2400 33RD ST GEOTECHNICAL INVESTIGATION 2018-01-02 MF Import

sc 130 Milbor-PitaaV4C underground storage tanks, septic tanks and leach fields, and contaminated soil as required by regulationstspecifications. It is our understanding that four major areas and numerous secondary areas of contaminated soil were identified in the 1997 PTI Environmental Services report (see section 2.0 for reference) as requiring removal. These areas are described in detail in the PTI report, and that report should be used fo; definitive criteria for removal of soil. The City of Everett desires to use State Residential -Use criteria for the cleanup. Milbor-Pita performed a survey of the al,; ve-ground porticns of the buildings to assess them for the presence of asbestos, lead paint and PCB light ballasts. This data is presented under separate cover and is not in this report. Milbor-Pita, because of PTI's (currently known as the Exponent Company) work, did not perform any subsurface environmental testing or analysis. 5.1.2 Over -excavation /Subarade Preparation The following are recommendations for site preparation; 1. The area to receive high traffic loadings (bus traffic pattern, truck delivery areas, parking lot entrances) should be over -excavated. The depth should be 2 feet or 24 inches so that this minimum thickness of compacted structural fill is present to evenly distribute the differential traffic loadings. This will be discussed further in the pavement structure section. 2. All work should be performed in conformance with state industrial safety requirements and all applicable government agency regulations. Fencing and temporary barriers are the contractor's responsibility. 3. Care shall be taken to not damage adjoining utilities, pavements and the structure to remain after the completion of the work. 4. Upon completion of the site demolition and clearing, the entire site's surface, which is the subgrade, shall be 'raked clean' using a tracked dozer that scarifies the top 18 inches of the surface and brings to the surface loose debris such as pipes, wood, broken concrete, old footings, and large boulders. These materials should be removed and disposed of properly. 5. The subgrade soil should be compacted to a dense and unyielding condition and then proof -rolled with heavy construction -,(uipment such as a large, self- propelled vibratory roller or a fully -loaded dump truck. Successive passes of the roller or dump truck should be spaced to provide complete coverage of the subgrade. Proof -rolling should be performed under the full-time observation of a representative of MPA. Such proof -rolling will provide visual information for the assessment of the subgrade and its acceptability as a bearing stratum. If the subgrade is wet, saturated, or frozen, proof -rolling should not be performed. Under this circumstance, subgrade conditions should be evaluated by the geotecWcal observer using a steel probe. 6. Any areas exhibiting significant deflection, pumping, and/or rutting during the proof-rolling/probing process should be over -excavated and replaced with compacted structural fill in accordance with the following section. The over - excavation process should be observed by MPA. eolechniad, Tunnel and E nvirumnentat Engineers 30g0 125'" Ave NE GPhone (425) 969.3778 IkllcNw, WA 99005 Page Fu (425)961-0677