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Mr. Tan Schreiner -2- Jan. 19, :L996 I. (B) Pond #4, adjacent to Tunnel Drive, is to hold an acre foot of water, which is to be percolated into the ground. Pond #4 is to have an emergency spill- way located at the west. end of the pond. (The adequacy of the design is contradicted by the need for a spillway.) 1. What is the rationale for locating the spillway at the west end of the pond? Where would the watex then flow? 2. Would not this large amount of water to be held in pond #4, percolating into the ground, jeopardize the water main running under Tunnel Drive, the water supply to the fire hydrant nearby and the street itself? (C) It is unclear how the new plans will direct the water flow either north-east or south from the quarry area and approximately what per cent of a major storm would go each direction. According to Mr. Klco's calculations (report of Dec. 8, page 1, under Design of Site Stonrnaater Controls), "The four sediment ponds currently planned will total five acre feet of storage, approximately 148 of a 100- year storm potential." (Old Plan). In the Jan. 6 letter, page 2, #2, he says "#4 sediment pond wi1.L ho]rl a minimum one acre foot of storage and will intercept all storm watP_ not diverted at sed anent pond #1 and all areas not in the influence of t)ie diversion to the north. This is estimated to be less than 58 of the original watershed storm volume potential. Sediment ponds #2, #3, and #4, at a minimum of 2 acre feet of storage, should be of sufficient storage to retain that portion of the storm discharge from the site not handled by the diversion." When one compares information from the two paragraphs above: iO1d Plan) 5 acre feet of storage = 148 of 10)-yr. stone potentie~2. (New Plan) Pond #4 1 acre foot of storage = 38 of 100-yr. stone potent~.al Ponds #2 & #3 4 acre feet of storage = 118 of 100-yr. storm potential New Plan Total 5 acre feet 148 of 100-yr. stone potential II. (A) Mr. Klco's most recent Technical Revision shwas water from the upper part. of the mine flowing east into Sand Gulch. At present Sand Gulch receives water from a large watershed area.