Technical Memo: Draft soil gas sampling results, 8/12

Technical Memorandum

ITSIGilbaneCompany|2730ShadelandsDrive|WalnutCreek,CA94598|Tel:925‐946‐3100|Fax:925‐256‐8998www.itsigilbane.com

This technical memorandum documents the results of additional soil gas monitoring for evaluation of potential vapor intrusion in the San Gabriel Valley Area 1 Superfund Site, South El Monte Operable Unit, San Gabriel Basin, Los Angeles County, California.

The initial soil gas sampling event was completed in August 2011, in accordance with the Final Sampling and Analysis Plan, Supplemental Remedial Investigation/Feasibility Study, San Gabriel Valley Area 1 Superfund Site, South El Monte Operable Unit, San Gabriel Basin (SAP; Innovative Technical Solutions, Inc. [ITSI], March 2011a). Soil gas sampling results from the August 2011 sampling event presented in the South El Monte Operable Unit Supplemental Remedial Investigation/Feasibility Study, Soil Vapor Monitoring Results Technical Memorandum (ITSI, 2011) showed levels of volatile organic compounds (VOCs) well above the vapor intrusion screening levels; therefore additional sampling was performed in August 2012 throughout the SEMOU as specified in the Second Modification to the SAP (ITSI, 2012).

Background

The initial (August 2011c) soil vapor sampling locations were based on preliminary vapor intrusion evaluation results presented in Tables 3 and 5 of the Initial Evaluation of Potential Vapor Intrusion Associated with VOC Contamination in the South El Monte OU, San Gabriel Valley Superfund Site (2009 VI tech memo; CH2M Hill, 2009). Table 3 summarized cumulative risks and hazards associated with historic soil gas sampling results at 26 facilities. Table 5 summarized groundwater screening results and was used to prioritize residential areas for additional investigation of potential vapor intrusion from the downgradient groundwater plume.

Table 4-3 of the SAP (Locations and Rationale for Soil Gas Sampling) includes the specific rationale for soil gas sampling at 6 facilities and 4 downgradient plume locations considered to be high priority for an initial investigation of the potential for vapor intrusion. Additional rationale for soil gas sampling at the high priority locations was presented in Technical Memorandum, Soil Vapor Monitoring-Supplemental RI/FS, South El Monte OU-Additional Rationale for Monitoring Locations (ITSI, 2011b). The August 2011 soil vapor sampling was conducted at 5 of the facilities and 3 of the downgradient plume areas of the high priority locations. Access to the sixth facility (Phillips and Malone) was not obtained for the August 2011 sampling event. Further review of the groundwater plume concentrations indicated that the fourth groundwater plume location (CPR Industries) did not justify soil gas sampling because groundwater concentrations were less than Maximum Contaminant Levels (MCLs). In addition, CPR Industries was listed as a low priority site in Table 3 from the 2009 VI Tech Memo.

To: Rachelle Thompson, US EPA, Region 9

From: Don Gruber, Senior Hydrogeologist, ITSI Gilbane Company

Date: October 18, 2012

Subject: Draft Soil Gas Sampling Results August 2012, Supplemental Remedial Investigation/Feasibility Study, San Gabriel Valley Area 1 Superfund Site, South El Monte Operable Unit

Contract /TO: EP-S9-08-03/TO 47 ITSI DCN: 07136.0048.0040

SDMS DOCID# 1138189

Technical Memorandum (Continued)

Draft Soil Gas Sampling Results August 2012, Supplemental Remedial Investigation/Feasibility Study, San Gabriel Valley Area 1 Superfund Site, South El Monte Operable Unit

Draft Draft Soil Gas Sampling Results August 2012.docx Page 2 of 11

The August 2012 soil gas sampling event targeted the remaining 20 facilities listed in Table 3 in the 2009 VI tech memo and 2 additional locations based on review of existing background data. The sampling rationale was based on information presented in the 2009 VI tech memo and a review of background data for these facilities included in the Los Angeles Regional Water Quality Control Board background data files and the EPA Records Center. Fifteen of the 22 facilities were sampled in August 2012. The 7 remaining facilities were not sampled because access could not be obtained. Figure1 presents the facility locations for the August 2011 and August 2012 sampling events and the 7 locations that were not sampled.

Soil Gas Sampling Methods and QA/QC Procedures

Field activities for soil vapor monitoring were conducted from August 7 through 20, 2012. A total of 86 soil gas samples was collected from 42 temporary soil vapor monitoring wells at the 15 potential responsible party (PRP) facilities. As shown on Figure 1, the sampling locations are identified by their potential responsible party (PRP) facility name (i.e., Astro Seal, Inc.).

The direct-push drilling method was used to advance the temporary soil vapor monitoring well boreholes. Each well was drilled to 15.5 feet below ground surface (bgs) and completed with two separate well screens (4.5 to 5.5 and 15.0 to 15.5 feet bgs). Teflon tubing, extending from ground surface, was attached to each well screen and coarse-graded silica sand was used as a filter medium around each screen. The area between the screens and from the shallow screen to the ground surface was sealed with sodium bentonite, hydrated in place, to form individual sampling intervals. Practices presented in the SAP (ITSI Standard Operating Procedure for Soil Gas Sampling-Subsurface) were used to collect soil gas samples. The only deviation from the cited ITSI standard operating procedure (SOP) was the use of 1,1-difluoroethane rather than helium for leak detection. In addition, a purge volume test was performed following procedures documented in the California Environmental Protection Agency, Department of Toxic Substances Control, Advisory Active Soil Gas Investigation (April 2012). As specified in this advisory, purge volumes of one, three, and ten volumes were collected and analyzed for the first 5- and 15-foot soil gas samples collected from temporary soil vapor monitoring well SEMSG16-B1 (see Table 1).

Based on analytical results (e.g. highest concentrations) from the purge volume test, three purge volumes of soil gas were used for the five-foot wells and 10 purge volumes were used for the 15-foot wells. In accordance with the Second Modification to the SAP (ITSI, 2012), an on-site mobile laboratory (H&P Mobile Geochemistry, Inc. [H&P]) was used for sample analysis during this sampling event to evaluate soil gas concentrations in a “real-time” scenario. The vapor wells were purged and sampled by the mobile lab operator under supervision of ITSI personnel. The samples were collected using a glass syringe and analyzed for volatile organic compounds (VOCs) by EPA Method TO-15. Upon completion of soil gas sampling activities, all well construction materials were removed from each borehole. The boreholes were backfilled from total depth to 0.5 foot bgs with bentonite grout, and the remaining portion of each borehole was filled with material appropriate to match pre-existing conditions (asphalt or concrete). All used well construction and sampling materials were disposed of as non-hazardous waste.




Use of the on-site mobile laboratory required a modification to the data validation procedures for soil gas as presented in the SAP. Based on discussion between H&P, the EPA Quality Assurance Office, and ITSI, it was determined that 90% of the analytical data produced during this sampling event would receive Tier 1 (summary data review) data validation and 10% of the analytical data would receive Tier 3 (full in-depth data review) data validation.

