Remedial Action Plan - Rochford Field - Newhall Remediation Project

the vicinity of sprinkler system manifolds and along the fence line. The objective of the M&E
work was to minimize potential exposure to arsenic-containing soils in high traffic areas.
Following the M&E interim remedial measures, the Town reopened Rochford Field for public
use.
2.1.4 Nature and Extent of Soil and Groundwater Impacts
The Rochford Park fill deposits appeared to increase in thickness to the southeast and
northwest; generally following the path of the former stream observed in the 1934 aerial
photograph of the area. The greatest thicknesses of this material, 11 ft, was observed in RF-
HA209-MW, in the central portion of the field. The thickness of earthen fill covering the
industrial waste fill and miscellaneous fill is shown on Figure 4 in Appendix B. The combined
fill thickness is shown on Figure 5 in Appendix B.
In Rochford Field, fill materials were encountered above alluvial deposits and/or glaciodeltaic
sediments. Alluvial deposits, generally marking the location of former wetlands or standing
water bodies, ranged in thickness from 1.5 to 8 ft. Bedrock outcrops were not observed on the
site, and bedrock was not encountered during the explorations. Based on results of
explorations, conducted by others on adjacent properties, sedimentary bedrock likely underlies
glaciodeltaic deposits at approximately 50 ft below grade. Refer to Figure 3 in Appendix B for
subsurface profiles of Rochford Field.
Groundwater was encountered at or near the top of the natural overburden deposits in the
northern and southern portions of Rochford Field. Within the central portion of the field,
however, groundwater was encountered within the fill material. Refer to Figure 2B for
groundwater elevation information.
Due to the heterogeneous nature of the fill deposits, chemical testing detected various
polyaromatic hydrocarbons (PAHS), ETPH, and metals at concentrations in excess of PMC
and/or RDEC at widespread locations and depths within the fill. Results of chemical testing did
not detect evidence of significant impacts to natural overburden materials underlying the fill in
Rochford Field. Three out of 31 samples of natural overburden materials tested contained one
or more COCs at a concentration in excess of RSR RDEC. Lead and arsenic were detected
above the RSR RDEC in one alluvial sample; ETPH was detected above RDEC in another
alluvial sample; thallium was detected above RSR RDEC in a sample of glaciodeltaic sand.
Chemical testing of soil and groundwater explorations located in the northern portion of
Rochford Field detected elevated concentrations of petroleum hydrocarbons (ETPH) as well as
aromatic VOCs and SVOCs. Results of the geophysical survey did not indicate the presence of
drums.During the drilling of borings RF-HA108-MW, Haley & Aldrich encountered an oily
sheen and/or petroleum odors in samples collected from 5 to 7 ft and 7 to 9 ft below grade. A
similar odor and sheen was observed below the water table (approximately 6 ft below grade) in
RF-HATP-7. RF-HATP-7 was also observed to contain numerous, thin, cut pieces of sheet
metal and other metal objects immediately above and intersecting the water table. Bulk disposal
of scrap metal, which is typically oily or mixed with cutting oils, could have caused elevated
metal impacts associated with a dissolved hydrocarbon groundwater plume. Oil draining from
the metal would have also adsorbed to fine grained material within and underlying the fill. The
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