21720 - CDOT Basalt Storm Water Construction Services

Qualified General Contractors (GCs) are invited to bid on the construction of a storm water management infiltration basin, and drain pan and asphalt installation at CDOT’s Basalt maintenance facility located at 1109 Willits Lane, Basalt CO 81621.  This facility lies below the elevation of the adjacent highway and therefore receives storm water run-on that accumulates in front of the facility.  CDOT has a need to re-grade the yard to direct this water into a storm water infiltration basin and alleviate storm water accumulation in front of the shop and flooding into the building.
 
The main objective of the drainage improvements is to prevent ponding in front of the maintenance facility bay doors, and to improve the quality of storm water runoff released from the existing site. Proposed drainage improvements include a new concrete v-pan retrofitted into the existing pavement coupled with a rain garden. The new concrete v-pan on the east side of the building will convey surface runoff (that currently ponds in front of the bay doors) to a new rain garden on the west side of the building.  A soil media will be utilized in the rain garden to filter and treat water prior to releasing it from the site. A perforated underdrain system will be placed subsurface within the rain garden and designed to ensure a 12-hour drain time. Storm water will ultimately be discharged north of the rain garden toward an existing drainage swale located on site. An overflow spillway on the west side of the rain garden will be constructed to control flows in excess of the water quality capture volume.