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Edmonds Wtfnt Conn - GIP -6-22-18.pdfs111 SHANNON 8WILSON,INC. June 22, 2018 Parametrix, Inc. 719 2nd Avenue, Suite 200 Seattle, WA 98104 Attn: Ms. Sandy Glover THIS DOCUMENT HAS BEEN REVIMVED FOR GENERAL C'OMP:ITIBILITI.11•I.1II DESIGN CONC'EPTAND THE F01.1.01UN, IS NOTED: By: NO EXCEPTIONS TAKEN MAKECORREC'fl XS) ( st B-NI 1T ' EIZ111 11 RED REJ i 15: RE: REVISED GEOTECHNICAL INVESTIGATION PLAN, EDMONDS WATERFRONT CONNECTOR, EDMONDS, WASHINGTON This letter summarizes the subsurface explorations Shannon & Wilson proposes to conduct for the Edmonds Street Waterfront Connector Project (Project). This Geotechnical Investigation Plan (GIP) was prepared as part of Task 12.4 of our scope of services included in our Consultant Agreement with Parametrix, Inc., dated December 15, 2017. This GIP was previously submitted on June 14, 2018, but has been revised to incorporate comments and requests from Parametrix and the City of Edmonds (City). PREVIOUS STUDIES AND SCOPE Our scope of services for Project Task 12.4 includes the following field activities: Geologic mapping of the slope above the BNSF tracks. Drill one boring near a potential shaft location (original planned depth of 100 feet). Drill one boring near the south abutment (original planned depth of 60 feet). Install two vibrating wire piezometers (VWPs) in the borings to measure groundwater pressure and take manual readings on two occasions. Our geotechnical data collection efforts for the Project (performed as Part of Task 9) yielded available subsurface data along Sunset Avenue North and at the Edmonds Ferry Terminal. No data were available in Brackett's Landing North (BLN) along the alignment of the proposed bridge, west of the railroad tracks. Based on our experience with geologic conditions in the area, we anticipated soils in BLN will include loose sand and potential organics from a historic marsh. Our review and description of the available subsurface information was submitted in a letter to Parametrix dated May 15, 2018. 400 NORTH 34TH STREET, SUITE 100 P O. BOX 300303 SEATTLE, WASHINGTON 98103 206-632-8020 FAX 206-695-6777 TDD 1-800-833-6388 www shannonwilson com 21-1-30076-002 Parametrix, Inc. SHANNON 6WILSON, INC. Attn: Ms. Sandy Glover June 22, 2018 Page 2 of 10 PROPOSED SUBSURFACE EXPLORATIONS Based on the anticipated soil conditions in BLN and the configuration of the proposed bridge and embankment, we propose the following revised investigation program: Perform geologic reconnaissance only at the top of the slope along Sunset Avenue N. We will look for evidence of slope instability, including cracks or pavement settlement. We will not perform geologic mapping below the top of the slope, because existing vegetation on the slope is too dense to allow access to see geologic features. Retain a private utility locating company to check for utilities in the areas of the proposed explorations. Retain a drilling contractor to drill three borings for a total drilling footage of about 160 feet. Boring locations and depths are shown in Figure 1. We anticipate borings could be completed in three days. Install two VWPs to measure groundwater pressure and take manual readings on two occasions. The VWPs will be installed in two of the borings. Retain a testing contractor to perform cone penetration tests (CPTs) at three locations (shown in Figure 1). We plan this work to last for one day. We have discussed this revised program with you prior to preparing this GIP. Depending on the final depths of the borings, we estimate that the revised program can be performed within the original proposed budget. Shannon & Wilson will observe and coordinate these investigations. Preparatory Work Prior to conducting the fieldwork, we will mark the boring and CPT locations using stakes and flagging and/or white paint. We will contact the public Utilities Underground Location Center (1-800-424-5555) and the BNSF Railroad Company (BNSF) Locating Service (1-800-533-2891 and 1-800-832-5452) to mark utilities on public or railroad property. We anticipate that the public locate will not extend into the vegetated areas north of the restroom and the BNSF locate will not extend west of the railroad fence. Therefore, we plan to retain a private locating service to use surface -sensing methods and check the marked locations of the borings and CPTs. At the request of Parametrix, we will request the private locating service to check for utilities within about 50 feet of the railroad fence. The private locating service will scan for conductive utilities only. We will inform Parametrix once the locating work is completed so that Parametrix surveyors can record the utility locate markings. 