FIO - ClarkDryLake_SiteInspection.pdf

FINAL

Site Inspection Report Borrego Springs – Clark’s Dry Lake

San Diego County, California

U.S. Army Corps of Engineers Southwest IMA Region

FUDS Project No. J09CA701103 Contract: W912DY-04-D-0005

Task Order: 0009

Prepared For:

U.S. Army Corps of Engineers, Los Angeles District

915 Wilshire Boulevard Los Angeles, California 90017-3401 and U.S. Army Corps of Engineers

South Pacific Division Range Support Center

The views, opinions, and/or findings contained in this report are those of the author(s) and should not be construed as an official Department of the Army position, policy, or decision, unless so designated by other documentation.

Site Inspection Report

September 22, 2011September 22, 2011

Borrego Springs – Clark’s D ry Lake

San D iego County, California

U .S. A rm y Corps of Engineers Southw est IM A

Region

200-1e J09CA701103_01.09_0500_a

CONTRACTOR STATEMENT OF INDEPENDENT TECHNICAL REVIEW

Parsons Infrastructure and Technology Group, Inc. (Parsons) has completed the Final Site Inspection Report for Borrego Springs – Clark’s Dry Lake, San Diego County, California.

Notice is hereby given that an independent technical review has been conducted that is appropriate to the level of risk and complexity inherent in the project, as defined in the Quality Control Plan. During the independent technical review, compliance with established policy principles and procedures, utilizing justified and valid assumptions was verified. This included review of assumptions; methods, procedures, and material used in analyses; alternatives evaluated; the appropriateness of data used and level of data obtained; and reasonableness of the results, including whether the product meets the customer's needs consistent with law and existing Corps policy.

September 22, 2011 Study/Design Team Leader and Team Members

Independent Technical Review Team Leader

Significant concerns and the explanation of the resolution are as follows:

None

As noted above, all concerns resulting from independent technical review of the project have been considered.

Parsons Program Manager(s)

Parsons Parsons Infrastructure & Technology Group, Inc.

3577 Parkway Lane • Suite 100 • Norcross, Georgia 30092 • (770) 446-4900 • Fax: (770) 446-4910 • www.parsons.com

September 22, 2011

U.S. Army Corps of Engineers, Los Angeles District ATTN: CESPL-PM-M (Mr. Lloyd Godard) 915 Wilshire Blvd.

Los Angeles, CA 90017-3401

(213) 452-4014

Subject: Contract W912DY-04-D-0005, Delivery Order 0009 MMRP SI for SW IMA Region – Final Site Inspection Report Borrego Springs - Clark’s Dry Lake, San Diego County, California

Dear Mr. Godard:

Parsons Infrastructure and Technology Group, Inc. (Parsons) has prepared this Final Site Inspection (SI) Report in accordance with the Performance Work Statement (PWS) to include the completed Munitions Response Site Prioritization Protocol (MRSPP). The MRSPP notification announcement was prepared in coordination with USACE, Los Angeles District (CESPL) Public Affairs Officer (PAO) and the Project Manager (PM).

It appeared in the agreed newspaper prior to the TPP Closure Meeting held on August 30, 2011. Stakeholder comments for the Draft Final SI Report have been incorporated into the Final SI Report as discussed at the meeting.

One hard copy has been provided for your records. Six additional copies have been provided for your distribution to the regulators (Department of Toxic Substances Control) and stakeholders. We have also submitted a single copy of this document to CEHNC- EMM. Electronic copies have also been provided, including one to CEHNC-EMS and one to CEMVS-EC-P.

If you have any questions or comments, please contact me at (678) 969-2384 or

(404) 606-0346 (cell).

Sincerely, Parsons

Don Silkebakken, P.E.

MMRP SI Program Manager cc: Brian Jordan/James Lujan (SPD) – 1 CD Deborah Walker (CEHNC-EMM) – 1 copy/CD Dwayne Ford (CEHNC-EMM) – EKO Terry Walker (CEHNC-EMS) – 1 CD Rochelle Hance (CEMVS-EC-P) – 1 CD Project File (744653.91214)

U.S. Army Corps of Engineers

Southwest IMA Region

Site Inspection Report

Borrego Springs – Clark’s Dry Lake

San Diego County, California FUDS Project No. J09CA701103

In Support of

FUDS MMRP Site Inspection Program

Prepared for:

U.S. Army Corps of Engineers, Los Angeles District

915 Wilshire Blvd.

Los Angeles, California 90017-3401 and SPD Range Support Center

Contract: W912DY-04-D-0005 Task Order: 0009

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TABLE OF CONTENTS

Page

TABLE OF CONTENTS ..................................................................................................... i

LIST OF TABLES ............................................................................................................. vi

LIST OF FIGURES .......................................................................................................... vii

LIST OF ACRONYMS ................................................................................................... viii

