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O6ering, ~1~urth & Associates III ~~~~II~~~~III I~~ Consulting Civil Engineers Registered Land Surveyors 1015 Elkton Drive • Colorado Springs, Colorado 80907 • Phone (719) 531.6200 • Fax (719) 531-6266 Ext. 3 April 20, 1990 Mined Land Reclamation Division 1313 Sherman St., Room 215 Denver, CO Attn: Mr. Daniel I. Hernandez Reclamation Specialist Re: File No. M-77-210 Snyder Quarry Sediment Basin ~i Project No. 89002 ~ ~~ ~./ faPR ? 0 199U Dear Mr. Hernandez: MINED LAND RECLAMATION DIVISION On behalf of the applicant, Castle Concrete Company, we are resp~~nding to the questions included in your March 30th letter regarding the Final Design Plans, Sediment Basin, Snyder Quarry Access Road (M-77-210). The resiponses have been developed by ourselves (OWA) as Castle Concrete Company's Engineering Consultant, Mr. Mark Heifner as Castle's Reclamation Consultant, and CTL-Thompson as Castle's Geotechnical Consultant. The response relates numerically to the eight (8) questions included in the referenced March 30, 1990 letter. The subject oP each question and source of response input have been included for all eight questions. QUESTION NO. 1, FINAL GRADING/DRAINAGE. OWA/Heifner. RESPONSE: As indicated In the 1984 amendment to the quarry permit, the quarry pit will remain as a closed basin. Therefore, once the quarry floor is lowered there will not be any drainage Plow to the East Prom the quarry pit. The 1984 amendment also called for backfilling the open pit with waste after it had been lowered to maximum depth. The final elevation oP this backfill will still be Par below the elevation of the ridge separating the quarry pit and this drainage. Therefore, even after backfilling, no runoff will occur from the pit into this drainage. The sediment bay>in has been sized to handle only the runoff Prom the contributing areas as indicated on the plan. QUESTION NO. 2, FINAL SLOPES. OWA/CTL-Thompson. RESPONSE: We have discussed this question with Mr. Bill Hoffman at CTL-Thompson. During the preparation of the design we had ~>everal conversations with Mr. Hoffman and the conclusions we reached are reflected in our design statement regarding steeper slopes in rock. The analysis conducted by CTL-Thompson which resulted in the 3:1 ,and 2:1 recommendations was with granular material encountered in the Area 1-4 dtsturbances. The sediment basins are for the most part being excavated into native material, not granular itll. Subsurface conditions are likely going to be different than in the 1-4 areas. If Chis is Pound to be the case and iP the conditions allow for steeper slopes, the geotechnical consultant will make the field observation and determination. He will then