21-1-30076-002-Ll-rev2/wp/Rm 21-1-30076-002 Parametrix, Inc. Attn: Ms. Sandy Glover June 22, 2018 Page 3 of 10 SHANNON 6WILSON, INC. We understand Parametrix has coordinated with the City to allow the planned field work to proceed. The City has requested the following preparatory work to be performed, in addition to the utility locates: ■ Place a sandwich board near the restroom one week before the field work to inform the public about the work and related impacts to parking and turnaround access. ■ The night before the work, place no -parking signs in areas where parking spots are needed to perform the work (see subsequent discussion of parking blockage). We understand the City Parks Department (Parks) plans to go out the week before the field explorations to ensure there are no bird nests in the way of the work. If they are movable, Parks will move them. Some types of birds can't be moved - if this is the case, we understand the field work may be delayed. Access and Work Conditions We will access the site from the parking lot in BLN. We will remove the steel separation bollard at the southeast corner of the restroom to allow the exploration equipment to pass by the east side of the restroom. We will provide an exclusion zone during equipment moves and during drilling to prevent the public from coming too close to the equipment. The exclusion zone will consist of staff that are directing people away from the equipment and cones and flagging, as needed. A track -mounted rig will be used for the CPTs (P-1 through P-3) and boring B-1. The track rigs will be transported to the site on a trailer. To allow for parking of the trailer during the work, we plan to block off the first bay of parking spots at the southeast end of the BLN parking lot, as shown below. Parking areas to be blocked during the field work 21-1-30076-002-Ll-rev2iwpiRm 21-1-30076-002 Parametrix, Inc. Attn: Ms. Sandy Glover June 22, 2018 Page 4 of 10 SHANNON 6WILSON, INC. Several days before the work, we will place No -Parking signs adjacent to the affected parking spaces indicating the dates the parking spots will be blocked. The night before the work, we will move the signs into the parking spaces and cordon off the area using flagging. A portion of the turnaround will also be blocked (for about 2 hours) during completion of boring B-3 (see discussion on page 6). We will place a sandwich board adjacent to the restroom one week before the field work to inform the public about the planned blockage and impacts. We plan to perform the work during daylight, weekday hours, typically between 8 a.m. and 5 p.m. Depending on daily progress, we may work until 6 p.m. if required to more efficiently complete a task. We anticipate the explorations can be completed in about three days. Significant rain events may limit the ability for the drill rig or CPT rig to work in the vegetated areas north of the restroom. If significant rain events occur, our work may be delayed. Soil Borings Borings B-2 and B-3 will be performed using a truck -mounted drill rig by Holt Services, Inc., (Holt) subcontracted to Shannon & Wilson. Boring B-1 will be performed using a track - mounted drill rig. The borings will be drilled using mud -rotary drilling techniques. Upon completion, the boreholes will be backfilled with bentonite cement grout, bentonite chips, or other approved backfill per Washington State requirements. Non -contaminated drilling mud and spoils will be collected in 55-gallon drums and removed from the site. If contaminated soils are observed, the drums will be transported by Holt to the old Edmonds Public Works building at 200 Dayton Street until the results of analytical tests can be obtained to determine appropriate disposal. We will inform Parametrix if contaminated soils are observed. We will obtain soil samples at 2.5-foot intervals in the upper 20 feet, and at 5-foot intervals thereafter, using the Standard Penetration Test (SPT) method. This method provides both a soil sample and an SPT N-value, which can be used to estimate soil density or consistency. We will collect the samples in plastic jars and transport them to our laboratory for index testing. A Shannon & Wilson field representative will observe the samples and make other field observations as the borings are drilled by the drilling subcontractor. We will prepare boring logs summarizing our field observations and soil conditions. 21-1-30076-002-Ll-rev2/wp/Rm 21-1-30076-002 Parametrix, Inc. Attn: Ms. Sandy Glover June 22, 2018 Page 5 of 10 SHANNON 6WILSON, INC. We understand cultural monitoring is required for this site. Cultural monitoring will be performed by Cultural Resources Consultants (CRC), under subcontract with Parametrix. We will coordinate with CRC to be on site during our field exploration work. Following drilling, we will install VWPs in two borings to allow for future groundwater monitoring. The VWP consists of an instrument that is grouted into the borehole. An electronic cable extending from the instrument is routed to the ground surface for monitoring purposes. The depths of the VWPs will be dependent on the soil conditions encountered. A steel, flush - mounted monument