Appendix 3.6c Additional Site Assessment Report - Granicus

Weston Subdivision Project Encinitas, California Environmental Impact Report

Appendix 3.6c Additional Site Assessment Report

APPENDICES

Encinitas, California Weston Subdivision Project Environmental Impact Report

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T R A N S M I T T A L

To: DCM Properties, Inc. Date: February 17, 2016P.O. Box 232280Encinitas, California 92024 Project No. 11084.006

Attention: Mr. David Meyer

Transmitted: The Following: For:

Mail Draft Report X Your Use

X Courier/Overnight X Final Report As Requested

Pick Up Extra Report

Email Proposal

Other

Subject: Additional Site Assessment Report, Weston Property, 510 and 514 La

Costa Avenue, City of Encinitas, San Diego County, California 92024

(APNs: 216-030-10, -45, and -46)

LEIGHTON AND ASSOCIATES, INC.

By: Brian Pierce

Distribution: (1 + .pdf) Addressee

ADDITIONAL SITE ASSESSMENT REPORTWESTON PROPERTY

510 AND 514 LA COSTA AVENUEENCINITAS, CALIFORNIA 92024

EL NUMBERS 216-030-10, -45 -46

Prepared for:

DCM Properties, Inc.P.O. Box 232280

Encinitas, California 92023

Project No. 11084.006

February 17, 2016

February 17, 2016

DCM Properties, Inc. Project No. 11084.006P.O. Box 232280Encinitas, California 92024

Attention: Mr. David Meyer

Subject: Additional Site AssessmentWeston Property510 and 514 La Costa AvenueEncinitas, California 92024

Leighton and Associates, Inc. (Leighton) is pleased to present this Additional Site Assessment report for the proposed residential development located at 510 and 514 La Costa Avenue in the City of Encinitas, California (Site). This report has been prepared in general accordance with the current San Diego Department of Environmental Health, Site Assessment and Mitigation (SDDEH-SAM), Site Assessment and Mitigation (SAM) Program Manual.

If you have questions regarding this report, please contact us. We appreciate the opportunity to be of service.

Respectfully submitted,

LEIGHTON AND ASSOCIATES, INC.

Brian Pierce, PG 9411Project Geologist

Distribution: (1) Addressee

Additional Site Assessment Report - Weston Property Project No. 11084.006

I

TABLE OF CONTENTS

Section Page1.0 INTRODUCTION..............................................................................................- 1 - 2.0 BACKGROUND ...............................................................................................- 3 - 3.0 ADDITIONAL SITE ASSESSMENT.................................................................- 6 -

3.1 Pre-field Activities - 6 - 3.2 Geophysical Survey - 6 - 3.3 Soil Vapor Survey and Limited Soil Sampling - 6 - 3.4 OCP-impacted Soils Investigation - 7 - 3.5 Laboratory Analysis - 8 -

3.4.1 Soil Vapor Samples - 8 - 3.4.2 Soil Samples - 8 -

4.0 RESULTS OF INVESTIGATION ......................................................................- 9 - 4.1 Geology - 9 -

4.1.1 Undocumented Fill - 9 - 4.1.2 Old Paralic Deposits Qop - 9 - 4.1.3 Santiago Formation - Tsa - 9 -

4.2 Soil Vapor Analytical Results - 10 - 4.3 Soil Sample Analytical Results - 10 - 4.3 Statistical Analysis - 12 -

5.0 CONCLUSIONS.............................................................................................- 15 - 5.1 UST Investigation - 15 - 5.2 Soil Vapor Survey - 15 - 5.3 OCP-Impacted Soils Investigation - 15 -

6.0 RECOMMENDATIONS ..................................................................................- 17 -

List of Accompanying Figures, Tables, and Appendices

Figure 1 Site Location Map Figure 2 Site Plan with OCP ConcentrationsFigure 3 Site Plan with Remedial Excavation LimitsTable 1 Summary of Organochlorine Pesticides and Metal Analytical ResultsAppendix A ReferencesAppendix B Geophysical Evaluation ReportAppendix C Soil Vapor Analytical ReportAppendix D Soil Sample Analytical ReportAppendix E ProUCL Data SheetsAppendix F VAP Application


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1.0 INTRODUCTION

Leighton and Associates, Inc. (Leighton) performed an additional site assessment for the proposed residential development located at 510 and 514 La Costa Avenue, in the City of Encinitas, San Diego County, California (Site, Figure 1). The Site is a roughly rectangular shaped parcel and encompasses approximately 10.0 acres (437,500 square feet) located immediately adjacent to the north of La Costa Avenue (Figure 2). The majority of the Site is developed as former greenhouses with two residences and associated flower processing structures, sheds, offices, and packaging structures.The 510 La Costa Avenue residence is a one-story wood-frame structure with a detached garage. The 514 La Costa Avenue residence is a two-story wood-frame structure with a detached garage and a detached shed.

In general, the Site is bordered to the east by a commercial property, followed by a gas station and I-5; to the north by Batiquitos Lagoon; to the south by La Costa Avenue, followed by residential properties; and to the west by residential properties.

Based on our current understanding, the proposed residential development will consist of 51 single-family residential lots (including the existing residences) following the demolition of the existing greenhouses and associated Site improvements. The proposed residential buildings are anticipated to be typical 2-story wood frame structures with slab-on-grade foundations. Additionally, improvements at the Site will consist of associated roadways, utilities, landscape and hardscape.

The scope of work for the additional site assessment was based on the findings of the previous Phase I and Limited Phase II ESA report (Leighton, 2015) prepared for the Sitethat identified the following historical land uses that resulted in recognized environmental conditions (RECs):

Two 3,000-gallon underground storage tanks (USTs) containing diesel and/or gasoline and one 350-gallon fuel oil UST are present at the Site.

Historical agricultural site use has resulted in OCP impacts above US EPA Region 9 Regional Screening Levels (RSLs) for residential soil in shallow soils (<3 ft bgs) at the Site.

Leaking USTs at the adjacent La Costa Chevron may have resulted in a vapor encroachment concern at the Site.


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Based on the conclusions and recommendations of the Phase I and Limited Phase II ESA (Leighton, 2015), Leighton performed the following scope of work:

Conduct a Geophysical Survey to determine the precise location of the two 3,000 gallon USTs at the Site;

Advance four direct push borings to a total depth of 15 feet below ground surface (bgs);

Conversion of four soil borings into temporary, dual-nested soil vapor probes at 5 feet bgs and 15 feet bgs;

Advance 43 hand auger borings to a maximum depth of 3.0overlain on the Site;

Collection of soil samples from direct push boring SG-4, directly adjacent to the two 3,000-gallon USTs for total petroleum hydrocarbon (TPH) analysis;

Collection of soil samples from hand auger borings for organochlorine pesticide (OCP) analysis (Figure 2);

Collection of soil vapor samples from each soil vapor probe for volatile organic compound (VOC) analysis; and

Preparation of this report summarizing our findings and conclusions, including tables, illustrations, and appendices.


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2.0 BACKGROUND

Historically, the Site was vacant, undeveloped land prior to 1930. The residence at 510 La Costa Avenue was constructed in 1930 and the Site was used for agricultural purposes until 1958 when the 514 La Costa Avenue residence was constructed and portions of the Site were converted to greenhouses.

Currently, the Site is a roughly rectangular-shaped parcel, 10.0 acres in in size with a north-south orientation adjacent to La Costa Avenue (Figure 2). The Site is developed with two residences and greenhouses. The Site vicinity is developed primarily as residential properties.

Four septic systems are reportedly used to dispose of sewage at the Site; one septic system near each residence, one septic system near the employee restroom in the central portion of the Site, and one septic system near the flower packing structure in the eastern portion of the Site. The septic systems were not directly observed by Leighton during the preparation of the Phase I ESA.

Three underground storage tanks (USTs) are present at the Site; two 3,000 gallon USTs containing diesel and/or gasoline in the central eastern portion of the Site, and one fuel oil UST adjacent to the west of the 510 La Costa Avenue residence (Figure 2).

Based on the historical agricultural and greenhouse site use from approximately 1930 to a Limited

Phase II Investigation.

