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Mr. Allen Weaver, EFMC 3 C-82-055 <br />3. Rill and gully maintenance in backfilled slopes. <br />a. Rills and gullies have begun to develop on the slopes of the bac~lled highwalls <br />at the northwest end of the yard area. Gullies are prevalent on the backfilled slope directly <br />below the junction of sections A and B of Watershed Diversion 2. As stated previously, <br />EFMC personnel explained that all backfilled slopes would be "chiseled" on a line <br />perpendicular to the slope to remove existing gullies and to help slow the speed of runoff <br />thereby reducing future erosion and increasing soil moisture for revegetation. Division <br />inspectors will be watching this area closely to determine if greater erosion protection <br />measures are necessary. <br />b. Refuse Containment Ditch 2, located between the sediment pond and the refuse <br />pile, has failed at three locations. EFMC personnel have stated that Refuse Contaitunent <br />Ditch 2 might be removed and the slope regraded and "chiseled". The Division believes that <br />the refuse ditch should remain for the following reasons: <br />1.) Flow velocity of runoff from the slopes of the refuse pile is reduced within <br />the ditch due to the gentle gradient of the ditch. The reduction of flow velocity allows for <br />greater sediment deposition to occur within the ditch thereby reducing sediment delivery to <br />the pond. <br />2.) The ditch directs runoff from the refuse pile to the pond's southeast <br />corner, opposite of the primary outlet located in the pond's northwest corner. Pond <br />performance is enhanced by increasing the distance between pond inlet and primary outlet <br />which allow for greater sediment settling. Removal of the ditch may create a "short circuit" <br />in the sediment retention system. <br />3.) The location of the ditch checks runoff velocity thereby reducing erosion <br />of the 4 feet of cover overlying the refuse pile. <br />4. Design and maintenance of Watershed Diversions 1 and 2. <br />The steep section of Watershed Diversion 1 continues to present a maintenance issue. <br />Design and maintenance of this ditch was previously addressed during our meeting last <br />February and recorded in the follow-up letter dated March 30, 1994. EFMC has proposed <br />to resolve the design and maintenance issues by extending Watershed Diversion 2 to capture <br />runoff above Watershed Diversion 1, sections A, B, and C. Reclamation of Watershed <br />Diversion 1, sections A, B, and C would occur after completion of the extension of <br />Watershed Diversion 2. The Division is awaiting the submittal of the technical revision <br />containing the plans for the watershed diversion project. <br />