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Critical Stratigraphic Section

The CSS proposed by Applicant’s consultants includes the following two hydrostratigraphic units

in descending order:

1) An overburden groundwater flow system that occurs within the glacial till,

glaciolacustrine, and/or ice-contact deposits. It is defined as the first occurrence of groundwater

of any significance.

2) An upper bedrock groundwater flow system within weathered bedrock near an

interface between bedrock and overlying glacial sediment.

This Applicant-proposed CSS mis-represents the actual site conditions discussed below and

omits the most permeable and critical CSS unit present within the lower overburden. This flaw

has serious consequences on assessments of landfill vulnerability, the proposed groundwater

suppression system, and efficacy of the Applicant-proposed groundwater monitoring.

The contour map of the top of bedrock surface (Figure 6 in the HIR) shows three distinct

portions of the bedrock surface aligned parallel with the strike of the Devonian bedrock beds:

1) A steep southeasterly slope of the bedrock surface within the northwestern portion of the site,

2) A nearly-flat bedrock terrace portion, approximately 800 ft wide and trending to the northeast,

and 3) A gentler slope facing the Rt 86. The highly permeable lower overburden deposits are

present on the eroded terrace and the gentle slope portions.

The southern half of the proposed landfill extension is located within the terrace portion, with the

southernmost tip of the extension encroaching on the gentle slope portion (Figures 1 and 6 of

the HIR).

Lower Overburden Aquifer

The high permeability of the lower overburden deposits at the expansion site - relative to till

deposits of the upper overburden - is well documented by results of hydraulic conductivity

testing, descriptions on boring logs, and other indirect evidence.

Slug testing results for the “ice contact” wells indicate hydraulic conductivity values as high as

5x10-2 cm/s, see Table 6 in the HIR. (One can show that the results were biased low.) The

designation of soils on the boring logs as either “till” or “ice contact” deposit is subjective and

often arbitrary, as there are transitions between these and other type of glacial deposits, and it’s

their permeability characteristics that ultimately count. The distinctive characteristics of the

highly permeable lower overburden unit include the presence of exotics (like granite), deep

weathering and brighter colors reported on logs of borings from the terrace portion of the

expansion. These are much older deposits than tills in the upper overburden and on the steep

slope portion. The highly permeable lower overburden unit is found between approximate

elevations of 790 ft and 830 ft (Figures 8-12 in the HIR) . This unit can be correlated with

glaciofluvial deposits designated as “t” on the Waverly–Sayre area map east of the site

(Reynolds, 2003) and outwash sand and gravel deposits (“osg”) mapped by Miller et al. (1982)

in the Elmira area.

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The following provides specific examples of the presence of the highly permeable lower

overburden deposits in the landfill expansion area:

The log of exploratory boring EB-11, completed in the middle of the southern tip of the

expansion area (Figure 1 in the HIR), shows that a permeable sand and gravel deposit (denoted

as till on the log) is present from 52 ft (elev. 828 ft) to the top of bedrock at 84 ft (elev. 796 ft).

Methane gas was reportedly encountered in this exploratory hole at a depth 68 ft . The existing

nearby landfill is an apparent source of this methane, which would attest to a lateral continuity of

this highly permeable lower overburden unit in the area. The permeable sand and gravel

(denoted as ice contact deposit on the log) has also been mapped at EB-06B/C from a depth of

100 ft (elev. 805 ft) to the bedrock at 114 ft (elev. 791 ft). But the log indicates that the

permeable sand and gravel deposit is much thicker there and starts at least from 92 ft (elev. 813

ft). The same permeable sand and gravel deposit is found in EB-02 between 96 ft (elev. 811)

and 110 ft (elev. 797 ft). These boring logs data indicate the continuity of the lower overburden

aquifer unit, the critical unit of the CSS.

Alleged Upper Bedrock Flow Zone vs the Lower Overburden Aquifer

What the Applicant calls the top-of-bedrock (or upper bedrock) flow zone is an artificial creation

that is inconsistent with the known hydrogeologic framework of sedimentary bedrock sites.

Experience from numerous sedimentary bedrock sites, including Devonian bedrock sites in

Wisconsin, Minnesota and the Catskill Region of New York, shows that bedding parallel flow

prevails in bedrock at such sites, with the more transmissive bedding fractures providing major

flow pathways in a bedrock aquifer featuring multiple transmissive bedding fractures. Joints

provide for some leakage between the transmissive bedding fractures. This conceptualization

of the bedrock is also supported by icicles that can be observed in wintertime marking

groundwater discharges commonly from bedding fractures of (weathered) bedrock in the region.

Based on a gentle southerly dip of bedrock beds in the study area, one expects that a bedrock

recharge area contributing flow to the site extends to the other (northern) side of the

Shoemakers Mountain. There, transmissive bedding fractures crop out at higher elevations then

on the buried steep slope in the landfill area. The resulting gravity effect forces groundwater to

discharge into the overburden which the bedding fractures intersect at lower elevations. The

highly permeable lower overburden unit provides the ultimate receptor of the inflows from the

bedrock.

Unfortunately, groundwater level data provided in the HIR are limited to two sets of

potentiometric surface maps for the overburden and the top-of-bedrock bedrock units for

January 2011 and April 2011 (Figures 14 – 17). These maps do not include water levels from a

number of monitoring wells subsequently installed in the expansion area. Moreover, no

groundwater level data from the latter wells have been provided in Table 3 of the HIR. The

failure to provide any groundwater level data for post-2011 monitoring wells is a major

deficiency of the HIR, as these wells include the only two wells screened within the critical lower

overburden aquifer unit (MW-24C and MW-25C). Potentiometric heads in these wells are

expected to be lower than in the bedrock (“B”) and Upper Overburden (A) wells.

