APPCOR11982 - Laserfiche WebLink

Home Browse Search

David Berry -7- June 20, 1996 BRL requests that the DMG schedule a meeting as required by Rule 2.07.6(2)(d)(iv)(C) for the purpose of determining whether the interests of the public and affected landowners will be protected based on the provisions presented on page 2.05-26. 29. The DMG questions how BRL plans to control erosion at the outlet of the culverts shown on Maps 21-1 and 21-2 which outflow into relatively steep terrain. BRL considered this question during the design of the site drainage. The culverts are all extended to the bottom of the adjacent ephemeral drainages. Flexible ADS corrugated (PVC) pipe will in most cases be used to extend the culverts. The ephemeral stream channels should not require erosion protection. On a case by case basis, erosion protection will be provided at the outlet of the culverts if the ephemeral stream channels are not stable with regard to erosion. Enclosed is revised map 21-2. 30. The DMG questions why the permit application utilizes two different storm events (2.0" and 2.1") for the 25 year 24 hour storm. The DMG also states that it believes the correct figure should be 2.2" based upon an examination of the NOAA Atlas 2, 1973. BRL disagrees with the DMG's interpretation of the storm event. BRL examined Figure S-7, from the Handbook, Procedures for Determining Peak Flows in Colorado, SCS, March 1984. BRL believes the correct 25 year 24 hour storm event is 2.0". The DMG can consider the use of the 2.1" storm event to be conservative design. 31. BRL does not wish to debate the appropriate curve number for the burned area. Page Exh-8-3 was revised to show the burned area has a curve number of 81 based on Table 2-2d. The only place the burn area shows up in the run-off calculations is for Drainage Area D, page Exh-8-21, D-4 Burn 0.2 acres. Enclosed are revised pages Exh-8-3, 12, 13 & 21. 32. On page 4 of Exhibit 8, a curve number of 63 is assigned to the sagebrush rangeland area. On the next page, in the runoff volume table for pond B, a curve number of 63 is listed for sagebrush but a runoff of 0.00 inches of direct runoff is presented. The DMG is correct that for a 1.8 inch event, a curve number of 63 should result in a direct runoff of 0.06 inches. Page Exh-8-5 was revised so the 0.06 direct run-off number shows. However, the run-off Vol A-F does not change because the impact of the change is a increase in run-off of 0.0006 acre-feet. Enclosed is revised page Exh-8-5. 33. The run-off from the material storage area that is located below drainage area E and pond C does not go through a treatment facility. The DMG asked BRL to request a small area exemption status for the area. Enclosed are revised pages 2.05-32 & Exh-8-14 which presents the rationale for the SAE.