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Tom Schriner Fesponse • • Februory 25, 2000 Pnge 2 equal to or greater than the existing file drain. Field inspections of the existing drain tiles indicate that they aze either of 6" or 8" nominal diameter. The applicant has ' proposed replacing the existing file drains encountered by mining with a new file drain ' with across-sectional area that is 25% larger. This design criteria would allow for the '~ installation of 10" perforated drain pipe for all replacement drains. The current price for ~ ~ 10" perforated drain pipe is $3.00/ft. There is approximately 8000 lineaz feet of ~~, ~~ ~ proposed replacement and/or new drain lines. A maximum cost would be ~ approximately $24,000 for the materials. The installation will be done by the applicant. ~, ~~ The relocation of the Helps Seep Ditch on the western portion of the site has been ~` ~ ~ coordinated with the Office of the State Engineer and the Army Corps of Engineers. V , 'The ditch will remain an open channel conveyance structure and will be rerouted. The applicant will use on-site equipment and labor to complete this task. Exhibit E -Reclamation Plan 5. A wetlands delineation has been conducted for the 340 acre mining site. The mining plan will not disturb any wetlands. The reclamation plan does propose to create additional wetlands area as indicated on the Exhibit F. This area will be approximately 5 to 10 acres in size. A U.S. Army Corps of Engineers 404 permit application has not been applied for, because wetland disturbance is not anticipated. Exhibit G -Water Information 6. The dewatering of the pits will occur as the mining proceeds in each cell. The discharge locations for the dewatering operation aze indicated on Exhibit C. The cells will be dewatered using flotation pumps set in sumps and activated by float switches. The Vr water will be returned to the river immediately. The applicant will obtain a gravel pit well permit and a temporary substitute supply plan to allow for this operation. 8. The applicant will commit to: if at any time during the course of mining and/or reclamation the water level, as measured at any of the thirteen monitoring wells, increases more than eighteen inches above the baseline water level for that time of yeaz, the applicant will file a report with the Division within 30 days of such rise to define the cause of the water level increase and whether such rise has caused or has the potential to cause an offsite impact. If an offsite impact has occurred or the potential for such impact exists, then the applicant will submit a technical revision to the permit within 45 l/ days of such rise which addresses the following: 1) the extent of the offsite impact or potential for offsite impact that has occurred, 2) what aze the proposed mitigation measures, 3) a schedule for when mitigation measures will be implemented, and 4) the installation cost for such mitigation measures. 9. The applicant will obtain a gravel pit well permit and an approved temporary substitute ~, ' supply plan from the Office of the State Engineer prior to exposing groundwater at the site.