Environmental Monitoring Series
MONITORING GROUNDWATER QUALITY:
METHODS AND COSTS
Environmental Monitoring and Support Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Las Vegas, Nevada 89114
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL MONITORING series.
This series describes research conducted to develop new or improved methods
and instrumentation for the identification and quantification of environmental
pollutants at the lowest conceivably significant concentrations. It also includes
studies to determine the ambient concentrations of pollutants in the environment
and/or the variance of pollutants as a function of time or meteorological factors.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/4-76-023
May 1976
MONITORING GROUNDWATER QUALITY:
METHODS AND COSTS
by
Lome G. Everett
Kenneth D. Schmidt
Richard M. Tinlin
David K. Todd
General Electric Company—TEMPO
Center for Advanced Studies
Santa Barbara, California 93101
Contract No. 68-01-0759
Project Officer
George B. Morgan
Monitoring Systems Research and Development Division
Environmental Monitoring and Support Laboratory
Las Vegas, Nevada 89114
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
ENVIRONMENTAL MONITORING AND SUPPORT LABORATORY
LAS VEGAS, NEVADA 89114
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This report has been reviewed by the Environmental Monitoring and Support Labora-
tory—Las Vegas, U.S. Environmental Protection Agency, and approved for publication.
Approval does not signify that the contents necessarily reflect the views and policies of
the U.S. Environmental Protection Agency, nor does mention of trade names or commer-
cial products constitute endorsement or recommendation for use.
n
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ACKNOWLEDGMENTS
Dr. Richard M. Tinlin, Dr. Lome G. Everett, and the late Dr. Stephen
Enke of General Electric—TEMPO were responsible for management and
technical guidance of the project under which this report was prepared.
Dr. Everett and Dr. Kenneth D. Schmidt, a consultant to TEMPO from
Fresno, California, were principal authors of the report. Dr. L. Graham
Wilson, a consultant to TEMPO from Tucson, Arizona, made contributions
to the technical content. Dr. David K. Todd, a consultant to TEMPO from
Berkeley, California, also provided technical guidance and review.
The following officials were responsible for administration and technical
guidance of the project for the U.S. Environmental Protection Agency:
Office of Research and Development (Program Area Management)
Mr. Albert C. Trakowski, Jr.
Mr. John D, Koutsandreas
Environmental Monitoring and Support Laboratory Las Vegas
(Program Element Direction)
Mr. George B. Morgan
Mr. Edward A. Schuck
Mr. Leslie G. McMillion
Mr. Donald B. Gilmore
• • •
in
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ABSTRACT
This report describes various groundwater monitoring methods and pro-
vides a generalized cost breakdown of the major economic factors for each
method. All possible groundwater-related measuring techniques applicable
at the land surface, topsoil, vadose zone and zone or saturation are pre-
sented. Each monitoring method is described referenced and illustrated.
Estimates of itemized capital and operational costs are presented. The
material is presented for in-depth reference purposes without recommenda-
tions for least-cost techniques, a least-cost mix of groundwater monitoring
approaches, or an optimal information system.
IV
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TABLE OF CONTENTS
ACKNOWLEDGMENTS iii
ABSTRACT iv
LIST OF ILLUSTRATIONS vi
LIST OF TABLES viii
SECTION I - INTRODUCTION 1
Purpose 1
Scope 1
Hydrogeological Framework 2
Groundwater Monitoring Methods 4
Types of Cost 5
SECTION II - MONITORING AT THE LAND SURFACE 11
Introduction 1]
Nonsampling Methods 11
Sampling Methods 25
SECTION III - MONITORING IN THE VADOSE ZONE 29
Introduction 29
Soil Sampling and Well Drilling 31
Determination of Water Content 33
Determination of Water Movement 42
Water Movement in the Unsaturated State 44
Water Sampling in the Vadose Zone 49
SECTION IV - MONITORING IN THE ZONE OF SATURATION 57
Introduction 57
General Monitoring Procedures 57
Specific Monitoring Methods 62
SECTION V - ANALYSIS OF SAMPLES 100
Introduction 100
Custody Control 100
Quality Control 103
Soil 105
Water 113
REFERENCES 130
APPENDIX-METRIC CONVERSION TABLE 140
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LIST OF ILLUSTRATIONS
Figure No. Title Page
1 Schematic diagram of groundwater pollution from surface
sources.
3
2 Small-diameter well costs index and the ENR materials
component. 6
3 Large-capacity well costs index and the ENR construction
cost index. 7
4 Cost of testing submerged tanks of various volumes, November
1974. 14
5 Alerting procedure chart for hazardous material spills. 24
6 Cost of power-augering 8-inch diameter sample holes to
various depths and hole densities, November 1974. 32
7 Sketch of neutron moisture logger and accessories. 34
8 Moisture logs showing growth and dissipation of mounds in
the vadose zone. 37
9 Cost of neutron moisture logging for various depths and sample
space densities, December 1974. 38
10 A single manometer tensiometer. 3°
11 Cost of tensiometers for various depths and sample space
densities, December 1974. 39
12 Cost of multiple electrical resistance blocks and soil
moisture meter for various depths and sampling densities,
December 1974. 40
13 Relationship between grain size and water-storage
properties of alluvium from large valleys. 41
14 Cost of piezometers for various depths and sampling densities,
November 1974. 44
15 Cross section of suction cup assembly and backfilling
material. 53
16 Cross section of porous cup assembly with pressure control. 54
VI
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ILLUSTRATIONS (continued)
Figure No. Title Page
17 Cost of soil salinity sensors and a salinity bridge for various
depths and sampling densities, November 1974. 56
18 Cost of shallow, small-diameter monitor wells, October 1974. 66
19 Updated (1975) cost of 4-, 5-, and 6-inch wells in sand and
gravel- 77
20 Updated (1975) cost of 4-, 5-, and 6-inch wells in consolidated
rock. 78
21 Generalized cost of coring in unconsolidated and consolidated
formations, October 1974. 81
22 Cost of electrical conductivity (EC) and gamma logging,
September 1974. 83
23 Cost of steel tapes, September 1974e 84
24 Cost of electric sounder and cable, September 1974. 85
25 Approximate cost of sampling wells (one round), December
1974. 90
26 Cost of cable and flex hose for use with portable submersible
pumps, October 1974,, 92
27 Power costs for continuous pumping of 1 hour, 1 day, 1 week,
for specific pumping heads and specific discharge rates,
December 1974. 97
28 Costs for determinations of water content and bulk density
in soils, September 1974. 105
29 Modified Haines Apparatus for obtaining soil-water
characteristic curves. 108
30 Soil-water characteristic curve, showing hysteresis. 109
vii
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LIST OF TABLES
Table No. Title Page
1 Example of ENR indexes for September 12, 1974 8
2 Example of EROS data center standard costs—satellite
products, October 1974 17
3 Land-use classification system for use with remote-sensor
data 20
4 Total cost of aerial surveillance for I and-use mapping,
July 1974 21
5 Specific yield values assumed for the southern part of
the Central Valley, California 42
6 Earth resistivity survey costs, December 1974 64
7 Costs in dollars for well drilling in unconsolidated formations,
EPA Regions III and IV, October 1974 70
8 Costs in dollars for well drilling in consolidated formations,
EPA Regions III and IV, October 1974 71
9 Black pipe casing costs for wells in dollars, EPA Region IX,
October 1974 72
10 PVC pipe costs for wells in dollars, EPA Region IX,
October 1974 72
11 Average cost of submersible water pumps, found in EPA
Region IX, October 1974 93
12 Hydrologic laboratory tests and cost schedule, September 1974 110
13 Recommended sampling and preservation techniques for
inorganic chemical determinations 119
14 Costs of inorganic chemical determinations for groundwater
pollution, October 1974 122
15 Costs of organic chemical determinations for groundwater
pollution, October 1974 125
16 Recommended sampling and preservation techniques for
organic chemical determinations 126
VIII
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TABLES (continued)
Table No. Title Page_
17 Costs of bacterial analysis for groundwater pollution,
October 1974 128
18 Costs of radiochemical analysis in groundwater pollution,
October 1974 129
IX
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SECTION I
INTRODUCTION
This report is one of a series of five reports on the general subject of
monitoring groundwater quality. The basic report in the group is Monitoring
Ground-water Quality: Monitoring Methodology (Todd et al. , 1976), which
outlines a procedure for creating a monitoring program for groundwater
quality under the general supervision of the U. S. Environmental Protection
Agency. As an essential supplemental reference to the methodology volume,
this report documents the various methods and techniques available to moni-
tor groundwater quality and also presents detailed cost data for the methods
and techniques. Monitoring has been broadly interpreted to include all pos-
sible measuring techniques with the intent to make this report as useful as
possible.
PURPOSE
Developing a groundwater monitoring program in an area requires not
only an extensive understanding of the various monitoring techniques avail-
able but also a knowledge of their costs. Previous economic groundwater
studies dealt primarily with the cost of supplying groundwater for municipal
and industrial usage. More recent cost studies by D. J. Cederstrom (1970),
James P. Gibb (1971), and Robert H. Forste (1973) are directed toward
costs of producing wells of varying yields. In general, the subject of ground-
water monitoring methods and their associated costs is fragmented through-
out the hydrologic literature. The purpose of this report, therefore, is to
provide a general summary of each of the groundwater monitoring methods
such that a strategy can be derived based upon specific methods and actual
cost data.
SCOPE
This report describes the various monitoring methods and provides a
generalized cost breakdown of the major economic factors for each monitor-
ing method. The itemization of factors for each method is not exhaustive,
but it does serve to quantify reasonably well the cost of the monitoring tech-
nique. A cost'interpretation structure to update the 1974 data presented
herein and a scheme to cover the national spatial distribution of costs are
provided. It should be emphasized that the costs listed are the best avail-
able estimates from sources that are believed to be reliable. Mention of
specific products or services does not imply endorsement by EPA.
1
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The material in this report is presented for reference purposes without
recommendation for a least-cost technique, a least-cost mix of monitoring
approaches, or an optimal information system. Essentially, the cost data
are intended to serve as line price guides for the various monitoring meth-
ods. * Furthermore, it should be noted that with few exceptions costs
presented here are those associated with goods and services only. Any or-
ganized monitoring program in a local area will have personnel costs — super-
visors, technicians, clerical staff, etc. - and overhead costs such as for
offices, supplies, communication, and transportation. Thus, the data pro-
vide specific technical costs but do not attempt to encompass total budgets
for monitoring programs.
HYDROGEOLOGICAL FRAMEWORK
The following discussion concerns the most common types of groundwater
pollution from sources at or near the land surface. Seawater intrusion, deep
well waste disposal, and groundwater overdraft are other types of water
quality changes that are of major significance in many local areas. There
are diffuse, line, and point sources of waste discharge. Figure 1 illustrates
the sequence of events that occur when a well is polluted by surface wastes.
Considerable confusion exists in groundwater quality investigations be-
cause of a lack of understanding of the pertinent physical, chemical, bio-
logical, soil, and geologic factors. The diagram illustrates the five basic
portions of the system: (1) the land surface, (2) topsoil, (3) vadose zone,
(4) saturated zone, and (5) well. Sanitary engineers and surface water hy-
drologists focus attention primarily on water at the land surface. Soil sci-
entists usually study the topsoil and secondarily the vadose zone. Geologists
are generally concerned with the portion below the water table, while water
supply agencies concentrate on well extraction where groundwater is used as
a source of supply. The entire system illustrated in the simplified diagram
must be studied in order to understand groundwater pollution.
Sampling at the land surface, in the topsoil, in the vadose zone, and from
the saturated zone will be discussed in detail. Understanding of quality
changes in the topsoil requires a knowledge of (1) soil water, (2) soil phys-
ics, (3) soil chemistry, (4) microbiology, and (5) physical chemistry. His-
torically, soil scientists have been concerned more with growing crops than
with the quality of percolating waters. Today this situation has changed;
now many studies concern the quality of percolate. An extensive body of
literature is available on water quality changes in the topsoil, such as in
Soil Science Society of America Proceedings and Journal of Environmental
Quality. This information has often been overlooked in groundwater quality
studies.
^Considerable assistance on cost data was provided by Federal and State
agencies and several private companies.
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Understanding of groundwater quality below the water table requires a
knowledge of (1) hydrogeology, (Z) well hydraulics, (3) geochemistry, and
(4) physical chemistry. Of principal importance is knowledge of the hydro-
geologic framework. The hydraulic and physical features of the groundwater
system must be established before groundwater quality can be understood.
An extensive body of literature is available on natural groundwater quality.
LAND
SURFACE
WASTE
DISCHARGE
WELL
DISCHARGE
5«ra»*-";-Sr*ii "riStfwKS'S
Figure 1. Schematic diagram of groundwater pollution from surface sources.
The vadose zone is commonly approaclied by the "black box" method, es-
pecially by geologists. Many vadose zones are not composed of "soil" in the
sense of the topsoil known to agricultural workers. The vadose zone often
extends to geologic formations beneath the topsoil. These may have differ-
ent physical characteristics from the topsoil. Soil scientists have made
great strides in analyzing the chemical quality changes that occur in the va-
dose zone (Wilson, 1971; Pratt, 1972; and Stout et al., 1965).
A major difficulty in past groundwater pollution studies has been the pre-
diction of travel times of pollutants from the land surface to the water table.
Predictions based on theoretical calculations often yield travel times that
are much too slow. Two items argue for a relatively rapid vertical move-
ment in many cases: (1) water balance calculations, i.e., comparison of
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leaching volumes versus storage capacity of the vadose zone; and (2) hydro-
logic and water quality evidence in areas where actual field measurements
have been made (Wilson, 1971; and Stout et al. , 1965). The rate of vertical
movement of pollutants in the zone of aeration is of prime importance in
developing a groundwater monitoring methodology.
GROUNDWATER MONITORING METHODS
The discussion of monitoring methods is presented in four sections: Sec-
tion II, Monitoring at the Land Surface; Section III, Monitoring in the Topsoil
and the Vadose Zone; Section IV, Monitoring in the Zone of Saturation; and
Section V, Analysis of Samples. This order considers major subdivisions of
a monitoring effort; however, it is not intended to convey the impression that
the major subdivisions are not closely related. The successful implementa-
tion of a groundwater monitoring methodology will largely depend on an ap-
propriate combination of monitoring methods.
Land surface monitoring includes sampling of surface water bodies for
pollution, particularly streams and lakes, as well as rainfall sampling.
Source monitoring deals with both solids and liquids that may impact on
groundwater quality. Land surface monitoring thus includes water sampling,
solids sampling, land use surveys, and inventories of amounts of wastes.
The tools available besides sampling include remote sensing, pipeline and
tank testing for leaks, and testing of artificial liners for leakage.
In most cases wastes applied at the land surface travel through significant
thicknesses of topsoil and geologic materials before reaching the water table.
Pollutants can be significantly retained or attenuated in the topsoil and the
vadose zone. The storage capacity of the vadose zone for percolating waters
may also be great. Long travel times from the land surface to the water
table may necessitate detailed sampling in the vadose zone. Past studies in
the vadose zone have largely been accomplished beneath point sources.
The primary site of groundwater quality monitoring lies in the saturated
zone, as this is where water is ultimately pumped from wells for use at the
land surface. Water sampling from wells is a key item, and along with
source monitoring is the primary groundwater pollution monitoring approach.
The techniques of well sampling and well drilling (for cases when existing
wells do not suffice) are discussed extensively. Past groundwater pollution
studies have demonstrated the usefulness of well sampling.
Subsurface sampling in both the vadose zone and in the zone of saturation
requires considerable experience and careful judgement due to the complex-
ity of most soil-aquifer systems.
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TYPES OF COST
The cost structure is broken into four areas: capital, amortization,
maintenance, and operational. The capital costs refer to those items that
are fixed by location, such as screens, casings, pumps, or are fixed by
their initial investment and subsequent repetitious use, such as pH meters,
water samplers, etc. Interest on the initial capital investment may be con-
siderable, especially over long periods of time. The annual writeoff or
amortization expense of capital plus interest over each 1-year period is de-
pendent upon the interest rate at which the money was loaned and the life of
the depreciation fund or the effective life of the capital item. The effective
life of water wells is about 20 years and the expected life of water pumps is
about 10 years.
Based on the work of Cederstrom (1970), it is estimated that 1 percent of
the total capital costs is sufficient to provide for the maintenance of drilled
wells. Special consideration, however, is given to small-diameter driven
wells as these are more frequently replaced in total. The operational costs
of groundwater monitoring are a major item. Capital, amortization, and
maintenance costs relate primarily to wells, while the remaining monitoring
methods are primarily service functions involving operating costs.
Updating Cost Data
Rapid changes in the cost of labor and materials within the United States
require that published cost data be updated to current costs prior to use.
A convenient method to update costs is based upon the Engineering News-
Record (ENR) indexes. Verification of cost estimates can be made by ob-
taining bids on specific items.
The Engineering News-Record Construction Cost Index was created in
1921 to diagnose the erratic price gyrations that occurred during and imme-
diately following World War I and to evaluate their effects on construction
costs. The index was designed as a general purpose construction cost index
to chart basic costs. It is a weighted aggregate index of constant quantities
of structural steel, portland cement, lumber, and common labor. This hypo-
thetical block of construction, repriced weekly, was valued at $100 in 1913
prices. The original use of common labor in the Construction Cost Index
was based on the idea that it set the trend for all wage rates. In the 1930's,
however, wages plus fringe benefits climbed faster for laborers than for the
skilled trades,
The Engineering News-Record Building Cost Index was introduced in 1938
to weigh the impact of skilled labor on cost trends. For its labor component
it uses an average of carpenter, bricklayer, and structural ironworker
wages. Its materials component is the same as used in the Construction
Cost Index.
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Figure 2 shows the time variation of well construction costs and the ma-
terials component of the ENR index. It can be seen that domestic and farm
well costs agree closely with the trend of the index. Similarly, Figure 3
shows that large-capacity well costs are associated with the Construction
Cost Index.
MOO
1200
1000
800
600
400
200
.DOMESTIC AND f ARM_
WELL INDEX-
-MATERIALS
"COMPONENT
-(NOT AN tNOEX)-
J 1 I
1910
1920
1930
1950
1960
1970
1971
1972
1973
1974
1975
Figure 2. Small-diameter well costs index and the ENR materials component (after Gibb,
1971).
To update costs and to consider regional influences requires the formula-
tion of multiplicative factors based upon the ENR indexes. These multiplica-
tive factors can be formulated as simple ratios from graphical and tabular
information. Figure 2 enables the determination of the materials component
for any prior cost data back to 1913. Table 1, taken from the September 12,
1974 issue of ENR provides indexes on a monthly basis for 20 cities within
the United States and the U. S. 20-city average index. At least 1 of the cities
listed is found in each of the 10 EPA regions.
To apply the'update method, the ratio of the materials component of the
future date to the materials component of the date of the report cost data is
required. The materials component associated with the report cost data
can be obtained from Figure 2 or 3, depending upon the well size of interest.
The materials component associated with the future date can be determined
from the latest issue of ENR. Future costs as a national average can then
be computed by multiplying the cost data given in this report by the computed
ratio.
For example, assume that in May 1977 the estimated cost of 200 feet* of
8-inch diameter PVC pipe in Region VII is desired. From Table 10 (Section
IV) it can be seen that the cost of the pipe is $1120 in Region. IX in October
1974. Figure 2 shows the materials component for October 1974 as 850.
Assume that the materials component of the May 1977 issue of the ENR
shows an increase to 1300. The cost of the PVC pipe in 1977 is then deter-
mined by multiplying the October 1974 costs ($1120) times the ratio of the
*See Appendix for Metric Conversion Table.
6
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2200
200
180C
1600
O
2
H 1400
*
1/1
O
u
1200
Q
Z
1000
800
600 -
400
CONSTRUCTION
COST INDEX
LARGE-CAPACITY
WELL INDEX
1945 1950 1955 1960
YEAR
1965
1970
1974
Figure 3. Large-capacify well costs index and the ENR construction cost index
(modified after Gibb, 1971).
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TABLE 1. EXAMPLE OF ENR INDEXES FOR
SEPTEMBER 12, 1974
ENR COST INDEXES IN 22 CITIES
(based on 1913 U.S. average = 100)
City
Atlanta
Baltimore
Birmingham
Boston
Chicago
Cincinnati
Cleveland
Dallas
Denver
Detroit
Kansas City
Los Angeles
Minneapolis
New Orleans
New York
Philadelphia
Pittsburgh
St. Louis
San Francisco
Seattle
U.S. -20 Cities' Average
Montreal
Toronto
••• — — — — — ————————
Construction cost
Sep74
index
1,588.9
1,786.94
1,562.04
2, 174.06
2,205.91
2,400.44
2,375.78
1,660,59
1,658.39
2,387.69
2,261.63
2,290.23
2,093.94
1,610.74
2, 568. 37
2,203.17
2, 067. 52
2,321.94
2,446.14
2,111.96
2.088.82
1,880.84
1,972.44
—SS^SSSSS^S^^^^S^ss^s
Percent change
from last
month
+0.2
-0.9
+0.8
+0.2
-1.6
0
-5.0
-0.5
-0.3
-0.1
-1.0
+6.7
0
0
+0.1
-1.0
-0.1
+0.2
-0.2
+11.5
+0.6
-5.0
+0.4
^^--^— ^— *_
year
+5.9
+0.4
+9.6
+10.4
+5.4
+9.5
+8.5
+4.8
+5.9
+7.)
+9.2
+10.0
+7.4
+9.4
+6.6
+12.6
+9.3
+9.8
+9.9
+ 14.5
+8.3
+19.7
+9.5
Building cost
Sep74
\ ndfix
,080.22
,174.56
,082.28
,299.15
,296.94
,328.34
1,312.39
1,063.05
1,157.37
1,341.53
1,240.71
,278.83
,205.24
, 104.52
,461,86
,341.82
,317.06
,179.43
, 339. 67
,149.32
1,237.71
1,134.69
1,109.91
Percent change
from last
month
+0.3
-0.7
+1.7
+0.1
-2.8
-5.0
-5.0
-0.8
-0.4
-0.1
-1.7
+3.1
-5.0
0
+0.1
-1.6
-0.2
-0.6
-0.4
+0.7
-0.2
0
+0.5
year
+5.5
+0.4
+8.3
+ 11,2
+6.1
+9.8
+7.2
+4.1
+6.5
+7.4
+7.0
+8.8
+7.1
+11.8
+6.8
+11.1
+7.0
+6.9
+8.1
+ 12.2
+7.6
+21.5
+6.7
ENR WAGE, MATERIALS AND COST INDEXES IN 20 CITJES
City
Atlanta
Baltimore
Birmingham
Boston
Chicago
Cincinnati
Cleveland
Dallas
Denver
Detroit
Kansas City
Los Angeles
Minneapolis
New Orleans
New York
Philadelphia
Pittsburgh
St. Louis
San Francisco
Seattle
(based on each city's 1967 average = 100^
Common
Sep74
index
206.64
229.39
198.35
205. 36
193.79
233,59
196.92
236. 65
177.88
201.72
236.98
199.55
189.51
199.27
180.36
220.00
191.32
198.70
197.22
186.21
labor
% change
from
Sep73
+7.7
+2.5
+12.3
+10.7
+5.1
+9.0
+8.7
+7.1
+6.7
+7.0
+9.4
+7.9
+7.0
+7.3
+5.3
+12.2
+9.3
+11.2
+10.4
+14.9
Skilled labor
Sep74
index
185.86
190.69
193,45
189.93
190.93
209.29
193.91
186.50
191.47
199.60
206. 37
192. U
184.24
183.12
177. 19
198.85
183. 56
574.26
181.24
176.39
% change
from
Sep73
+8.6
+4.2
+12.0
+12.3
+5.8
+8.6
+6.8
+8.1
+8.4
+7.3
+5.9
+7.8
+5,9
+9.8
+4.2
+9.4
+5.2
+8.4
+7.9
+11.6
Sep74
index
172.97
175.14
167.05
187.44
155.14
197.42
172.19
154.75
163.37
157.23
175.84
184.86
179.23
181.03
194.83
200.34
195.58
173.32
178.41
190.03
% change
from
Sep73
+ 1.7
-4.2
+4.0
+9.8
+6.5
+11.4
+7.8
-0.5
+3.8
+7.8
+8.4
+10.3
+8.6
+14.2
+ 11.5
+ 13.5
+9.4
+5.0
+8.4
+13.1
Const
cost
index
195.30
202.58
187.22
200.45
182.92
225.90
169.60
210.14
169.71
190.62
218.67
194.24
182.61
192.59
184.68
215.06
185.77
192.22
193.25
187.08
Building
cost
index
180.01
183.72
180.28
188.90
174.81
207.64
184.62
175.98
176.96
181.48
191.59
185.76
174.93
182.13
183.81
199.53
178.83
172.78
180.05
181. B2
8
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1977 materials component (1300) to the 1974 component (850), or
$1120 X^^ = $1713 ,
the approximate cost of the PVC pipe in Region IX in May 1977. To obtain
the cost of the PVC pipe in Region VII would require a similar procedure
using October 1974 and the May 1977 ENR cities material prices, an exam-
ple of which is given in Table 1.
