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HomeMy WebLinkAboutItem K February 14, 2000 STAFF REPORT To: Mayor Yost and Members of the City Council Attention: Keith R. Till, City Manager From: Lee Whittenberg, Director of Development Services Subject: CITY RESPONSE LETTER RE: "DRAFT - WORK PLAN FOR LONG-TERM GROUNDWATER MONITORING AT INSTALLATION RESTORATION SITES 40 and 70, NAVAL WEAPONS STATION, SEAL BEACH" SUMMARY OF REQUEST Authorize the Mayor to sign the draft response letter, with any additional comments determined appropriate. Receive and File Staff Report. DISCUSSION The Department of the Navy is requesting comments on the "Draft Work Plan for Long-Tenn Groundwater Monitoring at Installation Restoration Sites 40 and 70, Naval Weapons Station, Seal Beach" by February 19, 2000. Review by Environmental Quality Control Board: The Environmental Quality Control Board (EQCB) reviewed this matter on January 26, 2000, and authorized the Vice-Chairman to sign the letter, with some non-substantive revisions. The matter is now before the City Council for final review and authorization for the Mayor to sign the comment letter also. AGENDA ITEM /—N, C:1My Documents WAVWPSTA\Draft Groundwater Work Plan, ER Sites 40&70.CC.doc\LW\01-27-00 City Response Letter re:Draft Work Plan for Long-Term Groundwater Monitoring, IR Sites 40 and 70, Naval Weapons Station, Seal Beach City Council Staff Report February 14, 2000 Overview of Work Plan: This Work Plan provides the framework and guidance to conduct groundwater monitoring at the subject Installation Restoration (IR) Sites. The groundwater monitoring program will involve installing 15 new monitoring wells, monitoring groundwater surface elevations, and collecting groundwater samples for analysis from 28 selected wells. The duration of the monitoring program is 5 years. After 5 years, recommendations will be made to continue monitoring, reduce the sampling frequency, or discontinue monitoring. Previous investigations have identified the presence of chlorinated solvents in groundwater at IR Sites 40 and 70. The extent of contamination has been delineated, and a feasibility study is currently being conducted under a separate scope of work to evaluate remedial alternatives. The monitoring program is designed to measure chemical concentrations within and around the chlorinated solvent plume over time. The data will be used to establish contaminant concentration trends, assess the effectiveness of remedial actions, when implemented, monitor for natural attenuation of the chemicals of concern, and assess whether downgradient receptors have the potential to become affected by the contaminant plumes. In addition, metals were reported in groundwater at IR Site 70. The extent of mercury concentrations above statistical background and hexavalent chromium concentrations above the detection limit was not fully delineated during previous investigations. Further delineation of these metals will be performed as part of the groundwater monitoring program. IR Site 40 IR Site 40 includes a concrete gravel pit located in the Locomotive Shop (Building 240) and a gravel area located north of and adjacent to the building. During previous investigations, a volatile organic compound (VOC) plume consisting primarily of tetrachloroethene (PCE) and trichloroethene (TCE) was identified in groundwater. The VOC plume extends several hundred feet downgradient of the source area(s) and is generally limited in extent to approximately 66 feet below ground surface (bgs). Please refer to Figure 2-1, Well Locations and Extent of VOC Plume in Groundwater, IR Site 40, page 2-3, provided as Attachment 3. IR Site 70 IR Site 70 consists of multistory office and production buildings, asphalt-paved parking areas, an assortment of aboveground tanks and attendant above- and below-ground piping distribution systems, several concrete-lined sumps, and underground storage tanks. During previous investigations, a VOC plume was delineated and extends approximately 2,400 feet downgradient of the presumed source area. An area proximate to the presumed source area is suspected to contain dense nonaqueous-phase liquid (DNAPL) in dispersed droplet and/or ganglia form. Draft Groundwater Work Plan, IR Sites 40&70.CC 2 City Response Letter re.