GLOSSARY OF TERMS .................................................................................................. xi

EXECUTIVE SUMMARY ...........................................................................................ES-1

CHAPTER 1 INTRODUCTION .................................................................................. 1-1

1.1 Background ...................................................................................... 1-1

1.2 Project Objectives ............................................................................ 1-2

1.3 Project Scope ................................................................................... 1-3

CHAPTER 2 PROPERTY DESCRIPTION AND HISTORY ..................................... 2-1

2.1 Site Description ............................................................................... 2-1

2.2 Site Location and Setting ................................................................. 2-1

2.2.1 Topography and Vegetation ................................................... 2-1

2.2.2 Climate ................................................................................... 2-2

2.2.3 Significant and Inhabited Structures ...................................... 2-2

2.2.4 Demographics ........................................................................ 2-2

2.2.5 Current and Future Land Use ................................................. 2-3

2.3 Site Ownership and History ............................................................. 2-3

2.4 Site Operations and Waste Characteristics ...................................... 2-4

2.4.1 Munitions Response Site-Specific

Descriptions/Operations ......................................................... 2-4

2.4.2 Regulatory Compliance ......................................................... 2-5

2.5 Previous Investigations/Clearance Actions ..................................... 2-5

2.5.1 Historical Dedudding Operations .......................................... 2-5

2.5.2 1994 Inventory Project Report .............................................. 2-5

2.5.3 1997 Archive Search Report .................................................. 2-5

2.5.4 2006 Aerial Photo Analysis for RI/FS ................................... 2-6

2.5.5 2006 Draft Final Work Plan Borrego Maneuver

Area ........................................................................................ 2-6

2.5.6 2008 Archives Search Report Supplement ............................ 2-7

TABLE OF CONTENTS

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CHAPTER 3 SITE INSPECTION TASKS .................................................................. 3-1

3.1 Historical Record Review ................................................................ 3-1

3.2 Technical Project Planning Summary ............................................. 3-1

3.3 Nonmeasurement Data Collection ................................................... 3-4

3.4 Site-Specific Work Plan .................................................................. 3-6

3.5 Departures from Planning Documents ............................................. 3-7

CHAPTER 4 MUNITIONS AND EXPLOSIVES OF CONCERN FINDINGS ......... 4-1

4.1 General Information ......................................................................... 4-1

4.1.1 Qualitative Reconnaissance ................................................... 4-1

4.1.2 Data Quality Objectives ....................................................... 4-11

4.1.2.1 Munitions and Explosives of Concern Data

Quality Objective ................................................... 4-11

4.1.2.2 Munitions Constituents Data Quality Objective .... 4-11

4.1.2.3 Munitions Response Site Prioritization

Protocol Data Quality Objective ............................ 4-12

4.1.2.4 Hazard Ranking System Data Quality

Objective ................................................................ 4-12

4.2 MRS01 – Area E-1 Naval Impact Area ......................................... 4-12

4.2.1 Historical Munitions and Explosives of Concern

Information .......................................................................... 4-12

4.2.2 Inspection Activities ............................................................ 4-12

CHAPTER 5 EXPOSURE PATHWAYS AND RECEPTORS ................................... 5-1

5.1 Introduction ...................................................................................... 5-1

5.2 General Information ......................................................................... 5-2

5.2.1 Regional Geologic Setting ..................................................... 5-2

5.2.2 Regional Hydrogeologic Setting ............................................ 5-3

5.2.3 Regional Groundwater Use .................................................... 5-4

5.2.4 Regional Hydrologic Setting.................................................. 5-4

5.2.5 Regional Sensitive Ecological Resources .............................. 5-5

5.2.6 Sample Locations and Methods ............................................. 5-7

5.2.7 Background Concentrations ................................................. 5-10

5.2.8 Munitions Constituents Source Evaluation .......................... 5-11

5.3 MRS01 – Area E-1 Naval Impact Area ......................................... 5-11

5.3.1 Historical Munitions Constituents Information ................... 5-11

5.3.2 Groundwater Exposure Pathway.......................................... 5-11

5.3.2.1 Geologic and Hydrogeologic Setting ..................... 5-12

5.3.2.2 Releases and Potential Releases to

Groundwater ........................................................... 5-12

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5.3.2.3 Groundwater Exposure Pathways and

