Admin Order 58-12-14 - Laserfiche WebLink

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To: Therese Walch From: Hernan Rodriguez, PE and Krista Reininga, PE. Date: April 10, 2007 Subj ect: River Road Santa Clara Model Changes As requested by the City, URS has updated the XP -SWMM models developed for the River Road Santa Clara Stormwater Master Plan project (August 2002). Models were updated using survey data collected by Lane County between October and December 2005. Areas surveyed for updating the models were identified in Section 3.0 of the current draft basin plan (August 2002) and during a June 21, 2005 meeting and in a memo to the City from URS dated August 25, 2005. Once the survey was completed, the original subbasin delineations were refined to account for new information. In addition, drainage basins for UIC areas were delineated. The model was then run to simulate conditions both with and without UICs in place. This was done to get an initial idea of whether decommissioning of all UICs would result in additional flooding issues. The purpose of this memo is to summarize the following: • changes to the original model based on new survey information; • changes to the model based on updated subbasin delineations; • methods for modeling UICs; and • results from modeling conditions both with and without UICs. HYDRAULIC CHANGES The following changes were made, based on the new survey data collected between October and December 2005, when updating each subbasin model: Flat Creek Subbasin • Model segment RSFCO20E from node 72765 to 72764 was divided into 3 segments to incorporate the culvert under Hilo Dr. (node 75697 to 75698) that was not included in the original model. The new segment names are RSFCO20Da, RSFCO20Db, and RSFCO20E. • Model segment RSFCO50A from node 72244 to 72799 was divided into 5 segments to incorporate 2 culverts that were not included in the original model. The new segment names are RSFCO50A, RSFCO50B, RSFCO50C, RSFCO50D, and RSFCO50E. Spring Creek Subbasin • Model segment RSSCOIOD from node 85033a to 72012 was divided into 3 segments to incorporate a culvert not included in the original model. The new segment names are RSSC010D, RSSCOlODa, and RSSCOlODb. 1