SU0012813 - Laserfiche WebLink

Home Browse Search

V. POTENTIAL FOR WATER QUALITY IMPACTS I 4 Mining activities can impact surface and groundwater if hazardous materials or heavy a metals are used in the mining process or if discharge of turbid water to natural surface water 3:. courses occurs. The Brown Quarry uses no hazardous materials or heavy metals in the processing I of aggregate, and all storm water is retained on-site. Thus, these impacts are precluded from i occurring. C ` Storage and use of petroleum products (gas, oil, and diesel) must meet state and local agency requirements for secondary containment to protect water resources. Agricultural practices on the existing almond orchard and in the reclaimed areas create the potential for groundwater contamination from herbicides, pesticides, and nitrogen fertilizer. € Based on the reclamation plan, the minimum finished grade will be Elevation 110, which is about 15 feet above the expected minimum groundwater levels (see Figure 3). Reclamation Plan A calls for using settled fines as top soil in the bottom of all five mining areas to create a soil substrate capable of supporting crop production. Based on the calculated bottom areas and an estimate of i fines production of 20% of the volume excavated, the finished bottom elevations may be as much as 50 to 100 feet higher than the excavation depths shown on the plan, depending on the net r ►� � amount of fines placed back into the excavations. The depth to groundwater below the reclaimed area would then increase to an estimated 70 to 120 feet. The separation between the soil surface and the groundwater should preclude significant impacts from agricultural activities, provided use and application instructions for chemicals are 1 strictly followed and only applied and decomposed prior to the rainy season. Application of fertilizers should be limited to the crop need. Proper application of chemicals and fertilizers offer the best protection from groundwater contamination. " Neither groundwater nor surface contamination can be expected to occur as a result of the proposed mining expansion, as long as chemical use for mining and agricultural use follows recommended uses and application instructions. STODDARD&ASSOCIATES Assessment of Water Supply l Impacts AUGUST 1995 �PAGE 8 P