Receptors ................................................................ 5-12

5.3.2.4 Groundwater Sample Locations and Methods ....... 5-13

5.3.2.5 Groundwater Analytical Results ............................ 5-13

5.3.2.6 Groundwater Exposure Pathway Conclusions ....... 5-13

5.3.3 Surface Water and Sediment Exposure Pathway ................. 5-13

5.3.3.1 Hydrologic Setting ................................................. 5-14

5.3.3.2 Releases and Potential Releases to Surface

Water and Sediment ............................................... 5-14

5.3.3.3 Surface Water and Sediment Exposure

Pathways and Receptors ......................................... 5-14

5.3.3.4 Surface Water and Sediment Sample Locations

and Methods ........................................................... 5-14

5.3.3.5 Surface Water and Sediment Analytical Results .... 5-14

5.3.3.6 Surface Water and Sediment Exposure

Pathway Conclusions ............................................. 5-14

5.3.4 Soil Exposure Pathway ........................................................ 5-14

5.3.4.1 Physical Source Access Conditions ....................... 5-15

5.3.4.2 Actual or Potential Contamination Areas ............... 5-15

5.3.4.3 Soil Exposure Pathway and Receptors ................... 5-15

5.3.4.4 Sample Locations and Methods ............................. 5-15

5.3.4.5 Soil Analytical Results .......................................... 5-15

5.3.4.6 Soil Exposure Pathway Conclusions ...................... 5-16

5.3.5 Air Exposure Pathway ........................................................... 5-18

5.3.5.1 Climate ................................................................... 5-18

5.3.5.2 Releases and Potential Releases to Air ................... 5-18

5.3.5.3 Air Exposure Pathway Receptors ........................... 5-18

5.3.5.4 Sample Monitoring Locations and Methods .......... 5-18

5.3.5.5 Air Analytical Results ............................................ 5-18

5.3.5.6 Air Exposure Pathway Conclusions ....................... 5-18

CHAPTER 6 SCREENING LEVEL RISK ASSESSMENT ........................................ 6-1

6.1 Munitions and Explosives of Concern Screening Level Risk

Assessment ...................................................................................... 6-1

6.1.1 Conceptual Site Model ........................................................... 6-1

6.1.2 Introduction ............................................................................ 6-1

6.1.3 Qualitative Risk Evaluation ................................................... 6-2

6.1.4 Munitions and Explosives of Concern Risk Assessment ....... 6-4

6.1.5 Risk Summary ........................................................................ 6-4

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6.2 Munitions Constituent Human Health Screening Level Risk

Assessment ...................................................................................... 6-5

6.2.1 Conceptual Site Model ........................................................... 6-5

6.2.2 Affected Media ...................................................................... 6-5

6.2.3 Human Health Screening Levels ........................................... 6-6

6.2.4 Risk Characterization for Soil ................................................ 6-6

6.2.5 MRS01 – Area E-1 Naval Impact Area ................................. 6-6

6.2.6 Discussion .............................................................................. 6-7

6.3 Munitions Constituent Screening Level Ecological Risk

Assessment ...................................................................................... 6-7

6.3.1 Conceptual Site Exposure Model ........................................... 6-8

6.3.2 Affected Media ...................................................................... 6-8

6.3.3 Screening Levels .................................................................... 6-8

6.3.4 Ecological Risk Characterization for Soil .............................. 6-8

6.3.5 MRS01 – Area E-1 Naval Impact Area ................................. 6-9

6.3.6 Discussion ............................................................................ 6-10

CHAPTER 7 SUMMARY AND CONCLUSIONS ..................................................... 7-1

7.1 Summary .......................................................................................... 7-1

7.1.1 MRS01 – Area E-1 Naval Impact Area ................................. 7-2

7.2 Conclusions Regarding Potential Munitions and Explosives of

Concern ............................................................................................ 7-2

7.3 Conclusions Regarding Potential Munitions Constituent

Exposure Pathways ........................................................................... 7-3

CHAPTER 8 RECOMMENDATIONS ........................................................................ 8-1

CHAPTER 9 REFERENCES ....................................................................................... 9-1 v

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TABLE OF CONTENTS

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LIST OF APPENDICES

Appendix A Performance Work Statement Appendix B Technical Project Planning Session Documentation/Meeting Minutes Appendix C Interview Documents Appendix D Field Notes And Field Forms Appendix E Photo Documentation Log Appendix F Analytical Data Appendix G Analytical Data QA/QC Report Appendix H Geographic Information Systems Data Appendix I Geophysical Data Appendix J Conceputal Site Model/Conceptual Site Exposure Model Appendix K Munitions Response Site Prioritization Protocol Evaluations Appendix L Reference Copies vi

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LIST OF TABLES

No. Title Page

ES.1 Recommendations ...........................................................................................ES-3

1.1 Borrego Springs - Clark’s Dry Lake Munitions Response Site

Coordinates ........................................................................................................ 1-1

2.1 Population Information in the Vicinity of the Borrego Springs - Clark’s

Dry Lake ............................................................................................................ 2-2

2.2 Range and Suspect Past Department of Defense Activities .............................. 2-4

3.1 Sampling Rationale ........................................................................................... 3-8

4.1 Chemical Composition of Munitions and Explosives of Concern and

Potential Munitions Constituents ...................................................................... 4-3

4.2 Munitions and Explosives of Concern Data Quality Objective Worksheet .... 4-13

4.3 Munitions Constituents Data Quality Objective Worksheet ........................... 4-14

4.4 Munitions Response Site Prioritization Protocol Data Quality Objective

Worksheet ........................................................................................................ 4-15

4.5 Hazard Ranking System Data Quality Objective Worksheet .......................... 4-16

5.1 Federally and State-Listed Threatened and Endangered Species Potentially within the Borrego Springs – Clark’s Dry Lake Site ........................................ 5-6

5.2 Summary of Validated Analytical Results for Borrego Springs – Clark’s

Dry Lake Site MMRP Soil Samples Collected in February 2011 ..................... 5-8

5.3 Soil Background Concentrations ..................................................................... 5-10

5.4 Groundwater Wells in the Vicinity of MRS01 – Area E-1 Naval Impact

Area ................................................................................................................. 5-12