On July 21, 2015, Leighton personnel observed and documented 15 backhoe excavated geotechnical test pits (TP-1 through TP-15) at the Site. Soil samples were collected from each of the test pits at 0.5, 1.5, and 2.0 feet below ground surface (bgs). The location of each exploratory test pit is depicted on Figure 2.

Discrete soil samples were collected in laboratory-provided glass jars with Teflon-lined lids and were clearly marked with sample identification. Soil samples collected were placed in an ice-cooled chest for temporary storage and transported to a State of California Certified laboratory (Eurofins Calscience, Garden Grove, California) for selected chemical analyses with a completed chain of custody.

Total arsenic was detected in 14 of the 15 soil samples analyzed at concentrations ranging from 0.776 mg/kg (TP-13 at 0.5 feet) to 6.27 mg/kg (TP-7 at 0.5 feet). These


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concentrations are below the California Code of Regulation (CCR), Title 22 waste disposal criterion for arsenic of 500 mg/kg. In addition, all of the detected concentrations of arsenic in the 15 soil samples analyzed were below the DTSC Southern California Regional Background Arsenic level of 12 mg/kg (DTSC, 2009). Arsenic concentrations in the soil samples analyzed were consistent with background levels and are therefore not considered a chemical of concern (CoC) during redevelopment of the Site for residential use.

Organochlorine Pesticides (OCPs) were detected in 27 of the 30 soil samples collected and analyzed by EPA Method 8081. OCP concentrations were compared to their USEPA Region 9 Regional Screening Levels (RSLs) for residential soil.

-DDD was detected in 15 soil samples at concentrations ranging from 14 µg/kg (TP-1 at 1.5 feet) to 99 µg/kg (TP-14 at 0.5 feet);

µg/kg (TP-13 at 1.5 feet) to 750 µg/kg (TP-14 at 0.5 feet);

-DDT was detected in 26 soil samples at concentrations ranging from 5.7 µg/kg (TP-15 at 1.5 feet) to 1,200 µg/kg (TP-14 at 0.5 feet);

Dieldrin was detected in 15 soil samples at concentrations ranging from 5.1 µg/kg (TP-6 at 1.5 feet) to 69 µg/kg (TP-5 at 1.5 feet);

Endosulfane Sulfate was detected in two soil samples at concentrations of 12 µg/kg (TP-8 at 0.5 feet) and 32 µg/kg (TP-15 at 0.5 feet);

Endrin was detected in 19 soil samples at concentrations ranging from 5.2 µg/kg (TP-12 at 1.5 feet) to 120 µg/kg (TP-5 at 2.0 feet);

Endrin Ketone was detected in 20 soil samples at concentrations ranging from 5.4 µg/kg (TP-15 at 1.5 feet) to 83 µg/kg (TP-4 at 0.5 feet);

Toxaphene was detected in 19 soil samples at concentrations ranging from 110 µg/kg (TP-1 at 1.5 feet) to 17,000 µg/kg (TP-5 at 2.0 feet).

No other OCPs were detected in the soil samples analyzed.


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Detected concentrations of OCPs were below their respective USEPA Region 9 Regional Screening Levels (RSLs) for residential soil for all of the detected OCP compounds with the exception of toxaphene and dieldrin.

Detected concentrations of toxaphene exceeded the RSL for residential soil in 11 of the 30 soil samples analyzed;

Detected concentrations of dieldrin exceeded the RSL for residential soil in three of the 30 soil samples analyzed.

The proper characterization of OCP-bearing soils as a California hazardous waste (aka non-RCRA) or a Federal hazardous waste (aka RCRA) requires the analysis of soluble OCP concentrations. To assess whether a sample exceeds hazardous waste thresholds, the OCP analytical results are compared to the Total Threshold Limit Concentration (TTLC), the Soluble Threshold Limit Concentration (STLC), and the Toxicity Characteristic Leaching Procedure (TCLP) values for a particular OCP. As a general industry standard practice, if the total OCP concentration of a particular compound exceeds 10 times the STLC or 20 times the TCLP for that OCP, then a Waste Extraction Test (WET) is performed.

The TTLC threshold of 10 times STLC for toxaphene is 5,000 µg/kg and 20 times TCLP is 10,000 µg/kg. Samples TP-5 at 1.5 feet bgs and TP-5 at 2.0 feet exceeded thesethresholds at concentrations of 5,300 µg/kg and 17,000 µg/kg, respectively. Sample TP-5at 2.0 feet contained a concentration of 17 micrograms per liter (µg/L), which is below the California hazardous criterion of 500 µg/L. The STLC and TCLP concentrations for the other samples analyzed were below laboratory reporting limits (20 µg/L). Therefore, the soils analyzed during the Limited Phase II ESA investigation are classified as a non-hazardous waste and are suitable for disposal at a Class III Landfill (e.g. Otay Landfill in Chula Vista, CA).

Based on the results of the Limited Phase II ESA, OCP-impacted soils from historical agricultural use was determined to be an REC for the Site. Leighton recommended further assessment of OCP-impacted soils prior to redevelopment of the Site.


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3.0 ADDITIONAL SITE ASSESSMENT

3.1 Pre-field Activities

In accordance with standard environmental procedures, Leighton prepared a Site Specific Health and Safety Plan (HSP) describing safety aspects of the work to be performed at the site. The HSP was prepared in compliance with the Occupational Safety and Health Administration (OSHA) regulation 29 CFR 1910.120 and California Code of Regulations 5192.

As required by the State of California, Underground Service Alert (USA) was notified to provide public utility clearance of our planned explorations prior to exploration activities.

3.2 Geophysical Survey

On August 25, 2016, Leighton oversaw a geophysical evaluation at the Site performed by Southwest Geophysics, Inc. (Southwest Geophysics). The purpose of the geophysical evaluation was to assess the exact location of the two 3,000-gallon USTs in the central, eastern portion of the Site. The survey included the use of a Geonics model EM61 MK2 time domain instrument, Fisher M-Scope TW-6 pipe and cable locator, RD8000 line tracer, Schonstedt GA-52C magnetic gradiometer and GSSI SIR 3000 Ground Penetrating Radar (GPR) unit using a 400 MHz transducer.

The results of the geophysical evaluation revealed the presence of two potentialUST anomalies located inside the building just west of the reported fuel pump area (Figure 2). GPR traverses across these anomalies were limited; however, they revealed two objects at approximately 2 to 2½ feet deep. The precise size and shape of these features are unknown due to limited access inside the building.

The locations of the two 3,000-gallon USTs are depicted on Figure 2. A detailed map of the geophysical survey area is included in the Geophysical Evaluation report, prepared by Southwest Geophysics (Appendix B).

3.3 Soil Vapor Survey and Limited Soil Sampling

On August 29, 2016, Leighton directed the advancement and installation of fourtemporary, dual-nested soil vapor wells at the Site (Figure 2) by H&P Mobile


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Geochemistry (H&P) of Carlsbad, California, a State of California licensed driller. Soil vapor probe construction was performed utilizing a Strata probe® Direct Push Technology Rig by hydraulically pushing 2 inch-diameter steel soil gas probes to a total depth of 15 feet bgs. The rod was removed and the soil vapor probe tubing (nylon), with a small filter attached to the end, was inserted into the open borehole. Once the desired bottom depth was attained the probe tubing was gently lifted up approximately 3-inches and sand was poured down the borehole to encase the filter with 6-inches of sand pack. Approximately, 6-inches of dry granular bentonite was added above the sand pack to prevent moisture from infiltrating the sand pack. The borehole was then backfilled to the next sampling depth (5 feet bgs) using hydrated bentonite. The same procedure was completed at the 5-foot depth as was used at the deeper sampling depth and the remainder of the borehole was then backfilled to the surface with hydrated bentonite.

Following a minimum 2-hour equilibrium period (DTSC, 2015), a leak shut in test was performed for 60 seconds to ensure no ambient air intruded into the sampling equipment. Soil vapor samples were then collected in laboratory provided glass syringes and immediately transported to the onsite H&P mobile laboratory. A tracer compound, 1,1-difluoroethane (DFA), was used to test for leaks around the tubing at the ground surface and in the sampling system. The tracer was placed at the ground surface nearby the top of the sampling tube during sample collection. Absence of the tracer compound in the subsurface soil vapor samples indicated that there was no ambient air intrusion during the sample collection activities. The standard three purge volumes were purged from the tubing and sand pack prior to soil vapor sample collection (DTSC, 2015).

