HomeMy WebLinkAbout008 Appendix B - Stormwater Maintenance PlanAPPENDIX B
STORMWATER MAINTENANCE PLAN
03/03/23
22203 Norton
East Ranch Ph.
5B FP
INSPECTION AND MAINTENANCE FOR
STORMWATER MANAGEMENT FACILITIES
The Property Owners Association shall be responsible for the maintenance of the stormwater
drainage facilities within Norton East Ranch Subdivision, Phase 5.
Storm Water Facilities:
1. Drainage swales slope toward retention ponds to collect storm water runoff and channel it
to the retention ponds.
2. Retention Ponds collect storm water runoff and store the water until it evaporates and/or
infiltrates into the ground.
Post Construction Inspection:
1. Observe drain time 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 the stormwater drywells and catch basins after installation and clear any material
or obstructions in the drainage slots. Inspect the drywells after a storm event to insure
proper drainage.
3. Factors responsible for clogging should be repaired immediately.
Semi-Annual Inspection:
1. Check retention ponds and dry wells following three days of dry weather after a storm
event exceeding ¼ inch of precipitation. Failure for water to percolate within this time
period indicates clogging or poor-draining soils. Replace/repair as necessary.
2. Remove grass clippings, litter, and debris from drainage swales, catch basins, dry wells,
and retention ponds. Flush and/or vacuum drywells or stormwater pipes if excessive
material is observed in the facilities.
Standard Maintenance:
1. Remove sediment and oil/grease from retention ponds.
2. Inspect and remove debris from drainage swales, catch basins, dry wells, and retention
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.
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.
Wet Detention Basin:
Perform As Needed
1. Remove litter/debris from all components of the WDB.
2. Repair basin inlets, outlets, and all other structural components required for the basin to
operate as intended.
3. Repair and revegetate eroded areas.
4. Regularly manage all vegetation along maintenance right-of-ways and the embankment.
Remove all clippings.
5. Repair maintenance access routes, if applicable.
6. Inspect the WDB for signs of mosquito larvae during summer months and provide
treatment when breeding is found. If available, a local mosquito control service could be
used to carry out these inspections.
7. When necessary, drain the WDB during dry periods to prevent the release of untreated
water.
8. Inspect the WDB for damage and excessive sediment deposition following large storm
events.
Perform Semiannually
1. Trim vegetation for aesthetics and mosquito control. Prevent excessive growth of woody
vegetation on or near berms or embankments.
2. Evaluate the health of vegetation and remove and replace any dead or dying plants.
Perform Annually
1. Inspect all components of the WDB in accordance with an approved inspection form
according to local jurisdiction requirements. An example inspection form is provided in
Appendix F.
2. Open the riser to access and test the valves (if applicable).
Perform Every 1-4 Years
1. Remove sediment from the forebay before it becomes a significant source of pollutants
for the remainder of the WDB.
Perform Every 10-20 Years (or as needed)
1. Remove accumulated sediment from the bottom of the wetpool cell to maintain volume
and deter algae growth. This typically requires heavy equipment, designated corridors,
and considerable expense. Harvesting of vegetation may also be desirable for nutrient
removal. When removing vegetation from the pond, take care not to create or leave areas
of disturbed soil susceptible to erosion. If removal of vegetation results in disturbed soils,
implement proper erosion and sediment control BMPs until vegetative cover is
reestablished. Dispose of sediment properly (56).