•Draft Work Plan for Long-Term Groundwater Monitoring, IR Sues 40 and 70, Naval Weapons Station, Seal Beath City Council Stuff Report February 14, 2000 Dissolved contamination extends to a depth of approximately 195 feet bgs. At 195 feet, a continuous clay layer has been mapped and is presumed to act as a barrier for further downward migration of contamination. Please refer to Figure 2-2, Well Locations and Extent of VOC Plume in Groundwater, IR Site 70, page 2-5, provided as Attachment 4. A copy of the complete document was not provided to the EQCB or City Council due to the length of the document, 263 pages. Staff provided the "Summary", "Table of Contents", and Section 3 - "Monitoring Objectives and Rationale", to the EQCB and City Council for review in considering this matter. Given some of the issues raised in the document, staff has prepared a draft comment letter for the review and approval of the EQCB and the City Council. The draft comment letter is provided as Attachment 1. Previous City Review The City has commented on IR Sites 40 and 70 as indicated below: a On December 13, 1999, the City Council commented on the "Draft - Groundwater Feasibility Study Report, Installation Restoration Sites 40 And 70, Naval Weapons Station, Seal Beach", with the EQCB reviewing the document on November 24, 1999. o In June 1999, the City commented on a request by the California Department of Toxic Substances Control regarding "Request for Identification of Applicable and Appropriate Requirements (ARARs): Feasibility Study at IR Sites 40 and 70, Naval Weapons Station". ❑ In February 1999, the City commented on the "Draft Extended Removal Site Evaluation Report, IR Sites 40 and 70, Naval Weapons Station, Seal Beach". o In February 1997, the City commented on the "Pre-Final Extended Removal Site Evaluation Work Plan, IR Sites 40 and 70, Naval Weapons Station, Seal Beach". Proposed Response Letter The Navy is requesting comments on the subject document by February 19, 2000. Staff has prepared the initial draft of the response letter for consideration by the EQCB and ultimately the City Council, indicating general concerns of the City (See Attachment 1). As indicated above, the EQCB has reviewed the comment letter and authorized the Vice-Chairman to sign the letter with several non-substantive revisions, which have been reflected in Attachment 1. Draft Groundwater Wort Plan,IR Sites 40&70.CC 3 City Response Letter re:Draft Work Plan for Long-Term Groundwater Monitoring, IR Sites 40 and 70, Naval Weapons Station, Seal Beath City Council Staff Report February 14, 2000 RECOMMENDATION Authorize the Mayor to sign the draft response letter, with any additional comments determined appropriate. Receive and File Staff Report. NOTED AND APPROVED . / / / 4 / _ _ /1,Whittenberg, Director Keith R. Till /Development Services Department City Manager ATTACHMENTS: (5) Attachment 1: List of Acronyms/Abbreviations Attachment 2: Draft Comment Letter from EQCB and City Council to Department of Navy re: "Draft Work Plan for Long-Term Groundwater Monitoring at Installation Restoration Sites 40 and 70, Naval Weapons Station, Seal Beach" (As revised based on EQCB comments on January 26, 2000) Attachment 3: "Draft Work Plan for Long-Tenn Groundwater Monitoring at Installation Restoration Sites 40 and 70, Naval Weapons Station, Seal Beach", prepared by Bechtel Environmental, Inc. for Southwest Division, Naval Facilities Engineering Command, dated December 1999 Note: Complete document has not been provided to the City Council due to the length of the document, 263 pages. Staff is providing the "Summary", "Table of Contents", and Section 3 — "Monitoring Objectives and Rationale", to the City Council for review in considering this matter. Complete document available at the Department of Development Services for review. Draft Groundwater Work Plan,IR Sites 40&70.CC 4 City Response Letter re:Draft Work Plan for Long-Term Groundwater Monitoring, IR Sites 40 and 70, Maul Weapons Station, Seal Beach City Council Staff Report February 14, 2000 Attachment 4: Figure 2-1, Well Locations and Extent of VOC Plume in Groundwater, IR Site 40, page 2-3 Attachment 5: Figure 2-2, Well Locations and Extent of VOC Plume in Groundwater, IR Site 70, page 2-5 * * * * Draft Groundwater Work Plan,1k Sites 40&70.CC 5 II City Response Letter re:Draft Work Plan for Long-Term Groundwater Monitoring, IR Sites 40 and 70, Naval Weapons Station, Seal Beach City Council Staff Report February 14, 2000 ATTACHMENT 1 LIST OF ACRONYMS/ABBREVIATIONS ARARs Applicable and Appropriate Requirements bgs below ground surface DNAPL dense nonaqueous-phase liquid EQCB Environmental Quality Control Board IR Installation Restoration PCE tetrachloroethene TCE trichloroethene VOC volatile organic compound NOTE: A separate listing of Acronyms/Abbreviations directly relating to the subject report from the Navy is provided on pages viii and ix of the "Draft Work Plan for Long-Tenn Groundwater Monitoring at Installation Restoration Sites 40 and 70, Naval Weapons Station, Seal Beach". Draft Groundwater Work Plan,IR Sites 40&70.CC 6 City Response Letter re:Draft Work Plan for Long-Term Groundwater Monitoring, IR Sites 40 and 70, Naval Weapons Station, Seal Beath City Council Staff Report February 14, 2000 ATTACHMENT 2 DRAFT COMMENT LETTER FROM EQCB AND CITY COUNCIL TO DEPARTMENT OF NAVY RE: "DRAFT WORK PLAN FOR LONG-TERM GROUNDWATER MONITORING AT INSTALLATION RESTORATION SITES 40 AND 70, NAVAL WEAPONS STATION, SEAL BEACH" (As revised based on EQCB comments on January 26, 2000) Draft Groundwater Work Plan,1R Sites 40&70.CC 7 i •b x � ••.,, ," SEAL r #. 