Regional variations can be handled in a similar manner. For example,
in Table 1 the city which is closest in geographical location to the monitor
well activity is identified. The index for this city divided by the U.S. 20-
cities index gives a ratio. This ratio multiplied by the current costs as a
national average provides the updated current costs for a given region.
Effects of Scale on Costs
Manufacturers generally offer discounts for large purchases or to pre-
ferred customers. Water well casing suppliers, for example, do not dis-
count the price per foot of casing for the first 100 feet; however, discounts
of 20 percent are common above a 100-foot purchase, and discounts of 30
percent are not uncommon on purchases above 1000 feet. Because pumps
and grouting material are not purchased in large quantities for monitor wells,
the effect of scale is small. Water analyses are subject to discounting on
the basis of the number of routine tests performed on a sample rather than
on the number of samples analyzed. As many chemical analyses require
similar sample work ups, a routine or batch series of tests usually is con-
siderably cheaper than the total for each of the tests performed individually.
In-House versus Out-of-House Costs
The internalization of costs -within the Federal government and universi-
ties makes competition with commercial enterprises somewhat unbalanced.
Subsidies to many Federal and State laboratories, for example, often are
not reflected in water analysis prices. Federal government costs vary with
and within agencies. By way of illustration, the Water Resources Section
of the U.S. Geological Survey (USGS) has a water resource service geophys-
ical facility that has one price for users within the USGS water resource
sector, a second price for other USGS users, and a third price for Federal
agencies such as the EPA. On the other hand, many monitoring functions
performed within Federal agencies have one set price for all.
Accuracy and Costs
The cost of a monitoring method can vary with the accuracy of the tech-
nique. An aquifer model with 1000 nodes per unit area is much more
-------
expensive than a model with 10 nodes; the larger the model, the more accu-
rate but also the more costly it is.
The accuracy of water quality analyses has become an increasing prob-
lem. Some parameters have accuracies established by the EPA, the Corps
of Engineers, and local public health officials as well. Commercial labora-
tories performing water quality analyses usually report results in terms of
0. 1 mg/liter (0. 1 ppm). However, if accuracy to 0.01 mg/liter or greater
is required, an additional charge of approximately one-third is added for
each additional decimal point required.
10
-------
SECTION II
MONITORING AT THE LAND SURFACE
INTRODUCTION
Ground-water monitoring programs have normally concentrated primarily
on the saturated zone for indications of pollution. Too often, these programs
have not considered the information that is available through analyzing the
unsaturated zone and through monitoring of the land surface. In addition,
surface water monitoring of recharge areas is only beginning to be recog-
nized as a critical variable in pollution detection.
Monitoring of the land surface can be divided into nonsampling and sam-
pling methods. The nonsampling methods can be further divided into waste-
load inventory considerations, leaching potential calculations, pipeline and
tank tests, artificial liner testing, aerial surveillance, and notification and
emergency procedures. The sampling methods are divided into those for
surface water bodies, wastewater, and solid wastes.
NONSAMPLING METHODS
Waste-Load Inventory
Identification of sources and methods of disposal are key items. An in-
ventory of waste loads comprises data collection and tabulation of the vol-
umes of liquid wastes and weights of solid wastes and their compositions.
For most purposes, monthly data on volumes and weights will be sufficient,
and in some cases annual data will suffice. Acquisition of these data is
necessary as a basis for calculating the amounts of percolate that may occur
and concentrations of pollutants in the percolate.
Data on the physical, chemical, bacteriological, and radiological charac-
teristics of the wastes should be collected. For wastewaters, chemical
analyses are almost always included. Records of temperature and density
measurements are appropriate for cases where the wastewaters have char-
acteristics greatly different from native groundwaters. Turbidity records
are important in cases where the wastes bypass the topsoil, such as in dis-
posal or injection wells. Bacteriological analyses are important in the case
of disposal of human and/or animal wastes. Radiological analyses are of
foremost importance in the cases of nuclear waste disposal and certain min-
ing wastes, among others.
11
-------
For solid wastes, data on the chemical, bacteriological, and radiological
characteristics should be collected. Bacteriological analyses are important
in the case of sewage sludge and certain animal wastes.
Calculation of Leaching Potential
One of the key portions of a groundwater pollution monitoring program is
to calculate or determine the amount of water which percolates through the
topsoil and is in transit to the water table. The water budget approach may
be used, where the input at the land surface in the form of waste volume and
precipitation are compared to the output, or evapotranspiration. For diffuse
sources, such as return flow of irrigation water, annual values may suffice.
If evapotranspiration exceeds the water input at the land surface, then no
percolate may occur. For point sources where input may greatly exceed
evapotranspiration, annual values may also be sufficient. However, monthly
calculations are necessary where evapotranspiration is greater than the in-
put on an annual basis, but the input is greater than evapotranspiration in
some months. This is particularly true where most precipitation or much of
the waste disposal occurs during a few months of the year.
Precipitation records are usually available for most areas or can be ex-
trapolated. Evaporation from free water surfaces can be determined from
measurements for land or floating pans (Harbeck et al. , 1958; Kohler, 1954;
Follansbee, 1933; Rohwer, 1933). Quite often these values are unavailable
and measurements of pan evaporation must be made. Evapotranspiration in
irrigated areas can be determined by a number of methods (Gruff and
Thompson, 1967; Blaney and Griddle, 1962; Lowry and Johnson, 1942;
Penman, 1948; Thornthwaite, 1948). The residual value, or percolation,
is an important parameter, as it affects the subsequent dilution of wastes
that occur in the aquifer. The value also is necessary as an index of poten-
tial pollutant load escaping the land surface.
Pipeline and Tank Tests
Recent studies (Osgood, 1974; U.S. EPA, 1974b) indicate that buried
pipelines and storage tanks are potential sources of sewage, storm water,
and petroleum product contamination. The volume of flow from these
sources may be a secondary concern if the pollutant is of a toxic or noxious
character. The major consideration is to determine if and where the sys-
tem is leaking. Small leaks from service station storage tanks can release
15 to 20 thousand gallons of gasoline over time, without the operator being
aware of his loss (Osgood, 1974). Since the threat of fire or explosion is
of primary concern in oil and gasoline leaks, the National Fire Protection
Association (NFPA) has been active in setting up monitoring programs.
To date, the NFPA has not approved any pipeline tightness testing equip-
ment although this equipment is being developed; it has endorsed one kind
of tank tightness testing equipment.
12
-------
Exfiltration and infiltration occurring in sanitary and storm sewers is a
recognized engineering phenomenon. Where the system originally is poorly
designed and improperly installed or where the pipelines are old and in dis-
repair, leakage of substantial quantities of poor quality water into the soil
system can take place, eventually leading to contamination of groundwater.
It is difficult to accurately determine the amount of leakage from these bur-
ied sanitary lines. The use of pressure in pipelines which are designed not
to Leak is a straightforward technique; however, these techniques are diffi-
cult to use in sanitary and storm sewers. The cost of performing a pipeline
test would approximate the cost for a commercial tank test of the same
volume.
In Maryland the county health departments reported 60 cases of pipeline
and tank contamination in 1969-1970. These were detected from water in
surrounding wells and not the sources, however. If it is possible to conduct
input-output tests in sewer lines from basic flow data, large leaks may be
detected. Large fluctuations in the flow received at the treatment plant
which cannot otherwise be explained are another indication of leaks or
breaks. However, in most cases the number of leaks in storm and sanitary
drains will be large and individual losses will be low.
The testing of underground storage tanks can be done routinely. The
Pennsylvania Department of Environmental Resources estimates that 2600
new or replacement subsurface storage tanks are buried in the ground in
that State each year. If those replaced have failed, then this source of pol-
lution deserves further monitoring. Most storage tanks are monitored using
a calibrated "dip stick. " This is a rough measurement, better than nothing,
but not sufficiently sensitive to detect small leaks. The stick is usually read
in the morning and evening and any difference indicates a possible leak. If
a stick is not used, a manometer or float recorder may be used. These
monitoring tools generally provide only rough approximations.
A more sensitive car-transportable tank tester, endorsed by NFPA, in-
volves the use of a pressurizing device and a pressure loss recorder. The
tank system tightness tester costs about $2875 FOB and is used by various
consulting firms throughout the country. The average cost for an 8-hour
(1 man-day) tank test is $300. Normally one man can operate the tester;
however, he may need a pipefitter assistant under certain circumstances.
The largest tank tested to date has a capacity of about 24,000 gallons. The
cost of the tank test varies primarily with the size of the tank in question
and the size of the leak. The average cost of on-site testing of various tank
sizes is given in Figure 4. A tank with a bad leak may require only 15 to
30 minutes for leak detection after the tester has been set up, while a tight
tank can require 3-1/2 to 4 hours. The time required to test a series of
tanks or one large tank may be more than 8 hours. The rate charged usually
does not vary and remains around $35-$40 per hour for both transportation
13
-------
24
22
20
\8
16
14
a
O 20
u
O 10
*/>
Q£
O
1 6
i
900
750
600
450 u.
I
I
I
300
150
10 15 20 25
TANK VOLUME (1000 gallons)
30
Figure 4. Cosf of testing submerged tanks of various volumes, November
1974.
to the test site and actual testing. The test procedure can also be used to
determine if water is seeping into the tank.
Tank testing has not been widely used, possibly through lack of awareness
of the existence of test equipment. Owners have little legal responsibility to
test their tanks, This situation may be compared to fire extinguishers,
which are required by law and/or insurance companies to be routinely tested.
Tanks that have been abandoned by gas station operators, industries,
etc. are of considerable concern. Many of these abandoned tanks still have
hazardous materials in them and, if leaking, are potential pollution sources.
Testing Artificial Liners for Leakage
Large numbers of storage ponds and "evaporation ponds" leak and permit
substantial quantities of pollutants to escape the land surface. Artificial
liners are coming into wide use to limit such percolation. These liners may
be made of compacted clay, plastic, rubber, concrete, bentonite, and other
materials.
There are several ways to determine leakage. One method is to fill the
pond prior to use with a liquid of like composition to the waste to be con-
tained. Seepage can be calculated after precipitation and evaporation are
14
-------
determined. Another suitable test involves construction of a special collec-
tion device beneath the artificial liner. This is usually constructed by plac-
ing a relatively impermeable material several feet below the final liner.
Drain pipes are then placed above the layer, on a grade toward a central col-
lection point. Coarse-grained permeable materials are then placed in this
interval beneath the artificial liner. These collection devices enable rather
rapid determination of leakage from artificial liners. Seepage can also be
calculated if the permeability of the artificial liner can be determined.
Aerial Surveillance
Aerial surveillance can be especially useful in land surface monitoring
for groundwater pollution. Stockpiles, disposal and storage basins, and
accidental spills can be seen from the air. Aerial surveillance can be used
to determine what methods of disposal are being used under routine opera-
tion, as well as during accidents or unusual weather conditions. If, for
example, sewage effluent is bypassing percolation ponds and flowing into a
stream channel or canal this can be detected from the air.
In disposal operations such as mine tailing ponds, water may be present
in the ponds as free water, moist tailings, or wet tailings. Since the calcu-
lation of percolation requires estimation of evaporation and the evaporation
rate is different in each case, the relative concentrations of pond areas must
be periodically determined. As many such ponds cannot be freely traversed
on the surface, aerial surveillance is an important aspect. Photographs and
visual observations from various directions and heights can provide useful
information. Observations and surveys on the ground can be used as a con-
trol for the aerial surveillance.
Infrared photography is a proven tool in analysis of shallow groundwater
conditions and phreatophyte growth. Cropping patterns and irrigation can
also be analyzed. Chandler, Dowdy, and Hodder (1970) reported on the
utility of aerial surveillance methods in water quality monitoring; however,
most of their discussion was in reference to surface water.
Remote-sens ing technology, usually in the form of aerial and satellite
imagery, provides the land-use planner and manager with a new source of
data. Remote sensing can be employed in a land-use planning program to:
(1) provide an initial source of information, (2) identify the factors respon-
sible for change in the resource base, (3) help define management policy,
and (4) monitor the effect of these policies. In particular, septic field pol-
lution could be determined from population estimates which in turn could be
obtained from remote sensors. This estimate of population can be based on
housing occupancy ratios and counts of houses. Another method involving
remote sensing is sampling population densities per unit area of land-use
classes and then using the total area of a given land use as the multiplier
to calculate its total population.
15
-------
In-house costs are minimized more in remote sensing than in any other
groundwater monitoring technique. For example, the funding required to
produce the ERTS-1 (Earth Resources Technology Satellite), Skylab, or a
U-2 high-altitude sensor airplane are excluded from the purchase costs of
raw data gathered by this equipment. In addition, Federal agencies such as
the EPA and the USGS are active in remote-sensing research. The capital
costs incurred by these agencies to develop a remote-sensing capability are
difficult to determine; often only operational costs such as man-time, film,
airplane fuel, etc. are charged for land-use surveys.
A few guiding principles in the use of aerial and remote-sen sing surveys
are:
• The larger the area, the less the cost per unit area for data
acquisition and interpretation. This is true because the cost
of mobilization is usually prorated on a per kilometer basis
over the actual cost of acquisition, resulting in economies of
size.
• In general, the higher the resolution, the larger the scale or
the more specific the sensor, the higher the cost of acquisition,
processing and interpretation. This suggests a multilevel ap-
proach beginning with large area, low resolution generalized
coverage and proceeding to studies of selected smaller areas
with more specific higher resolution techniques. At each level
the available data should be exploited to the maximum degree
possible before proceeding to the next step.
• Multipurpose or multiresource programs reduce the cost ac-
corded to each end use. This follows because the costs of
data acquisition, processing, and capital investment for inter-
pretation can be shared among users,
• The cost of adding a sensor to an aerial platform is usually
relatively small. Most of the cost of data acquisition is the
cost of flying.
• Computer and computer-assisted interpretation becomes eco-
nomical when large areas are covered, a large number of
comparisons among several data types are required, and the
decisions to be made are relatively simple. The same is gen-
erally true of other machine-assisted techniques.
Data acquisition and processing refer primarily to the imagery and tape
costs. An example of the standard price list from the EROS Data Center,
Sioux Falls, South Dakota is given in Table 2. Upon request the Center will
provide a standard remote sensing order form. If the interpretation and
verification capabilities are available, the cost of the EROS data is minimal.
However, if interpretation and verification expertise is not available the
16
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TABLE 2. EXAMPLE OF EROS DATA CENTER STANDARD COSTS-SATELLITE PRODUCTS,
OCTOBER 1974
ERTS DATA
Image size
(inches)
2.2
2.2
7.3
7.3
7.3
14.6
29.2
Scale
13,369,000
:3, 369, 000
: 1,000, 000
•1,000,000
:1, 000, 000
:500,000
:250,000
image size
7.3 inches
Tracks
7
9
9
S190A image
size (inches)
2.2
2.2
6.4
12.8
25.6
Format
Film Positive
Film Negative
Film Positive
Film Negative
Paper
Paper
Paper
Black & White
unit price ($)
2.00
2.00
3.00
3.00
2.00
5.00
12.00
COLOR COMPOSITE GENERATION0
(when not already available)
Scale
1:1,000,000
Format
Printing master*5
COMPUTER COMPATIBLE TAPES
Density
(bits per inch)
800
800
1600
Format
4-tape set
4-tape set
4-tape set
Color composite
unit price ($)
NA
NA
12.00
NA
7.00
15.00
30.00
Unit price
$50.00
Set price ($)
200.00
200.00
200.00
SKYLAB PHOTOGRAPHY
Scale
1:2,850,000
1:2,850,000
1:1,000,000
1:500,000
1:250,000
Format
Film Positive
Film Negative
Paper
Paper
Paper
Black & White
unit price ($)
2.00
4.00
2.00
5.00
12.00
Notes:
QColor composites are portrayed in false color (infrared) and not true
Cost of product from this composite must be added to total cost.
Color unit price
($)
5.00
NA
7.00
15.00
30.00
color.
(continued)
17
-------
TABLE 2 (Continued)
AERIAL MAPPING PHOTOGRAPHY
Image size (inches)
9
9
9
18
27
36
Photo Index
NASA
Image size (Inches)
2.2
2.2
4.5
4.5
4.5
9.0
9.0
9.0
9x18
9x18
9x18
18.0
27.0
36.0
Format
Film Positive
Film Negative
Paper
Paper
Paper
Paper
Paper
Black & White unit price ($)
3.00
6.00
2.00
5.00
6.00
12.00
3.00
RESEARCH AIRCRAFT PHOTOGRAPHY
Format
Film
Film
Film
Film
Positive
Negative
Positive
Negative
Paper
Film
Film
Positive
Negative
Paper
Film
Film
Positive
Negative
Paper
Paper
Paper
Paper
Microfilm
16 mm (100-foot roll)
35mm (100-foot roll)
Kelsh Plates
Black & White
unit price ($)
2.00
4.00
2.00
4.00
2.00
3.00
6.00
2.00
6.00
12.00
4.00
5.00
6.00
12.00
MISCELLANEOUS
Contact prints on glass. Specify thick-
ness (0.25 or 0.06 inch) and method of
I-
Color unit price
($)
5.00
NA
6.00
NA
6.00
12.00
NA
7.00
24.00
NA
14.00
15.00
20.00
30.00
Black & White
roll price ($)
15.00
20.00
10.00
„
11 .I.
Color roll price ($)
35.00
40.00
18
(continued)
-------
TABLE 2 (Continued)
MISCELLANEOUS (continued)
Keish Plates (continued)
printing (emulsion to emulsion or
through film base).
Transformed Prints
From convergent or transverse low
oblique photographs
35-mm Mounted Slide
35-mm mounted duplicate slide where
available
Black & White
roll price ($)
7.00
.60
Color roll price ($)
costs involved escalate rapidly. For example, the level of detail required
may be Level I, II, or III. Examples of the kinds of detail observed at Lev-
els I and II are given in Table 3.
A review of work by Sizer*, Simonett^, and Thorley (1973) for land-use
mapping studies in the United States resulted in the cost figures for data ac-
quisition, processing interpretation, and map preparation presented in
Table 4.
The cost of a remote-sensing survey includes the costs of data acquisi-
tion, processing, interpretation, and verification. These costs in turn de-
pend on the sensor or sensors used. Sensor selection must depend on the
purpose and location of the survey, the areal size, the required level of de-
tail, existing information on the area, the available facilities and equipment
for processing and interpretation, labor availability and costs, platform
availability costs, shipping costs, and for some surveys the time of year.
Each of these factors can vary, which makes it impossible to define costs
except in general terms.
Notification Procedures
Warning systems to protect against accidental spills have previously been
developed by agencies other than those charged with groundwater quality
* Personal communication, 1973.
^Personal communication, 1973.
19
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TABLE 3. LAND-USE CLASSIFICATION SYSTEM FOR USE WITH REMOTE-SENSOR
DATA (Anderson et a!., 1972; Poulton, 1972)
Level
01. Urban and built-up
land
02. Agricultural land
03. Range land
04. Forest land
05. Water
06. Nonforested wetland
07. Barren land
08. Tundra
09. Permanent snow and
icefields
Level II
01.
02.
03.
04.
05.
06.
07.
08.
09.
01.
02.
03.
04.
01.
02.
03.
04.
01.
02.
03.
01.
02.
03.
04.
05.
01.
02.
01.
02
03.
04.
05.
01.
01.
Residential
Commercial and services
Industrial
Extractive
Transportation, commu-
nications, and utilities
Institutional
Strip and clustered
settlement
Mixed
Open and other
Cropland and pasture
Orchards, groves, bush
fruits, vineyards, and
horticultural areas
Feeding operations
Other
Grass
Savannas (palmetto
prairies)
Chaparral
Desert shrub
Deciduous
Evergreen (coniferous
and others)
Mixed
Streams and waterways
Lakes
Reservoirs
Bays and estuaries
Other
Vegetated
Bare
Salt flats
Beaches
Sand other than beaches
Bare exposed rock
Other
Tu ndra
Permanent snow and
icefields
20
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TABLE 4. TOTAL COST OF AERIAL SURVEILLANCE FOR LAND-USE MAPPING,
JULY 1974
Level of
detai 1
.evel 1
Level II
Level III
Scale of
final
product
1:250,000
to
1:500,000
1:250,000
to
1:63,360
1:63,360
1 :24, 000
to
1:63,360
1:12,000
to
1:40,000
Method or
basis
Satellite
Imagery
High-altitude
aircraft
imagery
Satellite
imagery only
High-altitude
aircraft
imagery
Multiscaled
approach
Commercial
Commercial
Data sources
1:250, 000 ERTS
imagery
1:50, 000 aerial
photographs
ERTS imagery
1:90, 000 aerial
photography
ERTS imagery, high-
altitude aircraft
photography and
ground truth
Relys on 1:90,000
high-altitude
ohorography
1:24, 000 aerial
photography
CostAm2
($)
0.15- 0.27
2.00- 3.60
0.25- 0.45
2.25- 4.05
0.75- 1.35
2.75 - 4.95
5.75- 10.35
control. The major agency responsible for control of these spills has been
the Department of Transportation. Apart from their other effects, spills
of very short duration, such as hours or days, can result in groundwater
pollution for decades or longer. Thus, prompt action is necessary, and ad-
vance warning of potential problems can be given by established notification
procedures. However, notification procedures for hazardous substance
transportation are poorly documented in most States and nonexistent in
others. Notification procedures require that a responsible body be notified
when any hazardous materials are to be moved. The intent is to insure that
when they are transported through a certain area the full potential of the
danger involved is realized and that emergency crews are alerted in case of
an accident. Of more importance, however, is the assurance that those do-
ing the transporting will abide by safety regulations governing the move.
21
-------
The majority of the States do not have a notification procedure tied into
their groundwater monitoring program, and thus basic cost data are not
available for warning systems and notification procedures. It is estimated
that a notification monitor would approximate a safety inspection officer in
training and salary, with the latter ranging from $10,000 to $15,000 per
year.
Although transportation of hazardous substances can be by boat, rail,
highway, air, or pipeline, the regulations for highway transportation are
perhaps the most relevant to groundwater problems. The majority of the
manpower required for notification procedures usually falls outside a moni-
toring agency's responsibility. The person charged with monitoring the pro-
cedure, however, should spot check to see that notification procedures are
followed.