will be placed at the ground surface to allow future access to the VWP cable. Our scope does not include removing the monument and VWP. Boring B-1 We propose to drill boring B-1 to a depth of about 80 to 100 feet at the location shown in Figure 1. This boring is needed to provide subsurface information for design of deep foundations supporting the west end of the bridge span that extends from Sunset Avenue N. over the railroad tracks. A photograph of the site conditions near boring B-1 follows: Site of Boring B-1, looking North We anticipate boring 13-1 can be completed in one day. Due to the loose sand ground between the restroom and the boring location, Holt services plans to use a track -mounted drill rig to perform the boring. Holt's track rig availability is limited during the summer, therefore boring 21-1-30076-002-Ll-rev2/wp/lkn 21-1-30076-002 Parametrix, Inc. Attn: Ms. Sandy Glover June 22, 2018 Page 6 of 10 SHANNON bVIALSON, INC. 13-1 is planned for August 13, 2018. It is likely that this schedule could be moved up, depending on rig availability. We will inform Parametrix once the dates for completing boring B-1 are finalized. Accessing boring B-1 will require driving north from the BLN parking lot, past the east side of the restroom, and then over about 300 feet of existing ground that is vegetated with low brush and/or grasses. In areas where logs are present, we will move them aside so the drill rig can pass. We will move the logs back to near the original position after the work is complete. Some vegetation will be impacted in areas over which the drill rig drives and around the boring. Holt plans to use mats or boards under the track of the drill rig in areas where the rig needs to turn, to minimize ripping up of vegetation. We understand the City will inspect the site following the field work to determine the level of restoration that is required. Restoration, including replanting vegetation or other efforts, is not included in our scope of services. Subsequent to the City inspection, we will coordinate with Parametrix to prepare a cost estimate for restoration and/or coordinate with other team members. Boring B-2 Boring B-2 is planned near the north end of the proposed south abutment of the bridge where it will connect to an embankment. We propose to drill boring B-2 to a depth of about 50 feet at the location shown in Figure 1. A photograph of the conditions near boring B-2 follows: Site of Boring B-2, looking South. 21-1-30076-002-Ll-rev2/wp/11n 21-1-30076-002 Parametrix, Inc. Attn: Ms. Sandy Glover June 22, 2018 Page 7 of 10 SHANNON 6WILSON, INC. Accessing boring B-2 will require driving north from the BLN parking lot, past the east side of the restroom, and then over about 80 feet of ground vegetated with sparse grasses. Holt plans to use a truck -mounted drill rig to perform the work. We anticipate boring B-2 can be completed in less than one day for the planned depth of 50 feet. However, we understand the project configuration in this area may change to include a deep foundation element instead of an embankment. For deep foundations, we recommend the boring extend at least 20 feet into very dense glacial deposits. Depending on the depth at which glacial deposits are encountered in Boring B-2, we may extend the depth of the boring beyond the planned depth of 50 feet. Boring B-3 We propose to drill a short (about 10 feet deep) boring at the north end of the parking lot (in the roundabout near the restroom) to check for the presence of organic soils. This location coincides with the south end of the proposed retained fill embankment. Historic information indicates a marsh was present in this area in 1892. An asphalt patch will be placed at the ground surface after the boring is completed and backfilled. We anticipate this boring can be completed in about two hours. During this time, access to the roundabout will not be available for public traffic. As previously discussed, we will place a sandwich board at the site one week before the work is performed to inform the public of the planned blockage and parking and traffic impacts. We will attempt to shift the turnaround to the south to allow for turnaround access during the work. This may require blocking additional parking spaces for the 2-hour period of the work at this location. We plan to complete this boring first, at the request of the City, and re -open the turnaround by 10 a.m. Cone Penetration Tests (CPTs) We have recommended CPTs for the project to supplement information provided by the borings and provide information for seismic design analyses, including liquefaction and lateral spreading. The CPTs will be performed from a track -mounted CPT rig by In Situ Engineering, subcontracted to Shannon & Wilson. The CPT consists of pushing a probe into the ground while obtaining continuous measurements through instruments. No drilling spoils are created and no soil samples are obtained. 