5.5 Soil Source Evaluation MRS01 – Area E-1 Naval Impact Area ..................... 5-17

6.1 Categories of Munitions and Explosives of Concern Presence ......................... 6-2

6.2 Categories of Munitions and Explosives of Concern Type ............................... 6-3

6.3 Categories of Site Accessibility ......................................................................... 6-3

6.4 Munitions and Explosives of Concern Risk Evaluation .................................... 6-5

6.5 Soil Human Health Screening Level Risk Assessment MRS01 – Area

E-1 Naval Impact Area ...................................................................................... 6-7

6.6 Soil Screening Level Ecological Risk Assessment MRS01 – Area E-1

Naval Impact Area ............................................................................................. 6-9

8.1 Recommendations ............................................................................................. 8-2 vii

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LIST OF FIGURES

No. Title Page

ES.1 General Site Overview ....................................................................................ES-4

1.1 Site Location ...................................................................................................... 1-4

2.1 Site Setting ......................................................................................................... 2-8

2.2 2000 Census Data .............................................................................................. 2-9

4.1 Qualitative Reconnaissance and Field Observation Locations ....................... 4-17

5.1 Wetlands .......................................................................................................... 5-19

5.2 Qualitative Reconnaissance and Sample Locations ........................................ 5-20

5.3 Water Wells within 4-Mile Buffer .................................................................. 5-21 viii

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ACRONYMS AND ABBREVIATIONS

APP Accident Prevention Plan AP-T Armor Piercing-Tracer ARC Annual Report to Congress ASR Archive Search Report Banks Banks Environmental Data bgs below ground surface CDF&G California Department of Fish and Game CDPH California Department of Public Health CDWR California Department of Water Resources CEMVR U.S. Army Corps of Engineers, Rock Island District CEMVS U.S. Army Corps of Engineers, St. Louis District CERCLA Comprehensive Environmental Response, Compensation, and

Liability Act CESPL U.S. Army Corps of Engineers Los Angeles District CFR Code of Federal Regulations CHE Chemical Hazard Evaluation CHHSLs California Human Health Screening Levels CNDDB California Natural Diversity Database CRREL Cold Regions Research and Engineering Laboratory CRWQCB California Regional Water Quality Control Board CSEM Conceptual Site Exposure Model CSM Conceptual Site Model CWM Chemical Warfare Materiel CZMP Coastal Zone Management Program DERP Defense Environmental Restoration Program DMM discarded military munitions DoD Department of Defense DOI Department of the Interior DQO Data Quality Objective DTSC Department of Toxic Substance Control EcoSSL Ecological Soil Screening Level EHE Explosive Hazard Evaluation EM Engineering Manual EOD Explosive Ordnance Disposal EPP Environmental Protection Plan ER Engineer Regulation ESV Ecological Screening Value °F Degrees Fahrenheit FTL Field Team Leader FUDS Formerly Used Defense Site FUDSMIS FUDS Management Information System ix

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GIS Geographic Information System GP General Purpose GPS Global Positioning System HEAT High Explosive Anti-Tank HE-T High Explosive-Tracer HHE Health Hazard Evaluation HQ Hazard Quotient HR Hydrologic Regions HRS Hazard Ranking System HTW Hazardous and Toxic Waste HVAR High-Velocity Aircraft Rocket INPR Inventory Project Report km kilometer

lb. pound m meter MC Munitions Constituent MCL Maximum Contaminate Level MD Munitions Debris MEC Munitions and Explosives of Concern mg/kg milligram per kilogram mg/L milligrams per liter MIDAS Munitions Items Disposition Action System MMRP Military Munitions Response Program MPA Marine Protected Area MRS Munitions Response Site MRSPP Munitions Response Site Prioritization Protocol NAAS Naval Auxiliary Air Station NAD North American Datum NCP National Oil and Hazardous Substances Pollution Contingency Plan NDAI No DoD Action Indicated NERRS National Estuarine Research Reserve System NHA National Heritage Area NHL National Historic Landmark NMS National Marine Sanctuaries NOAA National Oceanic and Atmospheric Administration NPS National Park Service NRHD National Register of Historic Districts NRHP National Register of Historic Places NRIS National Register Information System NWI National Wetlands Inventory NWRS National Wildlife Refuge System x

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OE ordnance and explosives OEHHP Office of Environmental Health Hazard Assessment OHP Office of Historic Preservation Parsons Parsons Infrastructure and Technology Group PETN Pentaerythritol Tetranitrate PM Project Manager PSAP Programmatic Sampling and Analysis Plan PWP Programmatic Work Plan PWS Performance Work Statement QA Quality Assurance QC Quality Control QR Qualitative Reconnaissance RA Removal Action RAC Risk Assessment Code RI/FS Remedial Investigation/Feasibility Study ROE Right-of-Entry RSL Regional Screening Level (prepared by USEPA) SAP Sampling and Analysis Plan SCAR Sub-caliber Aircraft Rocket SCIC South Coastal Information Center SI Site Inspection SLERA Screening Level Ecological Risk Assessment SLRA Screening Level Risk Assessment SPD RSC South Pacific Division Range Support Center SS-WP Site-Specific Work Plan SVT Site Visit Team T&E Threatened and Endangered TESS Threatened and Endangered Species System TPP Technical Project Planning USACE U.S. Army Corps of Engineers USAESCH USACE Engineering and Support Center, Huntsville USC U.S. Code USDA U.S. Department of Agriculture USEPA U.S. Environmental Protection Agency USFS U.S. Forest Service USFWS U.S. Fish and Wildlife Service USGS U.S. Geological Survey UTM Universal Transverse Mercator UXO Unexploded Ordnance WRCC Western Regional Climate Center xi

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GLOSSARY OF TERMS

Anomaly Any item that deviates from the expected subsurface ferrous and non-ferrous material at a site (pipes, power lines, etc.).