The best form of notification procedure is a specific permit to transport
hazardous substances. These permits should be based upon applications
submitted to a Transportation Board. An application for hazardous material
permit should include the following:
• Name and address of applicant
• Business of applicant
• Requested exemptions to regulations
• Reason a specific permit is required
• Points of origin-destination and proposed routes
• Evidence to establish that transportation can be accomplished
without undue hazard to public health and safety
• Period during which permit is to be effective
• Additional information as may be required.
The Transportation Board should then determine if a permit is required. If
a permit is needed it should:
• Describe the situation to which the permit applies
• Authorize such exemptions as may be warranted
• Establish the period of time in which the permit is effective
• Impose any new or special conditions which must be observed.
With the establishment of a permit system, a set of rules must be estab-
lished for both shipper and carrier to cover the safety aspects required by
the permit. The rules and regulations,for the shipper could specify accept-
able containers, marking, labeling, etc. , whereas those for the carrier
22
-------
should specify loading and unloading and vehicle operation procedures, driver
qualifications, etc.
The person charged -with monitoring the notification procedures would
check both shippers and carriers according to some sampling schedule to see
that the rules and regulations were being followed. The monitoring could in-
volve a review of a few permit applications that were accepted. Follow-up
inspections could be done to see that proper containers were used and that
the labeling was sufficiently clear. In addition, those permit applications
that were turned down could be investigated to determine if potentially dan-
gerous materials were still being transported. Carriers could be monitored
for fully operational vehicles. In addition, drivers' logs could be reviewed
for compliance with prescribed driving periods.
The transportation of hazardous material by highways is but one example
of the kind of notification monitoring that could be implemented. Currently
this type of monitoring is relatively rare; however, the reason primarily
has been a lack of rules and regulations on the handling of hazardous mate-
rials. Many States currently are developing legislation to cover the trans-
portation and monitoring of hazardous materials.
Emergency Procedures
Emergency procedures to cover accidents once they have occurred are
generally well defined. City and State police officials as well as Department
of Transportation personnel are informed as to procedures to follow when an
accidental spill occurs. The time required to correct the damage is very
important because if the material seeps into the soil subsurface excavation
can be costly. The emphasis, therefore, is on quickly reaching the site and
taking action to minimize the infiltration and contamination of the soil ma-
trix. The role of monitoring under these circumstances is to insure that the
emergency procedures are operational and that responsible personnel and
equipment are ready to react to a call. This monitoring responsibility may
be compared to that of a fire inspector who is charged with insuring that fire-
fighting equipment is ready should an alarm be sounded.
Many States have a disaster office which controls emergency procedures
for hazardous material spills. In the event of a hazardous substance spill or
serious threat of such a spill, warnings should be given to endangered per-
sons, to local authorities, and to the State Disaster Office (Figure 5).
Regardless of the makeup of the organization or the type of location of a
spill, certain basic operations must be carried out. The employment of any
or a combination of the suggested measures can be undertaken only after
technical advice has been sought and safety, feasibility, availability of ma-
terial and equipment, side effects, and consequences have been considered.
23
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IMMEDIATELY
ENDANGERED
CITIZENS
LOCAL
AUTHORITIES
MAJOR
HAZARDOUS
SPILL
DETECTION
U.S.
COAST GUARD
CONCERNED
FEDERAL
AGENCIES
STATE
OPERATING
AUTHORITY
ALTERNATE
ALTERNATE
CHAIRMAN
STATE SUPPORT
TEAM
STATE
OPERATING
TEAM
Figure 5. Alerting procedure chart for hazardous material
spills (after California Emergency Plan, 1970).
24
-------
Some of the following operations may be conducted a step at a time, but many
will of necessity be carried out simultaneously.
• Issue warnings and establish patrols
• Establish operations center
• Gather information
• Secure spill
• Containment, removal, and disposal of material
• Cleanup and rehabilitation of area.
All of the above operations require logistic support such as provisions,
materials and equipment, transportation, loading, unloading and storage fa-
cilities, and security provisions for same; communications; personnel; sam-
pling and analysis; equipment maintenance; medical services; collection and
recording of data (including photography) on a day-to-day basis; legal coun-
sel; and administration, record keeping, funding, and accounting.
The cost of monitoring the emergency procedures consists primarily of
the salary and travel expenses of an inspector. The inspector can check to
see that each person involved is aware of his responsibilities and that all
equipment is ready for mobilization. Through a sequence of phone calls,
personal visits, and actual equipment testing, the inspector can determine
if the emergency procedures are workable. An inspector's training would
often be derived from industrial safety programs rather than from a county
or State program.
SAMPLING METHODS
Surface Water Bodies
Surface water sampling includes rivers, lakes, estuaries, and canals that
are sources of groundwater recharge. Of primary concern are polluted sur-
face waters. Precipitation should also be sampled in areas where it directly
recharges the groundwater. Surface water sampling will be conducted
through federally mandated monitoring programs (U.S. EPA, 1974b), but
additional monitoring will be necessary in some areas to evaluate polluted
recharge. Sampling of surface water has been discussed by Hem (1970), and
Brown, Skougstad, and Fishman (1970).
To adequately determine the composition of a flowing stream, each sam-
ple, or set of simultaneous samples, must be representative of the entire
flow at the sampling site at that instant. Furthermore, the sampling process
must be repeated frequently enough to define changes with time that occur in
the water passing the sampling point. For most streams, one sample can-
not be safely assumed to represent the water composition closely for more
25
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than a day or two and for some streams not for more than a few hours. If
the average composition of the whole flow of the stream, or its changes in
composition over a period of time, are factors of principal significance,
sampling locations where mixing is incomplete should be avoided.
Daily sampling is generally believed to provide a reasonably complete
record for most large rivers. Composited daily samples can be used to cal-
culate mean annual chemical composition of streamflow and total loads of
dissolved solids carried with reasonable accuracy. For many kinds of water-
quality studies, however, compositing of samples is not desirable. As auto-
mated or continuous-recording equipment for conductivity and other variables
comes into wider use, properly designed supplementary sampling and chem-
ical analyses will provide many details on water-quality regimes which are
not attainable by daily sampling alone. Discharge or flow measurements
should be available for sampling sites.
Water stored in lakes and reservoirs commonly is poorly mixed. Single
samples from lakes or reservoirs can be assumed to represent only a single
location within the water body.
The EPA (U.S. EPA, 1974b) has summarized rules for intensive monitor-
ing of navigable waters. Station locations, parameter coverage, and sam-
pling frequencies are considered. Monitoring stations should be located so
as to measure inputs, transformations, movements, and outputs of pollutants
within a given survey area.
The physical, chemical, biological, microbiological, hydraulic, hydro-
logic, climatic, and geometric parameters to be measured during monitor-
ing surveys will depend upon the survey purpose and local conditions, and
should be tailored to the specific pollution problems of the area. Sampling
frequencies must be determined on the basis of variability of each of the
parameters associated with the pollution problem, and must be adequate to
define the pollution problem within statistically determined confidence inter-
vals. The sampling frequencies must be adequate to determine mass bal-
ances of pollutants where necessary to define fluctuations of water quality
and related parameters in receiving waters and pollutant sources.
Portions of surface water bodies can be selected for detailed sampling in
areas where groundwater recharge is significant. This determination can
be made on the basis of surface water budget analysis, groundwater level
contour maps, and interpretation of soils and hydrogeological factors. It
may be desirable to locate surface water sampling sites near wells or other
groundwater monitoring facilities in some cases.
26
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Wastewater
The American Public Health Association (1971) reported on the collection
of samples of domestic and industrial wastewaters for physical and chemical
analyses. Only representative samples should be used for analysis, but the
great variety of conditions under which collections must be made precludes
prescription of a fixed procedure. In general, the sampling procedure should
take account both of analyses to be made and the purpose for which samples
are taken.
When testing for average concentrations, a 24-hour composite sample is
considered standard for most determinations. When the purpose is to show
peak concentrations, the duration of peak loads, or the occurrence of varia-
tions, grab samples collected at suitable intervals, and analyzed separately,
are more appropriate. The sampling interval should be chosen on the basis
of the frequency with which changes may be expected, and may vary from as
little as 5 minutes to as long as an hour or more. Under other circum-
stances, a composite sample representing one work shift or less or a com-
plete cycle of a periodic operation may be required. Evaluation of the ef-
fects of special, variable, or irregular discharges and operations may re-
quire composite samples representing the periods during which such wastes
are present.
Composite samples cannot be used for analysis of constituents which are
subject to significant and unavoidable changes when stored. Such determina-
tions should be performed on individual samples as soon as possible after
collection, preferably at the sampling point. Analyses for all dissolved
gases, residual chlorine, soluble sulfides, temperature, and pH are exam-
ples of determinations of this type. Additional details are given by the
American Public Health Association (1971), part 200, the American Society
for Testing Materials (1969), and EPA {U.S. EPA, 1972, 1973, 1974a).
Current articles in the Journal of the Water Pollution Control Federation
commonly discuss wastewater sampling.
Two basic categories of wastewater sampling relate to groundwater pollu-
tion. The first is that of the discharge stream at the point of wastewater
discharge. In some cases the discharge stream contains solids as well as
liquids. This type of sampling has been common, especially in cases where
treatment plant performance is being evaluated. The second category is
sampling in percolation ponds and other types of ponds which may leak. For
monitoring groundwater pollution, the sampling of pond waters is often di-
rect and often requires either construction of special walkways or the use
of boats for sample retrieval. In others, where water is recycled, collec-
tion devices allow relatively easy sampling.
Of extreme importance is an understanding of how the wastewater is gen-
erated. For example, in sampling mine tailings pond wastewater a knowledge
27
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of what reagents are added at the mill, the type of ore being processed, and
any unusual occurrences is necessary to correctly interpret the results. In
sampling open waters, climatic factors such as rainfall and temperature are
very important. Consideration should be given to groundwater recharge in
the selection of sampling sites. Thus, wastewaters overlying more perme-
able soils and sediments should deserve primary attention.
Generally a 3-liter Kemmerer or Van Dorn style water sampler costing
from $120 to $200 is used to sample surface water bodies. The cost of sam-
pling varies primarily with the time required to obtain the samples. Travel
time and mileage to the site must be added to the time spent sampling the
water body. Provided a small boat and motor are available, one man can
sample up to about 50 locations per day in an average mine tailing pond.
The sampling time at each location depends primarily upon the depth from
which the sample must be retrieved. A 3-liter sample hand-drawn from
about 20 meters requires about 5 minutes.
In a river or a long reservoir, the distance between sample locations be-
comes important. Assuming that the boat must return to its original posi-
tion, samples from 15 to 25 locations over a 25-mile stretch can be taken in
1 day. If wastewater or solid waste samples are to be taken from point
sources, the travel time and mileage between the locations may be the prin-
cipal governing cost factor.
Solid Wastes
The chemical composition of many solid wastes can be categorized on the
basis of past experience and available data in the literature. For point
source solid wastes, sampling at the land surface is confined to occasional
samples of the waste for analysis. The primary monitoring in this case is
an inventory of the weight or volume of waste. For diffuse sources of sol-
ids, the main monitoring involves a complete inventory of amounts being ap-
plied on an annual basis. Monthly or weekly data may be necessary in some
cases, such as the application of nitrogen fertilizers, where the amount
leached will vary seasonally depending on crop uptake of nitrogen, tempera-
ture, irrigation applications, etc.
28
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SECTION III
MONITORING IN THE VADOSE ZONE
INTRODUCTION
Topsoil
The topsoil is the region that manifests the effects of weathering of geo-
logical materials, together with the processes of eluviation and illuviation
of colloidal materials, to form more or less well developed profiles (Simon-
son, 1957). Water movement in the topsoil usually occurs in the unsaturated
state, where soil water exists under less-than-atmospheric pressures. The
physics of unsaturated, soil-water movement have been intensively studied
by soil physicists, agricultural engineers, and others. Copious literature
is available on the subject in periodicals (Soil Science Society of America
Proceedings, Soil Science, and Journal of Environmental Quality) and text-
books (Childs, 1969; Kirkham and Powers, 1972). Saturated zones may de-
velop over horizons of low permeability. A number of books are available
on the theory of flow in perched water tables (Luthin, 1957; van Schilfgaarde,
1974). Soil chemists and soil micro biologists have also attempted to quan-
tify the chemical-microbiological transformations during soil-water move-
ment (Rhoades and Bernstein, 1971; Dunlap and McNabb, 1973).
Vadose Zone
Weathered materials of the topsoil gradually merge with underlying ma-
terials such as igneous or metamorphic rocks, alluvium, lake deposits,
eolian deposits, or lacustrine beds. The region beneath the topsoil and
overlying the water table, where water exists primarily in the unsaturated
state, is known as the vadose zone. Perched water tables may develop
above interfaces between layers having greatly different textures. Saturated
conditions may also develop beneath recharge sites as a result of prolonged
infiltration. In contrast to the large number of studies on water movement
in the topsoil, parallel studies in the vadose zone have been few. Meinzer
(1942) coined the term "no-man's land of hydrology" to describe the limited
knowledge of this zone.
Monitoring Techniques
A number of techniques have been developed for monitoring water move-
ment and water quality in the topsoil. Detailed descriptions, specifications,
and methods of many of these techniques were compiled in American Society
29
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of Agronomy Monograph No. 9, "Methods of Soil Analysis" (Black, 1969).
Monitoring in the vadose zone requires an extension of topsoil monitoring
technology. Examples are available where this approach has been used;
Apgar and Langmuir (1971), for example, successfully used suction cups,
developed for sampling soil solutions, to sample at depths up to 50 feet be-
low a sanitary landfill. Of primary interest are flow rates to the water table
and the storage capacity of the materials above the water table.
Water Content
Soil and underlying geologic materials consist of a solid and porous ma-
trix. Porosity is a measure of the amount of water which could be stored by
the materials under saturated conditions. Field capacity of a soil is repre-
sented by its water content (on a dry weight basis) at a certain time after the
initiation of drainage following an irrigation cycle (Peters, 1965). The defi-
nition of specific retention for geologic materials is essentially the same,
except that the water content is expressed on a volumetric basis. Specific
yield or effective porosity of geologic materials is the difference between
porosity and specific retention. At a given time, the volumetric water con-
tent of a material is a reflection of various forces acting on the soil-water
system, including gravity, capillary, and osmotic forces. Soil-water pres-
sure is a measure of capillary forces and is expressed in terms of negative
pressure; the relation between water content and pressure may be deter-
mined in the laboratory. This relation is essential to calculate water flow
rates in the vadose zone.
Water Flow
Infiltration is the movement of water across the soil surface from an ap-
plied water source. Factors affecting infiltration capacity, or the maximum
rate of infiltration, include soil texture, initial water content, and soil stra-
tification. Determination of the rate of water flow out of a given soil depth
may be determined from sequential drainage profiles (curves showing the
relation between soil depth and water content for various times after the
cessation of infiltration). The salinity and composition of the solution may
have a pronounced effect on water movement.
For saturated materials the pressure is positive and measured by piezom-
eters. For unsaturated materials the pressure is negative and measured by
tensiometers.
Chemical Changes
The interactions of infiltrating water and soil have been reviewed by
Ellis (1973), Rhoades and Bernstein (1971), Murrmann and Koutz (1972) and
McNeil (1974). Among the main reactions are: precipitation, dissolution,
ion exchange, adsorption, and oxidation-reduction.
30
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Changes in the concentration of a soil solution following surface applica-
tion include water removal by evaporation and transpiration. Precipitation
of slightly soluble salts, primarily calcium carbonate or calcium sulfate,
may occur as the soil solution is concentrated during evapotranspiration.
Dissolution of soil minerals contributes to the salinity of the soil solution.
Ion exchange represents an important soil-water interaction for altering the
composition of the soil solution. Ion exchange is a function of the cation ex-
change capacity of the soil, which in turn is related to colloidal clay miner-
als, soil organic matter, iron and aluminum sesquioxides, and hydrous
oxides.
Adsorption of metals onto the surface of soils is the most important pro-
cess for removing some chemicals from wastewater (Murrmann and Koutz,
1972). In contrast to ion exchange, in which ions retain their mobility, in
adsorption reactions ions are held so tightly that they become essentially
immobile. Methods to quantify the extent of adsorption of ions onto solids
have been developed. Oxidation and reduction reactions are of special im-
portance in the case of sulfur and nitrogen compounds in water, as well as
for many trace elements. These reactions affect the mobility of some ele-
ments and may result in the production of gases which can be lost from the
soil-groundwater system.
SOIL SAMPLING AND WELL DRILLING
A test drilling program may be necessary to supplement existing data on
the vadose zone at a site. Soil sampling and well drilling are generally ne-
cessary for all types of monitoring in the vadose zone. Test wells can also
function as observation wells, piezometers, or access wells.
Shallow Wei Is
In general, samples from the soil zone are obtained to (1) characterize
the average soil texture, water content, or chemistry in depth increments
(e.g. , 15 cm), (2) observe the precise depth distribution of soil texture, or
(3) determine the bulk density, or water-release curves, of soil increments.
For the first purpose land samplers such as post-hole augers, screw or
sleeve type augers, or power-driven augers are useful. For the second
purpose, cores are obtained by driving small-diameter (e.g., 2. 5 cm) tubes
into the soil to the desired depth. For the third purpose, larger diameter
core samplers are used—these may be hand-driven or power-driven. Cores
of a specific volume are obtained by each method. More information on cor-
ing is presented by Blake (1965).
The cost of a "bucket" type hand auger, is about $35. These augers are
available to cut core sizes from 2 to 4 inches in diameter. Four-foot exten-
sions for deeper sampling cost about $6 each. For deeper samples a hand-
driven soil sampler system can be purchased. These systems include soil
31
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sampling tubes, a drop hammer, and a tube puller jack to withdraw the tubes.
The soil sampling tubes vary from 4 to 16 feet in length and cost from $65 to
$115, respectively. The cost of the hammer and puller jack is about $200.
Deeper Wells
To sample throughout the vadose zone it may be necessary to drill deep
wells using standard techniques. Such techniques include jetting, rotary,
cable tool, augering, and air drilling. Of these methods perhaps augering,
using continuous flights, and air drilling provide the most usable samples —
problems develop in characterizing the distribution of indigenous salt and
water content with cable tool and rotary methods because of water additions
during the drilling process. The cost of power-augering multiple depth and
density holes is given in Figure 6. These augering costs are developed for
8-inch diameter holes.
1000
POWER AUGERING COSTS ($)
2000
Figure 6. Cost of power-augering 8-inch diameter sample holes to various depths
and hole densities, November 1974.
32
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One air-drilling technique (Becker Drills, Inc. , Denver, Colo. ) involves
driving a. double-wall tube by a pile hammer while concurrently forcing air
under pressure down the annulus of the pipe. Air and entrained material cut
by the bit return to the surface through the inside pipe. The sample, avail-
able continuously, is diverted into a cyclone sampler where it is bagged for
laboratory analyses. Changes in formation can be determined within a few
centimeters; furthermore, water seams can be determined immediately.
This feature is advantageous in locating the depth and thickness of perching
layers. Whichever technique is used, samples should be taken in specified
increments throughout the vadose zone.
DETERMINATION OF WATER CONTENT
Although a major concern of a monitoring program may be the movement
of water in the vadose zone, it is also important to account for the storage
capabilities of this zone. In western valleys with deep alluvium the vadose
zone may constitute a vast reservoir for such in-transit storage.
Examining this water content requires the extension of techniques em-
ployed in the soil zone downward to the water table. Fortunately, many of
the methods may also be used simultaneously to monitor water movement.
Neutron Moderation or Moisture Logging
For many years agriculturists have employed the principle of neutron
moderation or thermalization to measure the volumetric water content of
soils in situ. Recently, the technique has been used to monitor water stor-
age in the vadose zone, particularly to delineate perching layers and mounds,
and also to estimate flow rates.
The method of water content evaluation by neutron moderation depends on
two properties relating to the interaction of neutrons with matter: scatter-
ing and capture (Gardner, 1965). High-energy neutrons, emitted from a
radioactive source are slowed down, or thermalized, by collisions with
atomic nuclei. Hydrogen has a greater thermalizing effect on fast neutrons
than occurs with many elements commonly found in soils. This forms the
basis for detecting the concentration of water in a soil (Van Bavel, 1963).
The second property of interest in the neutron moderation method is capture
of slow neutrons by elements present in the soil with the release of energy.
The property of energy release during capture serves as a means of detect-
ing the concentration of slow neutrons.
When a source of fast neutrons is lowered into a soil through a suitable
well bore or casing, a cloud of thermalized neutrons is established. If a
suitable calibration is made to isolate the moderating effects of soil nuclei
other than hydrogen, changes in the volume of the thermalized cloud will re-
flect changes in water content. Finally, a detector which relies on capture
33
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of thermal!zed neutrons is used, in conjunction with suitable electronic cir-
cuitry, to measure the water content (on a volume basis).
Instrumentation used to measure water content by neutron thermalization
requires three principal components: (1) a source of fast neutrons, (2) a
detector of slow neutrons, and (3) an instrument to determine the count rate
from the detection equipment, as shown in Figure 7.
SOURCE OF NEUTRONS:
5 mC! RADIUM - BERYLLIUM
30 mCi AMERICIUM - BERYLLIUM
HV
UNIT
SCALER AND
COUNT RECORDER
^w
PROBE\
RADIUS OF MEASUREMENT
25cmAT0.10g/cc WATER
CONTENT
Figure 7. Sketch of neutron moisture logger and accessories (after
Holmes et al., 1967).
Americium-beryllium is commonly used as a source of fast neutrons.
Detectors of slow neutrons rely on high capture cross sections of detecting
materials (e.g., boron). A charged particle is emitted during capture,
which can be detected by a solid or gaseous counting device. The predomi-
nant detector is lithium-enriched BFs. Both the source and detector are
34
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located in a cylindrical probe, or tool, which is lowered via a cable into ac-
cess tubing either by hand or by motor-drive. The depth of measurement is
determined by graduations on the cable or, alternatively, by some type of
counter (Van Bavel, 1963).
The pulse emitted during the nuclear reaction resulting from capture is
amplified within the down-hole tool and transmitter through the cable to an
above-ground meter for counting. Count rate is converted to water content
via suitable calibration curves. The type of equipment that has been avail-
able for soils work is hand operated. Its use requires placing the down-hole
tool at a discrete depth, taking a count or number of counts, and then moving
the tool by hand to another discrete depth. This process is not troublesome
for shallow soils studies. However, for deeper access wells, in the vadose
zone, an inordinate amount of time would be involved. Recently, a motor-
ized unit became available (Well Reconnaissance of Dallas, Texas) which
permits lowering the,tool in the well at a constant rate, via a motor drive.
Internal electronic components concurrently translate pulse rate into water
content, which is automatically recorded.
The individual neutron moisture logger should be calibrated against sam-
ples of known water content. Such calibration may be done in the field by
comparing a count at a given soil depth with the water content of soil cores
from the same depth.
Access tubes for neutron moisture logging are usually constructed of
seamless steel or aluminum. Polyvinylchloride-cased wells may cause dif-
ficulty in that hydrogen or chlorine atoms in the tubing may moderate the
thermal neutrons, interfering with soil moisture evaluation. Aluminum-
cased wells may deteriorate in saline groundwaters. The inside diameter of
wells should be as close as possible to the outside diameter of the probe.
Work by Ralston (1967) showed that for a 100-millicurie (mCi) Am-Be source
in a 3. 8-cm OD tool, the water content could not be accurately evaluated in
well casings with an ID greater than 10 cm.
Wells drilled for shallow water content monitoring can be easily installed
by successively augering and driving the tube. Myhre et al. (1969) reported
on a simple power-driven auger for installing wells to 150-cm depths. For
deeper wells standard drilling techniques are necessary. During installation
by drilling techniques it is essential to establish a tight fit between the well
shaft and casing, to minimize the amount of vertical leakage of water. Drill-
ing mud, although facilitating the drilling operation, is not recommended
since it interferes with water content observations. In situations requiring
a tight fit, drilling techniques which do not require a drilling mud (jetting,
augering) are used.
