5A - Conditional Use Permit for the RV Resort Village at the Preserve (continued)

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f MEMO April 11,2006 Page 2 of 3 spaced out over the week is an unknown. However, it would be expected that during peak weekend occupancy with guests being entertained laundry water use would be below average with most of this water usage during the week. Restroom and shower water usage in the four buildings will be directly related to the guests that are visiting for a day or weekend. With 157 sites it is estimated that 25% (1/4 or 40 units) would have 2 or 4 guests visiting at any given time. This would mean approximately 120 guests would be utilizing the restroom and shower facilities on any given day. At 20 gallons per day for each guest the wastewater flows would be 2,400 gallons. This figure would provide for 240 (2 per person)water closet flushes, 240 hand washing events(1/2 gallon each wash) and 80 -ten minute showers at 2.5 gpm shower head water usage rate. The entrance building will house a couple of offices with restroom. A flow of 50 gpd will be used for this building. The existing home that would likely be used for a managers residence will be figured at 270 gpd which is a typical figure for residential wastewater. Average Daily Design Flow=23,850 gallons(18,880+2,250+2,400+50+270) The average daily flow is expected to occur over a 16-hour period. Treatment plant manufacturers will determine if diurnal flow equalization will be utilized for their system. If no flow equalization is utilized, the minimum recommended flow capacity of the treatment units would be 80 gpm. Wastewater strength parameters and discharge limits must also be established, on which the wastewater treatment facility design is based. The RV resort will be utilized as a permanent residence for a period of each year and not as transient type usage with weekly turnover. Therefore, wastewater strengths will more closely match typical domestic wastewater rather than the more concentrated wastewater associated with campground and marina dump stations. The following wastewater strengths will be utilized for treatment facility design. Total suspended solids - 500 mg/1 5-day biochemical oxygen demand - 400 mg/1 Chemical oxygen demand - 700 mg/1 Total nitrogen(TN) - 80 mg/1 Ammonia(NH4) - 15 mg/1 Total phosphorus - 30 mg/1 Fats, oils and grease - 60 mg/1 These values are 1.5 to 2 times those of published data for domestic wastewater. However,those typical values are for systems that include infiltration and inflow that dilute strengths. The RV resort collection system will have considerably less infiltration and inflow than average municipal systems. In addition, the estimated wastewater flows are lower than those for residential homes, so wastewater strengths are more concentrated. The wastewater strengths will be reviewed by the MPCA during permitting and may be subject to revision based on review comments with respect to the proposed treatment facility. The option of adding a dump station to collect wastewater from the RV units after they have been on the road for a week (coming up from the south each spring)will