316 STORMWATER MANAGEMENT (SWM) FILTRATION FACILITIES

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316.01 DESCRIPTION.
Construct stormwater management (SWMStormwater Management) filtration facilities as specified.
SWMStormwater Management Filtration Facilities Identification. SWMStormwater Management filtration facilities are identified by unique six-digit inventory numbers and include the following designations.
(a) Bioretention.
(b) Micro-Bioretention.
(c) Organic Filters.
(d) Surface Sand Filters.
(e) Submerged Gravel Wetlands.
(f) Landscape Infiltration.
(g) Rain Gardens.
(h) Infiltration Berms.
(i) Bio-swales.
316.02 MATERIALS.
No. 57 Aggregate       901.01
No. 7 Aggregate       901.01
No. 2 Aggregate       M 43, No. 2
Portland Cement Concrete       902.10, Mix No. 2
Topsoil       920.01.01 and 920.01.02
Bioretention Soil Mix (BSM)       920.01.05
Coarse Sand       920.01.05(a)(1)
Fertilizer       920.03.01
Shredded Hardwood Bark (SHB) Mulch       920.04.03
Soil Stabilization Matting (SSM)       920.05
Seed and Turfgrass Sod       920.06
Plant Materials       920.07
Water       920.09.01
Geotextile       919, Class PE, Type III
Securing Pins or Staples       919
Aggregate. Ensure aggregate has been adequately washed and is free of soil and fines.
Subdrain Pipe, Fittings and Geotextile Sock. Perforated and solid-wall polyvinyl chloride profile wall drain pipe (PPWP) meeting M-304 or corrugated polyethylene drainage pipe (CPP) meeting M-252, Type S and Type SP. Perforated pipe shall have two rows of slotted perforations with an opening area of 20 cm2/m to 21 cm2/m. When specified, use the geotextile sock recommended and supplied by the subdrain pipe manufacturer.
316.03 CONSTRUCTION.
316.03.01 Site Protection. Prior to constructing SWMStormwater Management filtration facilities, ensure that the SWMStormwater Management facility site areas are protected from vehicular traffic and is not used for erosion and sediment controls, stockpiles or equipment storage.
316.03.02 Site Preparation. Unless facilities are off-line and will receive no runoff, construct facilities only after all surrounding and adjacent areas are permanently stabilized. Divert flow from entering the SWMStormwater Management filtration facility areas unless same-day stabilization is specified for the SWMStormwater Management filtration facility location. Prevent trash, debris and sediment from entering SWMStormwater Management filtration facilities during construction.
316.03.03 Schedule. Perform SWMStormwater Management filtration facility activities during dry weather and when soil moisture conditions are suitable and unless the facility is off-line or flow diversions are in place. Only work with soil that is friable and not in a muddy or frozen condition. Cease operations when soil and overall conditions are otherwise unsuitable.
316.03.04 Excavation. Use methods of excavation that minimize compaction of the underlying soils. Where feasible, operate equipment from locations adjacent to SWMStormwater Management filtration facilities rather than within the facility area. Use only wide-track or marsh-track equipment, or light equipment with turf-type tires to excavate, grade, and place materials. Do not use equipment with narrow tracks or narrow tires, rubber tires with large lugs, or high-pressure tires.
310.03.05 Excavation Area Bottom Preparation. Only work with soil that is friable and not in a muddy or frozen condition. When present, remove any standing water from the excavation area. Prepare the bottom of the excavated area as follows.
(a) Submerged Gravel Wetlands. Rake surface to loosen soil.
(b) All Other SWMStormwater Management Filtration Facilities. Till to a minimum depth of 8 in. to loosen soil.
316.04.06 Geotextile. Place tightly against the vertical sides of the excavation area, pulling tight to eliminate wrinkles and folds and pin securely. Eliminate any voids between the geotextile and the underlying soil and avoid wrinkling and folding the geotextile. Maintain a minimum 12 in. overlap at the geotextile joint ends or breaks. Pin longitudinal joints, overlaps and edges securely with pins spaced no greater than 10 ft on center. Do not place geotextile on the bottom of the excavated area.
