Amendment 0007_DMC Slug Tests - Revised.pdf

ments were made on till samples from USGS test holes about 0.5 mi southeast of Durham Center. These data are summarized in table 3.

The hydraulic conductivities determined from the aquifer tests are higher than the laboratory-determined values, and this relation is consis tent with observations made elsewhere (Stephenson and others, 1988, table 3). The difference in hydraulic conductivity measured by field and laboratory tests is generally ascribed to the till having both primary (inter-granular) hydraulic conductivity and second ary hydraulic conductivity produced by fractures or other types of secondary openings.

Laboratory tests commonly measure only the primary hydraulic conductivity of a till matrix.

Aquifer tests, such as those done by Leggette, Brashears, and Graham, Inc. (1982), however, are more likely to measure the hydraulic con ductivity of the "bulk mass" of till that includes fractures or other secondary open ings. Because these aquifer tests were conven tional single-well response (slug) tests, they may also have underestimated the hydraulic conductivity of the bulk mass of a fractured till (D'Astous and others, 1989; Keller and others, 1989).

Hydraulic conductivity, porosity, and hydraulic gradient are commonly used to estimate the average linear velocity of water moving through granular materials such as till.

The porosity values in table 3 are laboratory

Table 3. Hydraulic properties of till, Durham, Conn.

[b, hydraulic conductivity of bulk mass of till; m, hydraulic conductivity of the till matrix; USGS, U.S.

Geological Survey; ft, feet; ft/s, feet per second; ft/d, feet per day; cm/s, centimeters per second; -, no data]

Location 1 Durham Manufacturing

Cb» monitoring wells OW-3 and 0W-7 (USGS s

Durham Manufacturing

Type of test and method of analysis

Single-well response (slug) test Analyzed using method described byHvorslev(l95i)

Single-well response

Hydraulic conductivity (feet per day)

0.22 to 0.57 (b)

.04 to 2.4 (b)

Porosity (percent) Remarks

Leggette> Brashears, and Graham, Inc.

(1982), Values ?i areconverted j froml^stoftM J

Do.

Co. monitoring wells OW-2,OW-6,andOW-8 (USGS wells D-193, D-197,andD-199) CherryJbane, Durham, es leis are from 2.6 to 3$Afrfcelbw: land surface" Durham-Middlefield landfill, Durham, Conn.;

3 core samples from deep trench

(slug) test. Analyzed using method described by Papadopolous and others (1973) Constant-head permeameter tests measuring vertical hydraulic conductivity

Constant-head permeameter tests measuring vertical hydraulic conductivity

,0005 to 0.05 (m) 21 to 28 Melvinand oiiiers (1992a converted Iron*

.014 to 0.07 (m) 32 to 27 Do.

GEOHYDROLOGY OF THE DURHAM CENTER AREA 31

A

A

A

A

A

A

A

M

AIN

STR

EET - C

T. RTE 17

CT.

RTE 68

SLUDGE

DRYING BEDS

METHYLENE

CHLORIDE

STORAGE TANK

INDUSTRIAL

WASTE

GALLERY

B A

LL B

R

O O

K

DMC

WELL 3

DMC

WELL 1

DMC

WELL 2

OW-5

OW-6

OW-7

OW-8

OW-3

OW-2

OW-1

DEGREASER

DEGREASER TANK

FORMER LEACH

FIELD AREA

AREA OF

SETTLING POND DITCH

AREA OF FORMER

SETTLING TANK

SEPTIC SYSTEM

PRIOR TO 1974

OW-2

Analyte Concentration (ppb)

PCE 650

TCE 21200

MeCl2 7100

1,1,1-TCA 9300

Barium 5400

OW-5

Analyte Concentration (ppb)

PCE 5

TCE 84

Benzene 50

OW-6

Analyte Concentration (ppb)

PCE 2900

TCE 118000

MeCl2 610 2-Butanone 2000

Toluene 37000 Barium 8500

OW-7

Analyte Concentration (ppb)

PCE 8

TCE 380

2-Butanone 860 Barium 2700

OW-8

Analyte Concentration (ppb)

PCE 9

TCE 140

1,1,1-TCA 260

Barium 1000

OW-3

Analyte Concentration (ppb)

PCE 17

TCE 430

MeCl2 300 2-Butanone 6900

Toluene 1300 Barium 3150

190200

0 20 40 60 8010 Feet

G

P ro je ct s\ C

O N

N E

C

TI

C U

T\ D

U R

H A

M \M ap s\

D M

C _1

2_

G W

.m xd

³

SOURCE: Legette, Brashears & Graham, Inc. 1982

Figure 4.2-2 CT RSR Exceedences in Groundwater:

LB&G 1982

DMC Study Area

Durham Meadows Superfund Site Durham, Connecticut

* Well locations are approximate.

** Historical features are underlined and italicized.

*** OW-4 is not depicted on figures in the 1982 LB&G Report.

LEGEND

Elevation Contours 20 Feet Contour Interval

Industrial Waste Gallery Sludge Drying Beds Tank

Roads

6 DMC Well A Monitoring Well

Hydrology

Wetland Pond Parcel Boundary

Durham Manufacturing Company

03/2005