Discarded Military Munitions (DMM)

Military munitions that have been abandoned without proper disposal or removed from storage in a military magazine or other storage area for the purpose of disposal. The term does not include UXO, military munitions that are being held for future use or planned disposal, or military munitions that have been properly disposed of consistent with applicable environmental laws and regulations.

Inhabited Structure Permanent or temporary structures, other than military munitions-related structures, that are routinely occupied by one or more persons for any portion of a day.

Magnetometer An instrument for measuring the strength of a magnetic field;

used to detect buried iron and other metal objects.

Military Munitions All ammunition products and components produced for or used by the armed forces for national defense and security, including ammunition products or components under the control of the Department of Defense, the Coast Guard, the Department of Energy, and the National Guard. The term includes confined gaseous, liquid, and solid propellants;

explosives, pyrotechnics, chemical and riot control agents, smokes, and incendiaries, including bulk explosives and chemical warfare agents; chemical munitions, rockets, guided and ballistic missiles, bombs, warheads, mortar rounds, artillery ammunition, small arms ammunition, grenades, mines, torpedoes, depth charges, cluster munitions and dispensers, demolition charges; and devices and components thereof.

Munitions and Explosives of Concern

(MEC)

Military munitions that may pose unique explosives safety risks, including UXO, DMM, or MC present in high enough concentrations to pose an explosive or other health hazard.

Munitions Constituents (MC)

Any materials originating from unexploded ordnance, DMM, or other military munitions, including explosive and nonexplosive materials, and emission, degradation, or breakdown elements of such ordnance or munitions.

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GLOSSARY OF TERMS

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Munitions Debr is

(MD)

Remnants of munitions (for example, penetrators, projectiles, shell casings, links, fins) remaining after munitions use, demilitarization, or disposal.

Munitions Response Response actions, including investigation, removal actions, and remedial actions, to address the explosive safety, human health, or environmental risks presented by unexploded ordnance, DMM, or MC, or to support a determination that no removal or remedial action is required.

Munitions Response Site (MRS)

A discrete location that is known to require a munitions response.

Projectile Object projected by an applied force and continuing in motion by its own inertia. This includes bullets, bombs, shells, grenades, guided missiles, and rockets.

Unexploded Ordnance

(UXO)

Military munitions that have been primed, fused, armed, or otherwise prepared for action; that have been fired, dropped, launched, projected, or placed in such a manner as to constitute a hazard to operations, installation, personnel, or material; and that remain unexploded whether by malfunction, design, or any other cause.

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EXECUTIVE SUMMARY

ES.1 The Borrego Springs – Clark’s Dry Lake Formerly Used Defense Site (FUDS) consists of one munitions response site (MRS) identified as MRS01 – Area E-1 Naval Impact Area. The site is located in northeastern San Diego County, California, in the Anza-Borrego Desert, approximately 0.5 miles north of County Highway S22 and 6 miles northeast of Borrego Springs, California (Figure ES.1). Historical documentation indicates the site was used from 1943 to 1955 by the Navy as an outlying field or emergency landing field, although its primary function was as a target for practice bombing. Navy records alternatively describe the site as a level bombing target and a dual purpose level and dive bombing target. The bomb target was located in the center of the site within the dry bed of Clark Lake and consisted of three concentric circles constructed of stones, many of which remain intact. The property was declared surplus in November 1955, ownership was exchanged, and the site was later used as a low-frequency radio facility. In the late 1980s, the majority of the property was transferred to the state of California and incorporated into the Anza-Borrego Desert State Park. A small part of the site is privately owned, and there are currently no facilities at the site.

ES.2 A site inspection (SI), documented in this report, was conducted to determine whether the MRS identified for Borrego Springs – Clark’s Dry Lake warrants subsequent characterization as part of a remedial investigation/feasibility study (RI/FS) or no Department of Defense (DoD) action indicated (NDAI). The SI was performed to gather and evaluate evidence of the potential residual presence of munitions and explosives of concern (MEC) and munitions constituents (MC) within the MRS associated with the site. To accomplish the objective, qualitative reconnaissance (QR) and MC sampling were performed within the MRS boundary.

ES.3 The Technical Project Planning (TPP) Team identified that, in addition to approximately 27.5 miles of QR, the collection of up to 13 surface soil samples (plus associated quality assurance [QA]/quality control [QC] samples), would be sufficient to meet the project objectives.

ES.4 The SI field activities were conducted from February 15 to 18, 2011, following the review and acceptance of the Site-Specific Work Plan (SS-WP) Addendum.

The SI evaluation included the conduct of approximately 29.8 miles of QR, as well as the collection of 14 surface soil samples (with two additional field duplicates). Eleven of the surface soil samples were collected from areas that represented the highest likelihood for the presence of MEC or MC contamination (within the MRS) and three surface soil samples were collected outside the MRS boundary to provide ambient data on metals.