The principal advantage of neutron moisture logging is that water content
profiles are obtained in situ with minimal soil disturbance. A history of
35
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profiles can be established during a monitoring program. Moisture logs
clearly show the presence of perched water tables, together with their
growth and dissipation (see Figure 8). Such logs may also be used to esti-
mate unsaturated flow rates. Water content exchanges at a given depth in a
succession of wells may provide clues on lateral flow velocities (Wilson,
1971).
Certain limitations should be noted. First of all, the presence of exces-
sive concentrations of other fast neutron moderators (e.g. , boron, chlorine)
may cause erroneous water content determinations. Neutron moisture logs
indicate only the water content of soils, and may not always manifest water
movement. However, water content values may be translated to equivalent
soil-water suction values via a soil-water characteristic curve.
The cost of a neutron moisture logger including the neutron source, slow
neutron detector, and surface counter is about $3000. Figure 9 gives the
cost of neutron moisture logging with various numbers of well loggings per-
formed at depth intervals of 2 feet. The costs in Figure 9 do not include the
capital cost of the instrument, but only the time required to conduct the log.
Tensiometers
Tensiometers are used to measure soil-water pressures during unsatur-
ated flow. If caution is exercised, they may also provide estimates of soil-
water content via suitable soil-water characteristic curves. Basically, a
tensiometer consists of a porous ceramic cup cemented to a rigid plastic
tube, small-diameter tubing leading to a manometer and terminating in a
reservoir of mercury, and a filler plug in the rigid plastic tube (see Figure
\-i ' ^ rP reservoir and the portion of the small-diameter tubing
filled with mercury, the internal volume of the system is completely filled
with water. When properly emplaced in the soil the pores in the cup form a
continuum with the pores in the soil. Water moves either into or out of the
tensiometer system until an equilibrium is attained across the ceramic cup.
The mercury level in the manometer tubing adjusts correspondingly.
Holmes et^al. (1967) have noted the precautions to be taken during instal-
lation of tensiometers. Prior to field installation, the system should be
purged of as much entrained air as possible and its response checked. The
tensiometer unit should be placed into soil cavities larger than the outside
diameter of the unit. The cup should be forced into the soil at the base of
the hole to ensure good contact. The hole is then backfilled with soil.
The principal limitation of tensiometers is that they are useful in measur-
ing soil-water pressures only up to about 1.0 atmosphere. Furthermore
the determination of water content via tensiometer values is subject to hys-
teresis: i. e , different water content versus pressure curves will be fol-
lowed depending on whether the soil is wetting or drying
36
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DEPTH BELOW GROUND SURFACE DATUM (ft)
S 8 6 8
CO
§
GO
CD w
-i -*
S
Q M
D JT
0. O
ol
CD 3
D.
CA
a
(D
N
O
, fT":SWL
T5WL
DEPTH BELOW GROUND SURFACE DATUM (ft)
O g SYL S B
. ,T. . I . . i i- I . . i
rv
>
"• ^ Z
o O _
^ o
°s>
^55
.^wky-'
8
-------
200
100
o
o
8
50 -
100
J_
_L
500 1000
LOGGING COST (i)
2000
3000
Figure 9. Cost of neutron moisture logging for various depths and sample
space densities, December 1974.
SINGLE MANOMETER-
FILLER PLUG
n
RtGID PLASTIC TUBE
POROUS CERAMIC CUP—*
Figure 10. A single manometer tenstometer.
38
-------
The cost of a tensiometer including a 6-foot plastic tube is about $30.
Figure 11 gives the capital costs of tensiometers placed at various depths
and at various sampling densities. The costs presented in Figure 11 do not
include installation.
20
15
Q_
u
o
Q_
LL
O
I
UJ
Q
10
-L
500 1000
TENSIOMETER COSTS {$)
1500
2000
Figure 11. Cost of tensiometers for various depths and
sample space densities, December 1974.
Electric Resistance Blocks
Electrical resistance blocks, used to measure either soil-water content
or soil-water pressure, consist of electrodes embedded in a suitable porous
material such as plaster of paris, fiberglass, or'nylon cloth. The principal
of operation of these blocks {Holmes et al. , 1967) is that water content (or
negative pressure) within the blocks responds to the water content (or suc-
tion) of the soil with which the blocks are in intimate contact and the electri-
cal resistance properties of the blocks change correspondingly. Moisture
blocks are calibrated in soil from the site at which they are to be installed.
Such calibration involves evaluating resistance readings against a range of
soil-water contents or negative pressures.
39
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Holmes et al. discuss the advantages of resistance blocks, indicating
that (1) they appear to be best suited for general use in the study of soil-
water relations, (2) they are inexpensive, and (3) they can be calibrated for
either suction or water content. Generally, for agricultural applications
the blocks are used for negative soil-water pressures greater than 0. 8
atmosphere.
The cost of a soil moisture block is about $4. The leads to the soil
ture blocks are very nominal in cost. A soil moisture meter costs about
$120. The capital cost, excluding emplacement, of electrical resistance
blocks, leads, and a soil moisture meter for various depths and sampling
densities is given in Figure 12.
COST OF SOIL MOISTURE TESTING EQUIPMENT ($)
Figure 12. Cost of multiple electrical resistance blocks and soil
moisture meter for various depths and sampling densities
December 1974.
750
40
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Calculation of Water Content
In-situ measurement of water content at some locations, such as beneath
waste disposal sites with large areas and relatively deep water tables, may
be too cumbersome and expensive to perform. One alternative is to evaluate
maximum storage capacity. Porosities for common geologic materials are
given in Figure 13. The storage capacity in the vadose zone will be less than
that indicated by the porosity because all of the materials are not saturated.
(WELL-SORTED AQUIFERS)
(WELL-SORTED AQUIFERS
I I
0.00?
CLAY
|0.1 1
SAND
MEDIAN GRAIN SIZE
100
COBBLES
Figure 13. Relationship between median grain size and water-storage proper-
ties of alluvium from large valleys (Davis and DeWiest, 1966).
Many areas can be divided into two types of vadose zones: those where
the specific retention of geologic materials has already been satisfied, and
those where it has not. The first case occurs primarily in humid areas
where water levels are relatively shallow and an abundant source of re-
charge has been present for many years. This case also occurs beneath
many alluvial basins of the arid west where water tables are within 100 to
200 feet of the land surface and water has been artificially applied at the
land surface for decades. The second case is common in arid areas with
relatively deep (300 or more feet) water tables. Low natural recharge at
the land surface for many years, combined with the presence of soil or sub-
surface restricting layers, may prohibit natural percolation to the water
table. In these cases, the geologic materials may be virtually devoid of
water.
41
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The storage capacity for percolated water in cases where the specific re-
tention is satisfied is defined by the specific yield. Representative specific
yields for geologic materials are given in Table 5. Where the specific re-
tention has not been satisfied, significant amounts of percolated water will
be stored in the vadose zone to make up this deficiency. The total storage
capability will then be some value less than the porosity.
TABLE 5. SPECIFIC YIELD VALUES ASSUMED FOR THE SOUTHERN
PART OF THE CENTRAL VALLEY, CALIFORNIA (Davis and
DeWiest, 1966)
Driller's Description
Gravel, sand and gravel, and similar
materials
Fine sand, tight sand, tight gravel, and
similar materials
Clay and gravel, sandy clay, and similar
materials
Clay and related materials
Crystalline rock (fresh)
Assumed Specific Yield
25
10
3
0
DETERMINATION OF WATER MOVEMENT
An evaluation of water movement above the saturated zone should account
for (1) infiltration across the soil surface and movement through the topsoil,
(2) movement in perched water tables, and (3) downward movement through
the vadose zone. Flux (volume per unit area per unit time) is the principal
flow characteristic to be defined in studying water movement in the vadose
zone. An important factor in calculating flux is the hydraulic conductivity.
Infiltration Across the Soil Surface
Flux across the soil surface is termed infiltration, the maximum value
of which is the Infiltration capacity. This characteristic is important in
land disposal operations because it indicates the rate at which effluent may
percolate to groundwater. Bouwer (1973) categorizes land disposal systems
as high-rate or low-rate, reflecting the infiltration rates used to effect ef-
fluent treatment.
For existing land disposal operations, effluent can be metered onto each
treatment area via suitable flumes, weirs, or flowmeters. Differences in
flow rate represent the amount of water which infiltrates on the area. The
42
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flux canbe calculated (it may be necessary to account for evaporation losses) if
the surface area contacted and time that a given volume infiltrated are known.
Movement in Perched Water Tables
Results of neutron logging observations during infiltration tests or exam-
ination of data on stratigraphy may indicate the locations of perched water
tables in the vadose zone. The principal techniques for monitoring move-
ment in these saturated zones are by the use of piezometers or observation
wells.
PIEZOMETERS. Piezometers consist of small-diameter pipes, driven,
augered or jetted into a known or expected saturated soil zone. The level of
water measured at the base of the piezometer indicates the water level in the
saturated zone.
Reeve (1965) discusses in detail the techniques for installing and cleaning
new piezometers. In general, it is important to maintain tight contact be-
tween the outer wall of the piezometer and the soil. For shallow units, pie-
zometers may be installed by augering and driving with a sledge hammer.
Deeper units will require jetting, or use of standard drilling equipment. It
may be necessary to fill the cavity between the well and borehole with grout
to ensure tightness of fit. As with regular wells, piezometers should be de-
veloped by pumping, bailing, etc. to open up material at the base of the unit.
In some situations, it may be necessary to install piezometers with screened
well points to prevent upward movement of saturated material into the unit.
Depth to water in piezometer units is measured by chalked tape, electric
sounders, or air lines. The use and cost of these tools is considered in de-
tail under "Monitoring in the Saturated Zone. " By referencing these meas-
urements to a common datum, groundwater levels can be determined for
the perched zones. The slope of these elevations indicates the direction of
lateral water movement.
Many field soils exhibit anisotropy. That is, the hydraulic conductivity
in the horizontal direction may be much greater than in the vertical direc-
tion. For such soils it may be advisable to install more than one array or
battery of piezometers in a lateral direction away from a recharge source.
The bottom openings of piezometers in sequential arrays should terminate
at the same elevation. Such an arrangement permits observing lateral head
differences resulting from horizontal flow.
The costs of 2- and 4-inch piezometers for various depths and sampling
densities are given in Figure 14. The piezometer costs presented do not
include installation.
43
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500
PIEZOMETER COSTS ($)
1000
2000
Figure 14. Cost of piezometers for various depths and sampling densities
November 1974. '
OBSERVATION WELLS. An observation well consists of an uncased
borehole or perforated pipe extending from ground surface into a perched
water table. This is similar to a piezometer, except that diameters and
depths may be greater.
WATER MOVEMENT IN THE UNSATURATED STATE
Methods for monitoring water movement in saturated regions cannot be
used to monitor unsaturated flow because water will not freely enter a soil
cavity unless the soil-water pressure is greater than atmospheric. Conse-
quently, special methods must be used in unsaturated soils. Of the available
methods the three most commonly used to infer unsaturated flow employ
44
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tensiometers, psychrometers, and neutron moisture logging. Several
newer techniques, although not extensively field tested, may also have
applicability.
Tensiometers
The principles of operation, methods of installation, and limitation of
tensiometers are discussed above. In general, tensiometers appear to be
the most effective technique for monitoring flow in the soil-water pressure
range down to about 0. 8 atmosphere (atm). Nielsen et al. (1973) observe
that tensiometers are still routinely used and nothing as reliable, accurate,
and inexpensive has replaced them in the past 35 years. The application of
tensiometers to depths greater than the soil zone is now possible with the
advent of pressure transducer units developed by Watson (1967) and others.
In characterizing the direction of water movement, a battery of tensiometers
must be installed, with units terminating at successive depths throughout the
region of interest.
As with piezometers, it is necessary to install more than one array of
tensiometers to detect horizontal flow. Thus, if individual arrays terminate
at varying depths, differences in total hydraulic heads between correspond-
ing units in successive arrays may suggest lateral movement in the unsatu-
rated state. Because of heterogeneity in soil properties, however, conclu-
sions on lateral flow may not be definitive.
Psych rometers
Tensiometers cannot be used to measure soil-water pressure below about
-1 atm because of air-entry problems. To measure lower negative pres-
sures, therefore, other instrumentation is required. In recent years, pro-
gress has been made in developing the thermocouple psychrometer for this
purpose. According to Watson (1974) in-situ pressure measurements down
to -30 atm are possible with these units. The principle of psychrometric
measurement of soil-water potential, discussed by Rawlens and Dalton
(1967), is that a relationship exists between soil—water potential and the
relative humidity of soil water.
Psychrometers consist of a porous bulb comprising a chamber to sample
relative humidity of a soil, a sensitive thermocouple, heat sink, reference
electrode, and associated electronic circuitry. Two types of thermocouple
psychrometers are available. One type, which is installed in access tubes,
consists of mounting psychrometers in porous cups at the base of tubing.
This unit may be withdrawn for recalibration. The second type, called
"sealed-cup" psychrometers by Merrill and Rawlens (1972), contains the
thermocouple unit permanently sealed into a porous enclosure.
45
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Each unit must be calibrated prior to field installation—techniques for
such calibration are given by Merrill and Rawlens. Also, in field installa-
tions it is important to record and correct for diurnal changes in tempera-
ture. Installation of a sensitive thermistor is recommended for diurnal
studies. Enfield et al. (1973) have used thermocouple psychrometers to
estimate the direction and rate of water flux in material above a water table
at a depth of 94 meters in a desert environment in Washington. Individual
psychrometric units were placed 3 meters apart within a specially designed
well casing.
Neutron Moisture Logging
Although the neutron thermalization technique is used mainly to determine
changes in volumetric water content of materials in the vadose zone, the
method may also be used to infer water movement. In particular, if a soil-
water characteristic curve is available for incremental depths throughout the
vadose zone, it may be possible to relate water content values to water pres-
sure. Hydraulic head gradients and, therefore, flow directions can then be
inferred. Unfortunately, the accuracy of the method may not be great
enough to detect slight water content changes, particularly in the dry range.
Wilson and DeCook (1968) and Wilson (1971) have used moisture logs from a
network of 30-meter deep access wells to infer the rates of lateral move-
ment of recharge waves in the vadose zone during river recharge and artifi-
cial recharge. The arrival of such waves was inferred by the change in
water content in a perched mound at about 10 meters.
Moisture Blocks
Moisture blocks of the type described earlier may be used to measure
soil-water pressure if suitable soil-water characteristic curves are avail-
able. A unit relying on the sensing of heat dissipation within the block
(Phene et al. , 1971) may have future promise.
Quantification of Flux in Unsaturated Media
Two of the physical characteristics of interest in the vadose zone are
soil-water flux and hydraulic conductivity. Under continuous flooding at
waste disposal facilities, the steady-state value of infiltration approaches
the saturated hydraulic conductivity. Presumably, the steady-state value
of flux below the soil surface also approaches this value; therefore an ap-
proximation of the flux value in the wetted soil profile can be obtained during
a wetting cycle.
Of equal interest is the flux during drying periods. Three major ap-
proaches to evaluating flux in the vadose zone during a drying cycle are:
(1) measuring water content changes in profiles as a function of time;
(Z) using appropriate mathematical expressions and empirically determined
46
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relationships between soil-water pressure, soil-water content, and hydraulic
conductivity; and (3) direct measurements using flowmeters.
RELATING WATER CONTENT CHANGES TO FLUX. The difference in
water content stored in a wetted profile between successive time measure-
ments above a certain depth is a measure of the amount of water which has
flowed out of that depth. The water content versus depth curves may have
been obtained from tensiometer data, moisture logs, etc. This relationship
assumes that the water in storage from the surface to the first tensiometer
equals the value at the first tensiometer times the thickness of materials
above this point.
EXPRESSIONS FOR FLUX AND HYDRAULIC CONDUCTIVITY. Field
plots instrumented with tensiometers are required to determine flux and hy-
draulic conductivity (Nielsen et al., 1973). Infiltration is allowed to pro-
gress in each plot to the point that steady-state values are reached. After
recession of the water surface, the soil surface is covered to prevent evap-
oration. When drainage has occurred to the point that the hydraulic gradient
becomes unity, tensiometer readings are taken in incremental time steps
from successive tensiometer units. At the completion of the study, intact
cores of soil are taken in increments throughout the profile. Such samples
are used for the laboratory determination of soil-water characteristic curves.
Subsequently, the soil-water pressure data taken by tensiometers during the
field study are translated to equivalent water content values. Spatial varia-
tions occur in the soil properties; consequently, a sufficient number of field
plots are needed to provide a measure of this variability. Furthermore,
even though the assumption of unit hydraulic gradient is fulfilled, problems
may arise if subsurface heterogeneities affect flow. Problems of anisotropy
and stratification will be accentuated with depth in the vadose zone. Realis-
tically, it may be expected that flux expressions are most useful in the soil
zone.
DIRECT MEASUREMENT OF FLUX. Attempts have been made in recent
years to develop equipment to measure soil-water flux in the unsaturated
state which do not require information on the hydraulic conductivity.
Two types of flowmeters reported by Gary (1973) involve (1) direct flow
measurement, and (2) the displacement of a thermal field by water in mo-
tion. The direct flow unit measures the flow of soil water intercepted by a
porous tube containing a sensitive flow transducer. The second unit meas-
ures very accurately the transfer of a heat pulse in water moving within a .
porous cup buried in the soil. Because of the intimate contact between the
soil and porous cup, the water moving in the cup forms a continuum wxth
soil water. Laboratory calibration curves are prepared to relate the output
of a sensitive millivolt recorder, during imposition of heat pulses, to empir-
ically measured flow rates.
47
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For field installation, porous discs containing either flow transducers or
heat sources are mounted in cylinders which are buried in the soil. A limi-
tation, therefore, is that flow is measured in disturbed soils. To date, no
data are available on the use of such flowmeters in deep vadose zones.
Calculation of Approximate Flow Rates
Vertical flow in the vadose zone is related to the infiltration rate of wa-
ters applied at the land surface, storage capacity of the vadose zone, and
depth to the water table. If the water table remains at a relatively constant
depth and a specific amount of water percolates from the topsoil, then the
flow rate of water in the vadose zone is partly controlled by the available
storage space therein. With point or line sources, significant lateral move-
ment can occur in Layered deposits above the water table; however, for dif-
fuse sources of large areal extent, such as agricultural return flow, these
lateral movements may be neglected.
For example, assume that Z5 feet of water is applied per acre per year at
the land surface and 20 feet percolate from, the topsoil. Assume the depth to
water is 55 feet and the vadose zone beneath the topsoil is 50 feet thick. As-
suming that the porosity is 30 percent and the specific yield is 15 percent,
and that the specific retention has already been satisfied, then the storage
capacity in the zone is a maximum of 50 times 0. 15, or 7. 5 feet. It is clear
that the vadose zone could hold this water for only a few months at the most.
As a second example, assume that 5 feet of water is applied per acre per
year at the land surface and 2 feet percolate from the topsoil. Assume the
depth to the water table is 310 feet and the vadose zone is 300 feet thick.
Assume that the porosity is 40 percent and the specific retention is 15 per-
cent but that the moisture content is only 5 percent. Thus, the storage ca-
pacity in the zone is a maximum of 300 feet times 0. 10 or 30 feet of water.
As a result it would require 15 years for the percolating water to satisfy
storage before reaching the water table.
Use of Tracers
Tracers such as salts, dyes, and radioisotopes can be employed to meas-
ure flow rates in the vadose zone. Care must be taken to insure that the
tracer moves at the same velocity as the water (which, however, is not ne-
cessarily the velocity of a specific groundwater pollutant). The practical
problem of detecting or sampling a tracer at increasing depths under unsat-
urated conditions should not be minimized. Smith (1974) reports on using
tritium as a tracer in the unsaturated zone.
48
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WATER SAMPLING IN THE VADOSE ZONE
In a program to monitor quality in the vadose zone samples may be needed
from both unsaturated and saturated (perched water table) regions.
Sampling in Saturated Regions
WELLS AND PIEZOMETERS. Preliminary hydrogeological surveys will
often delineate existing or potential perched water table regions. Many of
these regions may be instrumented with wells or piezometers which can be
modified or used directly for sampling water quality. In general, observa-
tion wells are unperforated throughout the vadose zone to prevent cascading
water from perched layers affecting water level measurements and water
quality at the water table. It may be possible, however, to modify such
wells for sampling without causing cascading. For example, the results of
neutron logging in a well may reflect the presence of perched layers. It is
possible to perforate the casing of abandoned wells at these depth intervals
and install packer assemblies to isolate these regions for sampling and pre-
vent cascading. Alternatively, if information on the location of perched
layers is known prior to the construction of a new well, the well can be de-
signed to permit sampling of these regions.
An array of piezometers can be used for water sampling in perched zones.
If the locations of such zones are known, individual units can be designed
with screened well points. If units in the individual arrays terminate at
varying depths, samples from such an array will indicate vertical quality
changes from movement of effluent. Similarly, if a number of arrays are
distributed in a horizontal transect, samples from individual units terminat-
ing at the same elevation will manifest quality changes from lateral spread
of effluent.
For programs to monitor the spread of heavy metals in effluent water it
is necessary to construct wells or piezometers from materials which will not
contribute metals to the sample. Wells cased with PVC pipe will avoid this
problem, particularly if screens are also of plastic, but require special
construction techniques.
To obtain water samples from wells it is necessary to employ some type
of sampling device. A simple bailer may often be used with ^cess This
unit consists of a tube with an open top and a ball check-valve at the bottom
to admit water samples.
Another commonly used sampler consists of a -« ^°r ta*
an air inlet line and a sample outflow line extending to the surface. The
lower end of £e body contains a spring-loaded
line extend* to the base of the
slight distance below the top.
49
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well to the sampling depth below the water table. After permitting the sam-
pler to fill, air pressure is applied to the air line and the sample is forced
to the surface through the sampler line. Advantages of this unit are that it
need not be removed from the well between samples. Also, samples are
obtainable at various depths below the water table. A disadvantage is that
air is introduced into the sample, possibly interfering with certain chemical
determinations. This possibility can be avoided by using compressed nitro-
gen gas.
Allison (1971) discusses a simple device for sampling water in auger
holes, which also could be used in cased wells. Basically, the unit consists
of plastic tubing of sufficient length to extend into the water table. The upper
end of the tube terminates in a collector flask. A second line from the flask
is connected to a hand-held vacuum pump. When the pump evacuates the
flask and tubing, water is forced up into the flask. According to Allison
such a system is capable of sampling water to a depth of 7.4 meters.
In addition to these samplers several other types are available, including
positive displacement pumps. Some operations may warrant the purchase
of a small-diameter submersible pump mounted on a flexible line.
With any sampling method it is important to ensure that an uncontami-
nated sample is obtained. The well should be bailed or pumped extensively
at the beginning of each collection period to ensure the movement of fresh
groundwater into the well. Similarly, the bailer or sampling lines should be
flushed out several times before a sample is collected.
SAMPLING TILE DRAIN OUTFLOW. If a tile drainage system has been
installed to promote rapid drainage of a perched water table, samples can
be collected from the tile outfall. In some cases it may be desirable to in-
stall commercially available composite or discrete sampling devices.
Willardson et al. (1973) discuss a "flow-path ground water sampler, "
which enables collection of water in different flow paths around a tile.
FIBERGLASS PROBES. Hansen and Harris (1974) describe a sampler
capable of discrete simultaneous sampling at several depths below a water
table. The unit consists of a series of isolated fiberglass prqbes in a well-
point, with individual lines from each probe running to the surface. Each
isolated area is filled with a sand matrix. During collection, all probes are
sampled simultaneously, via a vacuum pump, to minimize interference with
natural flow within the sampling region.