A review of performance documentation provided by H&P indicated that recent Rapid Return Performance Test (PT) results were slightly elevated. To address this concern, analysis and validation of the first set of samples collected during the sampling event was expedited. ITSI completed Tier 3 data validation on the first set of samples to ensure that all the mobile laboratory QA/QC results were within their respective acceptance limits. Additionally, H&P was requested to report their ongoing PT results to demonstrate the effectiveness of their internal corrective action program.

In addition to these modified quality assurance/quality control (QA/QC) measures, ITSI submitted split samples on 10% of the total sample group to the EPA Region 9 Laboratory for analysis and validation. The split soil-gas sample canisters were shipped via Federal Express under chain-of-custody documentation for VOC analysis by EPA Method TO-15.

The results for data validation performed by ITSI indicated there were no qualified data for the initial sampling event. A data quality assessment of the overall data QA/QC measures was prepared by the ITSI project chemist and data were determined to be acceptable for decision-making purposes. The chemist’s evaluation, including an evaluation of the split-sampling results, a recent PT Report, and the data validation report is included in Attachment 2.

Soil Gas Sampling Results

Table 1, South El Monte OU Soil Gas Monitoring Results, August 2012, presents the results for the analytes included in EPA Method TO-15. As shown in the table, the sampling locations are identified by their potential responsible party (PRP) facility name (e.g., Astro Seal, Inc.) and boring location ID. Concentrations of chemicals detected above their respective laboratory reporting limits are presented in bold-face type. Figures illustrating each sampling location are attached to this technical memorandum (Attachment 1). The figures include overview details of each location, PRP facility boundaries where appropriate, and soil gas sampling results for tetrachloroethene and trichloroethene.

Concentrations of chemicals detected at levels greater than their respective laboratory reporting limits were evaluated for potential risk to human health based on USEPA Regional Screening Levels (RSLs, April 2012) for Chemical Contaminants at Superfund Sites (residential and industrial scenarios for indoor air) or California Human Health Screening Levels (CHHSLs) when applicable. Soil gas to indoor air screening level concentrations have been calculated for the RSLs using residential and industrial attenuation factors of 0.002 and 0.001, respectively. In instances where the CCHSLs are used to identify screening level exceedances, the attenuation factors are estimated for a building constructed without engineered fill (no-fill) below the sub-slab. It should be noted that no indoor air RSL values are available for 1,3,5-trimethylbenzene




(TMB) at this time. Therefore, the RSL for 1,2,4-TMB was applied to reported 1,3,5-TMB analytical values for screening purposes. Instances where the detected chemical concentrations exceeded the industrial and residential RSLs are highlighted in Table 1. For comparison purposes, information regarding the VOCs that are contaminants of concern in groundwater and soil gas for the South El Monte Operable Unit is shown in Table 2, Contaminants of Concern-Volatile Organic Compounds in Groundwater and Soil Gas.

As stated in the SAP, the purpose for collecting soil gas samples at the selected PRP facilities was to provide current information on residual VOC concentrations in the vadose zone at those facilities. The SAP also states that soil vapor monitoring in downgradient areas of the shallow plumes would be performed to evaluate potential groundwater to indoor air risk.

The analytical data developed during the August 2011 and August 2012 soil vapor monitoring events described in this technical memorandum provide information suitable for the purposes stated in the SAP.

The screening results for PCE from all the facility locations indicate a possibility that the vapor intrusion pathway still exists; therefore, further characterization of the areas of concern should occur.




REFERENCES

CH2M Hill, 2009. Initial Evaluation of Potential Vapor Intrusion Associated with VOC Contamination in the South El Monte OU, San Gabriel Valley Superfund Site. December 16. ITSI, 2011a. Final Sampling and Analysis Plan, Supplemental Remedial Investigation/Feasibility Study, San Gabriel Valley Area 1 Superfund Site, South El Monte Operable Unit, San Gabriel Basin. March. ITSI, 2011b. Soil Vapor Monitoring-Supplemental RI/FS South El Monte OU-Additional Rationale for Monitoring Locations Technical Memorandum. May 26. ITSI, 2011c. South El Monte Operable Unit Supplemental Remedial Investigation/Feasibility Study, Soil Vapor Monitoring Results Technical Memorandum. October 31. ITSI, 2012. Second Modification to Sampling and Analysis Plan-Supplemental Remedial Investigation/Feasibility Study, San Gabriel Valley Area 1 Superfund Site, South El Monte Operable Unit. March 30. TABLES

Table 1 Soil Gas Sampling Results, August 2012, SEMOU Table 2 Contaminants of Concern–Volatile Organic Compounds in Groundwater and Soil

Gas FIGURES

Figure 1 Soil Gas Sampling Locations, August 2011 and August 2012, SEMOU ATTACHMENTS

Attachment 1 Facility Soil Gas Sampling Locations and Results Attachment 2 Data Quality Assessment




TABLES

ITSI Gil ~§i if§

Table 1South El Monte OU Soil Gas Monitoring Results

August 2012

Facility Name/ Boring Location ID

Sample Depth

SampleDate 1,

1,1-

Tric

hlor

oeth

ane

1,1,

2,2-

Tetra

chlo

roet

hane

1,1,

2-Tr

ichl

oro-

1,2,

2-tri

fluor

oeth

ane

1,1,

2-Tr

ichl

oroe

than

e

1,1-

Dic

hlor

oeth

ane

1,1-

Dic

hlor

oeth

ene

1,1-

Difl

uoro

etha

ne

1,2,

3-Tr

ichl

orop

ropa

ne

1,2,

4-Tr

ichl

orob

enze

ne

1,2,

4-Tr

imet

hylb

enze

ne

1,2-

Dib

rom

oeth

ane

(ED

B)

1,2-

Dic

hlor

oben

zene

1,2-

Dic

hlor

oeth

ane

1,2-

Dic

hlor

opro

pane

1,2-

Dic

hlor

otet

raflu

oroe

than

e

1,3,

5-Tr

imet

hylb

enze

ne

1,3-

Dic

hlor

oben

zene

1,4-

Dic

hlor

oben

zene

1,4-

Dio

xane

(p-D

ioxa

ne)

Ben

zene

Bro

mom

etha

ne

Car

bon

Tetra

chlo

ride

Chl

orob

enze

ne

Chl

oroe

than

e

Chl

orof

orm

Chl

orom

etha

ne

cis-

1,2-

Dic

hlor

oeth

ylen

e

cis-

1,3-

Dic

hlor

opro

pene

Eth

ylbe

nzen

e

Hex

achl

orob

utad

iene

m,p

-Xyl

ene

Met

hyle

ne C

hlor

ide

o-X

ylen

e

Sty

rene

Tetra

chlo

roet

hene

(PC

E)

Tolu

ene

trans

-1,3

-Dic

hlor

opro

pene

Tric

hlor

oeth

ene

(TC

E)

