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Home My WebLink About070125-08.1Terracon PresentationThe Ivy at Danville Site History and Environmental Overview Presentation grerracon Explore with us Introduction Site Address: 828 Diablo Road, Danville, CA APN: 196-270-029 Acreage: 2.72 Key Parties Developer: Park IV Group LLC / O&I Development Project Manager: Carissa Savant Environmental Consultant: Terracon Consultants, Inc. Project Manager: Sadie Bodiford Senior Reviewer: Tony Mikacich, P.G. 9918 Department Manager: Joe Rosenbery, P.G. ITerracon Explore with us t Environmental Engagement erracon was engaged by Park IV in early 2024 to prepare a Phase I Environmental Site Assessment (Phase I ESA) Irerracon Phase I Environmental Site Assessmen The Ivy at Danville OM Diablo Road Danville, Contra Costa County, California v 28, 2014 I -Ferrara. r se. 0.1247311 Pa., IV Group LLL lifer racoi Nationwide Terra<on.com :...,., What is a Phase I ESA? Identifies potentia or existing environmental concerns and associated liabilities. Typically conducted before the purchase, lease, or development of commercial or industrial property. • Phase I ESAs are conducted under the American Society for Testing and Materials (ASTM) Standard 1527-21 to meet the "All Appropriate Inquiries (AAI)" requirement under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). Explore with us Recognized Environmental Key Vocabulary Environmental Screening Levels efined by the ASTM Standard as: 1. The presence of hazardous substances or petroleum products in, on, or at the subject property due to a release to the environment; 2. the likely presence of hazardous substances or petroleum products in, on, or at the subject property due to a release or likely release to the environment; or 3. the presence of hazardous substances or petroleum products in, on, or at the subject property under conditions that pose a material threat of a future release to the environment. .r ierracon s or "ESLs") Several California e•era agencies have Screening Levels established (Waterboard, DTSC, EPA) • San Francisco Bay Regional Water Quality Control Board (SFBRWQCB) ESLs applicable to this project site. • SFBRWQCB ESLs include screening levels for direct exposure to soils in residential "unrestricted" land use. Explore with us [1890s — 1940s] [early 1950s] [late 1950s] [1970 — present] Undeveloped / vacant land Developed with a farmstead Farmstead expanded with ag land Existing nursery and landscaping materials operations. (1958) Sources Reviewed: • USGS Topographic Maps • Aerial Photographs • City Directories • Records from Contra Costa County Department of Environmental Health • Department of Toxic Substances Control • Owner -provided reports irerracon Explore with us Site History - Underground Storage Tank ulehholLijal 550 -gallon sol e Underground Sto • Removed in 1986 • Follow-up investigation in 1994-1996 • Remedial action included excavation of 131 cubic yards of soil. • Confirmation soil sample results below current residential (unrestricted) land use criteria. 550 -gallon UST Dimensions L = N6 feet D = N4 feet L.onciusion; runner we5 not. puse an environrnermai concern. Recommendation: No further action. le ierracon Sample ID B-1-15 (Excavation Base) SW -1-10 (Sidewall) SW -2-15 (Sidewall) SW -3-10 (Sidewall) SW -4-10 (Sidewall) Unrestricted Land Use Screening Level Gasoline 1.7 <0.2 <0.2 0.4 <0.2 430 Benzene 0.014 <0.005 <0.005 <0.005 <0.005 0.33 Toluene 0.046 <0.005 <0.005 <0.005 <0.005 1,100 Ethylbenzene 0.036 <0.005 <0.005 <0.005 <0.005 5.9 Concentrations in mg/kg (ppm) Xylenes 0.170 <0.005 <0.005 <0.005 <0.005 580 Lead Not Analyzed Not Analyzed Not Analyzed 5.0 Not Analyzed 80 Explore with us Buried Pesticide Containers • Area of buried pesticide containers identified in December 1998 • Container burial area remediated in 2001 with CA Department of Toxic Substances Control (DTSC) oversight. • Confirmation soil samples results below current residential (unrestricted) land use criteria. • Additional sampling completed by Terracon in 2024 with results below current residential (unrestricted) land use criteria. Conclusion: Former pesticide burial area does not pose an environmental concern. Recommendation: No further action. 