SITE INFORMATION AND CORRESPONDENCE

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Bert E. Van Voris - 12 - 17 September 2004 Supervising Engineer The RWD cites the maximum reservoir capacity as about 84.1 MG, as measured at a point two feet below the spillway, but does not take into consideration the eventual decrease in wastewater storage capacity as sludge volume increases. Provided all wastewater is treated to secondary standards prior to reservoir impoundment, the accumulation of sludge should be low. This accumulation rate, however, still should be considered in the RWD's Water Balances. Storm Water Runoff. The RWD utilizes storm water volumes developed by HDR based on a 100-year storm event using the Rational Method, as documented in Musco's Storm Water Pollution Prevention Plan. Based on technical information provided in this Plan for a 100-year stone, about 4.6 MG of storm water could be discharged from the Musco property to the natural drainage course and 0.41 MG could be discharged to the reservoir. The 100-Year Water Balance shows values for monthly rainfall totals for all months and shows runoff occurring only from November through March. Runoff volumes range from 8.4 (November)to 13.9 MG (January). The total volume of storm water runoff is estimated at 52.7 MG. The 100-Year Water Balance shows that of the 52.7 MG of projected stone water runoff, only 4.2 MG (or 50 percent of November's total runoff)will be of poor quality and captured and diverted to the reservoir. It assumes that the quality of storm water runoff from December through March will be comparable to background and therefore may be discharged to the natural drainage below the reservoir. Comments: The RWD should provide supporting calculations for monthly values for stone water runoff assumed in the Water Balances and should summarize storm water quality data collected to date to support its assumption regarding reservoir bypass of storm water runoff. Data submitted to date do not appear to support this assumption. Unless there is rational basis for future data to be more favorable,the 100-Year Water Balance should conservatively assume that all stone water runoff from lands that received discharges of waste will require capture and impoundment in the reservoir due to its poor quality compared to ambient levels. This conservative assumption will require either projected discharge flows be reduced (at a minimum during heavy rainfall years through reduced production) or additional storage be provided. Gross Irrigation Demand. The RWD indicates Musco plans to retire the 95-acre sprayfield first, and utilize the remaining LTU fields as a backup in average climate years. The 100-Year Water Balance calculates irrigation demand by using 147 acres of offsite use area and 65 acres of available onsite area. The RWD indicates that recycled water flows will not meet the irrigation demand of the combined offsite and onsite acreage (34 inches),recognizes that supplemental irrigation water will be necessary for the offsite acreage if all available acreage is cropped, and indicates Musco can install a new groundwater production well(s)to supply this water. Comment: The offsite acreage is reasonable, as the quality of soils in the proposed use areas is adequate for agricultural purposes and recycled water will be of a quality suitable for irrigation. The value for onsite acreage is questionable, however, due to the degraded quality of LTU soils resulting from the ongoing discharge. While Musco has apparently planted LTU soils with crops, as described in Table 8 (Cropping History), crop growth has been poor unless irrigation was via rainwater or the soil was pretreated with sulfuric acid. The RWD/RWR should evaluate the extent to which LTU soils can support a level of crop growth that would actually require the volumes projected as gross irrigation demand.