Tric

hlor

oflu

orom

etha

ne

Vin

yl C

hlor

ide

feet Units ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3 ug/M3

SEMSG10-B1 5 08/15/2012 <28 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 12,000 <19 <23 33 <28 <13SEMSG10-B1 5 08/15/2012 <100 <200 <200 <100 <90 <90 ‐‐ ‐‐ <200 <100 <200 <100 <90 <100 <200 <100 <100 <100 ‐‐ <70 <90 <100 <100 <60 <100 <50 <90 <100 <100 <200 <200 <80 <100 <100 9,800 <90 <100 200 J <100 <60SEMSG10-B1 15 08/15/2012 <28 <35 <39 <28 92 89 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 730 <23 <22 <54 <44 <18 <22 <22 12,000 <19 <23 10,000 <28 <13SEMSG10-B1 15 (dup) 08/15/2012 <28 <35 <39 <28 120 98 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 850 <23 <22 <54 <44 <18 <22 <22 12,000 <19 <23 10,000 <28 <13SEMSG10-B2 5 08/15/2012 <28 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 2,600 19 <23 <27 <28 <13SEMSG10-B2 15 08/15/2012 <28 <35 <39 <28 50 <20 <27 <31 <38 36 <39 <30 <21 <47 <71 <25 <30 <30 <37 20 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 2,200 37 <23 800 <28 <13SEMSG10-B3 5 08/15/2012 <28 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 22 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 41,000 <19 <23 140 <28 <13SEMSG10-B3 15 08/15/2012 43 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 67,000 <19 <23 1,300 <28 <13

SEMSG11-B1 5 08/09/2012 <28 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 6,200 22 <23 50 <28 <13SEMSG11-B1 15 08/09/2012 <28 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 44 <23 <22 <54 <44 <18 <22 <22 6,100 28 <23 1,100 <28 <13SEMSG11-B1 15 08/09/2012 <100 <200 <200 <100 <90 <90 ‐‐ ‐‐ <200 <100 <200 <100 <90 <100 <200 <100 <100 <100 ‐‐ <70 <90 <100 <100 <60 <100 <50 100 <100 <100 <200 <200 <80 <100 <100 5,500 <90 <100 1,900 <100 <60SEMSG11-B2 5 08/09/2012 <28 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 110,000 <19 <23 1,200 <28 <13SEMSG11-B2 15 08/09/2012 <28 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 310,000 <19 <23 9,200 <28 <13SEMSG11-B3 5 08/09/2012 <28 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 170,000 <19 <23 1,300 <28 <13SEMSG11-B3 5 (dup) 08/09/2012 <690 <870 <960 <690 <1000 <500 <680 <760 <940 <620 <970 <760 <510 <1200 <1800 <620 <760 <760 <910 <400 <990 <320 <590 <670 <620 <520 <1000 <580 <550 <1300 <1100 <440 <550 <540 160,000 <480 <580 1,900 <710 <320SEMSG11-B3 15 08/09/2012 32 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 330,000 <19 <23 5,400 <28 <13

SEMSG12-B1 5 08/10/2012 <28 <35 <39 <28 830 <20 <27 <31 <38 39 <39 <30 <21 <47 <71 <25 <30 <30 <37 200 <39 <13 <23 <27 <25 <21 690 <23 230 <54 340 <18 88 <22 1,700 200 <23 1,000 <28 680

SEMSG12-B1 15 08/10/2012 <28 <35 <39 <28 800 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 34 <39 <13 250 <27 <25 <21 590 <23 <22 <54 <44 <18 <22 <22 1,600 <19 <23 1,400 <28 190

SEMSG12-B2 5 08/10/2012 <28 <35 <39 <28 400 <20 <27 <31 <38 52 <39 39 <21 <47 <71 36 <30 <30 <37 110 <39 <13 82 <27 <25 <21 420 <23 220 <54 250 <18 88 <22 750 960 <23 360 <28 380

SEMSG12-B2 5 08/10/2012 <100 <100 <200 <100 2,400 <80 ‐‐ ‐‐ <200 100 <200 70 J <90 <100 <100 80 J <100 <100 ‐‐ 300 <80 <100 100 30 J <100 <40 1,600 <100 600 <200 600 <70 200 <90 900 2,300 <100 500 <100 1,100SEMSG12-B2 15 08/10/2012 <28 <35 <39 <28 200 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 1,300 <19 <23 370 <28 <13SEMSG12-B3 5 08/10/2012 <28 <35 <39 <28 190 <20 <27 <31 <38 27 <39 <30 <21 <47 <71 <25 <30 <30 <37 75 <39 <13 <23 <27 <25 <21 530 <23 41 <54 66 <18 33 <22 420 67 <23 220 <28 190

SEMSG12-B3 15 08/10/2012 <28 <35 <39 <28 50 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 2,600 <19 <23 900 <28 <13

SEMSG13-B1 5 08/08/2012 43 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 73,000 <19 <23 84 <28 <13SEMSG13-B1 15 08/08/2012 43 <35 <39 <28 <41 <20 <27 <31 <38 26 <39 <30 <21 <47 <71 <25 <30 <30 <37 32 <39 <13 <23 <27 <25 22 <40 <23 <22 <54 55 <18 32 <22 60,000 30 <23 130 <28 <13SEMSG13-B2 5 08/08/2012 <28 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 31,000 <19 <23 33 <28 <13SEMSG13-B2 15 08/08/2012 <28 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 28,000 <19 <23 160 <28 <13SEMSG13-B3 5 08/09/2012 R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R RSEMSG13-B3 5 08/09/2012 <280 <350 <390 <280 <410 <200 <270 <310 <380 <250 <390 <300 <210 <470 <710 <250 <300 <300 <370 <160 <390 <130 <230 <270 <250 <210 <400 <230 <220 <540 <440 <180 <220 <220 42,000 <190 <230 <270 <280 <130SEMSG13-B3 15 08/09/2012 29 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 40,000 <19 <23 64 <28 <13