4iC , • '1,. M _..-4.4,44,-,;4,741U4•.7.14, HALL + 711 EICAITH SUE a ti mac :i: .r aY+tia - 4-- *50011116044EAC AAlffORN1A,001 1562)131-2527 February 14, 2000 Weapons Support Facility Attn: Pei-Fen Tamashiro, :nstallation Resto,.ition Coordinator 800 Seal Beach Blvd. Seal Beach, CA 90740-5000 SUBJECT: "Draft Work Plan for Long-Term Groundwater Monitoring at Installation Restoration Sites 40 and 70, Naval Weapons Station, Seal Beach" Dear Ms. Tamashiro: The City of Seal Beach has reviewed the report from the Department of the Navy relative to "Draft Work Plan for Long-Tenn Groundwater Monitoring at Installation Restoration Sites 40 and 70, Naval Weapons Station, Seal Beach". It should be noted that the City has only reviewed in detail the "Summary", and Chapter 3 of the subject document. Upon a review of those portions of the document by the Environmental Quality Control Board and the City Council of the City of Seal Beach, the City has the following general and specific comments. General Comments on the Document The Environmental Quality Control Board and the City Council understand this Work Plan provides the framework and guidance to conduct groundwater monitoring at the subject Installation Restoration (IR) Sites. The groundwater monitoring program will involve installing 15 new monitoring wells, monitoring groundwater surface elevations, and collecting groundwater samples for analysis from 28 selected wells. The duration of the monitoring program is 5 years. After 5 years, recommendations will be made to continue monitoring, reduce the sampling frequency, or discontinue monitoring. The general format of the document is helpful to readers in providing a brief summary of the existing conditions at IR Sites 40 and 70, the reasons for the additional groundwater monitoring program proposed, and the summary of data quality objectives (DQOs) for each site as set forth in Table 3-1 and 3-2, respectively. I I (Ir Tables 3-1 and 3-2, Summary of DQOs for IR Site 40 and IR Site 70, respectively, are extremely helpful in providing a quick overview of the statement of the problem, inputs to the decision, boundaries of the study, decision rules, and limits on dec.sion errors for each of the subject sites. This type of presentation would be helpful in future documents as a way to provide an easily understood summary of the particular actions proposed and the decision points as to why this type of action is deemed achievable. As indicated in our comment letter of Decrmber 13, 1999, the City is appreciative of the Navy proceeding with this evaluation in an expeditious and timely manner. The length of time to conduct this type of evaluation and reach an action determination was a concern expressed in our letter of February 8, 1999. The timely preparation of this document, and the future decisions to be made based on public and regulatory agency reviews and comments, are sincerely appreciated by the City. The City would request further clarification as to the decision points the Navy would utilize to determine if annual or semi-annual monitoring is appropriate as proposed in Table 3-5 - Proposed Analysis and Monitoring Frequency. In referencing Figure 3-2, the City would appreciate further delineation as to the extent of increase in concentration or "highly variable data" that would lead to a decision to conduct semi-annual or annual monitoring. The Environmental Quality Control Board of the City of Seal Beach considered and reviewed the Draft Work Plan for Long-Term Groundwater Monitoring, IR Sites 40 & 70, Naval Weapons Seal Beach and an accompanying Staff Report on January 26, 2000, with the City Council considering and discussing these same documents and reports on February 14, 2000. Both the Environmental Quality Control Board and the City Council authorized the respective Chairman and the Mayor to sign this letter indicating the official comments of the City of Seal Beach. Thank you for your consideration of the comments of the City of Seal Beach. Please do not hesitate to contact Mr. Lee Whittenberg, Director of Development Services, City Hall, 211 Eighth Street, Seal Beach, 90740, telephone (562) 431-2527 if you have any questions regarding this matter. In addition, please provide a copy of the "Final Work Plan for Long-Tenn Groundwater Monitoring at Installation Restoration Sites 40 and 70" to Mr. Whittenberg for City information purposes when it is available. Sincerely, • 1-4-4 Paul Yost William G. Hurley, Vice-Chairman an Mayor, City of Seal Beach Environmental Quality Control Boar J I Distribution: City Council City Manager Planning Commission Director of Developme•,t Services Environmental Quality Control Board Archaeological Advisory Committee f, �r City Response Letter