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Given the lack of potentiometric data from these lower overburden aquifer (“C”) wells, one can

use the top of bedrock potentiometric map as an imperfect substitute for a potentiometric map of

the critical lower overburden aquifer. Although the potentiometric heads in the top of bedrock

are expected to be somewhat higher than in the lower overburden aquifer (to which

groundwater discharges from the bedrock), an overall potentiometric pattern would be similar as

the lower overburden aquifer controls the groundwater flow in the area. With this caveat, the top

of bedrock map for April 2011 (Figure 15 in the HIR) implies an east-southeasterly groundwater

flow within the critical lower overburden aquifer.

Due to the lack of monitoring wells screened within the critical lower overburden aquifer, it’s not

possible to determine a representative horizontal hydraulic gradient necessary to calculate

groundwater velocity in this unit. The flow can only be qualified as rapid, based on the character

of sand and gravel deposits that make this aquifer. Applicant-calculated groundwater velocity in

the HIR lacks merit. Although hydraulic gradient value cannot be properly quantified, it is very

low within the terrace and the gentle bedrock slope portions, reflecting the highly permeable and

continuous nature of the lower aquifer deposits there. The head values are only several feet

above the Chemung River level, which is indicative of aquifer connection with the river.

As groundwater from the bedrock discharges into the lower overburden, the top of bedrock

monitoring wells may have some value as piezometers, but not for monitoring of potential

releases from the landfill.

The Lower Overburden Aquifer is Highly Vulnerable to Contaminant Releases from the

Expansion Area

Very low overburden water levels have been measured in the overburden within the southern

half of the proposed expansion area. Wells MW-23A and MW-24A, installed in that area to

depths of 60ft and 56 ft, have always been dry. The two available overburden water table maps

(Figure 14 and 15 in the HIR) and cross-section D-D’ (Figure 10) document an inward and

downward hydraulic gradient and flow beneath the southern portion of the expansion area.

There is clearly a vertical permeability window there that results in a rapid vertical drainage into

the lower overburden aquifer beneath the southern portion of the expansion area. Its presence

is confirmed by descriptions of deposits on logs of EB-11 and EB-2, as well as by reported fast

disappearance of water added to these borings and the two dry wells. All these data indicate a

rapid vertical migration of potential releases from the landfill into the critical lower overburden

aquifer.

In this context, a vertical flow rate calculated by the Applicant of 0.07 feet per year, which would

require approximately 135 years to travel a ten-foot vertical distance (page 34 in the HIR), is a

fallacy unsupported by any real site data or testing results. The calculation ignored the fact that

significant landfill-related contamination (Benzene at 23 ug/l, Trichloroethene at 26 ug/L,

Toluene at 24 ug/L, and Chlorobenzene at 27ug/L) was detected in well MW-8A in October

2002 (FEIS, Vol. 1, 80). The top of screen in this well, located downgradient of Area 5, was 81 ft

below ground surface. At the Applicant-calculated rate, it would take1,090 years to travel this

vertical distance. The case of well MW-8A underscores the site vulnerability as well as the

misleading nature of Applicant’s calculations.

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The proposed permeable groundwater collection (suppression) system below the lower liner will

have an unintended impact of channeling potential landfill releases from the northern half of the

expansion area along the collection system downward into the critical lower overburden aquifer,

thus enhancing the vulnerability of the aquifer to the landfill-derived contamination.

Deficiencies of Proposed Groundwater Monitoring

The Environmental Monitoring Plan does not specify which of the proposed wells are

considered upgradient/background well and which are downgradient wells for the

expansion area (Cell V), the adjacent active landfill and Area 5.

When contaminants are detected in downgradient monitoring well(s), with the proposed

monitoring system it may not be possible to determine if such contaminants originated

from the proposed Cell V, currently active landfill or Area 5.

There are only two (2) monitoring wells (MW-24C and MW-25C) screened within the

critical lower aquifer unit at Cell V area. This is the most serious deficiency of the

proposed groundwater monitoring.

As stated earlier, the top of bedrock wells cannot be relied on for monitoring of landfill

releases. However, the sampling methodology that involves evacuation of three well

volumes prior to collection of analytical samples may reverse the original upward

gradient in a bedrock well and result in drawing water from the overburden. To avoid this

sampling artifact, low-flow sampling methodology should be used.

The proposed residential well monitoring plan does not include two supply wells for the

mobile home park, apparently the largest water user in the area. Also, there appears to

be a residence north of Residence 05 that is not included in the plan. These three wells

should be included in the sampling program as they are most likely to be impacted by

the known contamination in the MW-5, MW-8 and MW-12 area.

References

Heisig, P.M, 2015: Hydrogeology of Valley-Fill Aquifers and Adjacent Areas in Eastern

Chemung County, New York; USGS Scientific Investigations Report 2015–5092, available at

https://pubpublications.er.usgs.gov//sir20155092.

Miller T.S., A.D. Randall, J.L. Belli, and R.V. Allen, 1982: Geohydrology of the Valley-fill Aquifer

in the Elmira Area, Chemung County, New York, Open-File Report 82-110.

Reynolds, R., 2003: Hydrogeology of the Waverly–Sayre Area in Tioga and Chemung

Counties, New York and Bradford County, Pennsylvania, OF 02-284.

TOGS 2.1.3, 1990: Division of Water Technical and Operational Guidance Series (2.1.3.) Primary and Principal Aquifer Determinations (Originator: Mr. DeGaetano). Memorandum dated October 23, 1990, available at http://www.dec.ny.gov/docs/water_pdf/togs213.pdf.