SEMSG14-B1 5 08/17/2012 240 <35 460 <28 <41 <20 <27 <31 <38 300 <39 <30 <21 <47 <71 71 <30 39 <37 20 <39 <13 150 <27 110 <21 <40 <23 <22 <54 <44 <18 <22 <22 14,000,000 <19 <23 8,500 <28 <13SEMSG14-B1 15 08/17/2012 2,100 <35 6,300 150 <41 610 <27 <31 <38 63 <39 <30 <21 <47 <71 <25 33 <30 <37 21 <39 <13 590 <27 210 <21 280 <23 27 <54 <44 150 <22 <22 36,000,000 100 <23 11,000 <28 <13SEMSG14-B1 15 (dup) 08/17/2012 <140000 <170000 <190000 <140000 <210000 <100000 <140000 <150000 <190000 <120000 <190000 <150000 <100000 <230000 <350000 <120000 <150000 <150000 <180000 <81000 <200000 <64000 <120000 <130000 <120000 <100000 <200000 <120000 <110000 <270000 <220000 <88000 <110000 <110000 43,000,000 <95000 <120000 <140000 <140000 <65000SEMSG14-B2 5 08/20/2012 <140000 <170000 <190000 <140000 <210000 <100000 <140000 <150000 <190000 <120000 <190000 <150000 <100000 <230000 <350000 <120000 <150000 <150000 <180000 <81000 <200000 <64000 <120000 <130000 <120000 <100000 <200000 <120000 <110000 <270000 <220000 <88000 <110000 <110000 11,000,000 <95000 <120000 <140000 <140000 <65000SEMSG14-B2 15 08/20/2012 <140000 <170000 <190000 <140000 <210000 <100000 <140000 <150000 <190000 <120000 <190000 <150000 <100000 <230000 <350000 <120000 <150000 <150000 <180000 <81000 <200000 <64000 <120000 <130000 <120000 <100000 <200000 <120000 <110000 <270000 <220000 <88000 <110000 <110000 24,000,000 <95000 <120000 <140000 <140000 <65000SEMSG14-B3 5 08/20/2012 <140000 <170000 <190000 <140000 <210000 <100000 <140000 <150000 <190000 <120000 <190000 <150000 <100000 <230000 <350000 <120000 <150000 <150000 <180000 <81000 <200000 <64000 <120000 <130000 <120000 <100000 <200000 <120000 <110000 <270000 <220000 <88000 <110000 <110000 4,400,000 <95000 <120000 <140000 <140000 <65000SEMSG14-B3 5 08/20/2012 <24000 <30000 <34000 <24000 <18000 <18000 ‐‐ ‐‐ <33000 <22000 <34000 <27000 <18000 <20000 <31000 <22000 <27000 <27000 ‐‐ <14000 <17000 <28000 <20000 <12000 <22000 <9100 <18000 <20000 <19000 <47000 <38000 <15000 <19000 <19000 1,900,000 <17000 <20000 <24000 <25000 <11000SEMSG14-B3 15 08/20/2012 <140000 <170000 <190000 <140000 <210000 <100000 <140000 <150000 <190000 <120000 <190000 <150000 <100000 <230000 <350000 <120000 <150000 <150000 <180000 <81000 <200000 <64000 <120000 <130000 <120000 <100000 <200000 <120000 <110000 <270000 <220000 <88000 <110000 <110000 21,000,000 <95000 <120000 <140000 <140000 <65000

SEMSG15-B1 5 08/13/2012 57 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 31,000 <19 <23 110 <28 <13SEMSG15-B1 13 08/13/2012 49 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 24,000 22 <23 130 <28 <13SEMSG15-B2 5 08/13/2012 48 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 72,000 <19 <23 490 <28 <13SEMSG15-B2 15 08/13/2012 46 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 61,000 <19 <23 650 <28 <13SEMSG15-B2 15 (dup) 08/13/2012 <690 <870 <960 <690 <1000 <500 <680 <760 <940 <620 <970 <760 <510 <1200 <1800 <620 <760 <760 <910 <400 <990 <320 <590 <670 <620 <520 <1000 <580 <550 <1300 <1100 <440 <550 <540 67,000 <480 <580 910 <710 <320SEMSG15-B3 5 08/13/2012 <28 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 35,000 <19 <23 46 <28 <13SEMSG15-B3 15 08/13/2012 39 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 140,000 <19 <23 270 <28 <13SEMSG15-B3 15 08/13/2012 <2400 <3000 <3400 <2400 <1800 <1700 ‐‐ ‐‐ <3200 <2200 <3400 <2600 <1800 <2000 <3100 <2200 <2600 <2600 ‐‐ <1400 <1700 <2800 <2000 <1200 <2100 <900 <1700 <2000 <1900 <4700 <3800 <1500 <1900 <1900 120,000 <1600 <2000 <2400 <2500 <1100

SEMSG16-B1 (1PV) 5 08/07/2012 50 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 4,100 <19 <23 71 <28 <13 SEMSG16-B1 (3PV) 5 08/07/2012 42 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 4,200 <19 <23 79 <28 <13SEMSG16-B1 (10PV) 5 08/07/2012 49 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 4,100 <19 <23 60 <28 <13SEMSG16-B1 (1PV) 15 08/07/2012 67 <35 <39 <28 240 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 25 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 4,300 <19 <23 930 <28 <13SEMSG16-B1 (3PV) 15 08/07/2012 65 <35 <39 <28 120 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 5,200 <19 <23 1,100 <28 <13SEMSG16-B1 (10PV) 15 08/07/2012 69 <35 <39 <28 77 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 6,000 <19 <23 1,200 <28 <13SEMSG16-B2 5 08/07/2012 67 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 4,000 <19 <23 120 <28 <13SEMSG16-B2 5 (dup) 08/07/2012 65 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 3,700 24 <23 110 <28 <13SEMSG16-B2 15 08/07/2012 54 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 2,800 <19 <23 <27 <28 <13

SEMSG17-B1 5 08/16/2012 <28 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 30 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 63,000 <19 <23 6,900 <28 <13SEMSG17-B1 5 08/16/2012 <100 <200 <200 <100 <100 <100 ‐‐ ‐‐ <200 <100 <200 <100 <100 <100 <200 <100 <100 <100 ‐‐ 40 J <100 <200 <100 <70 <100 <50 <100 <100 <100 <300 <200 <90 <100 <100 38,000 <90 <100 4,900 <100 <60SEMSG17-B1 15 08/16/2012 <28 <35 <39 <28 72 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 49 <21 390 <23 <22 <54 <44 <18 <22 <22 120,000 <19 <23 41,000 <28 <13SEMSG17-B2 5 08/15/2012 <28 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 18 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 130,000 <19 <23 2,700 <28 <13SEMSG17-B2 15 08/15/2012 <28 <35 <39 <28 160 29 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 17 <39 <13 <23 <27 59 <21 1,100 <23 <22 <54 <44 <18 <22 <22 87,000 <19 <23 37,000 <28 <13SEMSG17-B3 5 08/15/2012 <28 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 41 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 44,000 <19 <23 6,100 <28 <13SEMSG17-B3 15 08/15/2012 <28 <35 <39 <28 96 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 26 <21 320 <23 <22 <54 <44 <18 <22 <22 65,000 <19 <23 26,000 <28 <13

SEMSG18-B1 5 08/17/2012 <28 <35 100 <28 <41 <20 <27 <31 <38 42,000 <39 <30 <21 <47 <71 18,000 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 6,200 <23 980 <54 3,700 <18 2,600 <22 2,000 69 <23 310 <28 <13SEMSG18-B1 15 08/17/2012 <28 <35 250 <28 51 58 <27 <31 <38 45,000 <39 <30 <21 <47 <71 14,000 <30 <30 <37 22 <39 <13 <23 <27 <25 <21 26,000 <23 3,000 <54 13,000 <18 8,400 <22 820 300 <23 340 <28 <13SEMSG18-B1 15 08/17/2012 <25000 <32000 <35000 <25000 <19000 <18000 ‐‐ ‐‐ <34000 88,000 <35000 <28000 <19000 <21000 <32000 24,000 <28000 <28000 ‐‐ <15000 <18000 <29000 <21000 <12000 <23000 <9500 38,000 <21000 <20000 <49000 <40000 <16000 <20000 <20000 <31000 <17000 <21000 <25000 <26000 <12000SEMSG18-B2 5 08/17/2012 37 <35 <39 <28 <41 <20 <27 <31 <38 950 <39 <30 <21 <47 <71 230 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 53 <18 45 <22 25,000 <19 <23 3,400 <28 <13SEMSG18-B2 15 08/17/2012 54 <35 <39 <28 <41 <20 <27 <31 <38 440 <39 <30 <21 <47 <71 140 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 660 <23 <22 <54 <44 <18 <22 <22 45,000 <19 <23 27,000 <28 <13SEMSG18-B3 5 08/16/2012 64 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 30,000 <19 <23 2,000 <28 <13SEMSG18-B3 15 08/16/2012 70 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 32,000 <19 <23 3,000 <28 <13