316.03.07 Miscellaneous StructuresBridges, culverts, catch basins, drop inlets, retaining walls, cribbing, manholes, end walls, buildings, sewers, service pipes, underdrains, foundation drains, steps, fences, and other features that may be encountered in the work and not otherwise classified.. Furnish and install according to Section 305.
316.03.08 Aggregate. Place aggregate in layers as specified. Prevent soil, fines, and other debris from contaminating the aggregate. Remove contaminated aggregate and replace with clean aggregate.
316.03.09 Subdrain Pipe. Cap the ends of all subdrain pipe not terminating in a cleanout, vent, or drainage structure unless otherwise specified. Ensure perforations are placed on the bottom of the horizontal subdrain pipe runs.
(a) Cleanouts. Install solid-wall pipe vertically and connect to horizontal subdrain with approved manufactured connections. Provide a counter-sunk screw cap on the exposed ends.
(b) Vents. Install solid-wall pipe vertically and connect to the horizontal subdrain with approved manufactured connections. Provide a ventilated screw cap on the exposed ends. Ventilation holes or slots shall be no larger than 1/4 in. in diameter or width. The sum total area of the openings shall be no less than 1 in2. Ensure that the ventilation openings are above the maximum specified water surface elevation.
(c) Observation Wells. Use perforated and solid-wall pipe. Place the geotextile sock over the perforated pipe portion and secure at both ends. Provide a screw cap on the exposed end extending 2 in. above the surface. When a concrete collar is specified, ensure the top of the well is flush with the surface of the concrete collar.
316.03.10 Coarse Sand. Place coarse sand in horizontal layers not exceeding 12 in. After each lift, spread the course sand to provide a uniform surface then spray or sprinkle water to saturate the lift until water flows from the subdrain outlet. Use an appropriate sediment control device to capture any discharged sediment-laden water from the subdrain outlet. Place, spread, and water course sand to uniform surface true to depth, line, cross section and elevation to ensure the completed work is as specified after settlement. Prevent soil, fines and other debris from contaminating the coarse sand. Remove contaminated coarse sand and replace with clean coarse sand.
316.03.11 Bioretention Soil Mix (BSM). Place BSM in horizontal layers not exceeding 12 in. After each lift, spread the BSM to provide a uniform surface and spray or sprinkle water to saturate the entire area of BSM until water flows from the subdrain outlet. Use an approved sediment control device to capture any discharge sediment-laden water. Place, spread, and water BSM to uniform surface true to depth, line, cross section and elevation to ensure the completed work is as specified after settlement. Prevent soil, fines, and other debris from contaminating the BSM. Remove contaminated BSM and replace with uncontaminated BSM.
316.03.12 Topsoil. Place topsoil as specified. Do not blend topsoil into BSM when topsoil is placed on top of BSM.
316.03.13 Check Dams.
(a) Topsoil Check Dams. Construct topsoil check dams to the dimensions, grades, and depths specified.
(b) Concrete Check Dams. Furnish and install concrete check dams as specified and according to Section 305.
316.03.14 Soil Stabilization Matting (SSM). As specified in Section 709.
316.03.15 Vegetation Installation and Establishment. Unless facilities are off-line or flow diversions are in place, install seed, sod, trees, shrubs, perennials, and annuals within SWMStormwater Management filtration facility areas immediately after final grading. In the event that vegetation cannot be installed and established due to time-of-year or weather restrictions, keep diversion controls in place until such time that permanent vegetation may be established. Do not use machinery other than hand held within the BSM footprint.
(a) Turfgrass Establishment. As specified in Section 705.
(b) Meadow Establishment and Wildflower Seeding. As specified in Section 707.
(c) Turfgrass Sod Establishment. As specified in Section 708.