A total of nine soil vapor samples (including field duplicate) were collected from four dual-nested soil vapor probes (labeled SG1 through SG4) installed at depths of 5 feet and 15 feet bgs in each boring. The locations of the direct push borings are depicted on Figure 2.

3.4 OCP-impacted Soils Investigation

On September 1 and October 6 2016, and January 18, 2017, Leighton personnel advanced 43 hand auger soil borings in areas of the Site intended to be developed for residential use. The soil sample locations were selected basegrid overlain on the Site. Soil samples were collected at 0.5 feet, 1.5 feet, and 2.5


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feet below ground surface (bgs). Sample locations were recorded in the field using the Avenza Maps® application on Samsung Galaxy S5 smartphones. The location of the hand auger borings are noted on Figure 2.

Each soil sample collected was placed in an ice-cooled chest for temporary storage and transported to a State of California Certified laboratory (Eurofins Calscience, Garden Grove, California) for selected chemical analyses with a completed chain of custody. Hand auger equipment was decontaminated before the commencement of any boring activities and between the collection of soil samples.

3.5 Laboratory Analysis

3.4.1 Soil Vapor Samples

A total of nine soil vapor samples (including field duplicate) were collected from four dual-nested soil vapor probes (labeled SG1 through SG4)installed at depths of 5 feet and 15 feet bgs in each boring. The locations of the direct push borings are depicted on Figure 2.

3.4.2 Soil Samples

A total of 90 soil samples were initially analyzed for organochlorine pesticides (OCPs) by EPA Method 8081. The deeper soil samples were placed on hold pending the initial analytical results. Nine additional soil samples from a depth of 2.5 feet and 3.0 feet bgs were analyzed for OCPs based on the elevated OCP concentrations in the 1.5 feet samples.

In addition, two soil samples collected from soil vapor boring SG-4 located approximately 10 feet north of the two 3,000-gallon USTs (Figure 2) were analyzed for total petroleum hydrocarbons (TPH) by EPA Method 8015B.


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4.0 RESULTS OF INVESTIGATION

4.1 Geology

The project area is situated in the Peninsular Ranges Geomorphic Province. This geomorphic province encompasses an area that extends approximately 900 miles from the Transverse Ranges and the Los Angeles Basin south to the southern tip of Baja California, and varies in width from approximately 30 to 100 miles (Norris and Webb, 1990). The province is characterized by mountainous terrain on the east composed mostly of Mesozoic igneous and metamorphic rocks, and relatively low-lying coastal terraces to the west underlain by late Cretaceous-age, Tertiary-age, and Quaternary-age sedimentary units. Most of the coastal region of the County of San Diego, including the Site, occur within this coastal region and are underlain by sedimentary units. Specifically, the Siteis located within the coastal plain section of the Peninsular Range Geomorphic Province of California, which generally consists of subdued landforms underlain by sedimentary bedrock.

4.1.1 Undocumented Fill

Based on our subsurface exploration, undocumented artificial fill was encountered in all hand auger borings at the Site with a thickness varying from approximately 1 foot to 2 feet bgs. Where observed in our exploration, the fill materials consisted of brown, moist, loose, silty sand. As observed, the undocumented fill soils were generally associated with the historical residential and agricultural development at the subject Site.

4.1.2 Old Paralic Deposits Qop

Previously, the site was mapped as being underlain by Quaternary-aged Terrace Deposits (Kennedy, 1975). More recent mapping by (Kennedy and Tan, 2008) has renamed the previously mapped geologic formation as Old Paralic Deposits. As encountered during our field investigation, these deposits consist of medium dense to dense, light brown to reddish brown, moist, silty sandstone with regions of interbedded poorly graded sandstone.

4.1.3 Santiago Formation - Tsa

The Tertiary-aged Santiago Formation was encountered underlying the Old Paralic Deposits and extended to the total depth explored of 76.5 feet


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bgs. As encountered in our boring explorations, the Santiago Formation generally consisted of medium dense to very dense, brownish yellow to light gray, moist, massive, friable, micaceous silty sandstone with regions of interbedded poorly graded sandstone.

4.2 Soil Vapor Analytical Results

Volatile organic compounds (VOCs) were not detected in any of the 9 soil vapor samples analyzed at concentrations above the laboratory reporting limits. The laboratory report containing soil vapor data is attached as Appendix C.

4.3 Soil Sample Analytical Results

TPH was not detected in the two soil samples (SG-4- SG-4-in the area of the two 3,000-gallon USTs at the Site.

Organochlorine pesticides (OCPs) were detected in 113 of the 131 soil samples collected and analyzed by EPA Method 8081 during this investigation and the Limited Phase II ESA performed by Leighton (Leighton, 2015).

Chlordane was detected in 1 of the 131 soil samples at a concentration of 5.2µg/kg (D5 at 0.5 feet bgs). The detected concentration of chlordane was below the Recommended Screening Level (DTSC-SL) for residential soil of 440 µg/kg in the soil samples analyzed (HERO, 2016).

-DDD was detected in 31 of the 131 soil samples at concentrations rangingfrom 5.1 µg/kg (E6 at 0.5 feet bgs) to 310 µg/kg (D5 0.5 feet bgs). Detected con -DDD were significantly below the United States Environmental Protection Agency (EPA) Region 9 Regional Screening Level (RSL) for residential soil of 2,300 µg/kg (EPA, 2016).

4,4 -DDE was detected in 113 of the 131 soil samples at concentrations ranging from 5.0 µg/kg (C3 at 0.5 feet bgs) to 1,100 µg/kg (C10 at 0.5 feet bgs).

-DDE were below the RSL for residential soil of 2,000 µg/kg in the soil samples analyzed (EPA, 2016).

-DDT was detected in 104 of the 131 soil samples at concentrations ranging from 5.4 µg/kg (A7 at 1.5 feet bgs) to 1,200 µg/kg (B10 at 0.5 feet bgs).


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-DDE were below the RSL for residential soil of 1,900 µg/kg (EPA, 2016).

Delta-BHC was detected in 2 of the 131 soil samples at concentrations ranging from 6.3 µg/kg (A7 at 1.5 feet bgs) to 12 µg/kg (D1 at 0.5 feet bgs). A RSL for residential soil for Delta BHC has not been established.

Dieldrin was detected in 67 of the 131 soil samples at concentrations rangingfrom 5.1 µg/kg (B7 at 1.5 feet bgs) to 83 µg/kg (A9 at 2.5 feet bgs). Detected concentrations of dieldrin exceeded the RSL for residential soil of 34 µg/kg in 18of the soil samples analyzed (HERO, 2016).

Endosulfan II was detected in 1 of the 131 soil samples at a concentration of 13µg/kg (A5 at 0.5 feet bgs). The detected concentration of Endosulfan II wasbelow the RSL for residential soil of 470,000 µg/kg (EPA, 2016).

Endosulfan Sulfate was detected in 2 of the 131 soil samples analyzed at concentrations ranging from 12 µg/kg (D7 at 0.5 feet bgs) to 32 µg/kg (F9 at 0.5 feet bgs). The detected concentrations of Endosulfan Sulfate were below the RSL for residential soil of 470,000 µg/kg (EPA, 2016).

Endrin was detected in 76 of the 131 soil samples at concentrations ranging from 5.2 µg/kg (B5 at 0.5 feet bgs) to 130 µg/kg (B9 at 0.5 feet bgs). Detected concentrations of endrin were below the RSL for residential soil of 19,000 µg/kg (EPA, 2016).

Endrin aldehyde was detected in one soil sample analyzed at a concentration of 9.6 µg/kg (D6 at 0.5 feet bgs), which is significantly below the RSL for residential soil of 19,000 µg/kg (EPA, 2016).

Endrin ketone was detected in 86 of the 131 soil samples analyzed at concentrations ranging from 5.2 µg/kg (C5 at 1.5 feet bgs) to 140 µg/kg (F10 at 0.5 feet bgs). The detected concentrations of endrin ketone were below the RSL for residential soil of 19,000 µg/kg (EPA, 2016).