re:Draft Work Plan for Long-Term Groundwater Monitoring, IR Sites 40 and 710, Naval Weapons Station, Seal Beath City Council Staff Report February 14, 2000 February 14, 2000 Weapons Support Facility Attn: Pei-Fen Tamashiro, Installation Restoration Coordinator 800 Seal Beach Blvd. Seal Beach, CA 90740-5000 SUBJECT: "Draft Work Plan for Long-Term Groundwater Monitoring at Installation Restoration Sites 40 and 70, Naval Weapons Station, Seal Beach" Rp► Dear Ms. Tamashiro: The City of Seal Beach has reviewed the report from the Department of the Navy relative to "Draft Work Plan for Long-Term Groundwater Monitoring at Installation Restoration Sites 40 and 70, Naval Weapons Station, Seal Beach". It should be noted that the City has only reviewed in detail the "Summary", and Chapter 3 of the subject document. Upon a review of those portions of the document by the Environmental Quality Control Board and the City Council of the City of Seal Beach, the City has the following general and specific comments. General Comments on the Document The Environmental Quality Control Board and the City Council understand this Work Plan provides the framework and guidance to conduct groundwater monitoring at the subject Installation Restoration (IR) Sites. The groundwater monitoring program will involve installing 15 new monitoring wells, monitoring groundwater surface elevations, and collecting groundwater samples for analysis from 28 selected wells. The duration of the monitoring program is 5 years. After 5 years, recommendations will be made to continue monitoring, reduce the sampling frequency, or discontinue monitoring. Draft Groundwater Work Plan, IR Sites 40&70.CC 8 City Response Letter re:Draft Work Plan for Long-Term Groundwater Monitoring, IR Sites 40 and 70, Naval Weapons Station, Seal Beach City Council Staff Report February 14, 2000 The general format of the document is helpful to readers in providing a brief summary of the existing conditions at IR Sites 40 and 70, the reasons for the additional groundwater monitoring program proposed, and the summary of data quality objectives (DQOs) for each site as set forth in Table 3-1 and 3-2, respectively. Tables 3-1 and 3-2, Sumunary of DQOs for IR Site 40 and IR Site 70, respectively, are extremely helpful in providing a quick overview of the statement of the problem, inputs to the decision, boundaries of the study, decision rules, and limits on decision errors for each of the subject sites. This type of presentation would be helpful in future documents as a way to provide an easily understood summary of the particular actions proposed and the decision points as to why this type of action is deemed achievable. As indicated in our comment letter of December 13, 1999, the City is appreciative of the Navy proceeding with this evaluation in an expeditious and timely manner. The length of time to conduct this type of evaluation and reach an action determination was a concern expressed in our letter of February 8, 1999. The timely preparation of this document, and the future decisions to be made based on public and regulatory agency reviews comments, are sincerely appreciated by the City. DR PF The City would request further clarification as to the decision points the Navy would utilize to determine if annual or semi-annual monitoring is appropriate as proposed in Table 3-5 - Proposed Analysis and Monitoring Frequency. In referencing Figure 3-2, the City would appreciate further delineation as to the extent of increase in concentration or "highly variable data" that would lead to a decision to conduct semi-annual or annual monitoring. The Environmental Quality Control Board of the City of Seal Beach considered and reviewed the Draft Work Plan for Long-Term Groundwater Monitoring and an accompanying Staff Report on January 26, 2000, with the City Council considering and discussing these same documents and reports on February 14, 2000. Both the Environmental Quality Control Board and the City Council authorized the respective Chairman and the Mayor to sign this letter indicating the official comments of the City of Seal Beach. Thank you for your consideration of the comments of the City of Seal Beach. Please do not hesitate to contact Mr. Lee Whittenberg, Director of Development Services, City Hall, 211 Eighth Street, Seal Beach, 90740, telephone (562) 431-2527 if you have any questions regarding this matter. In addition, please provide a copy of the "Final Work Plan for Long-Tenn Groundwater Monitoring at Installation Restoration Sites 40 and 70" to Mr. Whittenberg for City information purposes when it is available. Draft Groundwater Work Plan,IR Sites 40 at 70.CC 9 City Response Letter re:Draft Work Plan for Long-Term Groundwater Monitoring, IR Sites 40 and 70, Naval Weapons Station, Seal Beath City Council Staff Report February 14, 2000 Sincerely, Paul Yost William G. Hurley, Vice-Chairman Mayor, City of Seal Beach Environmental Quality Control Board P.