2009-03-04 P & R Packet - Laserfiche WebLink

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Location Drawbacks Benefits Southwest . Necessitates relocation of existing soccer field . Fuliy satisfies RCWD volume requirements for . Proximity to skate park, warming house, etc. downtown redevelopment. . Excess volume beyond what is required for downtown (potential for volume credit banking to be used on other projects with RCWD) . Proximity to ditch discharge point . Umited tree removal/less invasive to neighbors Southeast . 21' deep excavation below existing ground . No disturbance to existing park fadlities . Buffer tree removal for properties east of pond . located away from "active" areas of park . Does not fuliy satisfy RCWD volume . Proximity to ditch discharge point requirements for downtown (approximately 0.5 acre pond stili required) Table 3 Unlike locating a pond in the southwest comer of laMotte Park, there is no excess volume beyond what is required for downtown redevelopment with the southeast pond. Utilizing the laMotte Park southeast pond would require provision of approximately 0.7 ac-ft of volume within the downtown redevelopment. This correlates to a BMP footprint at the outlet of 0.5 acres (assuming the BMP is loS-feet deep and conservatively only accounting for above ground storage volume, rock void space not included in calculations). Also no excess volume is available for banking with RCWD. Assumptions There were several key assumptions made for this analysis: . The calculations are based on RCWD's Rules adopted 2.13.08. While revisions to these rules are not anticipated since they were adopted recently, it is impossible to predict what future rules may require. Also, the TMDL Implementation Plan for Centerville Lake is not complete. Based on previous correspondence with RCWD, the current rules generally align with the intent of the TMDL Implementation Plan, although this document may require further volume management that cannot be anticipated. . A final submittal has not been made to RCWD for their approval of the downtown project. Comments from the watershed may necessitate revisions, although discussions have been ongoing with their administrator and review staff. Next Steps Prior to proceeding with the laMotte Park pond option, there are several important items to be verified, including: . Depth to the groundwater table. The ordinary high water level (OHW) of Centerville Lake is B8S. This is potentially the approximate groundwater elevation. Based on this elevation the bottom of the proposed pond is four feet above the groundwater table. . Discharge into the ditch south of laMotte Park. The proposed outlet for the pond would be routed into the ditch that eventually discharges into Centerville Lake. Psge3014