3003 COLBY AVE COURTYARD BY MARRIOTT 2021-03-09

Proposed Everett Hotel Property Environmental Site Characterization and Everett, Washington Remediation Recommendations the MTCA cleanup level are all at least 15 feet below the existing ground surface. Section 173-340-740(6)(d) WAC of the MTCA regulations indicates that 15 feet below the ground s li ace lis kie pUirir of compliance for soil cleanup levels based on human contact. Given the ' depth at which the contaminated soil is present, the lack of impacts to ground water, and existing infrastructure in the area, it is our opinion that the high cost and disruption associated with excavation and removal of the contaminated soil is disproportionate to the environmental ' benefits that would be gained rForthlrfeason, under the-existing site-Conditions,-We propose that the petroleum contaminated soil be left in place and a restrictive covenant be placed on then- deed disclosing the presence of the contamination. 3.2 Excavation and Disposal of Petroleum Contaminated Soil As previously discussed, it is our understanding that redevelopment of the site as a hotel has been recently proposed. Initial development plans called for the lower level of the hotel to be constructed at approximately the same elevation as the ground surface elevation of the existing iparking lot. However, we now understand that conceptual development plans have changed to include three levels of below grade parking that would require excavating to a depth of at least 29 feet below existing grades. In addition, it is anticipated that the excavation would extend approximately 30 feet into the Colby Avenue right-of-way, likely encompassing all of the petroleum impacted area depicted on Figure 2. If the construction of the new hotel building proceeds as currently proposed, excavation and removal of the petroleum hydrocarbon impacted soil would not only become more ' economically feasible, it would likely be necessary__for construction. If the petroleum hydrocarbon contaminated soil is removed from the site, we recommend that it be disposed of at a suitable, licensed disposal facility, such as Cemex's Everett facility. We also recommend that field screening, soil sampling, and laboratory testing be conducted to segregate "clean" soils, from Class 2 and Class 3 petroleum impacted soils. Class 3 soils consist of those soils which contain petroleum hydrocarbon concentrations in excess of the MTCA cleanup levels. Class 2 soils consist of those soils which contain detectable concentrations of petroleum hydrocarbons below MTCA cleanup levels. Although the petroleum concentrations in Class 2 ' soils are below MTCA cleanup levels, they are generally not accepted as "clean" fill at disposal facilities, and it is recommended that their use is limited to backfill at the site of origin, fill in commercial or industrial areas, cover or fill in permitted landfills, or for use in road or parking lot construction (subgrade material only). Use of Class 2 soils in or near wetlands, residential properties, surface water, ground water, drinking water wells, or in utility erhess is not recp. nded. We estimate the total volume of Class trn � Class 2 and Class 3 soils \ ,--at the site and below the adjacent Colby Avenue right-of-way to be approximately 1,485 cubic yards and 1,769 cubic yards, respectively(Assumptions used to arrive at this estimate and the estimated—disposal costs were provided Yin our July 30, 2009 memorandum to the City of Everett. A copy of this memorandum is included in Appendix C. It should be noted that the "approximate limit of petroleum(contaminated soil" shown in Figure 2 refers to the estimated August 24, 2009 ASSOCIATED EARTH SCIENCES, INC. TJP/tb-KV090168A5-Projects1200901681KVIWP Page 11