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iGeoTest Services, Inc. November 16,2018 <br /> North Puget Sound Behavioral Health—Treatment Center Addition Job No. 18-0770 <br /> ' Stormwater Infiltration Potential <br /> 1 Based upon an evaluation of the data collected during this investigation, it is our opinion <br /> that subsurface conditions are generally unsuitable for the onsite infiltration of stormwater. <br /> GTS observed native soils on-site consisting of very dense, glacially compacted soils. <br /> Glacially consolidated till soils as found on site within one foot of the surface are <br /> considered a restrictive layer by the 2012/2014 Washington State Department of Ecology <br /> Stormwater Management Manual for Western Washington. Field explorations <br /> demonstrated that perched water conditions existed at varying elevations below the <br /> project site surface during the end of the dry season in western Washington. Under wet <br /> conditions we estimate that near surface perched water conditions may develop. We <br /> recommend that the design team consider connecting the new building and site <br /> stormwater controls to the existing system established within the campus to properly <br /> convey collected stormwater to a suitable disposal area. <br /> Geotechnical Consultation and Construction Monitoring <br /> We recommend that geotechnical construction monitoring services be provided. These <br /> ' services should include observation by geotechnical personnel during site stripping, <br /> subgrade preparation and fill placement/compaction activities to verify that design <br /> subgrade conditions are obtained beneath the proposed building and adjacent areas. We <br /> also recommend that periodic field density testing be performed to verify that the <br /> ' appropriate degree of compaction is obtained. The purpose of these services would be to <br /> observe compliance with the design concepts, specifications, and recommendations of <br /> this report. In the event subsurface conditions differ from those anticipated before the start <br /> of building construction, GeoTest will provide revised recommendations appropriate to the <br /> conditions revealed during construction. GeoTest Services would be pleased to provide <br /> these services for you. <br /> tGeoTest Services is also available to provide a full range of materials testing and special <br /> inspection during construction as required by the local building department and the <br /> International Building Code. This may include specific construction inspections on <br /> materials such as reinforced concrete, reinforced masonry, and structural steel. These <br /> services are supported by our fully accredited materials testing laboratory. <br /> USE OF THIS REPORT <br /> GeoTest Services has prepared this report for the exclusive use of Snohomish County <br /> Facilities Management and their design consultants for specific application to the design <br /> of the development to be located at 2801 10th Street in Everett, Washington. Use of this <br /> report by others or for another project is at the user's sole risk. Within the limitations of <br /> ' scope, schedule, and budget, our services have been conducted in accordance with <br /> generally accepted practices of the geotechnical engineering profession; no other <br /> warranty, either express or implied, is made as to the professional advice included in this <br /> report. <br /> Our site explorations indicate subsurface conditions at the dates and locations indicated. <br /> It is not warranted that they are representative of subsurface conditions at other locations <br /> and times. The analyses, conclusions, and recommendations contained in this report are <br /> based on site conditions to the limited depth of our explorations at the time of our <br /> exploration program, a brief geological reconnaissance of the area, and review of <br /> Page 15 of 17 <br />