REV99129 - Laserfiche WebLink

Home Browse Search

TECHNICAL REVISION REDDEST PROSPECT WATERSHED REMODELING The enclosed SEDCAD Hydrology and Sedimentology modeling run, associated map and information, is to demonstrate the adequacy of the existing Prospect Pond and South Collection Ditch designs. Additionally, design information is enclosed for a new proposed Section 16 Pond. In accordance with Rule 4.05.9(2), the Section 16 Pond will be considered a temporary impoundment and shall be designed and constructed in accordance with the requirements of Rules 4.05.6(2), (3) (d), (3) (e), (5), (6), and (8) through (12). Upon completion of the construction of the pond, a certified as built drawing will be forwarded to the Division. The pond will be added to the quarterly pond inspection list. It is intended that the enclosed information replace the introduction page, Table I, and entire Prospect Pond section in its entirety. This information can be found in the Colowyo Permit C-81-019, Volume 3, Exhibit 7 Hydrology Information, Section 8, Design of Surface Runoff Control Structures Permit Revision 1991. The following is a discussion of the issues raised in DMG's letter to Colowyo dated June 6, 1994. Mitigative Measures - Highway 13 Drainage Areas North Drainage Given the predominant rockiness, steepness and vegetative cover presently found at this location, it appears this drainage would benefit little from additional work. The preexisting conditions left after the highway construction remain today, even after the May 1993 storm event that was proven to have clearly exceeded the Rule 4 design requirements. Colowyo believes there should not be an obligation to rework this area being that initial conditions were inherited from the Colorado Department of Transportation. South Drainace This drainage area, likewise, was inherited by Colowyo with erosion gullies clearly resulting from highway construction. Colowyo's proposal to enhance the drainage in this area is described further in our letter to the DMG dated June 27, 1994 addressing the DMG inspection report of June 21, 1994. Sizing Demonstrations for South Collection Diversion Sizing demonstrations and related information is contained within the Prospect Pond data.