‘ DR Distribution: City Council City Manager Planning Commission Director of Development Services Environmental Quality Control Board Archaeological Advisory Committee Draft Groundwater Work Plan,IR Sites 40&70.CC 10 City Response Letter re:Draft Work Plan for Long-Term Groundwater Monitoring, IR Sites 40 and 710, Naval Weapons Station, Seal Beath City Council St'Report February 14, 2000 ATTACHMENT 3 "DRAFT WORK PLAN FOR LONG-TERM GROUNDWATER MONITORING AT INSTALLATION RES710RATION SITES 40 AND 70, NAVAL WEAPONS STATION, SEAL BEACH", PREPARED BY BECHTEL ENVIRONMENTAL, INC. FOR SOUTHWEST DIVISION, NAVAL FACILITIES ENGINEERING COMMAND, DATED DECEMBER 1999 NOTE: COMPLETE DOCUMENT HAS NOT BEEN PROVIDED TO THE BOARD DUE TO THE LENGTH OF THE DOCUMENT, 263 PAGES. STAFF IS PROVIDING THE "SUMMARY", "TABLE OF CONTENTS", AND SECTION 3 - "MONITORING OBJECTIVES AND RATIONALE", TO THE CITY COUNCIL FOR REVIEW IN CONSIDERING THIS MATTER COMPLETE DOCUMENT AVAILABLE AT THE DEPARTMENT OF DEVELOPMENT SERVICES FOR REVIEW. Draft Groundwater Work Plan,IR Sites 40&70.CC 1 1 CLEAN 3 CTO-0002/0020 Date: 12/21/99 SUMMARY This Work Plan provides the framework and guidance to conduct groundwater monitoring in the vicinity of the following Installation Restoration Program sites (IR sites) at Naval Weapons Station, Seal Beach, Seal Beach, California: • IR Site 40, Concrete Pit/Gravel Area; and • IR Site 70, Research,Testing, and Evaluation Area. The groundwater monitoring program will involve installing 15 new monitoring wells, monitoring groundwater surface elevations, and collecting groundwater samples for analysis from 28 selected wells. The duration of the monitoring program is 5 years. Groundwater surface elevations will be monitored monthly for the first year, and prior to each sampling event thereafter. The data will be used to evaluate seasonal variations in the groundwater potentiometric surface. Previous investigations have identified the presence of chlorinated solvents in groundwater at IR Sites 40 and 70. The extent of contamination has been delineated, and a feasibility study is currently being conducted under a separate scope of work to evaluate remedial alternatives. The monitoring program is designed to measure chemical concentrations within and around the chlorinated solvent plumes over time. The data will be used to establish contaminant concentration trends, assess the effectiveness of remedial actions, when implemented, monitor for natural attenuation of the chemicals of concern, and assess whether downgradient receptors have the potential to become affected by the contaminant plumes. In addition, metals were reported in groundwater at IR Site 70. The extent of mercury concentrations above statistical background and hexavalent chromium concentrations above the detection limit was not fully delineated during previous investigations. Further delineation of these metals will be performed as part of the groundwater monitoring program. Table S-1 summarizes the wells proposed for sampling. All the proposed wells will be monitored quarterly for volatile organic compounds and semiannually for natural attenuation indicators during the first year. Metals, including hexavalent chromium, will be monitored semiannually for the first year in six wells to the south and southeast of IR Site 70. Data collected during the first year will be used to establish the monitoring frequency for subsequent years. Monitoring for volatile organic compounds and natural attenuation indicators will be reduced to semiannual or annual, depending on the location of the well in relation to the plume, the direction of concentration trends, and the variability of the results. Monitoring for metals will be discontinued after the first year. Data will be reported following each sampling event. Data evaluation will be conducted after the first, third, and fifth years of monitoring. Evaluation will include observing variability in results, comparing chemical concentrations to screening levels established for groundwater, and observing trends in chemical concentrations over time. Recommendations for further action will be made if the data indicate that the plumes are reaching potential receptors. After 5 years, recommendations will be made to continue monitoring, reduce the sampling frequency, or discontinue monitoring. Draft Long-Term GW Monitoring Work Plan— IR Sites 40 and 70, WPNSTA, Seal Beach page i 12113/1999 904 AM pp i Om3n3v*or0_Frooesr^G cto0002rvorI W rp \9900163 doc CLEAN 3 CTO-0002/0020 Date: 12/21/99 Summary Table S-1 Summary of Groundwater Sampling Locations Initial Monitoring Frequency(First Year) Volatile Natural IR Organic Attenuation Site Well No. Status g Hezavalent Location Compounds Indicators* Metals Chromium 40 40-MW-03 Existing In plume, Q S NA NA crossgradient, perimeter 