover Crop.
6 If the slopes are not vegetated because of contractor delays, furnish and apply the slope protection at no additional cost to the department.
7 Reclaim by May 31 areas of erodible earth that were not revegetated but could have been before winter suspension. If not reclaimed by this date, apply an additional application of the erosion control agent, at no additional cost to the department.
215.4.3.10 Temporary Cover Crop
1 Plant a temporary cover crop to minimize soil erosion in the following situations:
winter work suspension.
suspension.
2 An erosion control agent in accordance with Subsection 215.4.3.9, Erosion Control Agent, may be placed instead of a temporary cover crop.
3 When soil is free of frost, plant by drilling seeds to a depth from 1 in to 2 in [25 mm to 50 mm]. Steeper slopes may require broadcast seeding. Prepare and use seeding rates for temporary cover crop areas as specified or as approved by the engineer.
4 Use seeds that will produce sterile plants.
215.4.3.11 Chemical Water Treatment
1 Where turbidity caused by fine silt particles in runoff that has passed through other sediment control devices is in excess of allowable limits, chemical settling agents may be required. Use manufacturer recommendations for the following:
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2 Ensure even mixing of the chemical settling agent with the storm water runoff.
215.5MEASUREMENT and PAYMENT
215.5.1 General
1 The engineer will measure:
of the lump sum price for Contractor Storm Water Control on the first monthly progress payment. Additional monthly progress payments will be prorated, based on the total project work actually performed as compared to the total original project cost. The total lump sum payment will not exceed the original lump sum bid except by a “Contract Amendment” (Form E- 61). Adjustments will only be made for significant added work.
Force Account Work, for work without individual pay items in the contract.
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1 The department will pay as follows:
Pay Item
Pay Unit Measure to the Nearest Pay to the Nearest Burlap Bag Curb FT [m] 0.1 ft [0.05 m] FT [0.5 m] Contractor Storm Water Control LS LS LS Department Storm Water Control $$ $$ $$ Erosion Bales EA [Ea] EA [Ea] EA [Ea] Erosion Control Agent ACRE, TON [ha, t] ft, 0.01 ton [0.5 m, 0.01 t]
0.1ACRE, 0.01 TON
[0.1 ha, 0.01 t] Excelsior Sediment Log FT [m] 0.1 ft [0.05 m] FT [0.5 m] Rock Check Dikes FT [m] 0.1 ft [0.05 m] FT [0.5 m] Silt Fence FT [m] 0.1 ft [0.05 m] FT [0.5 m] Triangular Silt Dike FT [m] 0.1 ft [0.05 m] FT [0.5 m]
215.5.2 Referenced Sections for Direct Payment
1 When specified, the engineer will measure and pay for:
Equipment, or in accordance with Subsection 109.4, Extra and Force Account Work.
Account Work.
Fertilizer, and Sodding.
with the associated technical section in these Standard Specifications.
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