Heptachlor epoxide was detected in 1 of the 131 soil samples at a concentration of 120 µg/kg (D5 at 0.5 feet bgs). The detected concentration of heptachlor epoxide exceeded the RSL for residential soil of 70 µg/kg in one of the soil samples analyzed (EPA, 2016).


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Toxaphene was detected in 66 of the 131 soil samples at concentrations rangingfrom 100 µg/kg (A7 at 1.5 feet bgs) to 17,000 µg/kg (A8 at 2.0 feet bgs).Detected concentrations of toxaphene exceeded the RSL for residential soil of 490 µg/kg in 33 of the soil samples analyzed (HERO, 2016).

One sample (A8 at 2.0 feet bgs) was also analyzed for STLC and TCLP based on the detected concentration of 17,000 µg/kg toxaphene. The soil sample was below laboratory reporting limits for both Waste Extraction Tests (WET).

No other OCPs were detected in the soil samples analyzed during this investigation. OCP results are summarized in Table 1. A copy of the laboratoryanalytical report for soil samples is provided in Appendix C.

4.3 Statistical Analysis

The following table summarizes the results of the OCP analyses. As first order analysis, the results were compared to the United States Environmental Protection Agency (EPA) Region 9 Regional Screening Levels (RSLs) for residential soil to determine if the detected concentrations of OCPs in soil were a chemical of concern (CoC) for the Site.

OCP No. ofdetections

Concertation RangeRSL Potential

CoC?Lowest HighestChlordane 1 5.2 5.2 440 No

-DDD 31 5.1 310 2,300 No-DDE 113 5 1100 2,000 No-DDT 104 5.4 1200 1,900 No

Delta-BHC 2 6.3 12 N/A NoDieldrin 67 5.1 83 34 Yes

Endosulfan II 1 13 13 470,000 NoEndosulfan

Sulfate 2 12 32 470,000 No

Endrin 76 5.2 130 19,000 NoEndrin Aldehyde 1 9.6 9.6 19,000 NoEndrin Ketone 86 5.2 140 19,000 No

Heptachlor Epoxide 1 120 120 70 Yes

Toxaphene 66 100 5300 490 Yes


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The following table summarizes the results of the statistical analysis of OCPs that exceeded their respective RSLs in soil at the Site. A comparison of the 95% upper confidence intervals (UCLs) of the data population to the RSLs was used to determine if the OCPs detected in soil are a chemical of concern (COC) for the Site. The statistical methods used during this investigation and the calculated

version 5.0 (USEPA, 2013). The data were imported into ProUCL and a statistical evaluation of OCP analytical results for the complete data set, including non-detects (concentration conservatively input as the reporting limit), was completed to calculate the confidence intervals for each potential CoC.

OCP RSL (µg/kg)

95% UCL Suggested UCL CoC?

Dieldrin 34 18.43 95% Gamma Approximate KM-UCL NoHeptachlor Epoxide 70 N/A One detection No

Toxaphene 490 1,109 95% KM (Chebyshev) UCL Yes

As indicated in the table above, the only OCP considered to be a COC for the Site is toxaphene. The 95% UCL for Toxaphene exceed its RSLs for residential soils in samples collected at the Site at a concentration of 1,109 µg/kg. Based on the results of the 95% UCL for toxaphene in soil, Leighton calculated the 95% UCL for soils remaining in-place if the upper 1 foot of toxaphene-impacted soils were removed from the Site.

OCP Depth RSL (µg/kg) 95% UCL Suggested UCL CoC?

Toxaphene0.5

490710.5 95% Approximate Gamma UCL Yes

1.5 to 3.0 934.9 95% KM(BCA) UCL Yes

As indicated in the table above, the toxaphene concentrations increase with depth, due to the low number of detections at 1.5 feet bgs. Based on theseresults, Leighton recalculated the 95% UCL if the upper 1 foot of soils and the hotspots with deeper toxaphene-impacts in grids A8, B7, and B9, were removed from the Site.


Toxaphene (1.5 to 3.0)-(A8, B7, B9) 490 125.4 95% -t UCL No


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Based on the results of the 95% UCL, removing the upper 1 foot of toxaphene-im areas in grids A8, B7, and B9, the remaining soils at the Site appear suitable for residential use at the Site. Copies of the ProUCL data sheets utilized in our analyses are included in Appendix E.


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5.0 CONCLUSIONS

5.1 UST Investigation

One heating oil underground storage tank (UST) and two 3,000-gallon USTs are present on-Site. Based on the geophysical survey conducted at the Site, the two 3,000-gallon USTs are currently underneath a building slab in the central eastern portion of the Site. Based on the soil samples collected adjacent to the USTs during the soil vapor survey conducted at the Site, there is a low potential that an unauthorized release has occurred. At the time of this report, UST permits werebeing obtained by Leighton to remove the three USTs from the Site. A UST Closure Report will be prepared for the Site under separate cover.

5.2 Soil Vapor Survey

No volatile organic compounds (VOCs) were detected above the laboratory reporting limit during this investigation. Based on the results of the soil vapor survey conducted at the Site, vapor encroachment is not a recognized

assessment of soil vapor at the Site is warranted at this time.

5.3 OCP-Impacted Soils Investigation

Based on the findings of the Limited Phase II ESA and Additional Site Assessment, Toxaphene appears to be the primary health risk driver at the Site. Leighton calculated the 95% UCL for OCPs that exceeded the RSL for residential soil at the Site.

OCP RSL (µg/kg)

95% UCL Suggested UCL CoC?

Dieldrin 34 18.43 95% Gamma Approximate KM-UCL NoHeptachlor Epoxide 70 N/A One detection No

Toxaphene 490 1,109 95% KM (Chebyshev) UCL Yes

Based on the results of the statistical analysis of toxaphene-impacted soils at the hotspot

mixing areas (Grids A8, B7, B9) were excavated and removed from the Site.


Toxaphene (1.5 to 3.0)-(A8, B7, B9) 490 125.4 95% -t UCL No


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Based on the results of the statistical analysis, removing the upper 1 foot of soils s A8, B7, and B9, the 95% UCL for Toxaphene

(125.4 µg/kg) is significantly below the RSL for residential soils (490 µg/kg) and the remaining soils are suitable for residential use at the Site.

Figure 3 depicts the areas of the Site with detected concentrations of Toxaphene that exceed the RSL for residential soil. Based on the removal of 1 foot of soil and the hotspot mixing areas depicted on Figure 3, approximately 6,911 cubic yards of OCP impacted soils will need to be removed from, or buried under slabs at the Site.The removal volumes for each grid containing toxaphene-impacted soils is summarized in the table below:

Grid Removal Depth Cubic Yards

A7 1 370.37

A8 1 100.00A8 Hotspot 3 181.48

A9 1 370.37A10 1 370.37A11 1 370.37B7 1 181.48

B7 Hotspot 2 66.67B8 1 370.37B9 1 181.48

B9 Hotspot 2 66.67B10 1 370.37B11 1 370.37C8 1 370.37C9 1 370.37C10 1 370.37C11 1 370.37D6 1 370.37D8 1 370.37D9 1 370.37D10 1 370.37D11 1 370.37E7 1 51.85F10 1 155.56

Total 6911.11


- 17 -

6.0 RECOMMENDATIONS

Based on the results of this Additional Site Assessment, remedial excavation of the upper 1 foot of soils impacted with toxaphene in excess of its RSL for residential soil and the hotspots will need to be conducted prior to Site redevelopment

(Figure 3). It is anticipated that this excavated material can be re-used onsite, if buried in inaccessible locations under the concrete slab footprints and front yards of the residential lots. Leighton recommends preparing a property mitigation plan (PMP) for the Site outlining:

Impacted areas and contaminants identified at the Site;

Planned approach for disposition of impacted soils; and

Procedures for confirmation soil sampling after excavation of OCP impacted soils.