12 1Ian•Il -IIUI. View all the excavation in progress,. Some of fhe pesticide containers are visible behind the laborers. Excav aieiI material has been temporarily s kj iIcd Vm �'Ull ucci1-c n red pavement Ilkr later Irlmler to the roll-I,II hir. View looking smut -ivies'. Sample ID B-6.5 -13MAR01 E-5.5 -13MAR01 WW -5.5' (3/29/01) N-5.5'- 13MAR01 Unrestricted Land Use Screening Level gamma -BHC (Lindane) 0.039 0.0025 ND 0.036 0.55 4,4' -Methoxychlor ND ND 0.036 ND - - Gamma -Chlordane ND ND 0.0054 ND 0.48 Gasoline ND ND ND ND 430 Diesel ND ND 3.1 ND 260 Ethylbenzene ND ND 0.073 ND 5.9 Xylenes 0.11 ND 0.16 0.12 580 Concentrations in mg/kg (ppm) ND = non -detect - - = not established ipe rerracon Pesticide Burial Area riot Explore with us 1 Historical Agricultural & Landscaping Supply Use The What & The Wh • Agricultural land use from 1950s to 1970s & Landscaping Supply operation from 1970s to present. Organochlorine pesticides (OCPs) are a class of pesticides that includes DDT, chlordane, and dieldrin. • OCPs used widely in California from 1940s through 1970s, and were banned between 1970s to 1980s. Chemical properties of OCPs: - Do not break down readily - Low solubility in water jTerracon Anton Geologic completed a subsurface investigation in 2009 Terracon completed subsurface investigation in July & August 2024. LEGEND APPROXIMATE SITE BOUNDARY D DUMPSTER G PORTABLE GENERATOR FORMER UNDERGROUND STORAGE TANK (ATRIM 1996) FORMER PESTICIDE BURIAL AREA (STEAMBORN 2001) ® FORMER SOIL BORING LOCATIONS (AG 2009) Ai_ COMPLETED SOIL BORING LOCATIONS Explore with us 2009 Subsurface Investigation (Anton Geologic) Included 10 surface soil samples from areas of pesticide storage, application, and property boundary Area most likely to have elevated levels EWdieldrin below brick, gravel and/or oikersurface layers Sample Dieldrin N S3 S4 0.190 0.470 Residential SL 0.037 Based on existing nursey operations, Anton Geologic recommended no further action at the tim CORN LEARNIN ENTER APPI(UX 11IATE SOIL SAM LOCATION (TYPICAL) FAL RIC SI-IADING FOR PLANT SALES AREAS ITerracon Explore with us 2024 Subsurface Investigation (Terracon) • Included 13 (B01 -B13) soil borings throughout the site and included additional sampling in the Buried pesticide container area Southern drainage ditch & stormwater drain Plant nursery Included analysis for petroleum hydrocarbons, volatile organic compounds, OCPs, arsenic and lead. Two borings were identified with Dieldrin at concentrations above residential ESLs. jrerracon • Included 13 soil borings (B14 -B26) throughout the Greenhouse and Plant Nursery to further delineate OCPs. 1 006 <0.0057 0 1 <Q.0064 0 24 B21 0.3 826 012 820 I 0.016 0.12 0.91 O 84 0.470 O 0 Green House 1313 - — 011 _ — '53 2.0 0.21 818 819 - .027 2.3 r 014 o , 12.08 O 015 823 024 0.0034 0.0079 0.0061 025 0.032 10 0 .0.190 816 O 0.17 810 <0.0059 0 Plant Nursery B09 <0.053 0 Explore with us Results of Subsurface Investigations B11 <0.0064 0 B22 0.41 0 VD B26 B21 B12 1320 I00.016 0.3 0.12 0.91 1 O 0 0 1 B25 1 0.032 10 S4 0.470 o Green House B13 BI7 2.0 I 0.21 q018 f B19 0 .027 2.3 014816 O • N 0.08 O c 0 0.17 0 0 015 0.0034 omM S3 0.190 0 B23 0.0079 1310 <0.0059 B24 0.0061 Plant Nurser y irerracon B09 <0.053 0 Pesticide impacts above residential (unrestricted) land use screening levels identified within the Green House and Plant Nursery area of the site. Impacts generally restricted to upper 6 -inches of soil with secondary soil samples collected from 1.0 to 1.5 feet below residential (unrestricted) land use screening levels. • Small area around B19 anticipated to have impacts extending to 2 feet below grade surface. Proposed Excavation ill 1 -foot depth 2 -feet depth Dieldrin Concentrations O Below Residential ESL O Above Residential ESL / Below Com -Ind and Construction ESL O Above Residential and Com -Ind ESL / Below Construction ESL O Above Residential, Com -Ind, and Construction ESLs Explore with us Proposed Next Steps Terracon will conduct the following: • Prepare a Removal Action Work Plan* • Prepare a Soil Management Plan* Will include provision for air monitoring. • Under the Removal Action Work Plan: • Oversee excavation, loading, and off -haul of soils. • Conduct Perimeter Air Monitoring during excavation activities • Conduct confirmation soil sampling for full range OCPs that will include dieldrin and other pesticides. • Prepare a completion report* *Includes a 3rd Party Review by an Environmental Consultant retained by the Town of Danville. erracon Total volume of soils with Dieldrin impacts estimated to be —115 Cubic Yards. Proposed Excavation Depth 1 -foot depth 2 -feet depth Proposed Confirmation Sample ■ Sidewall Sample (1 ft bgs) (23) • Base Sample (1 ft bgs) (25) ■ Sidewall Sample (2 ft bgs) (4) O Base Sample (2 ft bgs) (2) Explore with us Soil Management Plan - Provisions for: ➢ Safe earth working practices ➢ Dust mitigation ➢ Stormwater best management practices (BMPs) Perimeter Dust Monitoring ➢ Identify Up -Wind and Down -Wind Conditions for duration of earth working activities ➢ Stop work authority if unsafe conditions are recorded. Irerracon Explore with us Thank you! Contact Information Sadie Bodiford Project Manager D (916) 246-5080 Sadie. Bodiford@terracon.com Wrerracon Explore with us