2000-10-10_GENERAL DOCUMENTS - M2000002

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7tittleApplegate,lnc. Consultants for Land. Mineral and Water October l0, 2000 Adams County Department of Planning and Development Attn: Mr. Brad Johnson 4955 East 74'h Avenue Commerce City, Colorado 80022-1535 RE: Additional Material to Complete Application for Conditional Use Permit, Mobile Premix Concrete, [nc. a subsidiary of Lafarge Corp., Tanabe Pit, Case # RCU2000-00025 Deaz Mr. Johnson: The_fbllowing discussion and attachments are submitted on behalf oEour`clieht in.response to the additiotal iriformation/documentation requesfed.;for~the Tanabe,.Pit~.perinit,application.. More " -.: infortnation/documentation for the protection of adjacent,ground~i!ater<useis;was,requested.in a ,~: Metter to~l'am Acre (TuttleApplegate, Inc:)' dated Apn1.10; 2000 a Tbe;t'lnformahon and discussion ," - - ~:be]OW addresses the IequCSt.' - - ~ • ~• ; 1 ,'~ .jr( ".ri; ^. ry `.:~~ The proposed Tanabe pit is to be dry=mined below the alluvial groundwater table.: Water use at the :site will include evaporation, losses from exposed ground water:and water applied to haul roads and stockpiles for dust control. ~ Augmentation for Wese water losses has been accounted ' for in an approved Substitute Water Supply Plan obtained through the State Engineer's Office. Additionally, because ground water will be pumped from the pit area, a gravel pit well permit has also been obtained from the State Engineer's Office. Copies of the Substitute Water Supply Plan and gravel pit well permit are included in Attachment A. In addition to the approved plans and permits required by the State Engineer's Office, additional information/documentation has been collected to assure the protection of adjacent ground water users. The influence of pit dewatering operations was estimated for the proposed Tanabe site based on alluvial aquifer parameters discussed in the enclosed hydrostatigraphic report (Attachment B). Information presented in the hydrostratigraphic report was obtained from Rocky Mountain Arsenal Off-post Operable Unit remedial studies and investigations. Results indicate that the pumping rate from the pit dewatering trench will be approximately 630 gallons per minute and the drawdown will extend about 750 feet from the pit boundary. Once dewatering at the site begins, ground water levels within 750 feet of the proposed pit are expected to drop. However, the most severe drawdown is most likely [o be within 600 feet of the pit. Issuance of the gravel pi[ well permit required that the owners of wells located within 600 Page I •';'1 Granl ;; • JUIrC JO4 • Denver. CO 80233 Sad 1 Boeing Drive • Suite 200 • Loveland, CO 80538-385: ~+ ar v' ~i' "~ • ~Ax (3U3) 45'1-2759 (970) 461-9884 • Fax (970) 6t3 1177