The PMP should include a Community Health and Safety Plan (CHSP) to provideguidance for the handling of known and unknown hazards that may be encountered at the Site, as well as provide guidance for a safe work environment and for protection of the public by:

Reducing community exposures to potential hazards and nuisances caused by site work;

Promoting community awareness of the proposed remediation project; and

Monitoring and mitigating potential public hazards and nuisances caused by site work that may migrate off site: including OCPs, dust, and noise.

Leighton recommends entering into a County of San Diego Department of Environmental Health (SDDEH) Voluntary Assistance Program (VAP). The VAP is designed to provide

sessment pertaining to properties suspected or known to be contaminated with hazardous substances. California Health and Safety Code Sections 101480-101490 authorizes SDDEH to enter into voluntary agreements for the oversight of remedial action at sites contaminated by wastes. The SDDEH staff will review the Phase I and Limited Phase II ESA Report, Additional Site Assessment Report, and PMP and manage the project in accordance with applicable regulatory requirements, industry practices, and the current version of the SDDEH Site Assessment and Mitigation (SAM) Manual. Their goal throughout the project review is the protection of human health, water resources, and the environment. Upon completion of the project, SDDEH will issue a letter addressing the


- 18 -

appdocumentation and regulatory approval for any additional assessment or remediation work that may be required related to construction. A copy of the SDDEH VAP application is included in Appendix F.

In general, observations should be made during any future site development for areas of possible contamination such as, but not limited to, the presence of underground facilities, buried debris, waste drums, tanks, staining or odorous soils. Should such materials be encountered, further investigation and analysis may be necessary at that time.

³0 2,000 4,000

Feet

Figure 1

Scale:

Leighton

Base Map: ESRI ArcGIS Online 2017Thematic Information: Leighton

1 " = 2,000 '

Project: 11084.006 Eng/Geol: BCP

Map Saved as P:\Drafting\11084\006\Maps\11084-006_F01_SLM_2017-02-17.mxd on 2/17/2017 10:40:19 AM

Author: (mmurphy)

SITE LOCATION MAPWeston Property Additional Site Assessment

510 and 514 La Costa AvenueEncinitas, California 92024

ApproximateSite Location

Date: February 2017

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Map Saved as P:\Drafting\11084\006\Maps\Figure3.mxd on 2/16/2017 11:57:13 AM

Figure 3

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³0 100 200

Feet

Scale:

Base Map: ESRI ArcGIS Online 2017Thematic Information: Leighton

1 " = 100 '

Project: 11084.006 Eng/Geol: BCP

Author: (mmurphy)

Date: February 2017SITE PLAN WITH REMEDIAL EXCAVATION LIMITS

Weston Property Additional Site Assessment510 and 514 La Costa Avenue

Encinitas, California 92024

Legend

A!Approximate Hand Auger Location(Gray indicates Offsite Location)

&( Approximate Soil Gas Sample Location

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!Approximate Step-out Hand AugerLocation (Gray indicates Offsite Location)

Property Boundary

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2' Removal Area

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Approximate Location of (2) 3,000 GallonFuel USTs

Approximate Location of HeatingOil UST

Retained by Owner - Not A Part/No Grading

Table 1: Summary of Organochlorine Pesticides and Metal Analytical Results510 and 514 La Costa Avenue

Encinitas, California

6010 Metals

OCP-11-6'' A4-0.5 7/21/2015 0.5 <50 21 190 120 <10 6.9 <5.0 <5.0 6.1 <5.0 18 <10 170 2.44

OCP-11-18'' A4-1.5 7/21/2015 1.5 <50 <5.0 <5.0 <5.0 <10 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10 <100 --

A5-0.5 A5-0.5 9/1/2016 0.5 <50 <5.0 190 130 <9.9 <5.0 13 <5.0 <5.0 <5.0 <5.0 <9.9 200 --

A5-1.5 A5-1.5 9/1/2016 1.5 <50 <5.0 5.8 <5.0 <10 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10 <100 --

A6-0.5 A6-0.5 9/1/2016 0.5 <50 <5.0 180 130 <10 <5.0 <5.0 <5.0 <5.0 <5.0 9.7 <10 110 --

A6-1.5 A6-1.5 9/1/2016 1.5 <50 <5.0 5.2 <5.0 <9.9 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <9.9 <99 --

A7-0.5 A7-0.5 9/1/2016 0.5 <50 <5.0 120 100 <10 8.5 <5.0 <5.0 12 <5.0 14 <10 700 --

A7-1.5 A7-1.5 9/1/2016 1.5 <50 <5.0 9.3 5.4 <10 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10 100 --

OCP-5-6'' A8-0.5 7/21/2015 0.5 <50 30 300 420 <10 24 <5.0 <5.0 38 <5.0 53 <10 2,300 4.23

OCP-5-18'' A8-1.5 7/21/2015 1.5 <50 23 160 390 <10 69 <5.0 <5.0 56 <5.0 48 <10 5,300** --

OCP-5-24" A8-2.0 7/21/2015 2.0 <50 <50 220 330 <100 <50 <50 <50 120 <50 <50 <100 17,000** --

A8-3 A8-3 10/6/2016 3.0 <50 <5.0 27 9.8 <9.9 31 <5.0 <5.0 5.7 <5.0 9.3 <9.9 <99

A9-0.5 A9-0.5 9/1/2016 0.5 <50 <5.0 370 430 <10 11 <5.0 <5.0 31 <5.0 35 <10 710 --

A9-1.5 A9-1.5 9/1/2016 1.5 <50 <5.0 52 79 <9.9 18 <5.0 <5.0 14 <5.0 7.8 <9.9 <99 --

A9-2.5 A9-2.5 9/1/2016 2.5 <50 <5.0 67 140 <10 83 <5.0 <5.0 8.7 <5.0 14 <10 <100 --

A10-0.5 A10-0.5 9/1/2016 0.5 <50 <5.0 430 440 <10 14 <5.0 <5.0 32 <5.0 38 <10 700 --

A10-1.5 A10-1.5 9/1/2016 1.5 <50 6.9 62 110 <10 69 <5.0 <5.0 25 <5.0 11 <10 110 --

A10-2.5 A10-2.5 9/1/2016 2.5 <50 <5.0 39 75 <9.9 67 <5.0 <5.0 23 <5.0 11 <9.9 <99 --

A10-3 A10-3 10/6/2016 3.0 <50 <5.0 11 <5.0 <9.9 15 <5.0 <5.0 17 <5.0 16 <9.9 <99

OCP-1-6'' A11-0.5 7/21/2015 0.5 <50 15 280 250 <10 6.9 <5.0 <5.0 12 <5.0 37 <10 500 1.48

OCP-1-18'' A11-1.5 7/21/2015 1.5 <50 14 210 180 <10 21 <5.0 <5.0 23 <5.0 16 <10 110 --

OCP-9-6'' B3-0.5 7/21/2015 0.5 <50 <5.0 35 12 <10 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10 <100 <0.735

OCP-9-18'' B3-1.5 7/21/2015 1.5 <50 <5.0 <5.0 <5.0 <10 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10 <100 --

B4-0.5 B4-0.5 9/1/2016 0.5 <50 8.8 250 220 <10 5.5 <5.0 <5.0 7.0 <5.0 29 <10 310 --

B4-1.5 B4-1.5 9/1/2016 1.5 <50 <5.0 <5.0 <5.0 <9.9 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <9.9 <99 --

OCP-12-6'' B5-0.5 7/21/2015 0.5 <50 16 180 140 <10 <5.0 <5.0 <5.0 5.2 <5.0 14 <10 370 2.92

OCP-12-18'' B5-1.5 7/21/2015 1.5 <50 <5.0 <5.0 6.5 <10 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10 <100 --

440** 2,300 2,000 1,900 -- 34 470,000 470,000 19,000 19,000 19,000 70 490 12*

Heptachlor Epoxide (µg/kg)

Chlordane (µg/kg)

4,4'-DDD (µg/kg)

4,4'-DDE (µg/kg)

4,4'-DDT (µg/kg)

Delta-BHC

(µg/kg)

Sample ID Grid Sample Name Date Depth

(ft. bgs)

EPA 8081 Organochlorine Pesticides

Toxaphene (µg/kg)

RSLs - Residential Soil

Arsenic (mg/kg)

Dieldrin (µg/kg)