SEMSG19-B1 5 08/20/2012 46 <35 <39 <28 <41 <20 <27 <31 <38 41 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 130,000 <19 <23 1,300 <28 <13SEMSG19-B1 15 08/20/2012 98 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 260,000 <19 <23 6,400 <28 <13SEMSG19-B1 15 (dup) 08/20/2012 <690 <870 <960 <690 <1000 <500 <680 <760 <940 <620 <970 <760 <510 <1200 <1800 <620 <760 <760 <910 <400 <990 <320 <590 <670 <620 <520 <1000 <580 <550 <1300 <1100 <440 <550 <540 260,000 <480 <580 5,400 <710 <320SEMSG19-B2 5 08/20/2012 35 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 87,000 19 <23 290 <28 <13SEMSG19-B2 15 08/20/2012 74 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 260,000 <19 <23 1,600 <28 <13

Astro Seal, Inc.

Astronautic Enamelers

Cooper Drum Company

Custom Metal Products, Inc.

Hytone Cleaners

J. A. Bozung Co.

Mammoet Western Inc.

Manufacturer's Services Inc.

Phillips & Malone

Servex Corporation

Table 1South El Monte OU Soil Gas Monitoring Results

August 2012

Facility Name/ Boring Location ID

Sample Depth

SampleDate 1,

1,1-

Tric

hlor

oeth

ane

1,1,

2,2-

Tetra

chlo

roet

hane

1,1,

2-Tr

ichl

oro-

1,2,

2-tri

fluor

oeth

ane

1,1,

2-Tr

ichl

oroe

than

e

1,1-

Dic

hlor

oeth

ane

1,1-

Dic

hlor

oeth

ene

1,1-

Difl

uoro

etha

ne

1,2,

3-Tr

ichl

orop

ropa

ne

1,2,

4-Tr

ichl

orob

enze

ne

1,2,

4-Tr

imet

hylb

enze

ne

1,2-

Dib

rom

oeth

ane

(ED

B)

1,2-

Dic

hlor

oben

zene

1,2-

Dic

hlor

oeth

ane

1,2-

Dic

hlor

opro

pane

1,2-

Dic

hlor

otet

raflu

oroe

than

e

1,3,

5-Tr

imet

hylb

enze

ne

1,3-

Dic

hlor

oben

zene

1,4-

Dic

hlor

oben

zene

1,4-

Dio

xane

(p-D

ioxa

ne)

Ben

zene

Bro

mom

etha

ne

Car

bon

Tetra

chlo

ride

Chl

orob

enze

ne

Chl

oroe

than

e

Chl

orof

orm

Chl

orom

etha

ne

cis-

1,2-

Dic

hlor

oeth

ylen

e

cis-

1,3-

Dic

hlor

opro

pene

Eth

ylbe

nzen

e

Hex

achl

orob

utad

iene

m,p

-Xyl

ene

Met

hyle

ne C

hlor

ide

o-X

ylen

e

Sty

rene

Tetra

chlo

roet

hene

(PC

E)

Tolu

ene

trans

-1,3

-Dic

hlor

opro

pene

Tric

hlor

oeth

ene

(TC

E)

Tric

hlor

oflu

orom

etha

ne

Vin

yl C

hlor

ide

SEMSG20-B1 5 08/14/2012 <28 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 170 <21 <40 <23 <22 <54 <44 <18 <22 <22 13,000 <19 <23 <27 <28 <13SEMSG20-B1 15 08/14/2012 <28 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 21,000 <19 <23 62 <28 <13SEMSG20-B2 5 08/14/2012 200 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 92,000 19 <23 750 <28 <13SEMSG20-B2 15 08/14/2012 290 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 25 <40 <23 <22 <54 <44 <18 <22 <22 110,000 <19 <23 2,000 <28 <13SEMSG20-B2 15 08/14/2012 300 <200 <200 <100 <100 <90 ‐‐ ‐‐ <200 <100 <200 <100 <100 <100 <200 <100 <100 <100 ‐‐ <80 <90 <100 <100 <60 <100 <50 <90 <100 <100 <300 <200 <80 <100 <100 110,000 <90 <100 2,500 <100 <60SEMSG20-B3 5 08/14/2012 57 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 12,000 <19 <23 77 <28 <13SEMSG20-B3 15 08/14/2012 73 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 19,000 <19 <23 280 <28 <13

SEMSG21-B1 5 08/08/2012 40 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 2,600 <19 <23 29 <28 <13SEMSG21-B1 5 (dup) 08/08/2012 44 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 2,500 <19 <23 <27 <28 <13SEMSG21-B1 15 08/08/2012 73 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 4,500 <19 <23 280 <28 <13SEMSG21-B2 5 08/08/2012 33 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 45 <18 25 <22 490 43 <23 <27 74 <13SEMSG21-B2 15 08/08/2012 41 <35 <39 <28 42 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 22 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 69 <18 32 <22 750 74 <23 140 61 <13SEMSG21-B3 5 08/08/2012 89 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 17 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 45 <18 <22 <22 220 61 <23 <27 460 <13SEMSG21-B3 15 08/08/2012 49 <35 <39 <28 220 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 170 <19 <23 <27 130 <13SEMSG21-B3 15 08/08/2012 50 <10 <20 <10 200 <8 ‐‐ ‐‐ <20 <10 <20 <10 <9 <10 <10 <10 <10 <10 ‐‐ 6 J <8 <10 <10 <6 <10 <4 <8 <10 <9 <20 <20 4 J <9 <9 100 7 J <10 20 500 <5

SEMSG22-B1 5 08/14/2012 210 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 120 <21 <40 <23 <22 <54 <44 <18 <22 <22 4,000 <19 <23 260 <28 <13SEMSG22-B1 15 08/14/2012 560 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 39,000 <19 <23 5,500 <28 <13SEMSG22-B2 5 08/14/2012 210 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 3,300 <19 <23 82 <28 <13SEMSG22-B2 5 (dup) 08/14/2012 240 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 3,900 <19 <23 84 <28 <13SEMSG22-B2 15 08/14/2012 650 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 18 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 27,000 <19 <23 1,800 <28 <13

SEMSG23-B1 5 08/16/2012 85 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 39,000 <19 <23 120 <28 <13SEMSG23-B1 15 08/16/2012 230 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 20 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 74,000 <19 <23 1,000 <28 <13SEMSG23-B1 15 (dup) 08/16/2012 <690 <870 <960 <690 <1000 <500 <680 <760 <940 <620 <970 <760 <510 <1200 <1800 <620 <760 <760 <910 <400 <990 <320 <590 <670 <620 <520 <1000 <580 <550 <1300 <1100 <440 <550 <540 78,000 <480 <580 990 <710 <320SEMSG23-B2 5 08/16/2012 110 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 33,000 <19 <23 190 <28 <13SEMSG23-B2 15 08/16/2012 160 <35 <39 <28 51 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 50,000 <19 <23 160 <28 <13

