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Materials Testing & Consulting, Inc. <br />Geotechnical Engineering ● Materials Testing ● Special Inspection ● Environmental Consulting <br />December 14, 2016 <br />Craig Bergfalk <br />Fidalgo Construction <br />1004 Commercial Avenue #457 <br />Anacortes, WA 98221 <br />cc:Dale Herrigstad, P.E., P.L.S., Herrigstad Engineering <br />Subject: Infiltration Assessment <br />Proposed Stormwater Facilities – Bergfalk Short Plat <br />2307 37th Street, Anacortes, Washington <br />MTC Project No.:16B219 <br />Dear Mr. Bergfalk: <br />At your request, Materials Testing & Consulting, Inc. (MTC) has completed a targeted site <br />characterization for infiltration feasibility assessment at the above referenced site proposed for stormwater <br />facility improvements along with planned short plat development. MTC understands the client intends to <br />develop the project site, currently a generally level to gently sloping property, with a housing expansion <br />consisting of eight individual lots and associated infrastructure including a centralized cul-de-sac access <br />drive. According to the client descriptions and preliminary site drawings, preliminary stormwater design <br />proposes to utilize a rain garden feature in the central area of the cul-de-sac, with additional infiltration <br />locations to be determined by the exploration findings and recommendations of this study to best fit site <br />subsurface conditions. The client has requested this geotechnical infiltration assessment be performed to <br />identify site areas and depths suitable for on-site infiltration, and where feasible to provide soil <br />parameters and design rates in support of final facility design. <br />MTC has performed this infiltration assessment in general accordance with site characterization <br />guidelines presented in the Washington Department of Ecology Stormwater Management Manual for <br />Western Washington,2012 edition (SMMWW, 2012). A summary of MTC’s field findings, laboratory <br />results, interpretations, and recommendations pertaining to the proposed infiltration facilities including <br />design rates are provided herein. In addition, the results of Cation Exchange Capacity (CEC) analyses <br />conducted on representative soil samples from the infiltration area are attached at the end of this report. <br />C o r po ra t e • 77 7 Ch r ys l e r Dr i v e ∙B u r li n gt o n , W A 9 8233 ∙P h on e 360. 7 55 .1 990 ∙Fa x 36 0 .75 5 .198 0 S W R e <br />g io n • 2 118 Β λα χ κ Λ ακ ε Βλ ϖδ . Σ . Ω. ∙ Ο λ ψ μπ ι α , Ω Α 9 851 2 ∙ Π ηον ε 360 .5 34 .9 77 7 ∙ Φαξ 36 0 .5 34 .9 779 N W R e g <br />io n • 8 05 Δυ πον τ , Συ ι τ ε 5 ∙ Βε λ λι νγ η α μ, ΩΑ 9 8 22 6 ∙ Π ηον ε 360 . 647 . 606 1 ∙ Φαξ 3 60 .6 47 .81 11 Ki t s a p Reg ion • <br />545 1 Ν . Ω. Ν ε ω β ε ρ ρ ψ Η ι λλ Ρ οα δ , Συ ιτ ε 1 01 ∙ Σ ιλ ϖε ρ δ αλ ε , ΩΑ 9 838 3 ∙ Π ηο ν ε / Φ αξ 36 0 .6 9 8 .67 87 <br />ς ι σ ι τ ου ρ ω εβ σι τ ε :ω ω ω . μτ χ −ι ν χ .ν ε τ <br />05/21/2021 <br />SPL-2021-0002