Endosulfan II (µg/kg)

Endosulfan Sulfate (µg/kg)

Endrin (µg/kg)

Endrin Aldehyde

(µg/kg)

Endrin Ketone (µg/kg)

Leighton and Associates, Inc. Page 1 of 6 Project No. 11084.006



6010 MetalsHeptachlor

Epoxide (µg/kg)

Chlordane (µg/kg)

4,4'-DDD (µg/kg)

4,4'-DDE (µg/kg)

4,4'-DDT (µg/kg)

Delta-BHC

(µg/kg)


(ft. bgs)


Toxaphene (µg/kg)

Arsenic (mg/kg)

Dieldrin (µg/kg)



Endrin (µg/kg)

Endrin Aldehyde

(µg/kg)


B6-0.5 B6-0.5 9/1/2016 0.5 <50 <5.0 120 100 <10 <5.0 <5.0 <5.0 <5.0 <5.0 5.8 <10 410 --

B6-1.5 B6-1.5 9/1/2016 1.5 <50 <5.0 5.3 <5.0 <9.9 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <9.9 <99 --

OCP-6-6'' B7-0.5 7/21/2015 0.5 <50 30 350 410 <10 7.7 <5.0 <5.0 39 <5.0 30 <10 1,200 3.59

OCP-6-18'' B7-1.5 7/21/2015 1.5 <50 <5.0 14 48 <10 5.1 <5.0 <5.0 16 <5.0 7.3 <10 700 --

OCP-6-24" B7-2.0 7/21/2015 2.0 <50 <5.0 11 14 <10 5.3 <5.0 <5.0 11 <5.0 <5.0 <10 660 --

B7-3 B7-3 1/18/2017 3.0 <50 <5.0 <5.0 <5.0 <9.9 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <9.9 <99 --

B8-0.5 B8-0.5 9/1/2016 0.5 <50 <5.0 740 740 <10 45 <5.0 <5.0 38 <5.0 79 <10 2,700 --

B8-1.5 B8-1.5 9/1/2016 1.5 <50 <5.0 50 61 <9.9 <5.0 <5.0 <5.0 13 <5.0 8.5 <9.9 390 --

B8-2.5 B8-2.5 9/1/2016 2.5 <50 <5.0 12 18 <10 7.4 <5.0 <5.0 6.3 <5.0 <5.0 <10 100 --

B9-0.5 B9-0.5 9/1/2016 0.5 <50 <5.0 680 980 <10 39 <5.0 <5.0 130 <5.0 39 <10 970 --

B9-1.5 B9-1.5 9/1/2016 1.5 <50 <5.0 73 150 <10 37 <5.0 <5.0 24 <5.0 32 <10 1,000 --

B9-2.5 B9-2.5 9/1/2016 2.5 <50 <5.0 <5.0 7.0 <9.9 9.5 <5.0 <5.0 <5.0 <5.0 <5.0 <9.9 <99

OCP-14-6'' B10-0.5 7/21/2015 0.5 <50 99 750 1,200 <10 42 <5.0 <5.0 72 <5.0 58 <10 1,400 3.31

OCP-14-18'' B10-1.5 7/21/2015 1.5 <50 <5.0 9.1 9.7 <10 26 <5.0 <5.0 <5.0 <5.0 8.2 <10 <100 --

B11-0.5 B11-0.5 9/1/2016 0.5 <50 <5.0 530 790 <10 24 <5.0 <5.0 31 <5.0 37 <10 1,200 --

B11-1.5 B11-1.5 9/1/2016 1.5 <50 <5.0 62 67 <9.9 13 <5.0 <5.0 7.3 <5.0 5.4 <9.9 240 --

B11-2.5 B11-2.5 9/1/2016 2.5 <50 <5.0 <5.0 5.8 <9.9 5.9 <5.0 <5.0 <5.0 <5.0 <5.0 <9.9 <99 --

C3-0.5 C3-0.5 9/1/2016 0.5 <50 <5.0 5.0 <5.0 <10 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10 <100 --

C3-1.5 C3-1.5 9/1/2016 1.5 <50 <5.0 6.8 <5.0 <10 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10 <100 --

C4-0.5 C4-0.5 9/1/2016 0.5 <50 <5.0 160 140 <10 <5.0 <5.0 <5.0 <5.0 <5.0 11 <10 160 --

C4-1.5 C4-1.5 9/1/2016 1.5 <50 <5.0 12 12 <9.9 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <9.9 <99 --

C5-0.5 C5-0.5 9/1/2016 0.5 <51 <5.1 300 240 <10 <5.1 <5.1 <5.1 9.5 <5.1 19 <10 250 --

C5-1.5 C5-1.5 9/1/2016 1.5 <50 <5.0 33 17 <10 <5.0 <5.0 <5.0 6.8 <5.0 5.2 <10 <100 --

OCP-13-6'' C6-0.5 7/21/2015 0.5 <50 20 180 150 <10 <5.0 <5.0 <5.0 14 <5.0 20 <10 150 0.776

OCP-13-18'' C6-1.5 7/21/2015 1.5 <50 <5.0 5.8 <5.0 <10 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10 <100 --

C7-0.5 C7-0.5 9/1/2016 0.5 <50 <5.0 91 98 <10 <5.0 <5.0 <5.0 <5.0 <5.0 6.0 <10 180 --

C7-1.5 C7-1.5 9/1/2016 1.5 <50 <5.0 <5.0 <5.0 <9.9 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <9.9 <99 --

440** 2,300 2,000 1,900 -- 34 470,000 470,000 19,000 19,000 19,000 70 490 12*RSLs - Residential Soil





Epoxide (µg/kg)

Chlordane (µg/kg)

4,4'-DDD (µg/kg)

4,4'-DDE (µg/kg)

4,4'-DDT (µg/kg)

Delta-BHC

(µg/kg)


(ft. bgs)


Toxaphene (µg/kg)

Arsenic (mg/kg)

Dieldrin (µg/kg)



Endrin (µg/kg)

Endrin Aldehyde

(µg/kg)


C8-0.5 C8-0.5 9/1/2016 0.5 <50 <5.0 400 420 <10 8.1 <5.0 <5.0 16 <5.0 33 <10 750 --

C8-1.5 C8-1.5 9/1/2016 1.5 <50 <5.0 17 19 <9.9 <5.0 <5.0 <5.0 10 <5.0 7.4 <9.9 210 --

OCP-7-6'' C9-0.5 7/21/2015 0.5 <50 37 290 290 <10 14 <5.0 <5.0 37 <5.0 35 <10 980 6.27

OCP-7-18'' C9-1.5 7/21/2015 1.5 <50 <5.0 <5.0 <5.0 <10 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10 <100 --

C10-0.5 C10-0.5 9/1/2016 0.5 <50 <5.0 1,100 730 <10 20 <5.0 <5.0 78 <5.0 39 <10 1,000 --

C10-1.5 C10-1.5 9/1/2016 1.5 <50 <5.0 27 16 <9.9 <5.0 <5.0 <5.0 26 <5.0 <5.0 <9.9 280 --

C10-2.5 C10-2.5 9/1/2016 2.5 <50 <5.0 14 8.8 <10 <5.0 <5.0 <5.0 23 <5.0 <5.0 <10 230 --

OCP-2-6'' C11-0.5 7/21/2015 0.5 <50 25 270 340 <10 <5.0 <5.0 <5.0 29 <5.0 44 <10 1,200 4.01

OCP-2-18'' C11-1.5 7/21/2015 1.5 <50 <5.0 11 37 <10 <5.0 <5.0 <5.0 7.3 <5.0 5.7 <10 180 --

D5-0.5 D5-0.5 9/1/2016 0.5 5.2 310 160 <9.9 6.3 <5.0 <5.0 <5.0 <5.0 <5.0 <9.9 120 120 --

D5-1.5 D5-1.5 9/1/2016 1.5 <50 <5.0 <5.0 <5.0 <10 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10 <100 --

