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HomeMy WebLinkAbout001 Phase 5B Annexation03/03/23 22203 Norton East Ranch Ph. 5B FP APPENDIX A DRAIN TILE MAINTENANCE PLAN INSPECTION AND MAINTENANCE FOR DRAIN TILE FACILITIES Drain Tile Facilities: 1.The drain tile consists of 2,485 linear feet of 12” A-2000 PVC pipe. The PVC pipe has perforated and solid wall sections. The pipe is bedded in washed gravel and surrounded by non-woven geotextile fabric. Semi-Annual Inspection: 1. During periods of high ground water, check outlet for signs of erosion. Ensure that groundwater is allowed to flow freely from the system. Standard Maintenance: 1. The drain tile is a passive system, requiring minimal maintenance. If indications of erosion are found near the outlet, armor the outlet with Class 1 Rip Rap. Access to the outlet and Aajker Creek is provided via an easement on file at Gallatin County, under Document Number 2579167. Sediment accumulation: Sedimentation is not expected within the system. In most cases, sediment 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: The outlet point of the drain tile system is accessible through a public park and the aforementioned easement. An excavator may be required if the outlet is found to have evidence of erosion. Cost Estimate: Depending on the amount of rainfall in the given year, the cost to maintain the drain tile infrastructure will vary. It is estimated that the outlet will need to be inspected once or twice a year, with an estimated cost of $500 to do so. Placement of additional Class 1 Rip Rap has an estimated cost of $1,500. The costs for the drain tile maintenance and repair will be covered by the standard stormwater maintenance fees associated with the subdivision. G:\C&H\16\161140\Final Plat\DRAINTILE\Draintile Maintenance Plan.Docx APPENDIX B STORMWATER MAINTENANCE PLAN 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).