21-1-30076-002-Ll-rev2iwpi11m 21-1-30076-002 Parametrix, Inc. Attn: Ms. Sandy Glover June 22, 2018 Page 8 of 10 SHANNON 6WILSON, INC. We plan to extend the CPT probe through the upper loose to medium dense soils and to a maximum depth of about 50 feet (depending on soil conditions). At locations P-1 and P-2 (see Figure 1), shear wave velocity measurements will be obtained for use in our seismic analyses. The site conditions at location P-1 are like those previously shown for boring B-1. To access the site, the CPT rig will need to drive over ground vegetated with low brush and/or grasses. Locations P-2 and P-3 are near the restroom and will require driving over unvegetated ground or asphalt pavement. Each CPT is anticipated to be completed in two to three hours. CPT depths may be adjusted to allow for all three CPTs to be completed in one day. Groundwater Monitoring A Shannon & Wilson representative will return to the site on two separate occasions to obtain manual readings from the VWPs installed in borings 13-1 and B-2. This effort involves opening the monument lid, connecting a readout box to the cable, and obtaining a reading. Following the reading, the monument lid will be closed and locked down. PERMITS We do not plan to access BNSF railroad property; therefore, a Temporary Occupancy Permit is not required for our work. Further, we do not plan to place drill rig equipment close enough to the tracks to allow for potential track fouling. Therefore, we do not plan to arrange for railroad flagging. However, as a courtesy, we will inform BNSF of the drilling schedule and working conditions. All explorations are planned to be located in upland areas above the ordinary high water mark such that aquatic permits are not required. Further, we understand that Parametrix has confirmed with the City that a Shoreline Exemption letter will not be required. We understand that Parametrix has obtained authorization from the City and Parks to perform the work. We understand the City will prepare and issue a right-of-way permit for the work and prepare a press release. 21-1-30076-002-Ll-rev2/wp/Rm 21-1-30076-002 Parametrix, Inc. Attn: Ms. Sandy Glover June 22, 2018 Page 9 of 10 SCHEDULE SHANNON 6WILSON, INC. Based on the proposed plan outlined in this GIP and discussions with our subcontractors and Parametrix, we propose the following approximate schedule: ■ Week of June 25 through 29: Mark hole locations and call in utility locates. ■ Week of July 2 through 8: Meet with private utility locator at site and check public locate results. Sandwich board will be set out on Monday outside restroom to inform public of turnaround closure. No parking signs will be delivered to the site for placement on Sunday night, July 8. ■ July 9: Complete boring B-3 prior to 10 am. Start drilling boring B-2. Complete CPTs P-1 through P-3 . ■ July 10: Complete drilling boring B-2 and install VWP. ■ August 13 or earlier (2 days): Perform boring B-1. This work will be scheduled and coordinated at a later date based on subcontractor track rig availability. This schedule is approximate and may change based on site access, subcontractor availability, weather, etc. If this schedule is not acceptable, please let us know as soon as possible. CONTACT INFORMATION The following team members will be involved in the field explorations or may be contacted about various aspects of the field activities: Name Role Phone Email Rich Lindsay Parks Department maintenance manager 425-771-0289 (cell) 425 343-2269 (cell) rich. lindsaygedmondswa.gov Sandy Glover Parametrix project manager 206-394-3664 (office) 425-394-2007 (cell) sgloverg_parametrix.com Monique Anderson Shannon & Wilson project manager 206-200-1683 (cell) maa(a_shanwil.com Stephanie Williams Shannon & Wilson field coordinator and geologist 206-920-4864 (cell) saw e,shanwil.com Sonja Kassa Kleinschmidt CRC — Cultural Resources coordinator 360-395-8879 sonjakcrcwa.com Dan Romenelli In Situ Engineering Geologist 360-568-2807 danA_insituengineering.com Travis Stephens Holt Drilling coordinator 206-819-3630 (cell) tstephenskholtservicesinc.com 21-1-30076-002-Ll-rev2/wp/lkn 21-1-30076-002 Parametrix, Inc. Attn: Ms. Sandy Glover June 22, 2018 Page 10 of 10 SHANNON 6WILSON, INC. If you have any questions or require additional information, please contact me at 206-695-6837 or maanshanwil.com. Sincerely, SHANNON & WILSON, INC. Monique A. Anderson, PE Senior Associate MAA: WJP/maa Enc: Figure 1 — Proposed Exploration Plan 21-1-30076-002-Ll-rev2/wp/lkn 21-1-30076-002 � � r r ow `0 B-1 •Proposed Boring Designation and (50') Planned Depth Proposed Cone P-1 - Penetrometer Test (CPT) Location Existing Boring Designation and LS1"1 Approximate Location (Completed by Shannon & Wilson) \ Approximate Location of \ \ \ 1892 Marsh (PSRHP, 2018) 0 40 80 Scale in Feet NOTE Map adapted from aerial imagery provided by Google Earth Pro, reproduced by permission granted by Google Earth TM Mapping Service. sl aw �.� w M - D