SEMSG25-B1 5 08/10/2012 <28 <35 170 <28 2,400 33 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 29 <39 <13 <23 <27 <25 <21 570 <23 <22 <54 <44 <18 <22 <22 830 39 <23 1,200 <28 600

SEMSG25-B1 15 08/10/2012 <28 <35 190 <28 4,100 140 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 49 <39 <13 <23 <27 <25 <21 3,000 <23 <22 <54 <44 <18 <22 <22 370 28 <23 1,500 <28 2,400

SEMSG25-B1 15 (dup) 08/10/2012 <28 <35 190 <28 3,300 140 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 34 <39 <13 <23 <27 <25 <21 2,800 <23 <22 <54 <44 <18 <22 <22 370 <19 <23 1,400 <28 2,200

SEMSG25-B2 5 08/10/2012 140 <35 650 <28 2,800 35 <27 <31 <38 <25 <39 <30 <21 85 <71 <25 <30 <30 <37 28 <39 <13 <23 <27 33 <21 1,900 <23 <22 <54 <44 <18 <22 <22 27,000 64 <23 15,000 <28 35

SEMSG25-B2 15 08/10/2012 200 <35 390 <28 4,300 <20 <27 <31 <38 <25 <39 <30 <21 270 <71 <25 <30 <30 <37 19 <39 <13 40 <27 <25 <21 4,300 <23 <22 <54 <44 <18 <22 <22 89,000 20 <23 28,000 <28 42

SEMSG25-B3 5 08/13/2012 <28 <35 <39 <28 <41 <20 <27 <31 <38 28 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 2,400 <19 <23 <27 <28 <13SEMSG25-B3 15 08/13/2012 79 <35 <39 <28 <41 <20 <27 <31 <38 <25 <39 <30 <21 <47 <71 <25 <30 <30 <37 <16 <39 <13 <23 <27 <25 <21 <40 <23 <22 <54 <44 <18 <22 <22 3,300 <19 <23 180 <28 <13

Screening Level for Soil Gas ‐ Residential¹ 990000 15500000² 750² 105000² 1050² 3650² 120² 3650² NA 110² 36 26000² 55² 47000² 16000 420 320000 48000² 3200000 180 140000 530 13Screening Level for Soil Gas‐ Industrial ¹ 2800000 130000000² 7700² 880000² 8800² 47000² 1200² 47000² NA 1100² 120 220000² 530² 390000² 44000 1400 890000 1200000² 8800000 600 380000 1800 45

Detected results shown in bold.Results shown in italics are from split‐samples analyzed by the EPA Region 9 Laboratory.

exceeds Industrial and Residential Screening Levelexceeds Residential Screening Level

¹CA State Office of Environmental Health Hazard Assessment (OEHHA), September, 2010, Table 3‐ Soil Gas Screening Numbers for Volatile Chemicals Below Buildings Constructed Without Engineered Fill Below Sub‐Slab , unless otherwise noted. Screening levels represent the most conservative criteria which is no‐fill. ² Based on USEPA Regional Screening Levels (RSLs; April 2012) for Residential and Industrial. Calculated using a default soil gas to indoor air attenuation factor of 0.002 for Residential, and 0.001 for Industrial (U.S.EPA,2008 and DTSC,2005). dup = duplicate sampleJ = Concentration is estimated. Primary reason is because it falls between the method detection limit and laboratory reporting limit.NA = screening level not availableug/m3 = micrograms per cubic meterR = sample was rejected and re‐analyzed due to the detection of 1,1‐DFA‐‐ = compound not reported by Region 9 Laboratory

Screening Criteria

International Medication Systems Ltd.

Let's Go Precision Products

Pacific Coast Drum Company

Western Markings Inc.

Cardinal Industrial Finishes




TABLE 2

South El Monte Operable Unit

Contaminants of Concern – Volatile Organic Compounds in Groundwater and Soil Gas

Parameter

Groundwater MCLa (or CA DHS

NL) (µg/L)

EPA Method 524.2 Water

Quantitation Limit (µg/L)

Screening Level for Soil Gas -Residential (µg/m3) b

Screening

Level for Soil Gas -Industrial

(µg/m3) b

TO-15 Air

Quantitation Limit (µg/m3)

EPA 9 Laboratory

1,1-Dichloroethane

5 0.5 750 c 7,700 c

4

1,1-Dichloroethene

6 0.5 105,000 c 880,000 c

4

1,2,3-Trichloropropane

NE

(CA DHS 0.005)

CA DHS

0.005

155 c 1,300 c

6

Tetrachloroethene

5 0.5 180 600

6.8

Trichloroethene

5 0.5 530 1,800

5.4

cis-1,2-Dichloroethene

6 0.5 16,000 44,000

4

1,4-Dioxane

See Table 3-2d See Table 3-2d -- --

3.6

Notes a State of California Primary Maximum Contaminant Level (MCL). b California State Office of Environmental Health Hazard Assessment (OEHHA), September 2010, Table 3 – Soil Gas

Screening Numbers for Volatile Chemicals Below Buildings Constructed Without Engineered Fill Below Sub-Slab Gravel, unless otherwise noted. This table represents the most conservative criteria which is no-fill.

c EPA Regional Screening Levels (RSLs) for indoor air used as a basis (EPA, 2012). Soil gas screening levels are based on California’s recommended attenuation factors from soil gas to indoor air (Cal/EPA, 2005).

d Sampling and Analysis Plan, Supplemental Remedial Investigation/Feasibility Study, San Gabriel Valley Area 1 Superfund Site, South El Monte Operable Unit, San Gabriel Basin, 2010, Table 3-2

µg/L = micrograms per liter MCL = Maximum Contaminant Level µg/m3 = micrograms per cubic meter NE = not established CA DHS = California Dept of Health Services NL = (CA DHS) Notification Level EPA 9 = U.S. EPA, Region 9 RSL = (EPA R9) Regional Screening Level




FIGURES

ITSI Gil ~§i if§

1000

100

10

5

1

100

10

100

51100

50

105 10

10

5

100

10

10

50

50

10

GENCORP-AEROJET*

SOUTHERNCALIFORNIA

EDISON

CHAMPCORPORATION

WALL MACHINEWORKSINC.

ROC-AIRECORP.

FLEXFIRMPRODS

INACTIVE NIKEMISSILE SITE

LA VICTORIA

PLASTICDRESS-UPCOMPANY

LAWRENCEEQUIPMENT

DYANCOINC.

COMPRESSORPARTS &

REPAIR,INC.

JAMESANDRUSS'PROPERTY

DURHAMTRANSPORTATION MARGE

CARSONINC.

CRANVEYORCORPORATION

LOS ANGELESDIE MOLD

FORMS ANDSURFACES,

INC.

SARGENT-FLETCHERCO.

