2400 33RD ST CRANE LOADING 2018-01-02 MF Import

Northwest Washington Branch GRRnITE IIORTHUIEST. inc dbe Wilder Construction Company December 29, 2008 City of Everett Attn: Souheil Nasr, PE 3200 Cedar Street Everett, WA 98201 Re: Everett Station Phase 2 Sound Transit Project IF[3 NO. RTA/CP 21-06 Evaluation of Water Main Loading Mr. Souhcil, As you are aware, Granite Northwest is under contract with Sound Transit to build the second phase of the Everett Station project. This project includes the erection of a pedestrian bridge over the existing railroad tracks. Currently, the pedestrian bridge has been fully assembled on the ground with plans to use a large crane to lift the bridge into place. In order to lift the bridge into place, the crane will need to be positioned over the City of Everett's 48-inch water main that runs through the site. On December 16"', Granite met with the City of Everett to discuss the City's requirements for positioning the crane over the water main and lifting the bridge. At that meeting the City stated that 1) a stamped geotechnical report would need to be submitted to the City to evaluate the loading of the water main and identify the necessary protective measures that would need to be taken and 2) that standard highway loading would be acceptable and also that possibly higher loadings would be acceptable depending on the evaluation within the geotechnical report. Based on this information Granite's geotechnical engineer has performed the requested evaluation based on worst cast loading on the water main given the maximum loading on the crane outriggers, see attached report. In this worst case evaluation it is assumed that the crane outrigger will be placed directly above the water main, this will not be the situation during the lifting of the bridge as it is expected that the outriggers will be offset 5 to 10 feet from the edge of the water main. Given these worst case conditions, the conclusions of the geotechnical report show that by using an 8'x20' timber mat under the outriggers the resulting factor of safety is 3.5 when compared to standard highway loading. Based on the results from the geotechnical report, Granite will use 8'x20' timber mats under each outrigger as well as offsetting the crane outriggers from the water main as much as possible. Through the implementation of these protective measures, Granite believes that the City's water main will be adequately protected. Should the City have any concerns with these protective measures and/or the attached evaluation please contact me at your earliest convenience. Currently Granite is planning on performing a test lift of the bridge on January 0, with the final lift of the bridge occurring on January 12"'. Sincerely, E in-4 cc: Don Ross, PE — Granite Northwest File E IV CITY OF EVERETT Permit Services 1525 E. Marine View Drive Everett, WA 98201-1927 425.551.3100 Fax 425.5.51.311F,