LYSIMETERS OR SAMPLING CHAMBERS. In the context of this discus-
sion, a lysimeter, or sampling chamber, consists of a trench or large-
diameter culvert sunk vertically into a waste disposal area. Lysimeters
are installed to permit sampling of the soil solution throughout a vertical
50
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profile, usually several meters in thickness. Culvert type lysimeters were
used by McMichael and McKee (1966) in their studies on wastewater reclama-
tion at Whittier Narrows. Parizek and Lane (1970) used trench lysimeters
to collect samples from forest soil during effluent irrigation in Pennsylvania.
The lysimeters developed by McMichael and McKee (1966) employed pan
samplers for the collection of water during periods of saturation in a profile
to a depth of about 3 meters. These samplers were conical in shape, 61 cm
in diameter and 23 cm deep. The samplers were installed at various depths
at a radial distance of about 3 meters from the central well. Individual sam-
pling pans were filled with gravel to prevent clogging, and each was con-
nected to the central culvert via tubing. Excavations used for installation of
the samplers were carefully backfilled. During sampling, percolate inter-
cepted by the pans flowed by gravity to the central well and into collection
flasks.
The trench lysimeter described by Parizek and Lane (1970) also used pan
samplers. The largest such lysimeter consisted of a 1. 2-meter wide, 4-
meter long trench excavated to a depth of about 6 meters. The sides of the
trench were braced and lined with wood. Sampling pans were installed at
30-cm vertical intervals to the 6-meter depth of the lysimeter. The pans,
constructed from galvanized metal, were 30 cm by 45 cm with copper tubing
to permit sample drainage. Each unit was sunk into the soil a short dis-
tance from the side walls of the lysimeter. During application of effluent,
samples of percolate intercepted by the pans were collected in flasks within
the lysimeter.
A basic problem with collection pans, pointed out by Parizek and Lane
(1970) is that samples are collected only when the soil-water pressure is
greater than atmospheric. Consequently, after cessation of infiltration the
soil-water system may shift rapidly to the unsaturated state, prohibiting
sample collection. The same problem exists for piezometers, auger holes,
or other sampling methods requiring saturation.
Sampling in Unsaturated Regions
SOIL SAMPLING. One method for determining the quality of the soil so-
lution in unsaturated soils is to obtain field samples from which saturated
extracts can be obtained. An extensive program of soil sampling throughout
the duration of a waste disposal operation could be-prohibitively expensive,
however, particularly if samples were required from the entire vadose zone.
SUCTION CUPS. An alternative to soil sampling for characterization of
the water quality of unsaturated soils is to utilize ceramic cups like those
used in tensiometers. When placed in the soil, the pores in these cups be-
come an extension of the pore space of the soil so that the soil-water content
in the soil and cup become equilibrated at the existing soil-water pressure.
51
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Applying a slight vacuum to the interior of the cup causes the soil solution
to flow into the cup. The quality of the soil solution can be determined by
bringing this sample to the surface. Although ceramic cups have limitations,
at the present time they appear to be the best tool available for sampling un-
saturated media.
The basic design of the sampling unit is as follows: a ceramic cup is
sealed onto a rigid-plastic body tube that is equal in length to the desired
sampling depth. Small-diameter tubing is inserted through a rubber stopper,
which seals the top of the body tube, down to the inside base of the cup. The
other end of the tubing is attached to a collection flask through a two-hole
rubber stopper. Vacuum is applied to a second line in the flask causing the
air pressure inside the system to become less than the ambient pressure at
the cup's location. Soil solution is drawn into the cup and sucked through
the vacuum line to the collection flask. The technique used to emplace suc-
tion cups is the same as that for tensiometers. In particular, good contact
should be obtained between the cup and the soil.
Recently, alternative designs have been reported in the literature, most
notably by Parizek and Lane (1970) and by Wood (1973), that allow raising
samples from greater depths than is possible by vacuum withdrawal. The
design used by Parizek and Lane is shown schematically in Figure 15. The
body tube of the sampling unit is 2 feet long and holds about a liter of sample.
Two copper lines are forced through a two-hole rubber stopper which seals
the body tube. One line, the sample discharge line, extends to the base of
the ceramic cup, as shown, and the other, a pressure-vacuum line, termi-
nates a short distance below the rubber stopper. The discharge line con-
nects to a suitable vacuum-pressure pump. In operation, a vacuum is ap-
plied to the system with the discharge tube clamped shut. When sufficient
time has elapsed for the unit to fill with soil solution, the vacuum is re-
leased, the clamp on the outlet line is opened, and air pressure is applied
to the system to force the sample into the collection flask.
Figure 15 also illustrates another feature of the design of Parizek and
Lane. The installation method shown does not require an intimate contact
between the cup and the soil. Instead, a cavity larger than the cup is drilled
to permit backfilling with silica sand around the cup and with tamped back-
fill for the remainder of the length. This design permits the installation of
more than one unit in a hole, although three is about the maximum. Each
unit is sealed from adjoining units with bentonite. According to the authors
the silica sand provides a clean medium for soil moisture moving toward
the cup, ensures contact between soil and cup, eliminates unevenness in the
void space, and precludes clogging of the cup by colloidal material. Sam-
ples were recovered from a depth of 15 meters; 17 meters is about the max-
imum expected recovery depth with this basic design.
52
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-2-WAY PUMP
VACUUM PORT
AND GAUGE
DISCHARGE
TUBE
PLASTIC TUBE
AND CLAMP
COPPER
TUBE
PRESSURE
PORT
PLASTIC TUBE
AND CLAMP
PRESSURE-
VACUUM IN
3/16-tNCH
COPPER TUBE
PLASTIC PIPE
24 INCHES LONG
6-INCH HOLE
WITH TAMPED
SILICA SAND
BACKFILL
SAMPLE
BOTTLE
POROUS CUP.
BENTONITE
Figure 15. Cross section of sucfion cup assembly and backfilling
material (after Parizek and Lane, 1970).
Wood (1973) reports on a modified version of the design of Parizek and
Lane that overcomes a basic problem with their system, i. e. , solution be-
ing forced back into the soil during the release of vacuum and application
of pressure. A sketch of Wood's design is shown in Figure 16; details are
presented in his paper. The important feature, however, is that a check-
valve is included in the pressure-delivery tube assembly within the cup. In
operation, vacuum is applied to the system, inducing a flow of water into the
cup and tube assembly. Nitrogen gas pressure is applied to one tube and the
sample is forced to the surface. The check-valve prohibits pressurization
of the porous cup and, therefore, a sample within the cup does not flow back
into the soil.
53
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27"
TUBING TO SURFACE
CONNECTORS
PIPE THREAD SEALANT
FVC PIPE CAP
PVC PIPE
PVC CEMENT
POLYETHYLENE TUBING
BRANCH "T"
FEMALE ELBOW
POPPET CHECK VALVE
CONNECTORS
EPOXY CEMENT
POLYETHYLENE TUBING
POROUS CUP
Figure 16. Cross section of porous cup assembly
with pressure control (after Wood, 1973).
54
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Wood's installation procedure consisted of drilling a 10-cm hole with a
continuous flight auger to 45 cm from the desired depth. The auger was
then installed in the lowermost auger flight and the ensemble pressed back
into the hole to the final depth. The assembly was again withdrawn and a
suction cup unit was placed into the hole. Only one unit was installed per
hole; samples were collected from depths ranging to 36 meters.
Although suction cup assemblies are the best available techniques for ob-
taining samples of the soil solution in situ, certain problems accompany
their usage. One is that samples cannot be obtained over the entire range
of soil-water pressures: suction cups are capable of sampling only at pres-
sures greater than about -1.0 atmosphere. Because of the very small
pores in ceramic cups, inflow of suspended solids is inhibited, making tests
for biochemical oxygen demand (BOD) on collected samples inaccurate.
Similarly, bacteria may be filtered out. During application of vacuum to
the cups, it is important that the negative pressure closely match the pres-
sure of the soil-water system. If the vacuum differential is excessive, the
additional suction can influence the movement of soil water in the vicinity of
the cup.
SALINITY SENSORS. A recent development for in-situ evaluation of soil
salinity is the so-called "salinity sensor. " The basis of these devices is the
relationship between specific electrical conductance (EC) of soil solution and
the total concentration of salts in solution.
The salinity sensor described by Richards (1966) uses electrodes em-
bedded in porous ceramic to form a hydraulic continuum with soil water and
measure the specific conductance of the soil solution directly. EC values
can then be directly related to the total salt content by suitable calibration
relations. The unit described by Richards comprises a plate about 1 mm
thick with platinum electrodes fixed in place on opposing faces. An interest-
ing feature of the sensor is that the unit is spring loaded to ensure good con-
tact with soil. Because of the strong dependency of EC on temperature, it
is important to measure accurately the temperature of the soil solution.
Richards used a thermistor to provide temperature compensation.
Oster and Willardson (1971) have reviewed problems arising from cali-
bration and field use of salinity sensors. Of particular importance is their
observation that sensors should not be used at soil-water pressures less
than -2 atmospheres. Also they indicate that when sensors are placed in
trenches at field sites, the permeability of the materials in the back-filled
trench tends to be greater than in indigenous soil. During leaching trials,
therefore, the salinity measured with the sensors tended to be lower than in
adjacent soil. Differences were attributed to greater leaching in the trench,
probably because pore sizes in the trench soil were of a different range than
indigeneous soil.
55
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While salinity sensors may be useful to gage changes in the total salinity
of a soil solution, in waste disposal operations, concentrations of individual
constituents may be of more importance. Furthermore, the water pressure
of materials in the lower reaches of the vadose zone may be less than -2
atmospheres, thereby rendering the unit inoperative.
The cost of a salinity bridge is about $620. Each salinity sensor costs
about $35. Sensor cable costs about $0.50 per foot. Figure 17 gives the
cost for a salinity bridge and various depths and sampling densities for the
sensors.
100
50
o
l/l
z
UJ
l/l
u_
o
x
UJ
Q
10
1
1
1
500 1000 1500 2000
SALINITY SENSING EQUIPMENT COSTS (S)
4000
Figure 17. Cost of soil salinity sensors and a salinity bridge for various
depths and sampling densities, November 1974.
56
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SECTION IV
MONITORING IN THE ZONE OF SATURATION
INTRODUCTION
Differences in the mineral composition of rocks within the groundwater
reservoir, in the composition of soils, and in the chemical composition of
recharge waters, cause differences in groundwater quality from place to
place. Selection of a sampling site and collection of groundwater quality data
is more difficult than for surface water. This is due to the complexity and
accessibility of most aquifer systems and the multitude of factors which in-
fluence groundwater quality (Brown et al. , 1970). The superposition of pol-
lution zones on the natural system imparts an additional degree of complexity.
Knowledge of the hydrogeologic framework is important from two stand-
points: (1) prediction of groundwater movement, and (2) geochemical con-
siderations which affect natural groundwater quality. The three-dimensional
distribution of hydraulic head and geologic conditions largely determines
groundwater flow patterns. The pattern of movement of groundwater has a
major effect on the distribution of groundwater pollutants. Both regional
and local conditions are significant. Sources of pollution must be identified,
and volumes and quality of wastewater or percolate determined. The three-
dimensional distribution of groundwater quality must be delineated.
Methods employed in general groundwater studies are summarized in
this section, followed by details of specific methods of monitoring pollution
in the saturated zone. These methods illustrate some of the data required
for groundwater pollution monitoring.
GENERAL MONITORING PROCEDURES
Development of the hydrogeologic framework entails surface phenomena
(such as precipitation and streamflow), interactions in the topsoil and un-
saturated zone, and considerations of the saturated zone and well hydraulics.
In this section the saturated zone is of prime consideration. Brown et al.
(1972) have summarized international data on groundwater studies. The
U.S. Geological Survey has issued periodic reports under Techniques of
Water Resources Investigations. Textbooks on groundwater contain abun-
dant information on the subject, including Todd (1959) and Davis and DeWiest
(1966). Walton (1970) presented case histories of groundwater studies,
while issues of Ground Water and other periodicals contain numerous reports
on groundwater.
57
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Well Inventory and Well Data Collection
Most groundwater studies require a complete field well inventory and
office compilation of existing well data. Data such as driller's logs, elec-
tric logs, water-level measurements, pump tests, and chemical analyses
are gathered and organized. Field observations and interviews are used to
verify the correspondence between data and wells. Considerable confusion
can result when this process is not carefully done. It also promotes the
proper interpretation of results of a monitoring program. The cooperation
and assistance of local water agencies is necessary for successful accom-
plishment of this initial work.
Geological Framework
The geological framework for groundwater studies includes lithology,
texture, structure, mineralogy, and the distribution of the subsurface ma-
terials through which groundwater flows. The hydraulic properties of earth
materials depend on their origin and lithology, as well as the subsequent
stresses to which the rocks have been subjected. Weathering, tectonic move-
ment, and fracturing are examples of these stresses.
Surface geology is commonly mapped in the field if sufficiently detailed
reports or maps are not available. Photogeology is a useful tool in analysis
of surface or near-surface geologic conditions. Ray (I960) and Seker (1966)
discuss the use of aerial photographs in geologic interpretation and mapping
and applications to groundwater. Geologic maps are compiled to indicate
the distribution of rock types and structural features such as folds or faults.
Geophysical methods can provide information about the major features of
the underground materials. Zohdy et al. (1974) summarize the application
of surface geophysics to groundwater investigations. Geophysics can also
provide a good indication of where test drilling should be undertaken to as-
certain more information on the configuration of the subsurface materials.
Records of geologic materials penetrated during well drilling are ex-
tremely important. Driller's and geologist's logs can often be correlated
with borehole geophysics. Keys and MacCary (1971) summarize the appli-
cation of borehole geophysics to water-resources investigations. The verti-
cal distribution and occurrence of subsurface materials are thus documented
at the point where a well is drilled. Electrical resistivity and spontaneous
potential logs (electric logs) provide information on the subsurface lithology.
A gamma-ray log indicates clay content in sedimentary rocks. This method
is used in cased holes, and can be quite effective in alluvial materials (alter-
nating layers of sand and clay).
Once data on subsurface geology are compiled, cross sections are devel-
oped on the basis of geological correlation. The three-dimensional varia-
tions in the subsurface lithology are thus illustrated. Considerations of
58
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importance in water quality studies include chemical composition on the
underground materials and contained fluids.
Water Levels and Groundwater Movement
Groundwater movement depends on the permeability and the hydraulic
gradient within an aquifer. Permeability is related to the nature, size, and
degree of interconnection of pores, fissures, joints, and other openings.
Water-level measurements are used to draw contours of depth to water and
groundwater level elevation over the area of interest. Similarly, water-
level measurements at different depths in the aquifer can provide an indica-
tion of the vertical flow components. Schematic flow nets are made to illus-
trate the movement of groundwater in the aquifer (Casagrande, 1937; Davis
and DeWiest, 1966). Flow nets provide information on recharge to and dis-
charge from the aquifer, relative direction of groundwater movement, and
aquifer geometry and permeability.
Flow lines are perpendicular to water-level elevation contours only in the
case of homogeneous and isotropic media. The subsurface lithology is used
to evaluate locations where the direction of movement of groundwater may
not be perpendicular to these contours, such as in buried stream channels
in alluvium. Water-level contours are generally drawn for static conditions,
and pumping wells may alter the dynamic situation.
Groundwater velocities can be estimated on the basis of permeability or
transmissivity, hydraulic gradient, and porosity. Permeability and trans-
mis sivity are commonly determined from analyses of pumping tests. The
hydraulic gradient is "determined from the water-level contour map, and
porosities are known or can be determined for most materials. In the case
of confined aquifers and relatively impermeable confining beds, vertical
permeability and hydraulic gradients can be used to calculate upward or
downward leakage. Similarly, amounts of groundwater flowing through an
area can be calculated based upon permeability or transmissxvity and the
hydraulic gradient. Tracers such as dyes (UNESCO, 1975) or radionuclides
(Havely and Nir, 1962; Hanshaw et al., 1965; Kaufman and Orlob, 1956) can
also be used as an indication of groundwater flow velocity.
Pump Tests and Aquifer Analysis
The hydraulic properties of aquifers are determined using pumping or re-
charge tests, and water-level changes reflecting long-term conditions at the
aquifer boundaries. The first method is widely used because it may permit
evaluation of the aquifer parameters in a relatively short period of time.
Theis (1935), Jacob (1947), Ferris et al. (1962), Johnson Division UOP
(1966), Todd <1959), Davis and DeWiest (1966), and Walton (1970) summar-
ize methods of pump testing and aquifer analysis.
59
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The primary aquifer parameters determined from most pump tests are
transmissivity and storage coefficient. They are used to define groundwater
movement and the reactions of aquifers to pumping or recharge. Permea-
bility can also be determined, which helps indicate flow velocities. Calcula-
tion of groundwater flow through certain sections of the aquifer are valuable
in order to assess spread and dilution of pollutants from the land surface.
Much of the theory and equations developed for aquifer analysis apply to
confined aquifers in porous, granular, unconsolidated materials. Special
equations have been developed for unconfined aquifers, leaky aquifers, and
aquifers of very irregular geometry. Jointed, fissured, and cavernous rocks
are characterized by a high degree of heterogeneity. In rocks with second-
ary porosity and permeability developed by jointing or solution, single pump
tests of short duration seldom provide any information except localized aqui-
fer characteristics.
By considering a large area, variations and heterogeneity of local areas
tend to average out and usable figures on the hydraulic characteristics may
be obtained. If continuing records of recharge to and discharge from sizable
parts of the aquifer are available, along with records of seasonal fluctuations
of the water table, then reliable estimates of the regional hydrologic charac-
teristics can be made.
Water Budget and Modeling
The law of conservation of matter defines the groundwater basin water
budget. All water entering a specific area must go into storage within its
boundaries, be consumed therein, be exported therefrom, or flow out as
surface or groundwater.
Water budgets can be used to indicate regional conditions in an aquifer.
The reaction of the aquifer to pumping or recharge can be determined by
comparing the water budget with water-level hydro'graphs. Water budget
analysis can also serve as an independent check on the accuracy of individual
items in the budget. Mathematical and analog modeling, along with computer
methods, are important tools in analyses of regional groundwater systems
(Skibitzke, I960; Stallman, 1963; Walton and Prickett, 1963). Projections
of future changes in aquifer regime can be made based on these model
studies.
The groundwater regime is greatly influenced by climatic, hydrologic,
biologic, and soil factors. Groundwater is closely interrelated with surface
water and soil moisture. The groundwater budget requires quantification of
all these factors affecting inflow to, and outflow from, a groundwater reser-
voir, as well as storage changes. Few of the factors are directly measur-
able, but some can be determined by residuals of measured variables and
60
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others can be reasonably estimated. Of foremost importance is the proper
selection of groundwater basin boundaries based on hydrogeologic factors.
Water Temperature and Chemical Quality
Temperature of underground materials is influenced by the heat input and
output, as well as by the heat characteristics of the materials. Since the
rock and water below the land surface are poor conductors, the temperature
distribution is influenced by groundwater movement. Groundwater tempera-
ture is an important field of study. Well discharge and down-hole water
temperature measurements can indicate directions of water movement and
relative permeabilities of aquifer materials. Groundwater temperature af-
fects the chemical quality of groundwater. Groundwater temperatures can
be used as an independent check on concepts based on hydraulic and geologic
reasoning alone. Bredehoeft and Papadopulos (1965), Cartwright (1968),
Sammel (1968), and Bentall (1963) discuss the significance of temperature
measurements in groundwater.
Groundwater quality studies also provide an independent check on con-
cepts based on physical reasoning alone. A groundwater quality study is
based on a knowledge of the geochemistry of aquifer materials and the chem-
istry of recharge to the aquifer. Chemical equilibrium and kinetics evalua-
tions may indicate whether certain minerals are dissolving, or precipitating,
as well as rates of reactions. Hem (1970) has reviewed pertinent data on
natural water quality. Changes in groundwater quality during flow through
the aquifer can be assessed. The relative mobility of certain chemical spe-
cies and of biological and radiological parameters is of great concern.
Some constituents may move through the aquifer at the same rate as the
water, many move at slower rates, and some are virtually immobile.
*
Contours for constituent concentrations on an areal and vertical basis
are often prepared. These can be compared with geologic maps, flow nets,
and predominant sources at the land surface. Quite often several constitu-
ents such as sodium and chloride, or calcium and sulfate are interrelated
because of the subsurface presence of solid compounds. Subsurface lithol-
ogy and temperature may correlate well with groundwater quality. Numer-
ous graphical procedures are available for interpretative work. The tri-
linear diagram is a useful tool to compare water types. The major cations
(Ca, Mg, Na + K) are plotted on one triangle and the major anions (Cl, SO4,
HC03 + C03) are plotted on another. This tool is especially helpful m ana-
lyzing mixtures of two or more types of groundwater.
61
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SPECIFIC MONITORING METHODS
Surface Geophysics
Often, a major part of an investigation of groundwater pollution is to lo-
cate and define its extent. In special situations a resistivity survey can be
effectively used. These situations generally occur where:
1. There are either no wells or only a few in the polluted zone
2. The polluted water is of relatively high salinity compared
to native groundwater in the area
3. The subsurface geology is relatively well understood
4. The water table is fairly shallow.
Griffiths and King (1969) summarize the resistivity method and common ap-
plications. Zohdy et al. (1974) summarize the application of surface geo-
physics to groundwater investigations.
Earth materials containing groundwater of high electrical conductivity
will have lower resistivity values than surrounding materials containing nat-
ural groundwater. In some cases, the resistivity method can be used to de-
termine quickly the boundaries of the zone of polluted groundwater. Hack-
barth (1971) describes the use of resistivity measurements to analyze spent
sulfite liquor recharge movement. Merkel (1972) illustrates how resistivity
surveys could be used to analyze acid mine drainage in groundwater. Stollar
and Roux (1975) summarize the use of resistivity surveys to define ground-
water pollution.
Initially, multidepth electrical soundings are made of the area in an at-
tempt to see if the top and bottom of the polluted zone can be delineated. If
this can be done, a series of single-depth resistivity measurements are then
made at selected points to define the horizontal extent of the plume. By
varying the depth of the measurements within the vertical extent of the plume,
the three-dimensional extent of the polluted zone can be determined.
The resistivity survey has certain limitations that restrict wide applica-
tion. These include poor site access, interference of conductors such as
pipelines, insufficient contrast between the conductivity of the polluted and
the natural groundwater, depth to the top of the polluted zone, thickness of
the zone, and the complexity of the surficial geology (Stollar and Roux,
1975). An inherent problem in any resistivity survey which incorporates an
electrode configuration consisting of all surface electrodes is that of resolu-
tion when the lithology has high resistivity contrasts. A highly resistive
zone inhibits current flow in it or reaching regions below it. Similarly, a
highly conducting zone traps the current and again allows little current to
flow below it. For examinations at considerable depths, a technique has
62
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been developed which incorporates the use of a buried current source in a
drill hole.
The primary advantage of the resistivity method in groundwater pollution
investigations is to provide information on the extent of the polluted zone at
a reduced cost and within a short period of time. Hackbarth (1971) states
that resistivity measurements can be useful in supplementing data obtained
from piezometers, but cannot replace them.
In conducting a resistivity survey the variables of concern are the depth
to the top of the plume, the thickness of the polluted zone, and the areal ex-
tent of the polluted zone. If no data are available a feasibility study can be
done for about $1500 to determine whether the technique will work and to es-
timate the plume size. If the survey appears feasible, the cost that will be
incurred by an experienced geophysical team can be estimated from Table 6.
