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i. The applicant has agreed [o provide an equalizing pipeline or similar means [o eliminate the predicated decline north and east of the slurry wall. The applicant should provide demonstrative proof that this pipeline will mitigate [he groundwater decline. ii. The applicant has indicated that additional water could be used to increase groundwater levels north and east of the slurry. The applicant should provide demonstrative proof of what water rights and how this will be accomplished. iii. The applicant should consider reconfiguration ofthe slurry wall to mitigate the decline of water levels to the north and east of the slurry wall. iv. Finally, the applicant has indicated that it is willing to relocate the AWC nursery stock or conduct excavation to enable the continued sub-irrigation. c. All of these mitigation alternatives are valid, however, the applicant and AWC need to agree on specific mitigation measures prior to the issuance of the final DMG permit. I believe that these mitigation measures should be independent of the proposed triggers proposed by W WE. d. The applicant should agree to a period of 24 months to establish a "pre-mining" baseline local aquifer conditions that include the determination of the groundwater gradient in the vicinity of the modeling area, [he saturated thickness and the fluctuation of groundwater levels in the vicinity of the gravel mine. This "pre-mining" aquifer baseline should be used to refine W W E's water level decline trigger of 2 feet. W WE and CC should use the "pre-mining" data [o re-calibrate the model and aquifer predictions. 5. The proposed trigger mechanism is acceptable for all remaining wells in the vicinity of the gravel mine. However, the "pre-mining" data collection should be used to re-establish the trigger criteria. Sincerely, Forrest Leaf, P cc: Laura Coyle Brad Windell _ Water Rights • Hydrology • Hydraulics • Water Quality E:\Lea~CoyleUones Hei[ Pit Aquifer Lenerl.doc