40-MW-05 Existing In plume,center Q S NA NA MW-40-08 Existing In plume, Q S NA NA downgradient, perimeter MW-40-12 Existing In plume, Q S NA NA downgradient, perimeter MW-40-14 Existing In plume,center Q S NA NA MW-40-15 Existing Downgradient Q S NA NA MW-40-16 Existing Downgradient Q S NA NA MW-40-17 Proposed Downgradient Q S NA NA MW-40-18 Proposed Downgradient Q S NA NA MW-40-19 Proposed Crossgradient Q S NA NA (SW lateral) MW-40-20 Proposed Crossgradient Q S NA NA (SW lateral) MW-40-21 Proposed Background Q S NA (Upgradient) N 4 70 EW-70-01 Existing In plume, Q S NA NA upgradient MW-70-04 Existing In plume, center Q S NA NA MW-70-08 Existing In plume,center Q S NA NA MW-70-09 Existing In plume, center Q S NA NA MW-70-10 Proposed Crossgradient Q S 2Q NA (NE lateral) MVV-70-11 Proposed Crossgradient Q S NA NA (NE lateral) MW-70-15 Existing In plume, Q S NA NA downgradient MW-70-16 Existing In plume, Q S NA NA downgradient (table continues) f page ii Draft Long-Term GW Monitoring Work Plan— IR Sites 40 and 70, WPNSTA, Seal Beach 12/13/1999 9:04 AM 9x 11,cJsinlword ng1M0002waxp,ntrsnn.99001e3a ooc CLEAN 3 CTO-000210020 Date: 12/21/99 Summary Table S-1 (continued) Initial Monitoring Frequency(First Year) Volatile Natural IR Organic Attenuation Hexavalent Site Well No. Status Location Compounds Indicators' Metals Chromium MW-70-17 Proposed Crossgradient Q S 2Q 2Q (SW lateral) MW-70-18 Proposed Crossgradient Q S NA NA (SW lateral) MW-70-19 Proposed Background Q S NA NA (Upgradient) MW-70-20 Proposed In plume, Q S NA NA downgradient MIX-70-21 Proposed Background Q S NA NA (Downgradient) MW-70-22 Proposed In plume, Q S NA NA downgradient MW-70-23 Proposed Crossgradient Q S NA NA (NE lateral) MW-70-24 Proposed Crossgradient Q S 2Q 2Q (SW lateral) Note: Natural attenuation indicators: alkalinity, ammonia,anions, cations,total iron,ferrous iron,total dissolved solids,total organic carbon,dissolved gases, dissolved oxygen, and redox potential Acronyms/Abbreviations: 2Q—monitor for two quarters A—annual monitoring EW—extraction well IR—installation restoration MW—monitoring well NA—not applicable NE—northeast Q—quarterly monitoring S—semiannual monitoring SW—southwest Draft Long-Term GW Monitoring Work Plan— IR Sites 40 and 70, WPNSTA, Seal Beach page iii 12!1311999 904 AM pp v000n3,wc c_proms^9000 +n,cinen990016.L.0oc CTO-0002/0020 Date. 12/21/99 Summary This page left blank intentionally page iv Draft Long-Term GW Monitoring Work Plan— IR Sites 40 and 70, WPNSTA, Seal Beach 12/111999 901 AM PA I t illan3 port_poceson0clo00011rowkpl+nbrrin9900Ie doc CLEAN 3 CTO-000210020 Date: 12/21/99 TABLE OF CONTENTS Section Page SUMMARY ACRONYMS/ABBREVIATIONS viii 1 INTRODUCTION 1.1 Purpose 1-1 1.2 Scope 1-1 1.3 Organization 1-2 2 BACKGROUND 2.1 History 2-1 2.1.1 IR Site 40 and Surrounding Area 2-1 2.1.2 IR Site 70 and Surrounding Area 2-1 2.2 Previous Environmental Investigations 2-2 2.3 Physical Setting 2-7 2.3.1 Regional and Site Geology 2-7 2.3.2 Regional Hydrogeology 2-8 2.3.3 IR Site 40 Geology and Hydrogeology 2-8 2.3.4 IR Site 70 Geology and Hydrogeology 2-11 2.3.5 Groundwater Quality and Use 2-15 2.4 Nature and Extent of Contamination 2-16 2.4.1 IR Site 40 2-16 2.4.2 IR Site 70 2-16 3 MONITORING OBJECTIVES AND RATIONALE 3.1 Data Quality Objectives 3-1 3.2 Proposed Well Installation 3-1 3.3 Monitoring Frequency and Analytical Parameters 3-1 4 SUMMARY OF FIELD ACTIVITIES Draft Long-Term GW Monitoring Work Plan— IR Sites 40 and 70,WPNSTA, Seal Beach page v 12/13/1999 9.04 AM gna Lti..nNvory_prownain0 a vdrofnpY00,e3a.aoc CLEAN 3 CTO-0002/0020 Date: 12/21/99 TABLE OF CONTENTS (continued) Section 5 DATA INTERPRETATION METHODS 6 SCHEDULE 7 REFERENCES APPENDICES Appendix I WATER-LEVEL DATA II ISOCONCENTRATION MAPS ATTACHMENTS Attachment A FIELD SAMPLING PLAN B QUALITY ASSURANCE PROJECT PLAN C DATA MANAGEMENT PLAN D INVESTIGATION-DERIVED WASTE MANAGEMENT PLAN E AMENDMENT TO THE CTO-0127 SITE-SPECIFIC SAFETY AND HEALTH PLAN SUPPLEMENT page vi Draft Long-Term GW Monitoring Work Plan— IR Sites 40 and 70, WPNSTA, Seal Beach 12/14/1999 9.37 AM p I:04a/111torti pvcyasnVc100032\ otgianar it 99001 E3.o CLEAN 3 CTO-0002/0020 Date: 12/21/99 TABLE OF CONTENTS (continued) FIGURES Figure Pace 1-1 Site Location Map 1-3 1-2 IR Site 40 Base Map 1-5 1-3 IR Site 70 Base Map 1-7 2-1 Well Locations and Extent of VOC Plume in Groundwater, IR Site 40 2-3 2-2 Well Locations and Extent of VOC Plume in Groundwater, IR Site 70 2-5 2-3 IR Site 40— Site Physical Conceptual Model 2-9 2-4 IR Site 70—Site Physical Conceptual Model 2-13 2-5 Wells Within a 1.5-Mile Radius of Naval Weapons Station 2-17 3-1 Data Quality Objectives Decision Flow Diagram 3-7 3-2 Monitoring Frequency Decision Flow Diagram,Naval Weapons Station, Seal Beach 3-17 6-1 Monitoring and Reporting Schedule for Year 1 6-2 TABLES Table S-1 Summary of Groundwater Sampling Locations ii 3-1 Summary of DQOs