The first step in the survey is to determine the electrode spread. The
spread will depend upon the depth of the plume and its thickness. Both of
these variables may not be known but they can be estimated and used in
Table 6 (a) to determine the electrode spacing. The areal extent of the plume
must be estimated in acres and applied in Table 6(b) to determine the num-
ber of surveys to be conducted. From Table 6(c) the time required to con-
duct each study for a particular plume depth, thickness, and areal coverage
can be obtained. The cost per hour for a geophysical team including equip-
ment and interpretation is about $75 to $85 per hour. To obtain total costs,
the time from Table 6(c) is multiplied by $80. This figure does not include
travel costs, per diem, or additional time required in difficult terrain.
Well Construction
Most methods for sampling the saturated zone require wells. Where no
wells or other devices exist for sampling the saturated zone, well construc-
tion must be considered. Wells can be constructed by the following princi-
pal methods: (1) dug, (2) augered, (3) driven, (4) jetted, and (5) drilled.
The first four methods are usually employed for shallow wells (150 feet
deep or less}, while drilling techniques are used for both shallow and deeper
wells. These five methods and the physical characteristics of wells are de-
scribed in detail by Johnson (1971), Anderson (1967), Bowman (1911), Gib-
son and Singer (1971), the U.S. Departments of the Army and Air Force
(1957), the California Department of Water Resources (1968), and Campbell
and Lehr (1973).
Types of Shallow Wells
Dug wells are excavated by hand or power shovel to depths usually rang-
ing from about 10 to 40 feet. These wells commonly are about 5 to 8 feet
in diameter and extend only a few feet below the water table. The shaft may
63
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TABLE 6. EARTH RESISTIVITY SURVEY COSTS, DECEMBER 1974
$: Thic
~i 20
° 50
o
o 100
-£ 200
a_
a 500
-------
be lined with concrete rings, stone, brick, or wood. Dug wells are used
mostly for rural water supplies or for drainage water disposal, and can be
polluted relatively easily because large surface openings are generally pres-
ent. Such large diameter wells are not ordinarily necessary for monitoring
groundwater quality.
Shallow wells may be augered by hand or power equipment. Hand augers
can be used to penetrate clay, silt, and sands where cave-in will not occur
in an open hole. These holes are generally not economical when depths
greater than about 10 to 20 feet are encountered. In power augering by the
rotary bucket method, the bucket is filled with cuttings and raised to the sur-
face for dumping. In continuous-flight augering, the cuttings rise to the sur-
face on rotating spiral flights. The wall of an uncased auger hole usually
collapses below the water table after the auger is removed. Therefore, a
drive pipe and attached well point are commonly set in the open hole and
driven below the water table to the required depth immediately after the hole
is drilled. Where hollow stem augers are used, a 2-inch pipe and well point
can be set inside the hollow stem to the required depth. (Vertical movement
of water can occur in the annular space between the wall of the drilled hole
and the well casing. ) Monitoring wells to depths of 150 to 200 feet can be
sunk quickly in unconsolidated deposits by use of a power auger. The size of
an auger hole may range from 2 to 32 inches in diameter. Auger holes may
be of great value in monitoring relatively shallow polluted zones in unconsol-
idated deposits.
Driven wells (sometimes called sandpoint wells) generally consist of a
casing 1-1/4 to 2 inches in diameter and an attached drive point. The drive
point consists of perforated pipe with a steel point at its lower end to break
through pebbles or thin layers of hard material. These are installed to
depths generally up to 30 feet and usually cannot be pumped at rates greater
than a few tens of gallons per minute. Larger wells (up to 4 inches in diam-
eter) can be driven, however, and pumps installed inside the casing. The
chief disadvantages of driven wells are that construction is slow and difficult
when tightly compacted materials are encountered, driving is destructive to
the well itself, and yields are small. However, they are useful for monitor-
ing shallow aquifers in unconsolidated rock.
The jetting method employs a high-velocity stream of water to drill a
hole in the earth. The water stream loosens earth materials and washes the
finer particles upward and out of the hole. The jetting method is most suc-
cessful in sandy soils with shallow water tables. The technique is ineffective
against hard rock and boulders; tight clay and hardpan also present problems.
Water is commonly used in jetting wells, but a jetting fluid of greater vis-
cosity and weight can be made by mixing clay or bentomte with water The
casing is usually sunk as the jetting proceeds, and if too much resistance IS
encountered, the casing may be driven. A screen may be attached to the
casing during drilling or installed after the casing is driven to the final well
65
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depth.
deep.
Jetted wells are generally of small diameter and less than 150 feet
Costs of Shallow Wells
Monitor wells which are 2 to 4 inches in diameter and less than 200 feet
deep can be installed at relatively nominal cost as shown by Figure 18. The
cost of the first well is heavily weighted by the cost of transportation and
setting up of the equipment. The cost of a second well, assuming it is lo-
cated close by, is considerably less. The costs represented in Figure 18
represent the average of auger and jet methods and include 2-inch diameter
polyvinyl chloride (PVC).
200
UNCONSOLIDATED
MATERIAL
CONSOLIDATED
MATERIAL
200
400
600
WELL COST ($)
800
1000
2000
Figure 18. Cost of shallow, small-diameter monitor wells, October 1974.
Types of Drilled Wells
Drilled wells are constructed by the cable tool (percussion) method or by
rotary methods. The relative merits of the various methods of drilling vary,
and no one method is superior under all conditions.
In the cable tool method, the hole is formed by the percussion and cutting
action of a drilling bit that is alternatively raised and dropped. The drill
cuttings are removed at intervals by a bailer or sand pump. An open hole
can be drilled in consolidated rock, but in unconsolidated formations, casing
is driven down the hole during drilling. Above the water table, water is
added to the hole so that the cuttings can be readily bailed. The bottom of
the casing is fitted with a heavy-walled, hardened steel drive shoe. As the
66
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casing is driven in unconsolidated formations, frictional forces increase
until the casing cannot be sunk further without the use of special tools.
Small cable tool rigs can usually drill a 5-inch diameter hole to a depth
of about 300 feet. The largest cable tool rigs can drill a 5-inch diameter
hole to a depth in excess of 7000 feet. With medium and high capacity rigs,
18- to 24-inch diameter holes are commonly drilled to depths of several hun-
dred feet. The major disadvantage of cable tool drilling is its slow drilling
time and depth limitation; however, the latter is well below the monitoring
depths for most types of groundwater pollution.
Sampling and logging of geologic formations are simpler and more accu-
rate for the cable tool method than for most other drilling methods. The
samples are not contaminated by drilling mud, and clay, shale, and silt
fractions are not likely to be lost by dispersion in a drilling fluid. When a
potential aquifer is encountered, it may be tested by bailing or pumping.
The mobility of cable tool rigs give them an advantage in rugged terrain and
in isolated areas. Cable tool rigs can usually drill through fractured, fis-
sured, broken, or cavernous rocks. The method requires much less water
for drilling than most others, which is an important consideration in arid
areas.
A major advantage of the method for water quality monitoring is that
water samples can be obtained by bailing as each stratum is opened to the
bottom of the casing and upper strata, are cased off. The water-bearing
characteristics and static heads of various strata can also be determined as
the casing is being driven. Special methods have be,en developed for assur-
ing a tight seal around the casing.
Rotary drilling, used for oil wells, has virtually no depth limit for most
fresh groundwater systems. A variant method, reverse-circulation rotary
drilling, is also used. The rotary method is distinguished from the reverse-
circulation method by pumping a drilling fluid through the inside of the drill
pipe and out through the openings in the bit. The drilling fluid is a suspen-
sion of solids in liquids and commonly is termed "mud. " The drill stem is
rotated as a downward force is applied, and the mud flows back to the sur-
face through the annulus between the drill pipe and the hole wall. The mud
cools the bit, transports cuttings to the surface, and maintains hole stability.
The drilling fluid contains solids, the make-up water, and additives, all
of which may introduce contaminants into the system. Mud additives are
used to make the mud thicker, thinner, or heavier, or to otherwise adapt it
to special conditions. Bentonite is one of the most common additives.
New drilling mud additives have been developed in the water-well industry.
One such additive is a biodegradable material which does not contaminate
67
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water-bearing sands with clay particles and can be totally removed from the
well during development.
In unconsolidated deposits, the casing (and screen, if used) are installed
in a rotary hole after the final drilled depth is reached. The well is then
gravel-packed and developed. Gravel packing is done to minimise problems
of sanding and to improve the rate of inflow of water. Well developing is
done by various methods, with the primary purpose being to clean out drill-
ing mud that has entered the formation during drilling.
Direct-circulation (conventional) rotary drilling may be less desirable
than cable-tool for test-hole drilling. Drill cuttings tend to be mixed from
different depths and contaminated by drilling mud. The characteristics of
drilling mud may be time-variable so that cuttings brought to the surface can
vary with mud characteristics, rather than with where the material was pen-
etrated. Sample time lag in deeper holes can also become troublesome in
obtaining a reliable geologic log. Measuring static water levels, taking rep-
resentative water samples, and performing pump tests of individual aquifers
during drilling are often not practical with rotary drilling.
The principal advantages of the direct-rotary method are speed, great
depth capability, and the ability to run electric logs in an open hole prior to
casing installation.
In the reverse-circulation rotary method, the drilling fluid is muddy
water instead of drilling mud and is introduced down the hole outside of the
drill pipe. The drill cuttings are pumped up through the drill pipe as drill-
ing proceeds and are separated from the drilling fluid at the surface. From
20 to 500 gallons per minute (gpm) of make-up water, depending on the hole
diameter, may be needed at times when drilling through highly permeable
sediments.
The air rotary method is similar to the other xotary methods, except that
compressed air is used instead of drilling mud to bring the cuttings to the
surface. Mud or other chemical sealants may be required where the mate-
rials are loose and tend to cave. The conventional drill bit can be replaced
with a pneumatic drill bit which speeds up the drilling by pulverizing the
consolidated rock.
Costs of We 11 Drilling
Well-drilling costs vary depending on such factors as site accessibility,
labor and material costs, type of well design, use of the well, degree of
development, yield, and local geologic conditions. Bids submitted in con-
nection with well-construction contracts may be itemized or may simply
quote a lump-sum charge. Itemized bids generally show unit prices for
(1) moving in and setting up the rig, (Z) drilling, (3) casing, (4) screen or
68
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perforated casing, (5) grouting the annular space, (6) coring, (7) developing
time, (8) pumping test, and (9) geophysical logging. Providing and installing
pumps, pump houses, and controls are additional items whose combined
cost, especially in the case of public - supply wells, may exceed the cost of
constructing the well. Many of these items, however, can be neglected for
small observation wells.
In a well-construction program, the cost of drilling can be separated
from well development and can be generally approximated. The cost of drill-
ing will vary primarily with hole diameter, type of geologic formation, and
depth of well. Drilling costs for 40- to 1000-foot depths in unconsolidated
formations for various well diameters are given in Table 7. Similarly, drill-
ing costs for consolidated formations are given in Table 8. Although these
drilling costs are very general, they do provide a first approximation. It
is common for drillers to drill hole sizes from 4 to 27 inches. The well-
drilling costs provided in Tables 7 and 8 are averages for EPA Regions III
and IV, but drilling costs do not vary as much across the country as casing
and pump costs.
Well Casing and Costs
Campbell and Lehr (1973) summarized five types of pipe used in the water
well and plumbing industries: (1) standard pipe, (2) line pipe, (3) reamed
and drifted pipe, (4) drive pipe, and (5) water-well casing. Water-well cas-
ing is a thin-walled, fine-threaded casing differing in dimensions and threads
from all other types of pipe. Thread dimensions vary among different types
of pipe. An improper joint and possible casing failure can result if thread-
ing specifications are not adhered to. Specifications for water-well casing
often designate ASTM A- 120 and ASTM A-53. American Petroleum Institute
(API) casing is designated by the outside diameter and the wall thickness.
The size and weight of the casing must be designed to assure that drilling
tools, well screens, pumps, etc. can be inserted. Water-well casing is
often selected on the basis of its resistance to corrosion.
Black pipe is used for small-diameter wells since water-well casing is
not made below a 4-inch diameter. Four- to 6-inch diameter wells are
about the smallest size that will handle a submersible pump. These small-
diameter black pipe casing costs are given in Table 9. It can be seen that
the cost of black pipe in shallow wells compares closely with the drilling
costs in unconsolidated formations. On the other hand, polyvinyl chloride
(PVC) casing is becoming more popular and is available at less cost (Table
10) While the cost of small-diameter casing is more competitive than
large-diameter casing, these costs can vary with time and regional location.
Some wells are essentially open holes drilled into consolidated rocks and
may have only a short length of casing near the land surface. In wells in
69
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TABLE 7. COSTS IN DOLLARS FOR WELL DRILLING IN UNCONSOLfDATED FORMATIONS, EPA REGIONS II
AND IV, OCTOBER 1974.
\
^,
~
i
JO
.*
o
£
Depth of well (ft)
16
14
12
10
8
6
5
4
3
2
1
40
800
700
600
500
400
300
250
200
150
100
50
60
1200
1050
900
750
600
450
375
300
225
150
75
80
1600
1400
1200
1000
800
600
500
400
300
200
100
100
2000
1750
1500
1250
1000
750
625
500
375
250
125
140
2800
2450
2100
1750
1400
1050
875
700
525
350
175
180
3600
3150
2700
2250
1800
1350
1125
900
675
450
225
200
4000
3500
3000
2500
2000
1500
1250
1000
750
500
250
240
4800
4200
3600
3000
2400
1800
1500
1200
900
600
300
280
5600
4900
4200
3500
2800
2100
1750
1400
1050
700
350
300
6000
5250
4500
3750
3000
2250
1875
1500
1125
750
375
350
7000
6125
5250
4375
3500
2625
2188
1750
400
8000
7000
6000
5000
4000
3000
2500
2000
500
10,000
8750
7500
6250
5000
3750
3125
2500
600
12,000
10,50C
9000
7500
6000
4500
700
14, 000
12,250
10,500
8750
7000
5250
800
16,000
14,000
12,000
10,000
8000
6000
900
18,000
15,750
13,50C
11,250
9000
6750
1000
20,000
17,500
15,000
12,500
10,000
7500
VI
o
-------
TABLE 8. COSTS IN DOLLARS FOR WELL DRILLING IN CONSOLIDATED FORMATIONS, EPA REGIONS III AND
IV, OCTOBER 1974
\
c
diametei
c
_c
*
Depth of well (ft)
6
4
12
10
8
7
6
5
4
w
2
i
40
640
560
480
400
320
280
240
200
160
120
80
40
60
960
840
720
600
480
420
360
300
240
180
120
60
80
280
120
960
800
640
560
480
400
320
240
160
80
100
600
400
200
000
800
700
600
500
400
300
200
100
140
2240
960
1680
1400
1120
980
890
700
560
420
280
140
180
2830
2520
2160
1800
1440
1260
1080
900
720
540
360
180
200
3200
2800
2400
2000
1600
1400
1200
1000
800
600
400
200
240
3840
3360
2880
2400
1920
1680
1440
1200
960
720
480
240
280
4480
3920
3360
2800
2240
1960
1680
1400
1120
840
560
280
300
4800
4200
3600
3000
2400
2100
1800
1500
1200
900
600
300
350
5600
4900
4200
3500
2800
2450
2100
1750
1400
400
6400
5600
4800
4000
3200
2800
2400
2000
1600
500
8000
7000
6000
5000
4000
3500
3000
2500
2000
600
9600
8400
7200
6000
4800
4200
3600
700
11,200
9800
8400
7000
5600
4900
4200
800
12,800
11,200
9600
8000
6400
5600
4800
900
14,400
12,600
10,800
9000
7200
6300
5400
1000
16,000
14,000
12,000
10,000
8000
7000
6000
-------
TABLE 9. BLACK PIPE CASING COSTS FOR WELLS IN DOLLARS, EPA REGION IX, OCTOBER 1974
O ~3-
Standard well-bl
pipe diameter
6
5
4
3
2
1
40
335
264
190
126
61
29
60
502
397
285
188
92
43
80
670
529
380
251
122
58
100
837
661
472
314
153
72
140
1172
925
665
440
214
101
Depth of casing (ft)
180
1507
1190
855
565
273
130
200
1674
1322
950
628
306
144
240
2009
1586
1140
754
367
173
280
2344
1851
1330
899
428
202
300
2511
1983
1425
942
459
216
350
2930
2314
1662
400
3348
2644
1900
500
4185
3305
2375
600 700 800 900 1000
5022 5859 6696 7533 8370
VJ
ro
TABLE 10. PVC PIPE COSTS FOR WELLS IN DOLLARS, EPA REGION IX, OCTOBER 1974
\
£
£
E
0
T3
O)
O
U
£
Depth of casing (ft)
10
9
8
7
6
5
4
3
2
40
347
286
224
178
132
93
61
37
17
60
520
428
336
267
198
140
91
55
25
80
694
571
448
356
264
186
122
74
34
100
867
714
560
445
330
233
152
92
42
140
1214
999
784
623
462
326
213
129
59
180
1561
1285
1008
801
594
419
274
179
76
200
1734
1427
1120
890
660
466
304
184
84
240
2081
1713
1344
1068
792
559
365
221
101
280
2428
1998
1568
1246
924
652
426
258
118
300
2601
2141
1680
1335
990
699
456
276
126
350
3035
2498
1960
1558
1155
816
532
400
3468
2854
2240
1780
1320
932
608
500
4335
3568
2800
2225
1650
1165
760
600
5202
4281
3360
2670
1980
700
6069
4995
3920
3115
2310
800
6936
5708
4480
3560
2640
900
7803
6422
5040
4005
2970
1000
8670
7135
5600
4450
3300
-------
unconsolidated deposits, the hole must be cased to the bottom. Standard-
weight pipe is usually adequate for depths where casings of 6-inch diameter
or less are set.
Special types of casing may be needed in areas of certain groundwater
qualities and geologic characteristics. Cupronickel alloys are most suited
for sea-water production wells. Carbon steel has demonstrated a high re-
sistance to soil corrosion. Stainless steel offers considerable durability
and high reliability.
Plastic casing has increased in use recently. Maximum installation
depths for PVC pipe are normally less than 200 feet. Rubber-modified poly-
styrene has also been used as well casing, but is not recommended for
depths greater than 300 feet. Plastic well casings are usually not larger
than 6 inches in diameter for structural reasons. However, fiber glass-
reinforced, epoxy pipe has more desirable characteristics than pure plastics;
8- and 10-inch sizes have been used extensively to depths of about 300 feet
for water-well casing. Epoxy plastic pipe has a high resistance to corrosion
and reduced incrustation problems.
Wells in highly corrosive environments are sometimes cased with ceramic
tile, concrete, asbestos cement, or even wooden pipe, but most of these are
heavy, structurally weak, and are not readily available in many areas. Con-
crete and asbestos-cement pipe are subject to rapid deterioration in high-
sulfate soils and water.
Well Screens and Perforated Casing
When completing most wells in unconsolidated materials, openings in the
casing must be provided to permit entrance of water. In some areas no per-
forations are used and the pipe is left open, whereby water is drawn through
the end of the casing. In areas of relatively thick water-producing strata,
the casing is commonly perforated over intervals up to several hundreds of
feet. Casings can be perforated in the field by torch or can be factory per-
forated. Down-hole perforators can be used for blank casing already in a
well. Slotted casing has an open area of about 1 percent for 0. 030-inch slots
to about 12 percent for 0. 250-inch slots. Factory perforated casing usually
has an open area ranging from 4 to 18 percent.
A specialized piece of equipment, known as a well screen, has been de-
veloped for maximizing the open area percentage. For cage type,wire-
wound screens, the open areas range from about 2 percent for 0. 0006-inch
slots to over 60 percent for 0. 150-inch slots. Well screens may be made
of iron, fiberglass, brass, stainless steel, or PVC Well screens are es-
pecially applicable to sampling relatively thin (less than 50 feet thick) sec-
tions of the aquifer.
73
-------
The sizes of perforations, slots, or screen openings are chosen with re-
spect to particle size distribution of the water-bearing zones. Entrance
velocity into the screen or perforated casing is usually recommended to be
less than 0. 1 to 0. 2 feet per second. The amount of open area desired can
be calculated based on well discharge.
Gravel Packing
In a naturally developed well, the development process removes finer
material from the vicinity of the perforations or screen, leaving a zone of
coarser graded material around the well. This cannot be achieved in a for-
mation consisting of a fine uniform sand, due to the absence of any coarser
material. The object of gravel packing a well is to artificially provide the
graded gravel or coarser sand that is missing from the natural formation.
Two conditions in unconsolidated materials tend to favor gravel packing:
(1) fine uniform sand, and (2) extensively layered deposits. The latter con-
dition is common in alluvial fan deposits of the Southwest. The selection of
the grading of the gravel pack is usually based on the finest material in the
aquifer.
Gravel packing is also used for formation stabilization. Since drilling by
the rotary method through unconsolidated materials of necessity results in a
hole somewhat larger than the outside diameter of the casing, the annular
space around the well screen is gravel packed to prevent silt and clay above
the water table from caving or slumping into the well producing zone.
Screen openings or perforations are chosen so as to retain 90 percent or
more of the gravel-pack material. The gravel pack should consist of clean,
well-rounded, smooth grains. Quartz and other silica-based materials are
preferable. Gravel-pack envelopes are usually 3 to 8 inches thick.
Well Sealing
Grouting well casing involves filling the space around the casing with a
suitable slurry of cement of clay and sand. Isolation by grouting is desira-
ble to protect the producing zone from contamination by less desirable fluids
from other levels or from the surface. Cementing materials include port-
land cement, bentonite, pozzolana, perlite, diatomaceous earth, Gilsonite
and mixtures of these. '
To assure that grouting provides a satisfactory seal, the slurry must be
added continuously to prevent cold joints. The grout should be introduced at
the base of the grouting interval to minimize contamination or dilution of the
slurry and bridging of the mixture with upper formation material The
grout is usually pumped into the space to be filled; however, placement by
gravity is satisfactory in some cases.
74
-------
An increasing number of States are establishing requirements on sealing
wells to protect them against contamination by surface waters. In this case
a near-surface, upper annular-space seal of an aggregate of fine sand and
cement is commonly used. This type of seal generally extends from 10 to
50 feet or more in depth.
Well Development
The well is developed after it has been drilled, cased and packed. The
object of well development is to remove silt, fine sand, and other such ma-
terial from a zone immediately around the well. This creates larger water-
flow passages in the formation around the well.
Well development corrects clogging or compaction of the formation which
occurs during drilling. Drilling mud used in the rotary method effectively
seals the face of the borehole. All drilling methods do some damage to the
formation, and well development is used to correct this damage. Well de-
velopment also grades the material in the aquifer immediately around the
casing in such a way that a stable condition is achieved in which the well
yields sand-free water at maximum capacity.
To be effective, the development operation must cause reversals of flow,
or surging, through the perforation or screen openings. This is necessary
to avoid the bridging of openings by groups of particles that can occur when
the flow is continuously in one direction. The reversals of flow are caused
by forcing water out of the well through the screen or perforations and into
the aquifer, then removing the force to allow flow to occur from the aquifer
back into the well.
Mechanical surging is the name given to a process of operating a plunger
up and down in the casing like a piston in a cylinder. The tool used is called
a surge plunger or surge block. Before surging, the well should be washed
with a jet of water and bailed or pumped to remove the drilling mud cake on
the face of the borehole. Dispersing agents, mainly polyphosphates, are
added to the water in the well to counteract the tendency of the mud to stick
to sand grains. These agents are often applied at the rate of one-half pound
to every 100 gallons of water in the well. Materials brought into the well
by surging can be periodically removed by bailing. Surging can also be
achieved by alternately turning the test pump on and off.
High-velocity jetting, or backwashing of an aquifer with high-velocity
jets of water directed horizontally through the screen openings, is gener-
ally the most effective method of well development. The energy of the jets
can be concentrated over small areas at any particular time and all of the
screen or perforated area can be selectively treated. Thus uniform and
complete development is achieved throughout the length of the perforated
interval or well screen.
