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HomeMy WebLinkAbout12.0 Stormwater Mainentance Plan 03-29-2021INSPECTION AND MAINTENANCE FOR STORMWATER MANAGEMENT FACILITIES The Property Owners Association shall be responsible for the maintenance of the stormwater drainage facilities within the site. The following areas, facilities will be inspected and the identified deficiencies shall be corrected. Clean-out must include the removal and legal disposal of any accumulated sediments and debris from the entire stormwater management system. POA will be responsible for contacting local solid waste division with regards to legal disposal of sediments from stormwater facilities. Storm Water Facilities: 1. Retention Ponds/Detention Ponds: Inspect ponds annually and after major storms (following three days of dry weather after a storm event exceeding ¼ inch of precipitation.) and correct any identified deficiencies to ensure that it is working in its intended fashion and that it is free of trash and debris. Failure for water to percolate or pass through outlet structure within this time period indicates clogging or poor-draining soils. Replace/repair as necessary. Remove and properly dispose of any accumulated sediment or debris as needed. Inspect the embankments and drainage structures for settlement, slope erosion, and downstream swamping. Mow the embankment to control woody vegetation. Remove woody debris from the bottom of the pond. Inspect for channelization at bottom of pond and remove any channels observed. Regrade as required if any channels are found that are not an element of the original design. Remove grass clippings, litter, and debris from ponds. 2. Culverts: Inspect culverts 2 times per year (preferably in spring and fall) to ensure that the culverts are working in their intended fashion and that they are free of debris. Remove any obstructions to flow; remove accumulated sediments and debris at the inlet, at the outlet, and within the conduit and to repair any erosion damage at the culvert’s inlet and outlets around the reinforced concrete flared end section. 3. Detention Pond Outlet Structures: Inspect Outlet Control Structures 2 times per year (preferably in spring and fall) to ensure that these structures are working in their intended fashion, free of debris and that the orifice and trash racks are unobstructed from trash and debris. Clean structures when sediment depths accumulate to the invert of outlet or to the bottom of the inlet weir. Remove floating debris and hydrocarbons if observed at the time of the inspection. 4. Storm Drainage Piping and Manholes Inspect pipe system 2 times per year (preferably in Spring and Fall) via manhole cover access into structures. Clean system when sediment depth reaches the bottom of inlet and outlet piping. Remove and dispose of any sediments or debris (see note at the bottom of page 2 for further detail on sediment disposal). Inspect pipe for any obstruction and remove obstructions immediately. Repair/replace damaged pipes and manholes if observed. 5. Vegetated Areas: Inspect slopes and embankments early in the growing season to identify active or potential erosion problems. Replant bare areas or areas with sparse growth. Where rill erosion is evident, armor the area with an appropriate lining or divert the erosive flows to on-site areas able to withstand the concentrated flows. The facilities will be inspected after major storms and any identified deficiencies will be corrected. 6. Ditches, Swales, Stormwater Chases and other Open Stormwater Channels: Inspect 2 times per year (preferably in Spring and Fall) to ensure they are working in their intended fashion and that they are free of sediment and debris. Remove any obstructions to flow, including accumulated sediments and debris and vegetated growth. Repair any erosion of the ditch lining. Vegetated ditches will be mowed at least annually or otherwise maintained to control the growth of woody vegetation and maintain flow capacity. Any woody vegetation growing through riprap linings must also be removed. Repair any slumping side slopes as soon as practicable. If the ditch has a riprap lining, replace riprap on areas where any underlying filter fabric or underdrain gravel is showing through the stone or where stones have dislodged. Correct any erosion of the channel's bottom or side slopes. The facilities will be inspected after major storms and any identified deficiencies will be corrected. For concrete stormwater chase structures with metal “no slip” cover. Inspect covers to ensure metal edges aren’t protruding above the concrete surface. Correct deficiencies if found. Repair damaged or badly cracked stormwater chases if observed. Standard Maintenance Summary: 1. Remove sediment and oil/grease from retention ponds. 2. Inspect and remove debris from drainage swales, catch basins, and detention ponds. 3. Monitor health of vegetation and revegetate as necessary to maintain full vegetative cover. 4. Inspect for the following issues: differential accumulation of sediment, drain time, signs of petroleum hydrocarbon contamination (odors, oil sheen in pond water), standing water, trash and debris blockages. Note on sediment disposal: In most cases, sediment from a detention pond does not contain toxins at levels posing a hazardous concern. However, sediments should be tested for toxicants in compliance with current disposal requirements and if land uses in the drainage area include commercial or industrial zones, or if visual or olfactory indications of pollution are noticed. Sediments containing high levels of pollutants should be disposed of in accordance with applicable regulations and the potential sources of contamination should be investigated and contamination practices terminated. Equipment Type/Access: All detention/retention facilities will be cleaned using vacuum trucks. All vacuum trucks will access the site through the proposed alley and parking lot. Cost Estimate: Depending on the amount of rainfall in the given year, the cost to maintain the stormwater infrastructure will vary. It is estimated that the facilities will need to be vacuumed out once per year, with an estimated cost of $1,500 to do so. The applicant will be responsible for financing the maintenance of the stormwater infrastructure.