HomeMy WebLinkAbout6.1 Stormwater Maintenance Plan (09-2020)INSPECTION AND MAINTENANCE FOR STORMWATER MANAGEMENT FACILITIES
The Property Owners Association shall be responsible for the maintenance of the stormwater drainage facilities within the Fallon Apartments development. Storm Water Facilities: 1. Drainage swales slope toward retention and detention ponds to collect storm water
runoff and channel it to the retention or detention pond. 2. Retention Ponds collect storm water runoff and store the water until it evaporates and/or infiltrates into the ground. 3. Detention ponds collect storm water runoff while allowing some water to drain to
another location.
4. Culverts are pipes which channel storm water from ditches or swales under roads. 5. Pipe Networks convey storm water to different discharge locations underground. 6. Inlets are facilities where storm water runoff enters a pipe network. Inlets include storm water manholes and drains.
7. Catch Basins are sumps typically located directly below storm water inlets and allow
sediment to settle before storm water enters the pipe network. 8. Outlets are points where storm water exits a pipe network. 9. Drywells are underground storm water collection facilities that collect and temporarily store runoff from roof tops and landscaped areas before allowing storm water to infiltrate
into the ground.
Post Construction Inspection: 1. Observe drain time in retention ponds for a storm event after completion of the facility to confirm that the desired drain time has been obtained. If excessively slow infiltration
rates are observed then excavate a minimum 5 ft by 5 ft drain to native gravels (or native
well-draining material) and backfill with well-draining material (pit-run). 2. Observe that drywells, catch basins, and outlet structures are clear of any material or obstructions in the drainage slots. Inspect these structures to insure proper drainage following a storm event. Immediately identify and remove objects responsible for
clogging if not draining properly.
Semi-Annual Inspection: 1. Check retention ponds and dry wells three days following a storm event exceeding ¼ inch of precipitation. Failure for water to percolate within this time period indicates
clogging or poor-draining soils. Clear any clogs and replace any poor-draining soils with
well-draining gravely soils. 2. Check for grass clippings, litter, and debris in drainage swales, catch basins, dry wells, culverts and retention ponds. Flush and/or vacuum drywells or storm water pipes if excessive material is observed in the facilities.
Standard Maintenance: 1. Remove sediment and oil/grease from retention ponds and detention ponds. 2. Inspect and remove debris from drainage swales, catch basins, dry wells, and retention ponds. Use a vacuum truck to clean catch basins and dry wells.
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.
Sediment accumulation: In most cases, sediment from a retention 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 drywells 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 drywells 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.