The QR paths, surface soil sample locations, and field observation locations are shown on

ES-2

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Figure ES.1. No groundwater samples were collected due to the absence of municipal water wells at the site, per TPP Team agreement. No surface water or sediment samples were collected due to the absence of surface water at the site.

ES.5 All surface soil samples were analyzed by TestAmerica Denver for explosives, select site specific metals (aluminum, antimony, barium, copper, lead, and zinc), and pH. No explosives were detected in any of the surface soil samples collected from MRS01. The concentrations of MC metals detected in the surface soil samples were evaluated against the estimated background concentrations (from ambient samples) collected during the SI. All six MC metals were detected above background concentrations in the surface soil samples and were retained for further consideration in the human health screening level risk assessment (SLRA), where the maximum detected site concentration of each retained analyte was compared to risk-based human health screening levels. The maximum detected concentrations of five of the six retained MC metals (aluminum, antimony, barium, copper and zinc) did not exceed their human health screening values for soil; however, the maximum detected concentration of lead exceeded the screening value for residential soil. The SLRA concluded that a potential human health risk may exist due to exposure to lead in surface soil at MRS01.

ES.6 Borrego Springs – Clark’s Dry Lake is considered to be an important ecological place because the site supports wetlands, lies within a state park, and supports threatened and endangered (T&E) species and critical habitat. Therefore, ecological receptors are considered to be present at the site. The MC metals detected above background concentrations were retained for further consideration in the screening level ecological risk assessment (SLERA), where the maximum detected site concentration of each retained analyte was compared to a risk-based ecological screening value (ESV).

The maximum detected site concentration of antimony did not exceed its ESV. Since the soil pH at MRS01 ranged from 8.7 to 9.8, aluminum is not expected to pose a risk to ecological receptors because aluminum is only bioavailable at pH values less than 5.5.

The maximum detected concentrations of barium, copper, lead, and zinc exceeded their risk-ESVs for soil. The exceedances resulted in hazard quotient (HQ) values of 1.1 for barium, 1.2 for copper, 8.5 for lead, and 2.6 for zinc. The SLERA concluded that a potential ecological risk may exist at the site due to exposure to barium, copper, lead and zinc in surface soil at MRS01.

ES.7 MRS01 – Area E-1 Naval Impact Area was used from 1943 to 1955 by the Navy primarily as a target for practice bombing. Munitions known or suspected to have been used at MRS01 include Cartridge, .30 Caliber; Cartridge, .50 Caliber; Cartridge, 20mm, Ball, MkI; Cartridge, 20mm, Armor Piercing-Tracer (AP-T), M95; Cartridge, 20mm, Target Practice (TP), M21A1, M99; Cartridge, 37mm; Cartridge, 90mm, High Explosive-Tracer (HE-T), M71A1; Bomb, 3 lb., Miniature Practice, AN-Mk5, AN- Mk23; Bomb, 4.5 lb., Miniature Practice, AN-Mk43; Bomb, 100 lb., Practice, Mk15 Series and M38A2; Bomb, 100 lb., Photoflash, M46; Bomb, 250 lb., Practice, Mk86, AN-M57; Rocket, Aircraft, 2.25-inch Sub-caliber Aircraft Rocket (SCAR), Mk1, Mk2, Mk3, Mk4, Mk6; Rocket, High-Velocity Aircraft Rocket (HVAR), High Explosive, Anti- Tank (HEAT), 5-inch; and Dynamite, Military, M1. No MEC were observed within

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MRS01 during the SI field effort; however, abundant munitions debris (MD) were observed in the form of .30 caliber projectiles; .50 caliber links, cartridge cases, and projectiles; 20mm link and projectiles; a 37mm fragment; a 90mm fragment; 3 lb.,

4.5 lb., 100 lb., and 250 lb. practice bomb debris; and M1A1 spotting charge debris.

During 1994 site visits in support of the Inventory Project Report (INPR), MD from 6-inch and 100 lb. practice bombs and 20mm shells were observed. During 1997 site visits in support of the Archives Search Report (ASR), MD were observed that included Mk15 and M38A2 100 lb. practice bombs and spotting charges, Mk23 3 lb. practice bombs and spotting charges, and .50 caliber projectiles. Additionally during the ASR site visit, MEC in the form of one Mk23 3 lb. bomb containing a spotting charge was discovered and later destroyed by local explosive ordnance disposal (EOD) personnel.

ES.8 Based on historical information and the results of this SI, MRS01 – Area E-1 Naval Impact Area is recommended to proceed to RI/FS. Additional MC sampling during the RI/FS is considered warranted. The recommendations are summarized in Table ES.1.

Table ES.1 Recommendations

Borrego Springs – Clark’s Dry Lake San Diego County, California

MRS Acreage

Munitions and Explosives of

Concern and/or

Munitions Debris

Assessment(1)

Munitions Constituent

Assessment(2) Recommendation

MRS01 – Area E-1 Naval

Impact Area 5,580 Yes Yes

The confirmed presence of MEC and the presence of MD indicative of potential MEC presence warrants an RI/FS. Additional MC sampling during the RI/FS is warranted.

