Laserfiche WebLink
Prymorys Environmental Consulting, Inc. <br />.a-- <br />"Dedicating resources to tomorrow's mvimnm®t fm mday'a industry" <br />February 24, 2006 <br />Mr. Matt Carnahan <br />P.O. Box 1451 <br />Bayfield, Colorado 81122 <br />Re: Rock Dog Storm Water Facility Design <br />Mr. Matt Carnahan, <br />Please fmd below and attached to this letter, plans and specifications for storm water control facilities <br />ruommended for the Rock Dog Gravel Mine, as well as associated calculations for I OYR-24hr and <br />100YR-24hr storm events, in accordance with the memo you provided me from Allen Sorenson of the <br />Division of Minerals and Geology (DMG) dated January 25, 2006. <br />Detention Pond Design <br />The pond has a design voltune (Figure 2) for adequate storage of runoff from the PHASE A mining area <br />and the Staging Area along the Florida River during a 1 OYR-24hr storm even[ (Table 1). <br />As per the above Memo, the pond design has implemented a 3:1 exterior slope to prevent erosion, a <br />minimum 6 foot wide crest, and a spillway (Figure 3 & DWG 1) with capacity W safely pass peak Flows <br />from a 100YR-24hr storm event (Table 1). A 12 foot crest has been implemented on the pond damlberm, <br />along its south edge, to provide passage for cleav-out equipment. <br />Base of Mining Diversion Ditches <br />The aforementioned memo indicates that, at minimum, diversion ditches for [he mine area must safely pass <br />peak flows from a ] OYR-24hr storm event. The diversion ditches have been designed as such, with a <br />freeboazd of approximately 0.5 feet. Additionally, its I OYR-24hr freeboard will contain estimated peak <br />flows from a 100YR-24hr event. (DWG 2 & DWG 3). <br />In the event that you require more information or have any questions, please contact me at any time. <br />Sincerely, <br />DiaimlN egneE by J. Peter Jeroen <br />DN: CN - J. Purer Jaroen. C - US. O • Prymarya Emiormental Gmuluig. Inc. <br />Dam: 200B.d1.25 Ce:da:06 {r1'OU <br />J. Peter Jensen <br />Environmental Consultant <br />Prymorys Environmental Consulting, Inc. <br />(970)946-4935 <br />jpj@consuliant.com <br />----------'-----'--------P.O. ]bx 4470---------- ---- ---- --- <br />Durango, Colorado 81302 <br />