D6-0.5 D6-0.5 9/1/2016 0.5 <50 <5.0 470 470 <10 41 <5.0 <5.0 68 <5.0 21 <10 1,400 --

D6-1.5 D6-1.5 9/1/2016 1.5 <50 <5.0 23 18 <9.9 10 <5.0 <5.0 6.5 9.6 23 <9.9 120 --

D6-E-0.5 D6-E-0.5 10/6/2016 0.5 <50 12 340 250 <10 21 <5.0 <5.0 27 <5.0 45 <10 <100 --

D6-E-1.5 D6-E-1.5 10/6/2016 1.5 <50 <5.0 <5.0 <5.0 <10 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10 <100 --

D6-N-0.5 D6-N-0.5 10/6/2016 0.5 <50 6.0 240 170 <10 7.6 <5.0 <5.0 16 <5.0 32 <10 <100 --

D6-N-1.5 D6-N-1.5 10/6/2016 1.5 <50 <5.0 10 10 <10 9.0 <5.0 <5.0 <5.0 <5.0 24 <10 <100 --

D6-S-0.5 D6-S-0.5 10/6/2016 0.5 <50 38 260 250 <9.9 41 <5.0 <5.0 63 <5.0 68 <9.9 1,200 --

D6-S-1.5 D6-S-1.5 10/6/2016 1.5 <50 <5.0 9.8 11 <10 <5.0 <5.0 <5.0 5.4 <5.0 <5.0 <10 <100 --

D6-W-0.5 D6-W-0.5 10/6/2016 0.5 <50 79 370 380 <10 22 <5.0 <5.0 51 <5.0 62 <10 <100 --

D6-W-1.5 D6-W-1.5 10/6/2016 1.5 <50 <5.0 15 11 <10 <5.0 <5.0 <5.0 <5.0 <5.0 5.4 <10 <100 --

OCP-8-6'' D7-0.5 7/21/2015 0.5 <50 23 250 210 <10 11 <5.0 12 17 <5.0 34 <10 380 4.19

OCP-8-18'' D7-1.5 7/21/2015 1.5 <50 <5.0 9.7 <5.0 <10 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10 <100 --

D8-0.5 D8-0.5 9/1/2016 0.5 <50 <5.0 160 160 <10 28 <5.0 <5.0 14 <5.0 46 <10 820 --

D8-1.5 D8-1.5 9/1/2016 1.5 <50 <5.0 18 6.3 <9.9 20 <5.0 <5.0 18 <5.0 16 <9.9 <99 --

D8-2.5 D8-2.5 9/1/2016 2.5 <50 <5.0 <5.0 <5.0 <10 <5.0 <5.0 <5.0 <5.0 <5.0 5.9 <10 <100






Epoxide (µg/kg)

Chlordane (µg/kg)

4,4'-DDD (µg/kg)

4,4'-DDE (µg/kg)

4,4'-DDT (µg/kg)

Delta-BHC

(µg/kg)


(ft. bgs)


Toxaphene (µg/kg)

Arsenic (mg/kg)

Dieldrin (µg/kg)



Endrin (µg/kg)

Endrin Aldehyde

(µg/kg)


D9-0.5 D9-0.5 9/1/2016 0.5 <50 <5.0 330 280 <10 31 <5.0 <5.0 30 <5.0 58 <10 500 --

D9-1.5 D9-1.5 9/1/2016 1.5 <50 <5.0 11 5.8 <10 8.8 <5.0 <5.0 <5.0 <5.0 15 <10 <100 --

OCP-4-6'' D10-0.5 7/21/2015 0.5 <50 17 360 290 <10 69 <5.0 <5.0 79 <5.0 83 <10 490 5.18

OCP-4-18'' D10-1.5 7/21/2015 1.5 <50 <5.0 21 9.2 <10 <5.0 <5.0 <5.0 <5.0 <5.0 7.3 <10 <100 --

D11-0.5 D11-0.5 9/1/2016 0.5 <50 <5.0 470 500 <9.9 39 <5.0 <5.0 57 <5.0 55 <9.9 800 --

D11-1.5 D11-1.5 9/1/2016 1.5 <50 <5.0 38 23 <10 25 <5.0 <5.0 34 <5.0 17 <10 150 --

D11-2.5 D11-2.5 9/1/2016 2.5 <50 <5.0 <5.0 <5.0 <10 11 <5.0 <5.0 19 <5.0 7.1 <10 <100 --

E5-0.5 E5-0.5 9/1/2016 0.5 <50 12 130 110 <10 <5.0 <5.0 <5.0 <5.0 <5.0 7.6 <10 <100 --

E5-1.5 E5-1.5 9/1/2016 1.5 <50 <5.0 <5.0 <5.0 <9.9 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <9.9 <99 --

E6-0.5 E6-0.5 9/1/2016 0.5 <50 5.1 42 49 <10 <5.0 <5.0 <5.0 5.3 <5.0 6.2 <10 130 --

E6-1.5 E6-1.5 9/1/2016 1.5 <50 <5.0 <5.0 <5.0 <9.9 <5.0 <5.0 <5.0 <5.0 <5.0 7.3 <9.9 <99 --

E7-0.5 E7-0.5 9/1/2016 0.5 <50 <5.0 210 350 <10 22 <5.0 <5.0 <5.0 <5.0 40 <10 660 --

E7-1.5 E7-1.5 9/1/2016 1.5 <50 <5.0 7.0 14 <10 <5.0 <5.0 <5.0 <5.0 <5.0 5.5 <10 <100 --

E7-E-0.5 E7-E-0.5 10/6/2016 0.5 <250 <25 250 220 <50 <25 <25 <25 30 <25 <25 <50 <500 --

E7-E-1.5 E7-E-1.5 10/6/2016 1.5 <50 <5.0 5.6 <5.0 <9.9 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <9.9 <99 --

E7-N-0.5 E7-N-0.5 10/6/2016 0.5 <50 8.3 120 170 <10 8.0 <5.0 <5.0 9.2 <5.0 20 <10 200 --

E7-N-1.5 E7-N-1.5 10/6/2016 1.5 <50 <5.0 <5.0 7.3 <9.9 <5.0 <5.0 <5.0 <5.0 <5.0 6.0 <9.9 <99 --

E7-S-0.5 E7-S-0.5 10/6/2016 0.5 <50 10 280 260 <9.9 18 <5.0 <5.0 21 <5.0 37 <9.9 450 --

E7-S-1.5 E7-S-1.5 10/6/2016 1.5 <50 <5.0 7.9 15 <9.9 <5.0 <5.0 <5.0 <5.0 <5.0 6.8 <9.9 <99 --

E7-W-0.5 E7-W-0.5 10/6/2016 0.5 <50 16 360 370 <10 15 <5.0 <5.0 26 <5.0 69 <10 <100 --

E7-W-1.5 E7-W-1.5 10/6/2016 1.5 <50 <5.0 13 8.2 <9.9 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <9.9 <99 --

E8-0.5 E8-0.5 9/1/2016 0.5 <50 <5.0 190 180 <10 19 <5.0 <5.0 25 <5.0 31 <10 480 --

E8-1.5 E8-1.5 9/1/2016 1.5 <50 <5.0 7.3 7.5 <9.9 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <9.9 <99 --

E9-0.5 E9-0.5 9/1/2016 0.5 <50 <5.0 130 160 <10 14 <5.0 <5.0 12 <5.0 34 <10 150 --

E9-1.5 E9-1.5 9/1/2016 1.5 <50 <5.0 16 26 <9.9 8.2 <5.0 <5.0 6.2 <5.0 44 <9.9 <99 --

E10-0.5 E10-0.5 9/1/2016 0.5 <50 <5.0 140 100 <10 18 <5.0 <5.0 14 <5.0 28 <10 180 --

E10-1.5 E10-1.5 9/1/2016 1.5 <50 <5.0 7.1 <5.0 <9.9 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <9.9 <99 --






Epoxide (µg/kg)

Chlordane (µg/kg)

4,4'-DDD (µg/kg)

4,4'-DDE (µg/kg)

4,4'-DDT (µg/kg)

Delta-BHC

(µg/kg)


(ft. bgs)


Toxaphene (µg/kg)

Arsenic (mg/kg)

Dieldrin (µg/kg)



Endrin (µg/kg)

Endrin Aldehyde

(µg/kg)


