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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />4.6,2 Storm Dl"aina~e Criteria <br /> <br />During this master planning effort, a meeting was conducted on March 16, 1999 to discuss <br />the storm drainage criteria associated with each jurisdiction, Given the nwnber of jurisdictional ' <br />entities and the disparity in the drainage criteria, this meeting was scheduled to specifically address <br />the storm drainage criteria that pertain to the development and evaluation of the master drainage <br />plans. The discussion focused on the criteria that pertain to: (a) major road crossings; and (b) <br />detention ponds. The meeting 'resulted in the recommendations below with respect to storm <br />drainage criteria that would guide the development and evaluation of the master drainage plans, <br /> <br />Major Road Crossings: <br /> <br />No overtopping of the roadway during major storm events. <br /> <br />Detention Ponds: <br /> <br />For Godding Hollow Basin, limit the release from on-site <br />detention facilities (associated with future development) to <br />the lOa-year existing condition peak discharge during the <br />, lOO-year storm event and the lO-year existing condition <br />peak discharge during the lO-year storm event. <br /> <br />For the Tri- Town Basin, limit the release from on-site <br />detention facilities (associated with future development) to <br />the 2-year existing condition peak discharge during the 100- <br />year storm event for that portion of the basin south of Weld <br />County Road 18, North cifWeld County Road 18, limit the <br />release from on-site detention facilities (associated with <br />future development) to the lOa-year existing condition peak <br />discharge during the IOO-year storm event and the lO-year <br />existing condition peak discharge during the la-year storm <br />event. <br /> <br />These drainage criteria were utilized to identify potential problems along the major <br />drainageway. In general, violations related to the criteria were specifically noted where road <br />crossings exceeded maximwn allowable overtopping depths or detention facilities overtopped the <br />pond embankments during the storm events. <br /> <br />4.6.3 Modeling Results <br /> <br />Based on the existing condition analyses of the Godding Hollow and Tri-Town Basins, <br />several facilities or structures lack the capacity to safely convey the lOO-year design storm and <br />create potential flooding problems within the basin. The results of the hydrologic modeling for <br /> <br />T:\OPEMCoweJdOJlcoweldOi Inl rpt.wpd <br /> <br />4.9 <br /> <br />September 8, 1999 <br />