SBICCA OFCALIFORNIA

IRISHCONSTRUCTION

R&R CUSTOMCOACHWORKS,

INC.

AREMAC HEATTREATING

INC.

AIR DISTRIBUTIONPRODUCTS, INC

YIRNG SHENG CO.

DELLACORCO., INC.

MULTICHEMICALPRODUCTS

CALIFORNIAALLOYCO.DIV.ROLOCK

SCANBE DIVISION OFZERO CORP.

TRI-FITTINGMFG. CO.

CLAMP MAN. CO.

%

J.A. BOZUNG CO.

%

PALMER BATTERY*(RU-MORE)

%

MANUFACTURER'SSERVICE, INC.

%

J.C. INC.BARRY

ZWAHLEN

%

PACIFIC COAST DRUM COMPANY

%

CHEMRITECORP.

%

COOPERDRUM

COMPANY%TED LEVINE

DRUM COMPANY

%

CUSTOM METALPRODUCTS, INC.

% MAMMOETWESTERN, INC.

% ANCHORPLATINGCO., INC.

%

ONE DOLLAR CLEANERS

%

HYTONECLEANERS

%

EPAW416

%

EPAW414")

")

%

ASTRONAUTIC ENAMELERS

SERVEX

%

ARTISTICPOLISHING

%SMITTYBUILT,INC.

%

EEMUS MFG.

%

EAGLE METAL FINISHING

%

LETS GO PRECISION

%

WESTERNMARKINGS

INC

%

IMS LTD.

%

LEE PHARMACEUTICALS

%

PHILLIPS AND MALONE

%

CARDINAL INDUSTRIALFINISHES

%

SEACHROMECORPORATION

%

ASTRO SEAL, INC.

§̈¦10

§̈¦605

ST60

ST19

ST60

ST19

P

eck

Rd

T

yler

Ave

Rush St.

D

urfe

e Ave

Ga rv ey Ave

Val ley Blvd

W

alnu

t Gro

ve A

ve

Peck

Rd

Santa Anita

Ave

Durfee Ave

G:\ArcGIS\EPA\S_El_Monte\PROJECTS\Soil_Gas\Tech_Memo_2012_Oct\Figure_1.mxd 10/17/2012 [13:06 PM] LCARR, ITSI

Draft Soil Gas Sampling Results, August 2012Supplemental Remedial Investigation/Feasibility Study

San Gabriel Valley Area 1 Superfund Site, South El Monte Operable UnitLos Angeles County, California

USEPA Region 9

FIGURE 1SOIL GAS SAMPLING LOCATIONSAUGUST 2011 AND AUGUST 2012

Facility Sampled in 2012

Estimated Groundwater VOC Plume - Shallow Zone Sept/Oct 2011 data (ug/L)

OU Boundary

"!O0 1,500 3,000750

FEET

HYTONE CLEANERS

ARTISTIC POLISHING

ONE DOLLAR CLEANER

RED TEXT: SITE SAMPLED IN AUGUST 2012

GREEN TEXT: SITE SAMPLED IN AUGUST 2011

BLUE TEXT: SITE NOT SAMPLED

Facility Outline

* Downgradient Soil Gas Samples at Palmer Battery were collected in 2011. Site access was not granted for proposed 2012 soil gas sampling.




ATTACHMENTS

ITSI Gil ~§i if§




ATTACHMENT 1

Facility Soil Gas Locations and Results

ITSI Gil ~§i if§

G:\ArcGIS\EPA\S_El_Monte\PROJECTS\Soil_Gas\Tech_Memo_2012_Oct\SG_Astro_Seal.mxd 10/17/2012 [13:34 PM] LCARR, ITSI

FIGURE 1SOIL GAS WELL LOCATIONS AND TCE/PCE RESULTS

Astro Seal Incorporated9448 Rush Street, South El Monte, California (Current Address)

Soil Gas Boring Location##

NOTES:1) -Data results that are highlighted in red exceed Industrial and Residential Risk Screening Levels. -Data results that are highlighted in yellow exceed Residential Risk Screening Levels.

2) <27 = Not detected at analytical reporting limit.

50 0 50

Feet

o

Facility Boundary

SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG10-B1 5 12,000 33SEMSG10-B1 15 12,000 10,000SEMSG10-B1 15 (dup) 12,000 10,000

SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG10-B2 5 2,600 <27SEMSG10-B2 15 2,200 800

SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG10-B3 5 41,000 140SEMSG10-B3 15 67,000 1,300

ATTACHMENT 1DRAFT SOIL GAS SAMPLING RESULTS AUGUST 2012Supplemental Remedial Investigation/Feasibility Study

San Gabriel Valley Area 1 Superfund Site - South El Monte Operable UnitLos Angeles County, California

G:\ArcGIS\EPA\S_El_Monte\PROJECTS\Soil_Gas\Tech_Memo_2012_Oct\SG_Astronautic_Enamelers.mxd 10/17/2012 [13:35 PM] LCARR, ITSI


Astronautic Enamelers9758 Klingerman Street, South El Monte, California


NOTE:1) -Data results that are highlighted in red exceed Industrial and Residential Risk Screening Levels. -Data results that are highlighted in yellow exceed Residential Risk Screening Levels.

30 0 30

Feet

o

SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG11-B2 5 110,000 1,200SEMSG11-B2 15 310,000 9,200

SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG11-B3 5 170,000 1,300SEMSG11-B3 5 (dup) 160,000 1,900SEMSG11-B3 15 330,000 5,400


Facility Boundary



G:\ArcGIS\EPA\S_El_Monte\PROJECTS\Soil_Gas\Tech_Memo_2012_Oct\SG_Cooper_Drum.mxd 10/17/2012 [13:31 PM] LCARR, ITSI


Cooper Drum Company9629 El Poche Street, South El Monte, California


30 0 30

Feet

o


SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG12-B2 5 750 360SEMSG12-B2 15 1,300 370

SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG12-B3 5 420 220SEMSG12-B3 15 2,600 900

Facility Boundary



San Gabriel Valley Area 1 Superfund Site - South El Monte Operable UnittLos Angeles County, California

G:\ArcGIS\EPA\S_El_Monte\PROJECTS\Soil_Gas\Tech_Memo_2012_Oct\SG_Custom_Metal.mxd 10/17/2012 [13:32 PM] LCARR, ITSI


Custom Metal Products, Incorporated1524 Chico Avenue, South El Monte, California


NOTES:1) Data results that are highlighted in red exceedIndustrial and Residential Risk Screening Levels.

2) R = Sample was rejected and re-analyzed due to the detection of 1,1-DFA(leak detection compound).


