RecDoc2023-023544 200 Twin Dolphin STMMA

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Bioretention Area' Maintenance Plan for 200 Twin Dolphin December 13th, 2022 Bioretention areas function as soil and plant -based filtration devices that remove pollutants through a variety of physical, biological, and chemical treatment processes. These facilities normally consist of a ponding area, mulch layer, vegetation and biotreatment soil mix. Project Address and Cross Streets 200 Twin Dolphin at Shoreline Cormorant Drive Assessor's Parcel No. 111-910-150 Property Owner: 200-240 Twin Dolphin_ LLC Phone No.: Adam Voelker 610-334-0886 Designated Contact: Meris Ota Phone No.: 650-283-0547 Mailing Address: 415 Mission Street, 45th Floor, San Francisco, CA 94015 The property contains (4) bioretention area(s), located as described below and as shown in the attached site plan'. • Bioretention Area TCM No. 1 is located at the south of the parking garage. • Bioretention Area TCM No. 2 is located at the west of the office building and plaza. • Bioretention Area TCM No. 3 is located at the northeast of the office building, at Twin and Cormorant intersection, at the upper terrace. ■ Bioretention Area TCM No. 5 is located at the northeast of the office building, at Twin and Cormorant intersection, at the lower terrace. Routine Maintenance Activities The principal maintenance objective is to prevent sediment buildup and clogging, which reduces pollutant removal efficiency and may lead to bioretention area failure. Routine maintenance activities, and the frequency at which they will be conducted, are shown in Table 1. Table 1 Routine Maintenance Activities for Bioretention Areas No. Maintenance Task Frequency of Task 1 Remove obstructions, accumulated sediment, debris and trash Monthly, or as needed after storm events from bioretention area and dispose of properly. 1 Bioretention areas include linear treatment measures designed to filter water through biotreatment soil media. A bioretention area that has no waterproof liner beneath it and has a raised underdrain in the underlying rock layer to promote infiltration, as shown in Section 6.1 of the C.3 Regulated Projects Guide, may also be called a "bioinfiltration area". z Attached site plan must match the site plan exhibit to Maintenance Agreement, Page 1 Revised 1/1/22 Bioretention area O&M Template C-4 ATTY/AGR.2023.051/Trammell Crow Company (200 Twin Dolphin - STMMA) (Page 19 of 25)