75
-------
Test Pumping
Test pumping is commenced upon completion of well development opera-
tions. Often the well is pumped at low rates during early phases of the test
and high rates at later phases. Periodic surging may be necessary if the
well does not appear to be developed. Often the well is pumped at a much
greater rate than that intended for use. This further acts as a well develop-
ment procedure. By increasing well discharge in a step pattern, a step-
drawdown test can be run. This can be followed by a constant discharge
test. In alluvial aquifers, pump tests of 24 to 72 hours may be sufficient.
For aquifer analyses in consolidated rocks, pump tests from 1 week to 1
month or longer may be advisable. Pump testing for aquifer analysis re-
quires consideration of aquifer geometries as well as inhomogeneities and
anisotropies in the aquifer.
Total Well Construction Costs
While general data have been provided for drilling and casing costs, addi-
tional costs such as for screens, gravel packing, grouting, well development,
etc. are highly dependent upon local conditions. It is therefore more appro-
priate to provide separate cost data for completed wells in sand and gravel
and wells in consolidated formations. Detailed well cost analyses have been
done by Cederstrom (1970) and Gibb (1971).
Gibb provides a total cost analysis for small-diameter domestic and farm
wells. Since these small bore wells approximate the size of most monitor
wells, these cost data are presented here. Cost information for 345 wells
of various types constructed in sedimentary rocks throughout Illinois during
1967, 1968, and 1969 was collected by Gibb. All data were adjusted to a
common 1969 economic level by using a domestic and farm well index de-
veloped as a part of the study. This index, shown earlier as Figure 2, indi-
cates the increase in the costs of farm and domestic wells in Illinois from
1913 through 1969. Figure 2 also illustrates the increase in costs of large-
capacity wells. It can be seen that the small-diameter domestic and farm
well index closely follows the materials component of the Engineering News-
Record.
Recent applications of the materials component to Gibb's cost data closely
approximate the current cost of small-diameter wells. For this reason his
data have been updated to March 1975 using the materials component of the
Engineering News-Record. Well-cost data were divided into two categories
by Gibb, according to the aquifer tapped and the type of well construction.
Thus, commercially screened, drilled wells completed in water-bearing
sand and gravel deposits are shown in Figure 19, while drilled wells com-
pleted in water-bearing sandstone, limestone, and dolomite of consolidated
bedrock formations are shown in Figure 20,
76
-------
- — —-80% CONFIDENCE
100 200 300 4000 100 200 300 4000 100 200 300 400
DEPTH OF WELL, d (ft)
Figure 19. Updated (1975) cost of 4-, 5-, and 6-inch wells in sand and gravel
(after Gibb, 1971).
The final sets of data may include materials and/or labor cost for the
following:
1. Setting up and removing the drilling equipment
2. Drilling the well
3. Installing casings and liners
4. Grouting and sealing the annular spaces between casings
and boreholes
5. Installing well screens and fittings
6. Developing the well.
Test Drilling
Test holes can be drilled to permit water sampling of polluted ground-
water. For diffuse sources of pollution, existing wells can often be used.
Near point or line sources of pollution, test holes can also be used for
77
-------
VJ
00
80% CONFIDENCE
LIMITS
0 100 200 300 400 5000 100 200 300 400 5000 100 200 300 400 5
DEPTH OF WELL, d (ft)
Figure 20. Updated (1975) cost of 4-, 5-, and 6-inch wells in consolidated
rock (after Gibb, 1971).
-------
delineation of subsurface lithology, water level information, determination
of aquifer parameters, and sampling of geologic materials. Test holes and
subsequent water sampling and analysis is the most direct method of moni-
toring groundwater pollution where existing wells are insufficient in number.
The location, method of construction, well specification, and density of mon-
itor wells for a given polluted zone depend upon local conditions.
Geological Sampling
Campbell and Lehr (1973) have provided a summary of formation identi-
fication and evaluation. The success of a well depends largely upon the de-
gree of care used in obtaining geologic samples. Sampling materials in the
saturated zone is used where significant pollutants have been retained in this
zone. This will generally occur in cases of shallow water tables (thin vadose
zone), or where the vadose zone is bypassed, such as in deep well disposal.
The primary strata of interest will usually be the finer grained deposits,
such as silt or clay, because of their ability to retain certain pollutants.
Cable-tool rig samples are usually representative of the interval drilled
between bailing operations. Some contamination of the cuttings occurs in un-
consolidated materials due to the cable rubbing against the upper, uncased
part of the hole. When fine-grained saturated sands and silts are encoun-
tered, care must be used in bailing to avoid heaving materials into the hole.
Rotary rig samples are usually collected at regular intervals. These
samples contain some cavings and fragments circulated in the drilling mud.
Differential settling occurs between light and heavy fragments in the drilling
mud and this leads to complications in logging. The collection of samples
at the surface lags behind the actual cutting of a given stratum at depth.
This lag may amount to more than 20 feet in a 300-foot hole. This lag de-
pends upon the pump size and speed, the hole size, the drill pipe ID, and
the viscosity of the drilling fluid. An electric log can be used in conjunction
with a geologist's log to provide information on the time lag. Rotary r£g
samples from unconsolidated materials may be poor, particularly when rel-
atively thin layers of sand, gravel, and clay are being drilled. Soft clays
become dispersed in the drilling mud and are difficult to ascertain. Coring
is recommended in such strata.
Samples obtained from compressed-air rotary drilling are generally su-
perior to those from other methods. Casing is usually necessary in order
to minimize contamination if soft, fine-grained material is higher in the
hole.
Excellent samples can be collected during drilling with reverse-circulation
rotary rigs. The highly turbulent fluid velocities up the drill stem result in
little or no separation of the fines with a minimum time lag. The bit tends
79
-------
to loosen materials rather than grind them up, and the cuttings are drawn
into the bit and delivered at the surface.
Coring is a sampling method as well as a drilling method. It is usually
done with rotary equipment and individual cores are often less than 4 inches
in diameter and 10 feet in length. Numerous rock types can be successfully
cored with any core bit, but soft and friable formations are difficult to core.
Unconsolidated deposits of interbedded soft clays, sand, and gravel are
usually difficult to core. However, a split-core, drive sampler will often
provide excellent samples of these materials. A number of coring devices
are available, ranging from 1-1/2 to 6 inches in diameter. These devices
may be forced into the deposits by the weight and rotation from the rotary
rig or by "drive coring" with the cable-tool rig. Barton (1974) reports on
borehole sampling of saturated unconsolidated sands and gravels. A great
variety of samplers have been specially designed for these materials. In
extreme situations it may be necessary to stabilise the strata prior to sam-
pling. Sidewall sampling is gaining wider application for unconsolidated
materials.
Drilling mud should be avoided if possible when sampling formations for
groundwater pollution studies. Air rotary and reverse-circulation rotary
drilling methods are preferable since neither method requires the use of
drilling "additions. " Cable-tool drilling is also useful, but relatively slow.
In-place samples are extremely important in aquifer evaluation of permea-
bility and other considerations. Intact, in-place samples are less important
in chemical quality and pollution studies; that is, geologic samples can be
physically disturbed to some degree.
The cost of obtaining geologic samples other than by coring is primarily
a function of the time spent by the geologist who does the logging. Regis-
tered geologists charge about $150 to $250 per day for their services. Cor-
ing services vary with the kinds of rigs used, the core diameter, and the
sampling frequency. A generalized cost diagram is given in Figure 21.
The cost figures are generalized to cover small-diameter coring (2 to 3
inches) for shallower depths and larger coring sizes (3 to 5 inches) for
deeper samples, since larger bore diameters are required when drilling
to depths greater than 100 feet. The first core taken includes a 1-hour
setup and. travel time cost while the second includes just the drilling cost
(Figure 21). It is apparent that in unconsolidated formations the travel and
setup constitute a relatively larger part of sampling costs than for consoli-
dated formation sampling. At greater depths, the time involved in taking
the samples overrides the drilling time.
80
-------
3000,
25001
2000
> 500
1ST CORE
2CO
150f
100
2ND CORE
FORMATION
•UN-CONSOLIDATED
•CONSOLIDATED
-I
50 100
CORING DEPTH (ft)
150
200
Figure 21. Generalized cost of coring in unconsolidated and consolidated
formations, October 1974.
Borehole Geophysics
Geophysical well logging, or borehole geophysics, includes all techniques
of lowering sensing devices in a borehole and recording some physical pa-
rameter that may be interpreted in terms of the characteristics of the rocks
and the fluids in the rocks. Geophysical logs can be interpreted to deter-
mine many groundwater parameters. The single most important factor that
has limited the use of geophysical logging in groundwater studies in the past
is cost. Logging generally is more feasible in deeper, more expensive
wells.
The electrical conductivity or resistivity of fluid in a well bore or the
surrounding aquifer is one of the most useful parameters that can be derived
from geophysical logs. If the chemical nature of the water in an aquifer is
81
-------
known from chemical analyses, and the ion ratios are consistent, resistivity
or conductivity from logs can be used to determine the approximate quanti-
ties of those ions present. The relationship of water in the hole to water in
the surrounding materials must be understood in order to interpret a num-
ber of geophysical logs. The chemical quality of fluid in the hole is not ne-
cessarily similar to that of fluid in the surrounding materials. After a hole
is completed, it may be as much as several months before chemical and
thermal equilibrium is reached.
The electric log is very useful in determining subsurface lithology and is
generally the most common geophysical log run in water wells. An electric
log can be run only in an uncased hole that is filled with a conducting fluid.
The electric log usually includes the spontaneous potential curve in the left-
hand column and one or more resistivity curves in the right-hand column.
Spontaneous potential logs are records of natural potentials developed be-
tween the borehole fluid and the surrounding materials. The use of spon-
taneous potential for determination of groundwater quality in fresh-water
aquifers is not advisable (Keys and MacCary, 1971).
Resistivity logging devices measure the electrical resistivity of a known
or assumed volume of earth materials under an electric current. Normal
logs measure the apparent resistivity of a volume of earth materials sur-
rounding the electrodes. The short normal log records the apparent resis-
tivity of the invaded zone (extent of drilling mud penetration). The long nor-
mal log records the apparent resistivity beyond the invaded zone and is use-
ful in determining aquifer water quality. The normal logs give poor results
in high resistivity rocks.
One method of estimating water quality from electric logs makes use of
mathematical expressions which relate the following parameters (Turcan,
1966):
1. Field-formation resistivity factor and fluid resistivity
2. Fluid resistivity and specific conductance
3. Specific conductance and dissolved solids.
The field-formation factor is established from preexisting electric logs and
water analyses. When a new well is drilled and logged, the resistivity
curve is used to determine fluid resistivity in the aquifer by the use of the
formation factor. This value is converted to specific conductance at stand-
ard temperature from tables or formulas. The specific conductance is then
converted to dissolved solids by empirical relationships previously developed.
Electric logs can thus provide an indication of the vertical distribution of
groundwater salinity at or near a specific well. However, knowledge of the
chemical type of waters at different depths must be available. Interpretation
82
-------
of electric logs can supplement measurements of electrical conductivity made
on drilling mud during drilling. For ground-water pollution studies, the tool
would be applicable to polluted zones of high electrical conductivity compared
to native groundwater.
A portable electric logging system can be purchased for about $6000 to
$7000 with an additional cost of $3500 to $4000 for a gamma-ray option. The
cost of conducting an electrical conductivity survey including interpretation
is given in Figure 22. Travel costs are not included and may be an impor-
tant item in remote areas.
1000
200
300 400
LOG DEPTH (ff)
500
700
1000
Figure 221 Cost of electrical conductivity (EC) and gamma
logging, September 1974.
Wafer-Level Measurements
Water-level measurements for groundwater pollution studies can define
a mound beneath a point source or a ridge beneath a line source. In areas
with a paucity of water-level measurements supplementary measurements
may be necessary to define the depth to water and the direction of ground-
water movement. Water-level measurements on a regional basis contribute
to the hydro geologic framework; the discussion here will be limited to meas-
urements in localized areas. The most common tools for measurement of
water levels are the steel tape, electric sounder, airline, and mechanical
recorder.
STEEL TAPE. The surveyor's steel tape has been used for many years
by the U.S. Geological Survey as a water-level measuring device and is
83
-------
available in lengths of 100, 200, 500, and 1000 feet. Coefficients of stretch
and temperature expansion are provided by the manufacturer for each tape.
For most groundwater pollution studies, correction for stretch and tempera-
ture changes will not be necessary, due to the relatively shallow depths of
interest. The tape is usually lowered by hand; however, in deep wells a
motor-driven tape reel may be used.
The water level in a well is measured by suspending a known length of
tape below a measuring point so that at least the lower few feet of tape are
below the water level. The lower portion of the tape is usually coated with
blue chalk or some other substance which exhibits a marked color change
when wetted. The water-level measurement is obtained by subtracting the
length of the wetted portion from the total length suspended below the meas-
uring point.
One disadvantage cf using the steel tape is that if the approximate depth to
water is unknown, too short a length of tape may be lowered into the well,
thereby necessitating a number of attempts. Also, water inside the casing
or cascading water may wet the tape above the true water table and result
in errors in measurement.
The number of wells measured per day depends primarily on well density,
access to well sites, depth to water, well ownership, access for the meas-
uring device, and well obstructions. For dense municipal wells under a
600
300
COST {$)
Figure 23. Cost of steel topes, Sepfember 1974.
84
-------
common manager, up to 40 to 50 water-level measurements per day can be
made where the depth to water is less than 100 feet. For irrigation wells
spaced at about 1/2-mile intervals in an agricultural area, about 20 to 30
water-level measurements per day can be made where the depth to water is
less than 100 feet. For widely scattered stock wells in an undeveloped area,
fewer than five water-level measurements may be possible in 1 day.
Measurement time is decreased considerably when the person performing
the measurements is familiar with the area and the wells. For initial meas-
urements in new programs, a much longer period of time is necessary.
Prior to initiating well measurements, a comprehensive well data collection
and organization program may be necessary. This provides pertinent hydro-
geologic data for the wells to be measured.
Costs for steel tapes normally employed to measure water-well levels are
summarized in Figure 23.
ELECTRIC SOUNDER. The electric sounder consists of a reel with a
meter, one or two electric wires, and a sounding tip. The reel and meter
remain at the land surface while the wire and tip are lowered down the well.
A battery-powered electrode assembly is usually used; when in contact with
water, it causes a sharp needle deflection on a large, sensitive current
1000
800
O
600
400
200
1
~0 100 200
COST (S)
300
Figure 24, Cost of electric sounder and cable, September 1974.
85
-------
meter. The wire is mounted on a small reel that is used for lowering and
withdrawing the wire and sounding tip. Depth control is aided by metal tags
on the wire.
Electric sounders are often used in pump tests where a number of meas-
urements must be taken at small time intervals. Also, electric sounders
are of great value in cases where cascading water is present. A measure-
ment can be made in less than 5 minutes in most wells less than 100 feet
deep.
The average cost of electric sounders is given in Figure 24.
AIRLINE. The airline can be a very practical device in certain situations,
such as where pumping produces turbulence inside the well casing. Com-
monly, an airline is used by pump testers or well drillers as a rapid means
to obtain water-level measurements in deep wells.
The airline consists of a small-diameter copper or iron tube which is in-
stalled in the space between the pump column and the casing. The tube is
usually strapped to the pump column, and the two installed simultaneously.
The airline should be free of leaks, open at the bottom, and extend several
feet below the lowest pumping water level. The airline should preferably be
straight and plumb, and the depth of the lower opening must be known. The
top of the airline is connected to a source of compressed gas. An air-
pressure gauge is used to measure the pressure in the airline.
Pressure is applied until all the water has been expelled from the airline,
and the gauge can then be read. The gauge reading indicates the length of
the expelled water column (the height of water above the airline opening).
To obtain depth to water, the length of this column is subtracted from the
length of the airline. This measurement can usually be made in several
minutes.
The tubing, which is normally left in the well, may cost as little as $10.
The tubing can also be installed for access by the electric sounder. The
air compressor and storage tank can cost as much as $250, but a hand pump
is frequently satisfactory.
MECHANICAL RECORDER. A simple recording device commonly used
consists of a cylindrical recording chart actuated mechanically by a float
that moves with fluctuations in the water level. A small-diameter stranded
cable or tape is attached to the float, and a counterbalance is suspended over
a pulley on the recorder. The pulley is geared to the chart so that the chart
rotation is proportional to float movement. A clock drive slowly moves a
recording pen across the chart. The mechanical recorder is used when many
measurements are necessary over short time periods, and is especially
86
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useful when relatively rapid water-level fluctuations occur, such as in ob-
servation wells during pump tests. These recorders cost about $375. If
a digital system rather than a chart is desired, the unit can cost about $675.
Most recorders come with about 20 feet of line and an extra charge of $0. 25
per foot is charged for additional line.
Garber and Koopman (1968) summarized methods of measuring water lev-
els in deep wells. Accurate measurement of water levels deeper than 1000
feet in wells requires special equipment. Correction for stretch and ther-
mal expansion of measuring tapes must be considered.
Water Sampling
Most of the physical factors which promote mixing in surface waters are
absent or much less effective in groundwater systems. A well can be con-
sidered as a sampling point in a large body of slowly moving water, which
differs in chemical composition vertically as well as areally. Unfortunately,
most techniques for well sampling at discrete depths are usable only in un-
finished or nonoperating wells. A more reliable means of evaluating the
quality of water tapped by a well is an analysis of a pumped sample.
The volume of water that is generally collected for chemical analysis
from individual widely scattered monitoring wells is relatively insignificant
volumetrically. Therefore, either many more monitoring wells must be
sunk or a smaller number of existing wells must be pumped at higher rates
or more frequently to obtain representative values. Most wells are inte-
grators of complex systems of surface water, soil water, and groundwater.
In some cases the integrated sample is of most importance because it rep-
resents the water used, or likely to be used in the future. In other cases,
an integrated sample is not of interest, but rather a sample from a specific
depth zone. This requires either careful selection from existing wells or
construction of special monitoring wells.
Well Hydraulics
The composition of water obtained from a well is likely to be influenced
by well construction, well development, and pump operation, and these
should be considered in the sampling program. Well co.Mtru^°* C"tle' „
termine the depth of zones from which the water is coming and ^lue^ce ^e
local groundwater flow pattern. Perforations above the water table can per-
mit cascading water, or direct movement of groundwater from shallow
perched layers above the water table, to flow down the inside of *•*•£*
the water table. Drilling mud remaining from well construction can contain
contaminants, as can well casing, seals, and pump parts.
Well hydraulics can cause chemical changes in the
pumped sample. For example, pressure changes associated with velocity
87
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changes at the well inlet can cause changes in oxidation state, pH, and tem-
perature which, in turn, affect certain chemical constituents. Thus, a
sample from the well discharge may differ significantly in quality from
groundwater in the aquifer. Also, in cases where chemicals are added at
the discharge pipe, care must be taken to ensure the chemical composition
of the sample is not altered.
Time Changes in Quality
Quality changes in groundwater are usually much slower than those in
surface water. The composition of well samples from a large, relatively
homogeneous aquifer usually will not change much over long periods of time.
Therefore, changes in groundwater quality can be described satisfactorily
by monthly, seasonal, or annual sampling schedules. However, exceptions
usually occur in cases of groundwater pollution.
Just as water levels in a well change drastically soon after a pump is
turned on, so can the quality of pumped water. This is particularly true
where there is vertical stratification of groundwater quality. These short-
term changes in some cases may be linear with pumping time, whereas in
other cases they may be exponential. In the case of high-yielding wells
(greater than 500 gpm), several days or weeks of pumping may be necessary
to purge the well of atypical water due to local conditions. These local con-
ditions could include poor quality, shallow water cascading down the well
casing and accumulating in or near the well during nonpumping periods or
vertical leakage down a gravel pack to a deeper producing zone. Often,
field measurements of water temperature and electrical conductivity at the
well discharge as the well is pumped can yield useful information on short-
term changes in water quality. For short-term testing, consideration
should be given to a logarithmic frequency of sample collection, analogous
to the procedure for water-level measurements during a pump test. Short-
term trends should be evaluated before adequate data are collected to de-
termine long-term time trends in groundwater quality.
In the early days of water-level measurement programs, weekly or
monthly measurements were made to discover seasonal fluctuations; else-
where, semiannual measurements, related to high and low water levels for
a year, were instituted. In some areas significant seasonal fluctuations
occur in the quality of groundwater. In these areas seasonal trends must
be established in the first stages of the development of monitoring programs.
Specific locations where seasonal changes are likely to occur include:
1. Near large-volume point or line sources of recharge or
pollution
2. Near disposal sites for highly concentrated wastes
-------
3. In areas of permeable soils and geologic materials above
the water table
4. Where wells tap shallow portions of aquifers.
Sampling at the Well Discharge
Water samples can be collected directly from pumping wells or flowing
artesian wells. Nonpumping wells equipped with a pump require pumping
for a substantial period after start-up to obtain a representative sample from
the aquifer. In wells without fixed pumps, special portable pumps may be
installed to retrieve water samples.
Water-well pumps can be classified into two groups:
1. Constant displacement pumps which deliver substantially
the same quantity of water against any head within their
operating capacity
2. Variable displacement pumps which deliver water in quan-
tity varying inversely with the head against which they
operate.
Major types of constant displacement pumps include: (1) piston or recipro-
cating, (2) rotary, and (3) screw or squeeze displacement pumps. Major
types of variable displacement pumps are: (1) centrifugal, (2) jet, and
(3) suction-lift pumps. A submersible pump is a centrifugal pump closely
coupled with a submersible electric motor.
A pump installed above a well is called a suction-lift pump. A pump
installed in the well at some depth below the water table is called a positive
submergence pump. Suction lift by a pump is accomplished by developing
negative pressure head at the pump intake. The maximum suction lift is
limited by atmospheric pressure, vapor pressure, head losses due to fric-
tion, and the required inlet head of the pump. At sea level the best designed
pumps usually achieve a suction lift of about 25 feet, while the suction lift
of an average pump varies from 15 to 18 feet. The maximum suction lift
decreases with an increase in altitude.
Where the depth to water is greater than the practical suction limit, a
hand-operated pitcher pump, a centrifugal pump, a submersible pump, or
a shallow-well jet pump is commonly used. Submersible and jet pumps re-
quire a minimum casing diameter of 4 and 2 inches, respectively. In large-
diameter wells where the depth to water exceeds the suction limit, a sub-
mersible, deep-well jet, or a deep-well turbine pump is commonly used.
Before a pump can be intelligently selected for any installation, information
on required capacity, location, operating conditions and total head is
necessary.
89
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The time involved in sampling at the well discharge is highly dependent
on whether a pump is installed and is operating, travel time between sites,
and time required to gain permission to sample the wells. If the pump must
be started, additional time is required.
With closely spaced, actively pumped wells in an urban area that are un-
der the managership of only one or a few agencies, as many as 30 to 50
wells can be sampled in one day (without field analyses or treatment). In
remote areas with widely spaced nonpumping wells and different owners,
fewer than a half dozen samples per day may be possible.
The cost to sample each well, therefore, is a function of the travel time
and man-time at each well. The salary of water sampling technicians is
from $8000 to $10,000 per year. The cost to sample a number of wells un-
der three categories of well spacings is given in Figure 25. It is assumed
that a technician can sample 30 to 50 wells daily in a municipal well system,
10 to 15 irrigation wells in a rural area, and 4 to 7 in an isolated area.
2000
200
NUMBER OF WELLS
Figure 25. Approximate cost of sampling wells (one round),
December 1974.
