REP24413 - Laserfiche WebLink

Home Browse Search

~]5 , A statement of pertinent professional observations and rnnclusions made durine the completion o[ the certification. The condition of the pond appears to be little changed over the past year. There were no indications of swctural weakness, erosion, or hazardous conditions. Conclusions include a requirement for minor maintenance [fill and re-compact gopher burtows (all apparently shallow) and reseeding of bare areasj. Inlet ditch invert head erasion was observed, and stabilization of the inlet has been suggested. The lack of a gage stake in the pond is not a serious detriment Levels of water and measurements of sedimenu were determined by cursory survey methods. For efficienry, and complete compliance with the permit, the placement of two gage stakes has been suggested. j~6 A statement of compliance with the prudent state-of-the-art. The pond is in compliance with the prudent stateof-the-art. 7!1 A statement of rnmpllance with the approved mine plan and cermit specifically referencing appropriate portions of the cermlt documents (plans, maps and text). With respect to Permit topics found in Section 2,05.3 (Operation Plan -Permit Area); Ponds, Impoundments and Diversions (page 2.05-2, Rev.3-1-94; and page 2.05-3), specific observations include: Location In compliance (Drainage Control 1993 Reclaimed Areas, Map 8, 10-20-91). Design and construction This certification is limited to the maintenance and operation of the existing sedimentation pond, not design and construction. No stake to monitor sediment volume was ob- served in this pond. Capacity The as-built capacity of the pond (to the principal spillway invert) is 0.9 acre feet (Sedimentation Pond As-Built, Kaiser Steel, Chimney Rock, Pond No. 003, 5-30.91, Rev. 1). The runoff (10-year, 24 hour storm event) attributed to Pond 3 is 0.7 aae- feet (Greystone letter, Oaober 8, 1990, RE: Sedimentation Pond Certification Chimney Rock Mine -Permit No. C-81-023)). The difference, 0.2 acre-feet, is taken as available for sediment storage. Maintenance In substantial compliance. The volume of sedi- ment in the pond at the time of the 4th quarter inspection was estimated at 0.06 acre feet [30% of storage capacity, below the allowable 60% (Section 2.05.3, Ponds. Impoundments and Diversions. Page 2.05-2, Permit)]. Seeding of bare areas of the embankments has been recommended [Rule 4.05.6(11)(g)]. With respect to Section 2.01.2 of the Permit (Rule Periodic inspections to insure integrity of the 4): structure were made. Three quarterly inspections Chimney Rock Mine Pond #003 Inspection Report & Certification, 18 November 1994, Page 5 of 6