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SRF Consulting Group, Inc. 09/30/03 Eagle Brook Church Water Quality Modeling Assumptions and Results At the request of Rice Creek Watershed District, a water quality model of the proposed Eagle Brook Church site was developed to determine total phosphorus loading from the existing conditions, Phase I and Phase II development on the site on Lake Peltier. The P -8 Model software was utilized to analyze the efficiency and potential phosphorus removal rates of infiltration basins, swales, and ponding areas proposed in the project. The modeling includes the following assumptions. Input Data for all models 1. NURP 50 particle distribution 2. Actual temp data files utilized for all model scenarios. Air temperature and data recorded at MSP airport between January 1949 and December 1997. 3. Rainfall scenarios modeled include: a. Actual 49 -year rainfall data from MSP Airport, recorded between January 1949 and December 1998 b. One -year storm event (Minnesota Zone 1) c. Ten -year storm event (Minnesota Zone 1) Existing Model 1. The model includes all areas within the property lines as well as a minor drainage area at the north side of the property that drains into the proposed church property under existing conditions. Model separates the area outside of the construction limits. The area outside of the construction limits is for informational purposes only, and was not included in the summary results. 2. Assumed B Soils based on NRCS soils mapping. 3. The existing land use is primarily row crops, with the exception of the farmsteads and the tree farm. 4. The wetland /swale device does not contribute to infiltration for the site as the soils are likely saturated as a result of the current lake levels. 5. Low infiltration rates (0.1 in /hr) are assumed for the depression area 6. Swales and ponds are assumed to have no infiltration. Phase I Model 1. Parking lot and building construction per the DD plan set have been modeled. 2. Associated infiltration areas and ponding devices included in the DD design are included in the model. 3. All row crop areas are converted to native prairie meadows. 4. Swales and ponds are assumed to have no infiltration. 5. Infiltration within the infiltration basin devices is assumed to be low (0.1 in /hr), to match Existing condition infiltration assumptions. 6. Flow routing - in general: infiltration basins to swales to ponds to Lake Peltier H:\ Civi1'O47\4443\sent\BWBR11O- 17 -03\P8 Narrative - Eaglebrook.doc