for IR Site 40 3-3 3-2 Summary of DQOs for IR Site 70 3-5 3-3 Well Construction Summary 3-8 3-4 Summary of Historical Results and Sampling Rationale 3-11 3-5 Proposed Analyses and Monitoring Frequency 3-18 Draft Long-Term GW Monitoring Work Plan— IR Sites 40 and 70, WPNSTA, Seal Beach 12/15/99 9.47 Ml rim I:1tlssn3MwwO_prooawnpkso0002 9.914919 99 9Y00,ea,.Ooe page vii CLEAN 3 CTO-0002/0020 Date: 12/21/99 ACRONYMS/ABBREVIATIONS bgs below ground surface BNI Bechtel National, Inc. CBCEC California Base Closure Environmental Committee CERCLA Comprehensive Environmental Response, Compensation, and Liability Act CLEAN Comprehensive Long-Term Environmental Action Navy COC chemical of concern COPC chemical of potential concern Cr(VI) hexavalent chromium CTO Contract Task Order DON Department of the Navy DQO data quality objective ERSE extended RSE °F degrees Fahrenheit FS feasibility study FSEC Facilities Systems Engineering Company FSI focused site inspection FSP Field Sampling Plan IAS initial assessment study IDV' investigation-derived waste IR Installation Restoration JEG Jacobs Engineering Group, Inc. LCA LeRoy Crandall and Associates Aga- micrograms per liter mg/L milligrams per liter MPN most probable number NASA National Aeronautics and Space Administration OU Operable Unit PA preliminary assessment PCE tetrachioroethene QAPP Quality Assurance Project Plan page viii Draft Long-Term GW Monitoring Work Plan— IR Sites 40 and 70, WPNSTA, Se& Beach 12/13/1999 9:04 AM pxp 19 n?w,ati_yrvcassanQcto00C2444orkyantlref119900183s aoc CLEAN 3 CTO-0002/0020 Date 12/21/99 ACRONYMS/ABBREVIATIONS (continued) RCRA Resource Conservation and Recovery Act RFA RCRA facility assessment RRSEM Relative Risk Site Evaluation Model RSE removal site evaluation RT&E Research, Testing, and Evaluation SI site inspection SWDIV Southwest Division Naval Facilities Engineering Command TCE trichloroethene TDS total dissolved solids U.S. EPA United States Environmental Protection Agency UST underground storage tank VOC volatile organic compound WPNSTA (Naval) Weapons Station Draft Long-Term GW Monitoring Work Plan— IR Sites 40 and 70, WPNSTA, Seal Beach page ix 12113/1999 904 AM 9xq I:C4sn3wo d y0c444fi^O%nc0002*wNcyantrs4r19900183a Doc CLEAN 3 CTO-0002/0020 Date: 12/21/99 ACRONYMS/ABBREVIATIONS (continued) This page left blank intentionally page x Draft Long-Term GW Monitoring Work Plan— IR Sites 40 and 70, WPNSTA, Seal Beach 12/13/1999 9 04 AM o;a wrn3wafl-y40gyyrwctp0007workpLandrsm9900183.aoc CLEAN 3 CTO-0002/0020 Date. 12/21/99 Section 3 MONITORING OBJECTIVES AND RATIONALE As discussed in Section 2.4, the primary COCs at IR Sites 40 and 70 are chlorinated solvents. Mercury and hexavalent chromium are COPCs at IR Site 70 because they have not been fully delineated. The objectives of the monitoring program are to monitor the concentrations of VOCs in groundwater, establish contaminant concentration trends, assess the effectiveness of remedial actions, monitor for natural biodegradation of the COCs, further delineate mercury and hexavalent chromium at IR Site 70, and assess whether downgradient receptors have the potential to become affected by the contaminant plume. The attached FSP presents the detailed DQO process as well as the details for installing new wells and collecting the required groundwater samples. The attached QAPP presents the analytical procedures and quality assurance measures to be implemented. All the proposed remedial options (BNI 1999b) include monitored natural attenuation as part of the remedial process. Monitored natural attenuation relies on naturally occurring in situ processes (e.g., biodegradation, chemical transformation, volatilization, dilution, dispersion, and adsorption) to achieve removal action objectives within a reasonable time frame (U.S. EPA 1997). Under certain conditions, these natural processes act to reduce the mass, toxicity, mobility, or volume of VOC-contaminated groundwater. Monitoring is necessary to measure cleanup progress. Therefore, collection and analysis of samples for various inorganic analyses will also be conducted to monitor the natural attenuation effects. 3.1 DATA QUALITY OBJECTIVES The technical approach for the groundwater monitoring program is based on the seven- step DQO development process (U.S. EPA 1994), described in detail in the FSP. The DQO process provides a mechanism to develop the technical assumptions used to design the investigation. The seven steps of the DQO process are briefly summarized in Tables 3-1 and 3-2 for IR Sites 40 and 70, respectively. Figure 3-1 shows the DQO decision flow process. 3.2 PROPOSED WELL INSTALLATION The installation of new wells is proposed for both IR Sites 40 and 70 to fill data gaps and protect downgradient receptors. These wells will be located outside the contaminant plume and will assure that each plume has upgradient, crossgradient, and downgradient wells to monitor for plume migration. Figures 2-1 and 2-2 show the proposed locations of the new wells for IR Sites 40 and 70, respectively. Table 3-3 summarizes the proposed well construction details and well placement rationale. 