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HomeMy WebLinkAboutFile Documents.208 E Main St.0044.2017 (2).ARBK MAINTENANCE AND OPERATION PLAN FOR 208 EAST MAIN STREET CITY OF ASPEN COUNTY OF PITKIN, STATE OF COLORADO A. Introduction As part of the Certification of Occupancy, the following maintenance plan has been prepared for 208 East Main Street in the City of Aspen, Colorado. B. Site Description and Drainage Pattern The proposed site is approximately 3,002 square feet (0.069 acres). The east and west property lines adjoin Lot N and Lot 1, respectively. Both of the adjoining lots are Mixed- Use properties in the City and Townsite of Aspen. The north property line borders the alley of Block 73 between East Main Street and East Bleeker Street. The south property line adjoins the East Main Street Right-of-Way. The site construction was an interior remodel of an existing historic commercial building and replacement of a pre-existing addition with a two-story building with a basement. The drainage improvements that were installed as part of the construction include area inlets, a trench drain and roof downspouts/drains that capture drainage and is piped to the drywell near the south property line. The water quality drywell was designed to be 4 feet in diameter and 10 feet deep with 1 feet of gravel surrounding the drywell. The drywell installed is 12 feet deep, including a 2 foot cone and a concrete slab separating the solid chamber and perforated chamber. A majority of the site runoff is captured by roof drains and downspouts. Runoff from some exterior pathways are captured by a trench drains and area inlets. If the drywell exceeds capacity, stormwater should backflow the east storm pipe and overtop the northeast area inlet. C. Site BMP Maintenance The following Best Management Practices (BMPs) shall be implemented to prolong the life of the storm water infrastructure and to assure that the drainage facilities are functioning properly. Refer to the As-Built plan created by High Country Engineering for locations of the drainage facilities. The list below describes BMPs that shall be implemented after construction. 1. All drainage facilities shall be inspected for damages on an annual basis. If structures are damaged to a point that they cannot function properly, then the structure must be replaced. 2. Leaves and debris shall be removed from the roof drain system in the spring, after snow melt and in the fall once the trees have lost their leaves to prevent clogging. If the roof drain system and drain pipes are functioning properly, water will not back up in the roof drains. Storm water shall drain to the vault, where most runoff will be treated and then stored in the drywell detention vault. The drain pipes shall be cleaned by using a brush system or a hose to flush out the debris. The drain pipes may need to be jetted with a high pressure water system to remove any clogged debris. 3. The proposed trench drain and area inlets shall be inspected and cleared of rubbish and debris quarterly as well as after large storm events. The drains shall be inspected after large storm events to insure proper function. If standing water is observed within the area inlet, then the grates shall be removed and the drains shall be jetted clear. 4. Detention drywell must be inspected and maintained yearly to remove sediment and debris that is washed into it. Minimum inspection and maintenance requirements include the following: a. Closely manage sediment loads on drainage facilities to prevent high sediment concentrations from clogging the drainage systems. b. Runoff from areas with pollutants that have the potential to contaminate groundwater will be treated in the WQCV vault and then released to the detention vaults. c. Periodically remove sediment and debris that accumulates in the underground detention vault and upstream drainage facilities. d. Routinely evaluate the drain-down time of the detention vault structure to ensure the maximum time of 24 hours is not being exceeded. If drain- down times are exceeding the maximum, drain the vault via pumping and clean out the percolation area. The gravel in the percolation area will need to be cleaned or removed if storm water is not percolating. Monitor the percolation rate as a preemptive measure to detect changes in performance. If slow drainage persists, the system or components may need to be replaced. e. Dispose of sediment, debris/trash, and any other waste material removed from the detention vault at suitable disposal sites and in compliance with local, state, and federal waste regulations. 5. WQCV vault within drywell must be inspected, maintained and quarterly and following all rainfall events greater than 0.25 inches to monitor water level and accumulation of sediments in chamber. Closely manage sediment loads on drainage facilities to prevent high sediment concentrations from clogging the drainage systems. 6. The overflow control alarm shall be inspected quarterly to ensure the alarm is functioning properly. The owners of the property will be responsible for the maintenance and upkeep of the drainage facilities. The property owner shall dispose of sediment and any other waste material removed at suitable disposal sites and in compliance with local, state, and federal waste regulations. D. Proper Function of Best Management Practices The drainage facilities will need to be inspected quarterly as well as after large storm events to assure that they are accepting all flow directed to them and to assure that they are functioning properly. Any removed material shall be disposed of in a City of Aspen approved location such as the landfill. If the roof drains, inlets and drain pipes are functioning correctly, water will not back up in the surrounding areas. Storm water shall drain to a piping system, where the runoff will be conveyed to the dry well. If the dry well is functioning properly, storm water will collect and percolate into the gravel filter material along the perimeter and bottom of the dry well. Water from a storm event should not be visible within 24 hours after a minor storm event. If water remains present in the dry well after small/minor storm events, the percolation area may be need to be pumped and jetted to remove sediment accumulated in perforations. The removed material shall be disposed of in a City of Aspen approved location such as the landfill. The proposed drywell will need to be inspected quarterly as well as after large storm events to assure that it is accepting all flow directed to it and to assure that it is functioning properly. As described above, the gravel may require cleaning or replacement if percolation rates have reduced significantly over time. The infiltration area will need to be inspected annually as well as after large storm events to assure that they are accepting all flow directed to them and to assure that they are functioning properly. If the infiltration area is functioning properly, storm water will infiltrate into the filter material along the bottom of the basin. Water from a storm event should not be visible within 24 hours after a minor storm event. E. Record Keeping The above BMP plan shall prolong the lifespan of the storm water drainage facilities. The operation and maintenance of the storm water facilities shall be in compliance with the City of Aspen’s Urban Runoff Management Plan (URMP). If the owner cannot perform the routine facility checks discussed above, then they shall hire someone that can perform the duties in order to comply with the City of Aspen’s URMP. All inspections and any maintenance performed on the drainage facilities shall be recorded in inspection and maintenance logs and made readily available for review by the City of Aspen upon their request.