for Highway Construction Page 168 of 715 SECTION 212 – EROSION AND SEDIMENT CONTROL
212.01 Description.
This work consists of constructing, installing, maintaining, and removing when required, best BMPs during the c ontract to prevent or minimize erosion, sedimentation, and pollution of waters of the U.S. as covered in 107.17, including wetlands. The Contractor will coordinate the construction of temporary BMPs with the construction of permanent BMPs to ensure economical, effective, and continuous erosion and sediment control throughout the work. Control erosion and sediment using berms, dikes, dams, sediment basins, erosion blankets , netting, fiber wattles, compost socks, inlet protection, gravel, mulches, grasses, slope drains, and other approved erosion control devices or methods. Install erosion control BMPs before sediment control BMPs. Items not included in the contract , in the approved SWPPP, or in the PPP will be installed and maintained on a contingency basis and as approved. Provide a qualified WPCM as a construction stormwater manager throughout the work. See 107.17 for WPC M qualification requirements.
212.02 Materials.
Provide mater ials as specified in: Seeding ................................................................................................................................... 621.02 Aggregate for Untreated Base, Treated Base , and Road Mix (9.0% or less passing the #200) ........................................................................ 703.04 Metal Apron ............................................................................................................................. 708.21 Pipe .............................................................................................................................................. 706 Riprap ...................................................................................................................................... 711.04 Commercial Fertilizer ............................................................................................................... 711.07 Mulch ....................................................................................................................................... 711.10 Rolled Erosion Control Product (RECP) .................................................................................. 711.11 Turf Reinforced Mat (TRM) ...................................................................................................... 711.12 Fiber Wattle ............................................................................................................................. 711.20 Compost Sock ......................................................................................................................... 711.21 Inlet Protection ......................................................................................................................... 711.23 Gabion and Revet Mattress .......................................................................................................... 715 Geotextile ....................................................................................................................... 640 and 718 Provide other approved materials that meet commercial grade standards. for Highway Construction Page 169 of 71 5 212.03 Construction Requirements.
A.General. Submit for approval a plan and schedule as specified in 107.17 for installing temporary and permanent erosion and sediment control measures at the preconstruction conference o r before the start of the applicable construction. Incorporate ground disturbing activities, including haul roads, material sources, staging areas, and excess material sites. Do not start work until the plan including the erosion and sediment control schedule and methods of operations have been approv ed. Refer to the Department’s BMP manual and the standard drawings for appropriate selection and installation guidance. Stop earthwork operations when erosion or sediment control BMPs are determined by the Engineer to be inadequate. Resume only after demonstrating effectiveness of erosion and sediment contr ol BMPs. Provide temporary erosion control measures immediately when seaso nal limits prohibit permanent measures. Do not construct slopes more than 15 feet vertically, regardless of slope angle, before installing perimeter sediment control measures. For projects 5 acres or less or located in an arid, semi -arid areas during the seasonally dry period, sta rt installation of stabilization measures immediately in any areas of exposed soil where construction activities have stoppe d. Complete installation within 14 calendar days after start . For projects more than 5 acres start installation of stabilization measures immediately in any areas of exposed soil where construction activities have sto pped. Complete installation within 7 calendar days after start . Incorporate erosion and sediment control measure to prevent sediment transport from cut or embankment slopes Control measures may require the removal of sediments during maintenance operations. The Engineer may allow sediments removed to be used (e.g., topsoil ). Preserv e the function of control measures and prevent water pollution when disposing of sediments. Install all BMPs in accordance with the manufacturer’s written instructions, details, or as directed. Size and place BMPs to adequately handle the runoff water from a 2- year, 24- hour storm event.
B.Temporary Erosion and Sediment Control Measures . Refer to the Department’s BMP Manual for guidance on temporary erosion and sediment control measures .
C.Permanent Control Measures.
1.Seeding, Rolled Erosion Control Products (RECP), Turf Reinforced Mats (TRM), and Mulching. Seed slopes and other ground disturbed areas. It is not necessary for slopes to be completely constructed before seeding a finished portion of the slope. Seed as specified in 621.
2.Install RECPs, TRMs, mulch , and HECPs as specified 621.03.E and 621.03.F.
3.Gabion and Revet M attress . Provide and construct as specified in 512.
4.Stone Filter Berms/Dams. Use rock in constructing stone filter berm/dam that is graded with a minimum size of 1 inch to a maximum of 8 inches measured along the longest dimension.
5.Sediment Basins. Construct sediment basins as specified or as directed. Stabilize the inlet, outlet, and emergency spillway of the basin as approved.
6.Inlet and Outlet Protection. Protect the ground at the inlet and outlet of pipes and other water discharges. for Highway Construction Page 170 of 71 5 D. Water Pollution Control Manager. Prepare, maintain, revise, and amend the stormwater pollution prevention plan (SWPPP). Ensure project compliance with the erosion and sediment control and pollution prevention installation and maintenance requirements, water quality monitoring and discharge reporting requirements. Manage all pollution control measures at the project site, including field controls, inspections, records and CGP requirements specified in
107.17 and the CGP through the life of the contract .
E.Erosion Control Maintenanc e Coordinate erosion control maintenance operations before performing the work.
1.Maintain the erosion control according to the SWPPP or PPP .
2.Remove, replace and reinstall BMPs damaged due to general construction activities.
3.Provide small quantity BMP repair, installation or maintenance that does not require directed survey.
4.Provide additional temporary erosion control BMPs as needed.
5.Maintain a daily record of hours for Erosion Control Maintenance. Provide the records weekly f or approval or hours recorded.