3.3 MONITORING FREQUENCY AND ANALYTICAL PARAMETERS The monitoring frequency is based on recommendations in the Long-Term Ground Water Monitoring Program Guidance (CBCEC 1994). The objective of the monitoring program is to monitor the contaminant plumes to evaluate the remedial effort once implemented, and to monitor for downgradient or lateral migration of the plume. Therefore, only wells in the center (near the suspected source area) or the perimeter of the Draft Long-Term GW Monitoring Work Plan— IR Sites 40 and 70, WPNSTA, Seal Beach page 3-1 12/1411999 940 AM>•Itiesra.porp r g ct pp ,ygdv ttre\99OQ i 13d cloc CLEAN 3 CTO-0002/0020 Date: 12/21/99 Section 3 Monitoring Objectives and Rationale plume are recommended for monitoring. Other wells will be used for monitoring groundwater elevations, or may be used later as part of the monitoring for the chosen remedy. Table 3-4 presents the rationale for monitoring or not monitoring each well. Figures 2-1 and 2-2 show the locations of the wells for IR Sites 40 and 70, respectively. Wells will initially be sampled quarterly for four consecutive quarters to establish baseline COC trends (Figure 3-2). At the conclusion of the fourth quarter of sampling, the data will be evaluated in order to modify the monitoring frequency to semiannually or annually (with Navy and regulatory agency concurrence)depending on the location of the well, contaminant concentration trends, and concentration variability. Wells with increasing contaminant trends or highly variable data will be sampled semiannually. Other wells will be sampled annually. The methodology for determining concentration trends and concentration variability is discussed in Section 5. Monitoring is scheduled to be conducted over a period of 5 years; however, monitoring of individual wells may be terminated, with the concurrence of the regulatory agencies, if the data indicate that monitoring is no longer required. In addition to frequency evaluation at the end of the first year, the well sampling frequency will also be evaluated at the end of the third and fifth years of sampling. Table 3-5 lists the analytical parameters proposed for IR Sites 40 and 70. Chlorinated solvents have been identified as COCs at each site. In addition, mercury and hexavalent chromium have been identified as COPCs at IR Site 70 because the lateral extent has not been fully delineated to the east and south of the site. Therefore, two rounds of metals and hexavalent chromium analyses are proposed in wells to the south and east of IR Site 70. Natural attenuation indicators will also be monitored in addition to VOCs (and metals at IR Site 70). Table 3-5 lists the analytes and initial monitoring frequency. Natural attenuation indicators are proposed for semiannual or annual monitoring, depending on the frequency with which the well is to be sampled. page 3-2 Draft Long-Term GW Monitoring Work Plan—IR Sites 40 and 70, WPNSTA, Seal Beach 12/1311999 9 O4 Au xp hbaan3word yooeer 0000zwo,xianoasnhaaootek ooc 0 .o ' - A o y = g _e m_m ,'? 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N hN cUOaOw5'aWc � --WF Q oC o6 a CLEAN 3 CTO-000210020 Date: 12/21/99 Section 3 Monitoring Objectives and Rationale Metals Have metals Yes Perform 4 quarters of been Recommend no further sampling and analysis for adequately action for metals VOCs;and perform delineated? 2 quarters of sampling and analysis for metals No V VOCs Recommend further delineation of metals ill Continue monitoring No V Adjust monitoring frequency for COCs Is the plume No Has 5 years of following decision flow reaching monitoring in Figure 3-2 potential A been receptors? completed? Yes Yes Recommend evaluation of additional remedial actions Do COC concentrations indicate stable or decreasing Yes trends? No T ( Recommend reducing the Recommend continued monitoring frequency or monitoring discontinue monitoring Figure 3-1 Data Quality Objectives Decision Flow Diagram Draft Long-Term GW Monitoring Work Plan— IR Sites 40 and 70, WPNSTA, Seal Beach page 3-7 12/13/1999 904 AM pap I 1dein3* rc_Procey mp\Ct00002\wonkyarodne1090016b.Ooc . 1 h O L c a cc v, o v, -. N on n or, n in b y g `n n v `-' N h M N t7 N n N v'i n N h ICD n Cl.• G a rec o t N v n n n n n `n 000, . n O r. '7 N M . R V 00 Q CO ^ N arc O V F a a . .. d � v, hIr- tT n n n n nM N 6 ^ n ; v N M v, v, M f7 ,O M kO �D M vO Q O F is N v, C = Z � N OM t`% t. en M el Cv VI M VP M 'C ' h O - O Q iz « 1 1 1 1 1 1 1 1 1 1 1 I 1 I1 1 E C d ,� v1 O v, O O N O O O O O O P 1 CO O 640 7 v • O+ N M N v N n N n n Nvl en t'9 O en 0 C c .� u v v a, d u.v t u u u °J .. 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