Immediate Removal Action is not required at this time.

Notes:

(1) "Yes" in the "MEC/MD Assessment" column of the table indicates confirmed MEC or MD presence indicative of potential MEC presence and RI/FS recommendation for the MRS. “No” in this column of the table indicates no confirmed MEC or MD indicative of potential MEC presence that would pose an explosive safety risk to human or ecological receptors and NDAI recommendation for this MRS.

(2) "Yes" in the "MC Assessment" column of the table indicates confirmed MC presence at levels indicating a potential elevated risk to human health or ecological receptors and RI/FS recommendation for the MRS. “No” in this column of the table indicates absence of MC at levels indicating a potential significant risk to human health or ecological receptors and NDAI recommendation for this MRS.

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General Site Overview

General Site Overview

Image: 2005 Aerial Photos Projection: UTM Zone 11 NAD83, Units in Meters

Site Location in California

Legend

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!( Biased Soil Sample Location

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CHAPTER 1

INTRODUCTION

1.1 BACKGROUND

1.1.1 Parsons Infrastructure and Technology Group, Inc. (Parsons) received Contract No. W912DY-04-D-0005, Task Order No. 0009, from the United States Army Corps of Engineers (USACE), Engineering and Support Center, Huntsville (USAESCH) to perform a Site Inspection (SI) at the Borrego Springs – Clark’s Dry Lake Formerly Used Defense Site (FUDS). The site is located in northeastern San Diego County, California, in the Anza-Borrego Desert, approximately 0.5 miles north of County Highway S22 and 6 miles northeast of Borrego Springs, California (Figure 1.1).

Historical documentation indicates the site was used from 1943 to 1955 by the Navy as an outlying field or emergency landing field, although its primary function was as a target for practice bombing. In the late 1980s, the majority of the property was transferred to the state of California and incorporated into the Anza-Borrego Desert State Park.

1.1.2 The Borrego Springs – Clark’s Dry Lake site has been identified as being FUDS eligible and assigned FUDS Project Number J09CA701103. The Archives Search Report (ASR) Supplement established one 5,580-acre munitions response site (MRS) at the site, identified as MRS01 – Area E-1 Naval Impact Area. The acreage and coordinates for the MRS are listed in Table 1.1.

Table 1.1 Borrego Springs – Clark’s Dry Lake Munitions Response Site Coordinates

MRS

MRS

Acreage(1) X-Coordinate(2)

(meters) Y-Coordinate(2)

(meters)

MRS01 – Area E-1 Naval

Impact Area 5,580 567856.00 E 36888796.00 N

(1) Acreage based on review of ASR Supplement, the FUDS Management Information System (FUDSMIS), and the Annual Report to Congress (ARC).

(2) Universal Transverse Mercator (UTM) Zone 11 North American Datum (NAD) 83 (MRS Centroid).

1.1.3 The Department of Defense (DoD) established the Military Munitions Response Program (MMRP) to address DoD sites suspected of containing munitions and explosives of concern (MEC) or munitions constituents (MC). Under the MMRP, the USACE is conducting environmental response activities at FUDS for the Army, the DoD’s executive agent for the FUDS program.

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1.1.4 Pursuant to the USACE’s Engineer Regulation (ER) 200-3-1 (USACE, 2004) and the Management Guidance for the Defense Environmental Restoration Program (DERP) (Office of the Deputy Under Secretary of Defense [Installations and Environment], 2001), USACE is conducting FUDS response activities. All work is performed in accordance with the following:

The DERP statute (10 U.S. Code [USC] 2701);

The Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) (42 USC §9601 et seq);

Executive Orders 12580 and 13016; and

The National Oil and Hazardous Substances Pollution Contingency Plan (NCP) (40 Code of Federal Regulations [CFR] Part 300)

1.1.5 USACE is conducting remedial SIs, as set forth in the NCP, to evaluate hazardous substance releases or threatened releases from eligible FUDS.

1.1.6 While not all MEC/MC constitute CERCLA hazardous substances, pollutants, or contaminants, the DERP statute provides DoD the authority to respond to releases of MEC/MC, and DoD policy states that such responses shall be conducted in accordance with CERCLA and the NCP.

1.1.7 This report summarizes the work performed during the SI and presents an accounting of any MEC and MC contamination identified on the site. The SI was limited exclusively to MEC and MC contamination issues requiring collection of a sufficient and appropriate amount of information, but does not consider other unrelated hazardous and toxic waste (HTW) concerns the site may pose. Per ER 200-3-1, guidance for conducting an SI, Section 4-4.1.2:

The SI is not intended as a full-scale study of the nature and extent of contamination or explosive hazards. The objectives of the remedial SI are to: (i) Eliminate from further consideration those releases that pose no significant threat to public health or the environment; (ii) Determine the potential need for removal action; (iii) Collect or develop additional data, appropriate for Hazard Ranking System (HRS) scoring by [US]EPA; and

(iv) Collect data, as appropriate, to characterize the release for effective and rapid initiation of the Remedial Investigation/Feasibility Study

(RI/FS).

