2010/12/08 Council Agenda Packet

identifying any record of the presence of hazardous substances, underground storage tanks (USTs), or hazardous substance spills. The database report will be provided by Environmental Data Resources,Inc. Following their review of available environmental data, HWA will perform a site reconnaissance to inspect the bridge site to determine if potential sources of contamination might exist. Based upon the above findings, HWA will request a file review at the Washington Department of Ecology(Ecology)Northwest Regional Office. C. Field Geotechnical and Geo-Environmental Investigation HWA will plan,coordinate, and conduct a field investigation that includes exploratory borings at two corners of California Street(intended for pedestrian signal), exploratory borings at the four existing abutment corners along Broadway Avenue, and exploratory borings down in the railroad right-of-way near the existing interior piers. Four exploratory borings will be drilled along Broadway at the four existing abutment corners to explore and evaluate soil conditions for the new bridge abutment design. Two borings will be drilled on either side of Broadway at the intersection with California Street to explore and evaluate soil conditions for a new pedestrian/bicyclist signal. These six borings will all be drilled using a truck-mounted drill rig operating in the outside lane and/or shoulder of Broadway Avenue. Temporary lane and/or shoulder closures will be necessary to complete this work; HWA will develop and submit a proposed traffic control plan for City review and approval. HWA will utilize certified flaggers and traffic control personnel to set up and maintain the approved traffic control plan during the field investigation. The exploratory borings will be drilled under full time observation of an HWA geotechnical engineer or engineering geologist. Standard Penetration Test(SPT) soil samples will be taken at 2'/2- to 5-foot intervals in each boring. The four bridge borings will each be drilled to depths of 75 feet below existing roadway surface. The pedestrian signal borings will each be drilled to 20 feet below existing roadway surface. Four additional borings will be drilled below the existing bridge structure to explore and evaluate soil conditions for new interior pier design. These borings will be drilled using a lightweight hand-portable drilling rig. These borings will each be drilled to depths of 25 feet below existing ground surface. SPT soil samples will be collected at 2'/2 to 5-foot intervals. It is assumed that right-of-entry permission from BNSF will be required, and that a BNSF flagger will need to be on site full time during all drilling work in the BNSF right-of-way. HWA will require assistance from the TranTech team to obtain right-of-entry permission. At each sampling interval, the field staff will log the soil samples and obtain and record pertinent information including soil sample depths, stratigraphy, ground water occurrence, and any visual or olfactory observations regarding the presence of contamination. We will screen soil boring soil samples by photoionization detector(PID) headspace analysis. Although the PID is not capable of quantifying or identifying specific organic compounds, this instrument is capable of measuring relative concentrations of a variety of organic vapors. 18