(d) Tree, Shrubs and Perennial Installation and Establishment. As specified in Section 710.
(e) Annuals & Bulb Installation and Establishment. As specified in Section 711.
316.03.16 Soil Amendments and Fertilizer. Apply according to Sections 705, 706, 707, 708, 710, or as specified. Use the following for plant materials installed in BSM.
(a) Non-Vegetated BSM. Do not apply compost, other soil amendments, or fertilizer to non-vegetated BSM.
(b) Trees, Shrub, and Perennials in BSM. Do not apply compost or other soil amendments to backfill soil or to planting beds.
Apply fertilizer to each planting pit per 710.03.04 when trees, shrubs, perennials, perennial plugs, or other plant materials are installed in BSM per Section 710.
(c) Seeded or Sodded BSM. Do not apply compost or other soil amendments.
Uniformly apply either of the fertilizers in Table 1 at the rate specified over the installed surface of the BSM when BSM will be permanently vegetated with Turfgrass Establishment, Shrub Seeding Establishment, Meadow Establishment, Turfgrass Sod Establishment, or other seeded or sodded vegetation establishment as specified.
BIORETENTION SOIL MIX

TABLE 1 - FERTILIZER APPLICATION RATES

FERTILIZER LB PER SY LB PER ACRE
20-16-12 (83% UF with MAP and SOP) 0.052 200
14-14-14 polymer coated or granular 0.062 275
(d) Nutrient Management Reporting. Record the fertilizer analysis, the square yards covered, and the pounds of fertilizer applied on the Nutrient Management Reporting Form. Submit the Form within 24 hours after applying fertilizer.
(e) Fertilizer. Refer to (b). Rake fertilizer that is broadcast over the surface of the BSM for seeding or sodding to a depth of 1/8 to 1/2 in. Raking may be performed as part of seeding or sodding operations. Complete raking before soil stabilization matting or sod is installed.
316.03.17 Shredded Hardwood Bark (SHB) Mulch. As specified in 710.03.13.
316.03.18 Inspection and SWMStormwater Management Facility As-Built CertificationA document which verifies that the material and work complies with the applicable specifications and includes the actual test results to confirm the statement. The contents of the certification shall be on the Contractor's/vendor's/manufacturer's letterhead or approved document and shall be duly signed by a company officer. Certifications for metal products, when required, shall include a statement that the material was melted and manufactured in the United States except as provided in Section 165 of the Surface Transportation Assistance Act of 1982, as amended by Section 1041(a) and 1048(a) of the Intermodal Surface Transportation Efficiency Act of 1991 with regard to the furnishing and coating of iron and steel products. A nationwide waiver for this provision has been granted for pig iron and processed, pelletized, and reduced iron ore.. Inspect and document each step of construction of SWMStormwater Management filtration facilities and complete the applicable checklists and furnish the SWMStormwater Management facility as-built certification according to the Contract DocumentsThe written agreement executed between an Administration and the successful bidder, covering the performance of the work and furnishing of labor, equipment and materials, by which the Contractor is bound to perform the work and furnish the labor, equipment and materials, and by which the Administration is obligated to compensate him therefore at the mutually established and accepted rate or price. The Contract Documents shall include the Invitation for Bids, Notice to Contractors, Instructions to Bidders, Proposal, Contract Forms and Bonds, General Provisions, Specifications, Supplemental Specifications, all Special Provisions, all Technical Provisions, all Plans and Notices to Proceed, also any written Change Orders and Supplemental Agreements that are required to complete the construction of the work in an acceptable manner, including authorized extension thereof.
316.04 MEASUREMENT AND PAYMENT.
Payment will be full compensation for all control of discharge from subdrain pipe, geotextile, watering, sheeting, shoring, dewatering, hauling, storing, re-handling of material, removal and disposal of excess and unsuitable material, tilling, grading and slope adjustments and for all material, labor, equipment, tools, and incidentals necessary to complete the work.