1.2 PROJECT OBJECTIVES

1.2.1 The primary objective of the MMRP SI is to determine whether or not a FUDS project warrants further response action under CERCLA. The SI collects sufficient and appropriate information necessary to make this determination, as well as:

determines the potential need for a removal action;

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collects or develops additional data, as appropriate, for HRS scoring by the U.S. Environmental Protection Agency (USEPA); and collects data, as appropriate, to characterize the release for effective and rapid initiation of the RI/FS.

1.2.2 Another objective of the MMRP SI is to collect the additional data necessary to complete the Munitions Response Site Prioritization Protocol (MRSPP).

1.3 PROJECT SCOPE

1.3.1 This SI for the Borrego Springs – Clark’s Dry Lake site evaluates potential MEC and MC presence. In general, the scope of work for the site included qualitative reconnaissance (QR) and MC sampling. The QR and MC sampling were focused within the MRS. The TPP Team concurred that the SI data collection efforts would focus on screening for MC contamination in surface soil. Groundwater, surface water, sediment, and air samples were not collected.

1.3.2 The primary project planning documents used to perform the SI included the USACE South Pacific Division Range Support Center (SPD RSC) Programmatic Work Plan (PWP) (Parsons, 2010a), the Programmatic Sampling and Analysis Plan (PSAP) (USACE, 2005), the PSAP Addendum (Parsons, 2006), and the Final Site Specific Work Plan (SS-WP) Addendum to the PWP for the Borrego Springs – Clark’s Dry Lake site (Parsons, 2010b). The Performance Work Statement for this project is included in Appendix A.

1.3.3 The USACE, Los Angeles District (CESPL), facilitated a TPP meeting on September 21, 2009, that included representatives from CESPL, California Department of Toxic Substances Control (DTSC), State of California Department of Parks and Recreation, and Parsons. The TPP Team unanimously concurred with the Technical Approach presented in the Final TPP Memorandum (Parsons, 2009), including the locations of surface soil samples, sampling methods, and laboratory analyses for explosives, select metals, and pH.

1.3.4 As detailed in the Final SS-WP Addendum, the TPP Team agreed that comparison criteria for the soil sampling results would include California Human Health Screening Levels (CHHSLs) supplemented with USEPA Regional Screening Levels (RSLs) (when CHHSLs are not available) for residential soil. Ecological Screening Values (ESVs) would include USEPA Ecological Soil Screening Levels (EcoSSLs) supplemented with the appropriate ESVs from the references cited by the PSAP Addendum. The TPP Team agreed that surface soil samples would be collected at depths of 0 to 6 inches below ground surface (bgs) outside the bed of Clark Lake and 6 to 12 inches bgs within the dry lake bed.

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Figure 1.1

Site Location

Site Location

Site Location in California

Legend

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MRS01 - Area E-1 Naval Impact Area

FUDS Eligible Boundary

Borrego Springs - Clark's Dry Lake

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CHAPTER 2

PROPERTY DESCRIPTION AND HISTORY

2.1 SITE DESCRIPTION

The Borrego Springs – Clark’s Dry Lake site is located in northeastern San Diego County, California, in the Anza-Borrego Desert, approximately 0.5 miles north of County Highway S22 and 6 miles northeast of Borrego Springs, California. The site consists of a single 5,580-acre MRS identified as MRS01 – Area E-1 Naval Impact Area. The MRS is situated on undeveloped desert land and occupies almost the entire area of Clark Lake.

Figures 1.1 and 2.1 show the site location.

2.2 SITE LOCATION AND SETTING

2.2.1 Topography and Vegetation

2.2.1.1 The topography of the Anza-Borrego Desert region is characterized by broad alluvial valleys with sandy washes and dry lake beds, and rugged low to mid elevation mountain ranges with steep ridges and deep canyons. The Borrego Springs - Clark’s Dry Lake site is located in Clark Valley between the Santa Rosa Mountains to the east and Coyote Mountain to the west. The majority of the site lies within the generally featureless and dry bed of Clark Lake. The northwest corner of the MRS extends very slightly into the base of the Santa Rosa Mountains and the southwest corner of the MRS extends slightly into Coyote Mountain. The topography is relatively flat throughout much of the MRS, with the exception of the northeast and southwest corners where elevations begin to rise into the mountain areas. Surface elevations range from approximately 555 to 560 feet above sea level in the dry lake bed and range from 560 to 600 feet in most of the MRS. The highest elevation is approximately 750 feet at the southwest corner of the MRS. Several washes are present in the southern part of the MRS that transmit surface water into Clark Lake during heavy rainfall events.

2.2.1.2 The dominant vegetative community in the Anza-Borrego Desert is the Desert Scrub. This community covers a wide range of habitats and is common in desert plains and the lower slopes of foothills where the soils are well-drained and the climate is hot and dry. The Desert Scrub Community is generally dominated by the Creosote bush and includes the Desert agave, Ocotillo plant, Burro brush, and a variety of cacti (County of San Diego, 2009). This community is dominant at the Borrego Springs - Clark’s Dry Lake site. The vegetation is generally sparse with symmetrically-spaced Creosote brush occurring in the alluvial plain areas. Vegetation density increases in some of the seasonal washes, and is very sparse within the bed of Clark Lake.

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2.2.2 Climate

2.2.2.1 The climate in the Anza-Borrego Desert region is typical of deserts in the…