50 0 50

Feet

o

Facility Boundary

SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG13-B1 5 73,000 84SEMSG13-B1 15 60,000 130


SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG13-B3 5 R RSEMSG13-B3 5 42,000 <270SEMSG13-B3 15 40,000 64


San Gabriel Valley Area 1 Superfund Site - South El Monte Operable UnittLos Angeles County, California

G:\ArcGIS\EPA\S_El_Monte\PROJECTS\Soil_Gas\Tech_Memo_2012_Oct\SG_Hytone_Cleaner.mxd 10/17/2012 [13:37 PM] LCARR, ITSI


Hytone Cleaners2702 North Mountain View Road, El Monte, California


30 0 30

Feet

o

SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG14-B1 5 14,000,000 8,500SEMSG14-B1 15 36,000,000 11,000SEMSG14-B1 15 (dup) 43,000,000 <140,000

SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG14-B2 5 11,000,000 <140,000SEMSG14-B2 15 24,000,000 <140,000

SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG14-B3 5 4,400,000 <140,000SEMSG14-B3 15 21,000,000 <140,000

NOTES:1)- Data results that are highlighted in red exceed Industrial and Residential Risk Screening Levels;

2) <140,000 = Not detected at analytical reporting limit.

Facility Boundary



G:\ArcGIS\EPA\S_El_Monte\PROJECTS\Soil_Gas\Tech_Memo_2012_Oct\SG_Bozung.mxd 10/17/2012 [13:40 PM] LCARR, ITSI


J.A. Bozung Company9401 Whitmore Street, El Monte, California


50 0 50

Feet

o



SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG15-B2 5 72,000 490SEMSG15-B2 15 61,000 650SEMSG15-B2 15 (dup) 67,000 910


Facility Boundary



G:\ArcGIS\EPA\S_El_Monte\PROJECTS\Soil_Gas\Tech_Memo_2012_Oct\SG_Mammoet_Western.mxd 10/17/2012 [13:41 PM] LCARR, ITSI


Mammoet Western Incorporated1419 Potrero Avenue, South El Monte, California


50 0 50

Feet

o

SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG16-B2 5 4,000 120SEMSG16-B2 5 (dup) 3,700 110SEMSG16-B2 15 2,800 <27

NOTES:1)- Data results that are highlighted in red exceed Industrial and Residential Risk Screening Levels. -Data results that are highlighted in yellow exceed Residential Risk Screening Levels.


3) PV = Purge volume test results.

Facility BoundarySAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG16-B1 (1PV) 5 4,100 71SEMSG16-B1 (3PV) 5 4,200 79SEMSG16-B1 (10PV) 5 4,100 60SEMSG16-B1 (1PV) 15 4,300 930SEMSG16-B1 (3PV) 15 5,200 1,100SEMSG16-B1 (10PV) 15 6,000 1,200



G:\ArcGIS\EPA\S_El_Monte\PROJECTS\Soil_Gas\Tech_Memo_2012_Oct\SG_Manufacturers_Services.mxd 10/17/2012 [13:44 PM] LCARR, ITSI

FIGURE 8SOIL GAS BORING LOCATIONS AND TCE/PCE RESULTS

Manufacturer's Services Incorporated - 2210 Chico AvenueElegant Cabinets - 2218 Chico Avenue

South El Monte, California


NOTE:1) -Data results that are highlighted in red exceed Industrial and Residential Risk Screening Levels.

30 0 30

Feet

o




Facility Boundary



G:\ArcGIS\EPA\S_El_Monte\PROJECTS\Soil_Gas\Tech_Memo_2012_Oct\SG_Phillips_Malone.mxd 10/17/2012 [13:47 PM] LCARR, ITSI



NOTE:1) -Data results that are highlighted in red exceed Industrial and Residential Risk Screening Levels.

30 0 30

Feet

o



Phillips & Malone1439 Lidcombe Avenue, South El Monte, California

Facility Boundary

SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG18-B1 5 2,000 310SEMSG18-B1 15 820 340



G:\ArcGIS\EPA\S_El_Monte\PROJECTS\Soil_Gas\Tech_Memo_2012_Oct\SG_Servex.mxd 10/17/2012 [13:51 PM] LCARR, ITSI



40 0 40

Feet

o


Servex Corporation9620 Klingerman Street, South El Monte, California

SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG19-B1 5 130,000 1,300SEMSG19-B1 15 260,000 6,400SEMSG19-B1 15 (dup) 260,000 5,400


Facility Boundary



G:\ArcGIS\EPA\S_El_Monte\PROJECTS\Soil_Gas\Tech_Memo_2012_Oct\SG_Western_Marking.mxd 10/17/2012 [13:54 PM] LCARR, ITSI



30 0 30

Feet

o

Western Markings Incorporated1930 Doreen Avenue, South El Monte, California




NOTES:1)- Data results that are highlighted in red exceed Industrial and Residential Risk Screening Levels.

-Data results that are highlighted in yellow exceed Residential Risk Screening Levels.


Facility Boundary



G:\ArcGIS\EPA\S_El_Monte\PROJECTS\Soil_Gas\Tech_Memo_2012_Oct\SG_Cardinal.mxd 10/17/2012 [14:59 PM] LCARR, ITSI


40 0 40

Feet

o

Cardinal Industrial Finishes1329 Potrero Avenue, South El Monte, California

SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG21-B1 5 2,600 29SEMSG21-B1 5 (dup) 2,500 <27SEMSG21-B1 15 4,500 280


NOTES:1) Data results that are highlighted in red exceedIndustrial and Residential Risk Screening Levels.

2) Data results that are highlighted in yellow exceedResidential Risk Screening Levels.


Facility Boundary

SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG21-B2 5 490 <27SEMSG21-B2 15 750 140

SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG21-B3 5 220 <27SEMSG21-B3 15 170 <27



G:\ArcGIS\EPA\S_El_Monte\PROJECTS\Soil_Gas\Tech_Memo_2012_Oct\SG_IMS.mxd 10/17/2012 [13:59 PM] LCARR, ITSI



30 0 30

Feet

o


International Medication Systems, Limited1919 Santa Anita Avenue, South El Monte, California

Facility Boundary


SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG22-B2 5 3,300 82SEMSG22-B2 5 (dup) 3,900 84SEMSG22-B2 15 27,000 1,800



G:\ArcGIS\EPA\S_El_Monte\PROJECTS\Soil_Gas\Tech_Memo_2012_Oct\SG_Lets_Go.mxd 10/17/2012 [14:03 PM] LCARR, ITSI


30 0 30

Feet

o

Let's Go Precision Products 1924 Doreen Avenue, South El Monte, California



Facility Boundary

SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG23-B1 5 39,000 120SEMSG23-B1 15 74,000 1,000SEMSG23-B1 15 (dup) 78,000 990




G:\ArcGIS\EPA\S_El_Monte\PROJECTS\Soil_Gas\Tech_Memo_2012_Oct\SG_PC_Drum.mxd 10/17/2012 [14:09 PM] LCARR, ITSI


Pacific Coast Drum Company2200 Rosemead Boulevard, South El Monte, California


100 0 100

Feet

o


SAMPLE ID DEPTH (FT) PCE (ug/m3) TCE (ug/m3)SEMSG25-B1 5 830 1,200SEMSG25-B1 15 370 1,500SEMSG25-B1 15 (dup) 370 1,400

NOTES:1)- Data results that are highlighted in red exceed Industrial and Residential Risk Screening Levels. -Data results that are highlighted in yellow exceed Residential Risk Screening Levels.


Facility Boundary







ATTACHMENT 2

Data Quality Assessment

Documents

Technical Memo: Draft soil gas sampling results, 8/12