OCP-3-6'' E11-0.5 7/21/2015 0.5 <50 26 180 280 <10 31 <5.0 <5.0 32 <5.0 32 <10 330 3.50

OCP-3-18'' E11-1.5 7/21/2015 1.5 <50 <5.0 11 7.9 <10 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10 <100 --

F6-0.5 F6-0.5 9/1/2016 0.5 <50 <5.0 34 43 12 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10 <100 --

F6-1.5 F6-1.5 9/1/2016 1.5 <50 <5.0 <5.0 <5.0 <9.9 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <9.9 <99 --

F7 -- -- -- -- -- -- -- -- -- -- -- -- -- --

F8 -- -- -- -- -- -- -- -- -- -- -- -- -- --

OCP-15-6'' F9-0.5 7/21/2015 0.5 <50 24 360 300 <10 <5.0 <5.0 32 30 <5.0 59 <10 430 5.34

OCP-15-18'' F9-1.5 7/21/2015 1.5 <50 <5.0 9.3 5.7 <10 7.5 <5.0 <5.0 <5.0 <5.0 5.4 <10 <100 --

F10-0.5 F10-0.5 9/1/2016 0.5 <50 <5.0 490 750 <10 76 <5.0 <5.0 110 <5.0 140 <10 1,300 --

F10-1.5 F10-1.5 9/1/2016 1.5 <50 <5.0 <5.0 <5.0 <10 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10 <100 --

F10-E-0.5 F10-E-0.5 10/6/2016 0.5 <50 20 420 510 <10 65 <5.0 <5.0 110 <5.0 130 <10 970 --

F10-E-1.5 F10-E-1.5 10/6/2016 1.5 <50 <5.0 83 13 <10 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10 <100 --

F10-E2-0.5 F10-E2-0.5 1/18/2017 0.5 <50 <5.0 270 220 <10 22 <5.0 <5.0 13 <5.0 39 <10 460

F10-E2-1.5 F10-E2-1.5 1/18/2017 1.5 <50 <5.0 7.6 7.0 <9.9 <5.0 <5.0 <5.0 <5.0 <5.0 14 <9.9 <99

F10-N-0.5 F10-N-0.5 10/6/2016 0.5 <50 14 360 330 <10 34 <5.0 <5.0 59 <5.0 71 <10 <100 --

F10-N-1.5 F10-N-1.5 10/6/2016 1.5 <50 <5.0 12 52 <10 19 <5.0 <5.0 15 <5.0 18 <10 110 --

F10-S-0.5 F10-S-0.5 10/6/2016 0.5 <50 11 340 350 <10 26 <5.0 <5.0 36 <5.0 54 <10 520 --

F10-S-1.5 F10-S-1.5 10/6/2016 1.5 <50 <5.0 14 15 <10 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10 <100 --

F10-S2-0.5 F10-S2-0.5 1/18/2017 0.5 <50 <5.0 320 350 <9.9 19 <5.0 <5.0 12 <5.0 58 <9.9 380

F10-S2-1.5 F10-S2-1.5 1/18/2017 1.5 <50 <5.0 12 <5.0 <10 <5.0 <5.0 <5.0 7.1 <5.0 <5.0 <10 <100

F10-W-0.5 F10-W-0.5 10/6/2016 0.5 <50 16 410 450 <10 63 <5.0 <5.0 94 <5.0 88 <10 1,100 --

F10-W-1.5 F10-W-1.5 10/6/2016 1.5 <50 <5.0 5.1 <5.0 <9.9 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <9.9 <99 --

F10-W2-0.5 F10-W2-0.5 1/18/2017 0.5 <50 <5.0 410 360 <9.9 50 <5.0 <5.0 39 <5.0 59 <9.9 450

F10-W2-1.5 F10-W2-1.5 1/18/2017 1.5 <50 <5.0 11 8.6 <9.9 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <9.9 <99

F11-0.5 F11-0.5 9/1/2016 0.5 <50 <5.0 330 290 <10 29 <5.0 <5.0 16 <5.0 32 <10 460 --

F11-1.5 F11-1.5 9/1/2016 1.5 <50 <5.0 51 46 <9.9 <5.0 <5.0 <5.0 <5.0 <5.0 5.3 <9.9 <99 --


Not sampled due to pavement

Not sampled due to pavement





Epoxide (µg/kg)

Chlordane (µg/kg)

4,4'-DDD (µg/kg)

4,4'-DDE (µg/kg)

4,4'-DDT (µg/kg)

Delta-BHC

(µg/kg)


(ft. bgs)


Toxaphene (µg/kg)

Arsenic (mg/kg)

Dieldrin (µg/kg)



Endrin (µg/kg)

Endrin Aldehyde

(µg/kg)


Notes:OCP = Organochlorine Pesticide TP = "Test Pit" -- = Not applicable or not analyzed

mg/kg = milligrams per kilogram Sample ID = Sample identification as recorded in the field / Chain of Custody (µg/kg) = micrograms per kilogram Sample Grid Name = Sample grid identification as reported

ft. bgs = feet below ground surface <5.0 = Concentration below Laboratory Detection LimitsRSLs = USEPA Region 9 - Regional Screening Level, dated June 2015 Bold indicates concentration above laboratory detection limit

* = Southern California Regional Background Arsenic Level (DTSC, 2008) Red indicates concentration above RSL** = HERO HHRA Note 3 (June, 2016)*** = indicates sample analyzed for soluble extraction STLC/TCLP; reported concentrations were below labroatory reporting limits


Additional Site Assessment Report -Weston Property Project No. 11084.006

APPENDIX A

REFERENCES


REFERENCES

County of San Diego Department of Environmental Health, Site Assessment and Mitigation Manual (2004).

Department of Toxic Substances Control (DTSC), 2009, Arsenic Strategies Determination of Arsenic Remediation, Development of Arsenic Cleanup Goals, dated January 16.

Department of Toxic Substances Control (DTSC) Human and Ecological Risk Office (HERO), 2016, Human Health and Risk Assessment (HHRA) Note Number 3, DTSC-modified Screening Levels (DTSC-SLs), dated June 2016.

Kennedy, M. P., and Tan, S.S, (Tan and Kennedy) 2008, Geologic map of the

Regional Geologic Map No. 2, scale 1: 100,000.

Leighton and Associates, Inc., 2015, Phase I and Limited Phase II Environmental Site Assessment Report, Weston Property, 510 and 514 La Costa Avenue,Encinitas, California, 92024, s 216-030-10-00, 216-030-45-00, and 216-030-46-00, dated August 20.

_________________, 2016, Update Geotechnical Investigation, Weston Property, 510

Numbers 216-030-10-00, 216-030-45-00, and 216-030-46-00, dated October 12.

United States Environmental Protection Agency (USEPA), 2013, Statistical Software ProUCL 5.0.00 for Environmental Applications for Data Sets with and without Nondetect Observations, dated September 19.

United States Environmental Protection Agency (EPA) Region 9, 2016, Regional Screening Level (RSL) Summary Table, dated May 2016.


APPENDIX B

GEOPHYSICAL EVALUATION REPORT

GEOPHYSICAL EVALUATION 510 LA COSTA AVENUE

ENCINITAS, CALIFORNIA

PREPARED FOR:

PREPARED BY:

SOUTHWEST GEOPHYSICS, INC.

TABLE OF CONTENTSPage

Figures

1. INTRODUCTION

2. SCOPE OF SERVICES

3. PROJECT DESCRIPTION AND BACKGROUND

4. GEOPHYSICAL INSTRUMENTATION AND APPLICATIONS

5. SURVEY METHODOLOGY

6. RESULTS, CONCLUSIONS AND RECOMMENDATIONS

7. LIMITATIONS

EM61 Data: CI = 100 mVoltsSITE DATA MAP

Figure 2

0

0 5 10 15 20 25 30 35 40 45 500

5

10

15

20

25

30

35

40

45

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60

65

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75

80

Building

Candidate UST

Candidate UST

GPR Anomaly at 3.5 Feet

Former Fuel Pump Area

LEGEND

X

Concrete Drain

Appendix 3.6c Additional Site Assessment Report - Granicus

Documents

Transcript of Appendix 3.6c Additional Site Assessment Report - Granicus