CCP 03-29-2004 - Laserfiche WebLink

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e . . ) '. provided with a sub grade filtration layer and collection pipe. The infiltrate from the parking lot surface will be conveyed in both directions by the underdrain pipe. Runoff from the area in and around the north side of the parking lot will drain towards the northeast and down the hill. Infiltrate collected from the north side of the parking lot will be conveyed by the underdrain to an outfall and down this same hill towards the north. Infiltrate from the south side of the parking area will be collected by the underdrain and conveyed to an outfall and infiltration area just north of the overhead power line structure. This low spot overflows around the power line structure and into a grass swale along the east side ofthe access road. A railroad tie in the upper section of the swale will induce additional infiltration before the runoff spills over the edge. This overflow will flow down the hill terminating at another infiltration area at the bottom of the hill north of the large wetland. This same infiltration area will collect runoff from the wooded area west ofthe access road via a small infiltration basin and 12" RCP. The access road runoff will sheet drain to either side collected by both infiltration areas. The steep terrain on the backside ofthe building will be graded on 3:1 slopes. Runoff will flow downhill over a proposed walking path terminating in an infiltration basin at the northwest corner of the building. Overflow from this basin will be conveyed by a 12" RCP to another infiltration basin south of the walkway. The overflow from this basin and local runoff from the hill behind the building will be conveyed by a riprap swale to a catch basin at the southwest corner of the building. The catch basin will collect this and surrounding runoff and convey the flow (via a new 12" RCP) to an existing catch basin at the bottom of the hill. Additionally, this catch basin will collect from the foundation drain tile. The resulting flow is discharged to a ditch on the south side of the campus road. The new building will be provided with roof drain down spouts in various locations. Infiltration basins have been proposed on the front side of the building to collect local and roof runoff before being discharging to the impacted wetland. The basins will be constructed with a layer of planting soil to enhance the infiltration process. This will allow vegetation to be planted on the top of these locations typical of a rain garden design. Roof runoff from the down spouts will slowly be conveyed by overland flow and be collected by the infiltration basins before discharging to the existing wetland. The large wetland to the cast is currently connected to the smaller impacted wetland by a 12" RCP. This culvert will be replaced in kind to accommodatc wctland rcplacement changes due to construction. The new wetland, connected to thc existing impacted wetland will be furnished with a riser pipe outlct at an invert of 915.0 and will be connected directly to thc existing catch basin 80 feet to the wesL The walkway will servc as a spillway to adequately pass the 10-year storm. Earthwork cut and fill volume computations arc included in Section L Approximately 2500 cubic yards of material is proposed for cut, 1400 cubic yards for fill, and the Contractor will transport the difference of 1100 cubic yards of earth off site. 3