212.04 Method of Measurement.
The Engineer will measure acceptably completed work as follows:
1.Slope drain and open- top culvert by the foot along the length of plastic liner or pipe .
2.Inlet p rotection, waterbar, stabilized construction entrance, sediment trap, and sediment basin by the each.
3.Silt fence , fiber wattle, and compost sock by the foot along the ground.
4.Diversion channel, diversion ditch, dike, berm, and siltation berm by the foot along the centerline of constructed item. This measure includes the excavation and embankment required to construct t he item, including the materials used to construct outlet and overflow structures .
5.Soil binder by the acre of surface treated.
6.Gabion and revet mattress by the cubic yard based on the nominal size of the units.
7.Stone filter berm and dam by the cubic yard using the average- end-area method.
8.WPCM by the lump sum. The lump sum includes full compensation for furnishing all labor, materials, tools, equipment, and incidentals.
9.Erosion Control Maintenance by the h our.
212.05 Basis of Payment .
The Department will pay for accepted quantity at contract unit prices as follows: Pay Item Pay Unit Slope Drain ............................................................................................. FT Sediment Trap ........................................................................................ Each for Highway Construction Page 171 of 71 5 Silt Fence ................................................................................................ FT Diversion Ch annel .................................................................................. FT Diversion Ditch ....................................................................................... FT Dike ........................................................................................................ FT Berm ....................................................................................................... FT Open- Top Culvert ................................................................................... FT Waterbar ................................................................................................. Each Siltation Berm ......................................................................................... FT Stabilized Construction Entrance ............................................................ Each Soil Binder .............................................................................................. Acre Gabion .................................................................................................... CY Revet Mattress ....................................................................................... CY Stone Filter Berm Type____ ................................................................... CY Stone Filter Dam Type____ .................................................................... C Y Sediment Basin ...................................................................................... Each Inlet Protection ........................................................................................ Each Fiber Wattle ............................................................................................ FT Compost Sock ........................................................................................ FT Water and Pollution ................................................................................ CA Water Pollution Control Manager ............................................................ LS Erosion Control Maintenance ................................................................. HR The Department will not pay to install or repair temporary erosion and sediment control measures required due to the Contractor’s negligence, carelessness, or failure to install permanent measures as part of the work. Erosion and sediment control measures required for areas outside the project site (e.g., borrow pits, materials sources, haul roads, plant sites, and storage and disposal areas) is incidental to the work. The Department will pay for seeding, RECPs, TRMs, mulching, HECPs, and other seeding items under the appropriate contract pay items in 621. The following work is incidental and included in other contract pay items :
1.Berm, ditch, pipe apron, rock, and excavation used to direct drainage to a slope drain or to construct a stabilized discharge area.
2.Geotexti le, rock, sandbags, and plastic liner used in construction of sediment trap, diversion channel, or diversion ditch.
3.Reinforced wire fence, geotextile, and posts for silt fence. for Highway Construction Page 172 of 71 5 4. Diversion channels, diversion ditches, swales, berms, and dikes constructed as a standard part of the Contractor’s normal operation within the slope limits.
5.Ditches built in conjunction with dikes and berms.
6.Swale and rolling dip.
7.Geot extile and graded aggregate for stabilized construction entrance.
8.Inspection of erosion and sediment control measures.
9.Maintenance of erosion and sediment control measures.
10.Removal of BMPs as determined necessary. The Department will pay for structure excavation and compacting backfill for gabion and revet mattres s under 210. The Department will pay for geotextile for gabion and revet mattress under 640. for Highway Construction Page 173 of 71 5 SECTION 213 – TOPSOIL
213.01 Description.
Excavate suitable topsoil from stockpiles, sources outside the roadway, or from its natural position within the right of way that will be occupied by the roadway. Place and key in the topsoil on designated constructed cut and fill slopes and other designated areas after grading operations are complete.
213.02 Materials.
Obtain topsoil from approved sources from the soil profile A horizon layer that has a friable, loamy character and contains an organic matter amount normal to the region. Obtain topsoil from well -drained arable land that d oes not contain subsoil (from the soil profile B horizon layer), refuse, roots, heavy or stiff clay, stones larger than 1 inch, coarse sand, sticks, brush, litter, pesti cides, contaminated soil, noxious weeds, or other material detrimental to vegetative growth and establishment. Ensure the county weed authority has visually inspected approved sources for presence of noxious weeds before delivery or placement . Test sources if noxious weeds are located within or adjacent to the source site, and obtain approval from the county weed authority or authorized personnel from the Department or Idaho State Department of Agriculture that the source is acceptable to use on the project site. Incorporate vegetative matter into topsoil, except brush, trees, or noxious weeds. Other deleterious material (e.g., plastic, glass, metal, rocks) will not exceed 0.1 percent by weight or volume. Provide microorganism inoculants that contain a diverse mix of regional specific mycorrhizal species for specific condition, provide macronutrients and micro- nutrients that are tolerant of chemical imbalances in the soil, produce humic compounds and binding compounds, and improve soil structure. Soil Amendments .................................................................................................................... 711.18 Remove and di spose of vegetation at topsoil sources before taking materials from the source. Provide topsoil as specified below in Table 213.02- 1 and Table 213.02-2 . Table 213.02-1 – Topsoil Gradation Sieve Size Percent age by Weight Required to Pass a Square Mesh Sieve 1 in 98 - 100 No. 4 95 - 100 No. 8 80 - 100 No. 200 15 - 80
Source: Idaho Standard Specifications for Highway Construction, 2023 Edition. Pages 204–208 of 768.