Agmt11 BKF Engineers-Redwood Creek

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EXHIBIT A- BKF 59780 GL be used for identifying locations of necessary channel upgrades. Generic concept level improvements and unit cost information will be presented for correcting typical Creek deficiencies. Items will include concrete patches, soldier pile walls and geocell walls. TASK 3. - Analyses BKF will pecform flow capacity analyses. BKF will utilize information collected in Task 1. Water levels will be calculated using the US Army Corps of Engineers (COE) HEC-RAS River Analysis System computer model. The model results include water surface levels at cross section locations where data is input. BKF will then identify locations of channel overtopping where the flow capacity is not adequate. Where the conveyance capacity is adequate, BKF will provide freeboard to top of bank. Resuhs ofthe model will be presented in tabular form and on the base map. BKF will provide the City with an electronic copy of the model input and output. The HEC-RAS computer model is available free of charge from the COE Hydrologic Engineering Center web site. For purposes ofthe project budgeting, cross section information will be input to the computer model with a spacing of about once every 500 feet creating 120 aross secflons). More frequent cross sections will be required at transitions between open channel and closed conduit flow. Also, more frequent cross sections will be used where abrupt changes occur to the channel configuration or design flow rate. No su�vey is proposed to supplement available data. TASK 4: Eaisting Couditions Assessment BKF will conduct an assessment ofthe Creek condition. BKF will walk all Creeks with the exception of the recently constructed box culvert through the dowmown area. Creek observations will be photographically documented and located using a handheld GPS device. Field measurements will be made of the extent of each deficiency. Tape measurements will be made for localized failures. Handheld GPS readings wil I be used where the tength of the deficiency is greater than 100 feet. A Geotechnical and Biological assessment will be made for three locations within vegetated portions of the Creek. A structural assessment will occur for the concrete lined sections ofthe Creek. The project team will work with the City when there are issues involved confined space. BKF will document obsarvations and recommendations made during the Creek walk. GPS will ba used to identify failure locations. Cornerstone Structural will walk the open channel, concrete lined portions of the Creek and will review headwalls and bank stabilization structures within the vegetated portion of the Creek. In addition, they will review identified areas of slope failures for background in developing mitigation measures. BAGG will review three failure areas identified by BKF during the Creek walk as being representative of other locations. Sandre Etchell will walk three specific areas of the Creek where significant improvements are identified. Key permftting and environmental constraints will be identified and associated project costs developed for the various Creek segments. z