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HomeMy WebLinkAboutAGENDA REPORT 1994 0518 CC REG ITEM 08FITEM F. F. � AGENDA R E PORT G =TY OF MC7C3RPARK TO: The Honorable City Council C FROM: Kenneth G1 be , 1 rt Director of Public Works �` DATE: May 10, 1994 (Council Meeting 13- 18 -94) SUBJECT: Consider Approval of a Hydrology Report Prepared for the Arroyo Vista Community Park Pedestrian /Equestrian /Bicycle BACKGROUND 1. In April of 1993 the City Council retained the services of VCE, Inc. to prepare the design for the Equestrian / Pedestrian Bridge for Arroyo vista Community Park. 2. In August of 1993 the City Council approved an amendment to that contract to expand the scope of work to include the preparation of soils reports required for t!ie preparation of the design. 3. In February of 1994 the City C'uunc;il approved an amendment to that contract to include thr• preparation of the subject hydrology report. DISCUSSION A. Floodplain Boundaries The present channel and levie_, for the Arroyo Simi will not contain storm flows from a i00 -year storm. The Federal Insurance Rate Maps ( FIRM) for the City of Moorpark show an area along the north and south sides of the Arroyo which are within the boundaries of a 100 -year storm and thus susceptible to inundation. B. Channel Widening Project The Ventura County Flood Controi District (VCFCD) is developing a channel improvement project for a portion of the Arroyo Simi, which includes the area where the Arroyo Vista Community Park pedestrian / equestrian bridge is to be constructed. When that project is completed a 100 -year storm will be contained within the channel. pedb�q� 199 l i2. Ped Bridge Hydrology May 1994 Page 2 C. Bridge Design Parameters The VCFCD channel improvement project calls for the lowering of the water level at the planned location for the pedestrian bridge. The design parameters for the pedestrian bridge are based on the proposed channel widening improvement project, and as such, calls for the construction of the bridge in a manner which will be compatible with the future ultimate channel widening project. The proposed lowering of the water surface by the channel improvement project enables the City to design and construct a pedestrian bridge which is both shorter and lower than what would be required if no channel modifications were being planned. The resultant bridge project is more functional, more compatible with surrounding properties and less expensive than a longer and higher structure. In light of the above, the pedestrian bridge design calls for the elevation of the soffit (bottom) of the bridge to be lower than the current elevation of a 100-year storm at the bridge location. This factor, combined with the construction of a slightly elevated bridge access roads and levy maintenance roads, will have the effect of creating an obstruction to storm waters flowing at and slightly lower than the 100-year flood elevation at this location. D. Hydrology Report The City Council authorized the preparation of the subject hydrology report to assess the potential flood impacts of proceeding with the construction of the pedestrian bridge prior to the channel improvements. A copy of this report has been provided to the City Council under separate cover. E. Conclusions of Report Based on the findings set forth in the subject hydrology report, it is the conclusion of the project engineer, V.C.E. , Inc. that the proposed project will have an insignificant impact on the flood plain of the Arroyo Simi. pedbrg6 Ped Bridge Hydrology May 1994 Page 3 RECOMMENDATION Staff recommends that the City Council accept the subject Hydrology Report and authorize staff to proceed with the project design and right-of-way acquisition required for the construction of the Arroyo Vista Community Park Pedestrian / Equestrian / Bicycle bridge. pedbrg6