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EBASCO SERVICES INCORPORATED --~-" 160 Chubb Avenue. Lyndhurst . NJ 07071 · (201) 460-1900

October 22, 1987 REM-WGH-10

Ms. Barbara Newman Remedial Project Manager U.S. Environmental Protection Agency Region I JFK Building Boston, Massachusetts 02203

SUBJECT:. WELL G&H PROJECT MODIFICATION OF WR GRACE SAMPLING PLAN WORK ASSIGNMENT NUMBER: 132-1L46 EPA CONTRACT NQMBER: 68-01-7250

Dear Ms. Newman:

Based on Ebasco's soil gas survey results, WR Grace's recent comments and our discussion of October · 21, 1987, we have developed the following modification to the field sampling program at WR Grace.

Sampling of Monitoring Wells

Since WR Grace has indicated they will · not be sampling their groundwater monitoring wells, Ebasco will have to do this sampling. A Work Assignment Amendment will be submitted as we discussed since this was not included in our scope of work. Table 1 shows the proposed list of 23 monitoring wells to be sampled. Analysis of samples will remain the same as that in Field Operations Plan for split samples which Ebasco planned to collect. Locations of the wells to be sampled are shown in the attached figure.

Soil Boring Locations

The 10 proposed soil boring locations in the Work Plan have been revised as follows:

0 Eliminate the following locations (see attached figure): SB1, SB7, SB9 and SB10.

SBl - Not a likely source area for soil and groundwater contamination based on our understanding of site history of waste disposal areas used in the past.

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SB7 - No groundwater contamination detected at Gl7 well.

SB9 & 10 - Not a likely source since this area has been

paved since mid 1960's based on review of aerial photograph.

o Designate new location for SBl and SB7 in back of building in area of soil gas readings as shown in the attached figure.

o Designate new boring location SB9 to collect soil sampling data in this area to the back.

o Leave SB4, SBS, SB6, and SB8 at present locations.

o Move SB2 and SB3 to the east to line up with Well Gl9S.

If you have any questions or comments on this revised plan at WR Grace, please do not hesitate to call me. Ebasco will start sampling theW R Grace wells the week of October 26, 1987.

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cc: R Boyd (Region 1-RM)T Kipp B Falotico

TABLE 1

PROPOSED LIST OF MONITORING WELLS TO BE SAMPLED AT WR GRACE

Shallow Wells Deep Wells

G3S G3D, 3GDD G6S G4D G7S GllD G9S G12D GllS G14D Gl2S G15D G14S G16D Gl5S G21D Gl9S G20S G21S G25S G26S G29S

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