Excavation. Excavation will be measured and paid for as specified in Section 201.
Miscellaneous StructuresBridges, culverts, catch basins, drop inlets, retaining walls, cribbing, manholes, end walls, buildings, sewers, service pipes, underdrains, foundation drains, steps, fences, and other features that may be encountered in the work and not otherwise classified.. Miscellaneous StructuresBridges, culverts, catch basins, drop inlets, retaining walls, cribbing, manholes, end walls, buildings, sewers, service pipes, underdrains, foundation drains, steps, fences, and other features that may be encountered in the work and not otherwise classified. will be measured and paid for per cubic yard of the specified mix concrete.
Aggregate. Aggregate will be measured and paid for at the Contract unit price for one or more of the following.
(a) No. 2 Aggregate for Stormwater Management Facilities per cubic yard.
(b) No. 7 Aggregate for Stormwater Management Facilities per cubic yard.
(c) No. 57 Aggregate for Stormwater Management Facilities per cubic yard.
Removal of contaminated aggregate and replacement with clean aggregate will be at no additional cost to the AdministrationShall mean any one of the Administrations within the Maryland Department of Transportation, as listed in GP 1.02..
Geotextile. Geotextile will not be measured but the cost will be incidental to the excavation.
Subdrain Pipe. Perforated and solid-wall subdrain pipe will be measured and paid for at the Contract unit price per linear foot for the specified size of subdrain pipe. Fittings, caps, geotextile sock, cleanouts, vents, observation wells, and other incidentals will not be measured but the cost will be incidental to the subdrain pipe.
Coarse Sand. Coarse Sand will be measured and paid for at the Contract unit price per cubic yard for Coarse Sand for Stormwater Management Facilities.
Removal of contaminated coarse sand and replacement with uncontaminated coarse sand will be at no additional cost to the AdministrationShall mean any one of the Administrations within the Maryland Department of Transportation, as listed in GP 1.02..
Check Dams. Check dams will be measured and paid for at the Contract unit price for one or more of the following.
(a) Topsoil Check Dams per each.
(b) Concrete Check Dams per each.
Bioretention Soil Mixture (BSM). BSM will be measured and paid for at the Contract unit price per cubic yard.
Removal of contaminated BSM and replacement with clean BSM will be at no additional cost to the AdministrationShall mean any one of the Administrations within the Maryland Department of Transportation, as listed in GP 1.02..
Water. Water used for saturation of coarse sand and BSM will not be measured but the cost will be incidental to the pertinent items.
Shredded Hardwood Bark (SHB) Mulch. SHB Mulch will be measured and paid for at the Contract unit price per square yard for Shredded Hardwood Bark Mulching, 3 in. depth.
Sediment Control for Discharge from Subdrain Pipe Outlets. Control for any sediment-laden discharge from subdrain pipe outlets will not be measured but will be incidental to the pertinent Erosion and Sediment Control items.
Topsoil. As specified in 701.04.
Vegetation Installation and Establishment. Vegetation installation and establishment will be measured and paid for at the Contact unit price for the pertinent landscaping items as specified in 705.04, 707.04, 708.04, 710.04 and 711.04.
Soil Stabilization Matting. As specified in 709.04.
Stormwater Management (SWMStormwater Management) Facility As-Built CertificationA document which verifies that the material and work complies with the applicable specifications and includes the actual test results to confirm the statement. The contents of the certification shall be on the Contractor's/vendor's/manufacturer's letterhead or approved document and shall be duly signed by a company officer. Certifications for metal products, when required, shall include a statement that the material was melted and manufactured in the United States except as provided in Section 165 of the Surface Transportation Assistance Act of 1982, as amended by Section 1041(a) and 1048(a) of the Intermodal Surface Transportation Efficiency Act of 1991 with regard to the furnishing and coating of iron and steel products. A nationwide waiver for this provision has been granted for pig iron and processed, pelletized, and reduced iron ore.. As specified.