The cost of common field equipment for water quality tests is not signif-
icant over the useful life of the instruments. A portable electrical conduc-
tivity meter costs about $250 to $400. A portable pH meter can cost from
90
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$100 to $300. Specific ion meters can be purchased for about $200 to $250,
and additional probes cost about $100 to $150 each. Elaborate continuous
recording, digital readout, and multiparameter water quality instruments
can be quite expensive ($2000 to $3000) but are not necessary for routine
water well sampling.
Types of Well Sampling
Well sampling can be grouped into two broad types: water supply and
hydrogeologic. Water supply sampling is concerned primarily with the use
of the water. For drinking purposes a sample might be taken from the house-
hold tap rather than from the well discharge. For irrigation purposes, a
water sample might be taken from a ditch at the entrance to a field rather
than from a well. Hydrogeologic sampling is concerned with natural ground-
water quality or pollution. For hydrogeologic sampling, the water sample
would ideally be taken directly from the aquifer, not at the well discharge.
However, for practical purposes, a sample from the well discharge can be
used in most cases. Ideally, high-yielding wells (greater than 500 gpm)
would be used to evaluate large-scale or regional aquifer conditions; low-
yielding wells would be used to evaluate local conditions.
A low-yielding well (less than 50 gpm) generally reflects water quality
only in the immediate vicinity of the well. In many rural areas, for exam-
ple, a domestic well would be greatly influenced by local conditions, such
as lawn irrigation and septic tank waste disposal. A high-yielding irrigation
well in a rural area pumped continuously would produce a water sample
whose quality would reflect regional conditions, such as fertilizer applica-
tion, irrigation return flow, and canal recharge.
A 5-gpm domestic well pumped daily for 1 hour produces 300 gallons in
1 day A 3000-gpm irrigation well pumped continuously for 1 day pumps
almost 15, 000 times this volume of water. Erroneous interpretations have
been made in past groundwater quality studies due to a lack of considera-
tion of this factor.
High-yielding wells also can induce great vertical head differences dur-
ing pumpLg, and this should be considered for sampling P-poses In some
case* practical considerations will dictate that wells -nnot>e plac £ «n-
mediately adjacent to waste disposal sites. A sample from >.* ^£^
well would be more likely to show the effects of t^**^* *
cause it would be more likely to induce flow toward the well. This
cially true in areas of very slow groundwater movement.
Sampling in Open Wells
espe
91
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occur in a small area and only periodic pumping is required. Samples from
abandoned or inactive wells of unknown construction are often of limited
value. The cost of these pumps is a function of the pump size, cable load,
flex hose diameter, and sampling depth. The cost of submersible pumps for
various pumping lifts and well discharges can be obtained from Table 11.
In addition to the pump cost, the cost of the support cable and flex hose (Fig-
ure 26} must be added. The unit is usually placed on a power-driven reel.
400
300 -
£200
o
u
100
100 200 300
CABLE AND FLEX HOSE LENGTH (ft)
400
500
Figure 26. Cost of cable and flex hose for use with portable submersible
pumps, October 1974.
The power costs to run submersible pumps are given in Figure 27. The
power costs vary with the discharge rate, total head, pump efficiency, and
electrical costs. Figure 27 shows that the power costs for 1 hour operation
of a submersible pump are minimal. These costs include a motor efficiency
of 75 to 80 percent, a pump efficiency of 70 to 75 percent, and scaled elec-
trical costs of about 3 cents per kilowatt hour.
Water can be pumped from a well by releasing compressed air into a dis-
charge pipe lowered into the well. Air bubbles mix with the water, reducing
the specific gravity of the column of water sufficiently to lift it to the sur-
face. For best results, the submergence ratio of the air line (percentage of
the total length is below water while pumping) should be about 60 percent.
92
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TABLE 11. AVERAGE COST OF SUBMERSIBLE WATER PUMPS, FOUND IN EPA REGION IX, OCTOBER 1974
>. Head in feet
N. (pumping
\depfh)
Horse- N.
power ^y
1/3
1/2
3/4
3/4
3/4 .
1
1
1
1
1-1/2
1-1/2
1-1/2
1-1/2
2
2
2
3
3
60
490
450
2550
2880
80
460
350
•
2100
2640
300C
100
430
470
230
1380
1590
1450
2380
280C
300<
120
400
450
750
1100
1310
900
1400
2100
2610
) 2880
140
360
430
480
710
940
1230
1340
1740
2400
2760
160
340
410
470
690
850
1180
1320
1560
2290
270C
180
290.
380
470
640
520
760
1070
1250
960
201
252
200
240
280
300
350
400
500
600
700
800
gallons per hour
230
340
480
590
470
730
920
780
1170
1410
1620
2350
260
380'
470
440
660
510
730
1000
5290
1440
1930
200
350
400
420
630
360
700
900
1230
1410
1650
no
320
300
400
580
480
680
780
1170
1380
1320
270
360
500
460
620
770
1040
1310
190
310
400
430
570
730
880
1230
210
400
370
430
660
390
106
300
570
860
230
460
620
150
300
Well
Diameter
(inches)
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
Cost
(S)
200
250
300
300
300
250
350
300
300
550
500
450
450
600
500
500
600
550
CO
(continued)
-------
TABLE 11 .(continued)
\ Head in ft
\taumpinj
\depth
Horse- \^
power \^
5
5
5
5
5
5
5
5
5
5
7-1/2
7-1/2
7-1/2
7-1/2
7-1/2
7-1/2
7-1/2
7-1/2
7-1/2
10
10
60
80
100
120
140
160
180
200
240
280
300
350
400
500
600
700
800
900
1000
1100
1200
1400
1600
gallons per minute
200
300
180
160
140
270
120
230
190
170
140
190
180
160
150
130
70
90
20
20
40
80
80
50
10
90
60
80
50
70
90
90
50
70
50
60
80
70
40
60
50
70
60
50
40
50
40
70
60
50
40
40
40
50
50
40
30
40
40
40
20
30
20
20
10
20
10
20
10
10
10
10
10
10
Well
Diam-
eter
(in)
6
6
6
6
6
6
6
6
6
6
8
8
6
6
6
6
6
6
6
6
6
Cost
(S)
1400
1400
1300
1300
1300
1800
1300
1200
1300
1400
1600
1700
1500
1500
1500
1500
1600
600
700
700
700
(continued)
-------
TABLE 11 (continued)
\^eod In ft
(Dumping
Ndepth)
Horse- N.
power \
10
10
10
10
15
15
15
15
15
15
15
15
15
20
20
20
20
20
20
20
20
60
80
100
120
140
160
180
200
240
280
300
350
400
500
600
700
800
900
1000
100
200
1400
1600
%
gallons per minute
350
300
230
280
270
340
290
140
250
200
300
280
130
230
190
260
270
120
190
160
170
140
240
200
90
90
150
130
210
190
80
90
80
130
130
190
180
190
80
70
110
90
150
170
140
70
60
50
90
80
150
130
40
50
80
70
60
no
90
40
60
50
50
80
70
50
50
40
70
70
40
40
70
60
50
40
40
*
50
50
40
40
40
30
40
40
Well
Diam-
eter
(in)
6
6
6
6
8
8
6
6
6
6
6
6
6
8
8
6
6
6
6
6
6
Cost
(S)
1700
1700
1800
1900
2000
2100
2100
2100
2100
2200
2300
2300
2400
2600
2600
2800
2800
2700
2700
3000
3100
(continued)
-------
TABLE 11 (continued)
\Head in ft
^pumping
Ndepth)
Horse- \.
power \
20
30
30
30
30
30
30
30
30
30
40
40
40
40
40
40
40
60
80
100
120
140
160
180
200
240
280
300
350
400
500
600
700
800
900
1000
1100
1200
1400
1600
gallons per minute
570
510
420
550
500
440
320
260
300
250
240
210
290
180
190
280
250
150
170
140
250
200
130
130
210
150
180
120
160
140
100
90
140
130
50
80
70
120
40
80
70
60
110
90
40
70
70
50
90
40
70
60
50
80
80
30
50
50
50
80
70
40
70
60
Well
Diam
eter
(in)
6
8
8
6
6
6
6
6
6
6
8
8
6
6
6
6
6
Cost
(S)
3300
3300
3400
3600
3700
3700
3700
3600
4000
4100
4400
4700
4800
4800
4700
4900
5300
-------
500
400
o
<
300
<
6
200
1 HOUR
$1.10
- 1 DAY
$26.40
100
200
300
300
200
0 100 200
DISCHARGE (gpm)
Figure 27. Power costs for continuous pumping of 1 hour, 1 day, 1 week, for specific pumping heads and
specific discharge rates, December 1974.
300
-------
Air-lift pumping can be useful in monitoring wells that need to be pumped
only at periodic intervals. Johnson Division UOP (1966) presents data on the
relation between total lift, submergence of air line, and water discharged
per cubic foot of free air delivered by an air compressor.
Water samples may also be taken by bailing. During cable tool well drill-
ing periodic water samples are retrieved in the bailer and may provide ade-
quate information on the vertical distribution of groundwater quality. Where
pumping equipment is not available or where a pump cannot be installed be-
cause the diameter of a well is too small, a container such as a weighted
bottle or a short section of pipe capped at the bottom can be lowered into the
well to collect a sample of water. This sample will give an indication of the
chemical quality of water, but should not be used for bacteriological or de-
tailed chemical analysis because of the likelihood of contamination. This
method is not recommended except where other methods of sampling are
unavailable.
Where it is desired to collect water from a specific depth inside a well,
a special cylinder known as a Irthief sampler" can be lowered by cable into
the well and closed at a predetermined depth. Designs differ, primarily in
their closing mechanism. Most types consist of a cylinder that can be less
than 2 inches in diameter. A bar with a plunger or cork on each end runs
through the cylinder. When the sampler is lowered below the water table to
the desired depth and a continuous upward motion is imparted, the two ends
close. The most common type of thief sampler is spring loaded. With this
type a messenger is lowered along the cable to release the two end cups,
which in turn trap the water sample. Many thief samplers are custom made
for a specific use. The cost of these samplers is about $100 to $200.
Another method of collecting depth-controlled samples from uncased
holes is by installation of mechanical or inflatable packers which temporar-
ily isolate selected water-bearing zones for pumping. This method is of
limited value in gravel-packed wells due to vertical movement of ground-
water in the gravel pack.
Under special circumstances, continuous monitoring of wells may be
necessary. Among the devices used for this purpose are probes designed
to measure conductivity, temperature, and selected constituents. These
probes may be operated down the well or at the discharge outlet.
Yare (1975) describes a procedure for water sampling during rotary drill-
ing. This technique consists of:
1. Drilling a borehole to the base of a sampling horizon
2. Lowering a wire-wound well screen and riser pipe to the
bottom of the borehole and gxavel packing the screen
98
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3. Pumping the borehole well until the discharge is clear of
drilling fluid
4. Pumping at least 100 gallons of formation water before
collecting the sample.
The March-April 1975 issue of Ground Water contains at least six articles
dealing with monitor well construction and water sample retrieval. These
articles indicate how local conditions can influence the type of monitoring
which should be undertaken.
Other Methods of Sampling Groundwater
Tile or ditch drains can provide samples of shallow groundwater. Thomas
and Barfield (1974) discuss the limitations of tile effluent for monitoring per-
colate from soils. The primary limitation for monitoring below the water
table is that these samples may represent only the shallowest portion of the
aquifer. In some cases this provides very useful information. Springs rep-
resent groundwater discharge and can be sampled at the land surface. In-
terpretation of spring water qualities depends on knowing details of the hy-
drogeologic framework and groundwater flow patterns. Water sampling of
streams under base flow conditions can represent an integration of large
groundwater systems and thus be very useful. Proper selection of sampling
sites and times requires careful hydrologic judgment.
99
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SECTION V
ANALYSIS OF SAMPLES
INTRODUCTION
Samples, including soil and water, can be taken from the land surface,
the vadose zone, or the zone of saturation. In spite of the location of the
sample site, many of the sample analysis techniques are similar. A water
sample taken at the surface, in the vadose zone, or from the zone of satura-
tion is analyzed in the laboratory using much the same analytical techniques
for each parameter. The sample preparation, however, is often quite
different.
Soil tests can be divided into physical and chemical analyses. The physi-
cal tests are not routinely handled by many chemical analysis laboratories.
Agricultural laboratories often provide these services. The physical tests
include water content, bulk density or porosity, particle size distribution,
soil-moisture characteristic curve, and hydraulic conductivity. The chem-
ical analyses of soil samples include soluble salts, soluble ions, cation ex-
change capacity and exchangeable ions, and specific surface.
The water tests can be divided into physical, chemical, bacteriological,
and radiological analyses. The chemical analyses are further subdivided
into inorganic and organic tests. In the discussion of water analysis, con-
sideration is given to sample containers, sample preservation and treatment,
and quality control.
CUSTODY CONTROL
The EPA's Office of Water and Hazardous Materials has prepared a pro-
cedure (U.S. EPA, 1975) for a recommended "Chain-of-Custody" that will
minimize legal complications in obtaining and analyzing water samples. The
following comments are abstracted from this document.
Quality assurance should be stressed in all monitoring and in examina-
tion of self-monitoring programs no matter what the impetus for the spot
check or inspection. The successful implementation of a monitoring pro-
gram depends to a large degree on the capability to produce valid data and
to demonstrate such validity. No other area of environmental monitoring
requires more rigorous adherence to the use of validated methodology and
quality control measures.
100
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It is imperative that laboratories and field operations involved in the col-
lection of primary evidence prepare written procedures to be followed when-
ever evidence samples are collected, transferred, stored, analyzed, or
destroyed. A primary objective of these procedures is to create an accurate
written record which can be used to trace the possession of the sample from
the moment of its collection through its introduction into evidence. The pro-
cedures described here have been successfully employed and are presented
as suggested procedures insofar as they fulfill the legal requirements of the
appropriate State legal authority.
Preparation
The evidence-gather ing portion of a survey is characterized by the abso-
lute minimum number of samples required to give a fair representation of
the effluent or water body sampled. The quantity of samples and sample
locations are determined prior to the survey.
Chain-of-custody record tags are prepared prior to the actual survey
fieldwork and contain as much information as possible to minimize clerical
work by field personnel. The source of each sample is also written on the
container itself prior to any field survey work.
Field logsheets used for documenting field procedures and chain-of -
custody and to identify samples should be prefilled to the extent practicable
to minimize repetitive clerical field entries. Custody during sampling is
maintained by the sampler or project leader through the use of the logbook.
Any information from previous studies should be copied (or removed) and
filed before the book is returned to the field.
Explicit chain-of-custody procedures are followed to maintain the docu-
mentation necessary to trace sample possession from the time taken until
the evidence is introduced into court. A sample is in your "custody" if:
• It is in your actual physical possession; or
• It is in your view, after being in your physical possession; or
• It was in your physical possession and you locked it in a
tamper-proof container or storage area.
All survey participants should receive a copy of the study plan and be
knowledgeable of its contents prior to* the survey. A presurvey briefing
should be held to reappraise all participants of the survey objectives, sam-
ple locations and chain-of-custody procedures. After all chain-of- custody
samples are collected, a debriefing should be held in the field to check ad-
herence to chain-of-custody procedures and to determine whether additional
evidence samples are required.
101
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Sample Collection
1. To the maximum extent achievable, as few people as possible
handle the sample.
2. Water samples are obtained using standard field sampling tech-
niques. When using sampling equipment it is assumed that this
equipment is in the custody of the entity responsible for collect-
ing the samples.
3. The chain-of-custody record tag is attached to the sample con-
tainer when the complete sample is collected and contains the
following information: Sample number, time taken, date taken,
source of sample (to include type of sample and name of firm),
preservative, analyses required, name of person taking sample,
and witnesses. The front side of the card (which has been pre-
filled) is signed, timed, and dated by the person sampling.
The tags must be legibly filled out in ballpoint (waterproof) ink.
Individual sample containers of groups of sample containers
are secured using a tamper-proof seal.
4. Blank samples are also taken. Include one sample container
without preservative and containers with preservatives from
all of which the contents will be analyzed by the laboratory to
exclude the possibility of container contamination.
5. The Field Data Record logbook should be maintained to record
field measurements and other pertinent information necessary
to refresh the sampler's memory if he later takes the stand to
testify regarding his actions during the evidence-gathering
activity. A separate set of field notebooks should be main-
tained for each survey and stored in a safe place where they
can be protected and accounted for at all times. Standard for-
mats have been established to minimize field entries and in-
clude the date, time, survey, type of sample taken, volume of
each sample, type of analysis, sample number, preservatives,
sample location, and field measurements. Such measurements
include temperature, conductivity, dissolved oxygen (DO), pH,
flow, and any other pertinent information or observations. The
entries are signed by the field sampler. The preparation and
conservation of the field logbooks during the survey is usually
the responsibility of the survey coordinator. Once the survey
is complete, field logs should be retained by the survey coor-
dinator, or his designated representative, as a part of the
permanent record.
6. The field sampler is responsible for the care and custody of
the samples collected until properly dispatched to the receiving
laboratory or turned over to an assigned custodian. He should
assure that each container is in his physical possession or in
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his view at all times, or is locked in such a place and manner
that no one can tamper with it.
7. Colored slides or photographs are often taken which show the
outfall sample location and any visible water pollution. Written
documentation on the back of the photo should include the signa-
ture of the photographer, time, date, and site location. Photo-
graphs of this nature, which may be used as evidence, are
handled by chain-of-custody procedures to prevent alteration.
In addition to the above recommendations on sample collection, the EPA
(U.S. EPA, 1975) provides procedures on transfer of custody and shipment.
A section is also included which presents the EPA's National Field Investi-
gation Center's Laboratory Custody Procedures. These procedures should
be closely followed, primarily in compliance monitoring.
QUALITY CONTROL
Decisions made using groundwater data are far-reaching. Water quality
standards are set to establish satisfactory conditions for a given water use.
The laboratory data define whether that condition is being met, and whether
the water can be used for its intended purpose. If the laboratory results in-
dicate a violation of the standard, action is required on the part of pollution
control authorities. With the present emphasis on legal action and social
pressures to abate pollution, the field worker and analyst should be aware of
their responsibility to provide results that are a reliable description of the
sample. The technician must be aware that his professional competence,
the procedures he has used, and the reported values may be used and chal-
lenged in court. To satisfactorily meet this challenge, the data must be
backed up by an adequate program to document the proper control and ap-
plication of all of the factors which affect the final result.
Because of the importance of laboratory analyses and the resulting ac-
tions which they produce, a program to insure the reliability of the data is
essential. It is recognized that all analysts practice quality control to vary-
ing degrees, depending somewhat upon their training, professional pride,
and awareness of the importance of the work they are doing. However,
under the pressure of daily workload, analytical quality control may be
easily neglected. Therefore, an established, routine control program ap-
plied to every analytical test is necessary in assuring the reliability of the
final results.
The need for standardization of methods within a single laboratory is
readily apparent. Uniform methods between cooperating laboratories are
also important in order to remove the methodology as a variable in com-
parison or joint use of data between laboratories. Uniformity of methods
is particularly important when laboratories are providing data to a common
103
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data bank, such as STORET, or when several laboratories are cooperating
in joint field surveys. A lack of standardization of methods raises doubts
as to the validity of the results reported. If the same constituent is meas-
ured by different analytical procedures within a single laboratory, or in
several laboratories, the question is raised as to which procedure is supe-
rior, and why the superior method is not used throughout.
The physical and chemical methods used should be selected by the follow-
ing criteria:
• The method should measure the desired constituent with pre-
cision and accuracy sufficient to meet the data needs in the
presence of the interferences normally encountered in polluted
waters
• The procedure should utilize the equipment and skills normally
available in the average water pollution control laboratory
• The selected methods should be in use in many laboratories
or have been sufficiently tested to establish their validity
• The method should be sufficiently rapid to permit routine use
for the examination of large numbers of samples.
The use of EPA methods in all EPA laboratories provides a common base
for combined data between Agency programs. Uniformity throughout EPA
lends considerable support to the validity of the results reported by the
Agency.
Regardless of the analytical method used in the laboratory, the specific
methodology should be carefully documented. In some water pollution re-
ports it is customary to state that Standard Methods (APHA. 1971) have been
used throughout. Close examination indicates, however, that this is not
strictly true. In many laboratories, the standard method has been modified
because of recent research or personal preferences of the laboratory staff.
In other cases the standard method has been replaced with a better one.
Statements concerning the methods used in arriving at laboratory data should
be clearly and honestly made. The methods used should be adequately ref-
erenced and the procedures applied exactly as directed.
Knowing the specific method which has been used, the reviewer can apply
the associated precision and accuracy of the method when interpreting the
laboratory results. If the analytical methodology is in doubt, the data user
may honestly inquire as to the reliability of the result he is to interpret.
In field operations, the problem of transport of samples to the laboratory,
or the need to examine a large number of samples to arrive at gross values
will sometimes require the use of rapid field methods. Such methods should
104
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be used with caution, and with a clear understanding that the results obtained
may not compare in reliability with those obtained using standard laboratory
methods. The data user is entitled to know that approximate values may
have been obtained for screening purposes only, and that the results may not
represent the customary precision and accuracy obtained in the laboratory.
SOIL
Physical Analyses
WATER CONTENT. The water content of field samples is commonly ob-
tained by gravimetry with oven drying (Gardner, 1965). The sample is
placed in a drying oven at about 105°C. The difference in mass before and
after drying represents the water content on a dry mass basis. (Gardner
also describes a field method for determining water content using gravime-
try with drying by burning alcohol. )
The cost of a soil-moisture drying oven varies between $300 and $450.
The cost of conducting a water content analysis varies from about $4 to $6
per sample. Figure 28 gives the cost of multiple water content determina-
tions including a discount rate.
10,000
g 1,000
01
1/1
z
s
o
u
100
BULK DENSITY
1
_L
10 100
NUMBER OF TESTS
1000
Figure 28. Costs for determinations of water content and bulk density in
soils, September 1974.
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BULK DENSITY AND POROSITY. Bulk density is used to calculate soil
porosity. Also, together with water content data, bulk density may be used
to estimate the amount of water to bring the soil to saturation. Soil cores
obtained in the field are oven dried at 105°C until constant weight is attained.
The bulk density of the sample is the oven-dry mass divided by the volume.
Blake (1965) presents alternative methods to calculate bulk density, includ-
ing determination in place by filling the soil cavity with a measured volume
of sand. Blake also discusses a double-probe technique for measuring bulk
density in situ via gamma radiation.
The cost of a bulk density determination is around $6 to $10 per sample;
however, discount rates may be quite high for these determinations. The
cost of multiple bulk density tests including a discount rate is given in
Figure 28.
PARTICLE-SIZE DISTRIBUTION. Information on particle-size distribu-
tion of drilling samples provides explicit data on the vertical distribution of
gravels, sands, silts, and clays. Such data may subsequently be related to
gamma logs. According to Day (1965) fractionation and particle-size analy-
ses mainly involve sieving and sedimentation procedures.
Sieving is used to separate particles coarser than 0. 05 mm. In practice,
a sample is prepared in standard fashion and passed through a net of sieves
with openings graded to permit separation of various particle sizes. Either
wet sieving or dry sieving is used.
Sedimentation is used principally to determine the percentage of clay in
a sample. This fraction is highly active in ion exchange and adsorption.
The presence of layers with high clay levels tends to cause lower relative
permeability. Sedimentation is accomplished by either the pipette or hy-
drometer method. Results are usually presented on a curve which plots the
percentage of particles, by weight, smaller than a given size, versus the
logarithm of the particle size.
The basic equipment used in particle size analysis is a set of sieves and
a sieve shaker. Each sieve costs about $12 to $16. A full set of U.S.
Standard or Tyler series can cost as much as $225. However, reduced
numbers of sieves can be used for soil particle size analysis. The USDA-
recommended set of soil sieves costs about $60. The average cost of a
mechanical shaker is about $300. Under specialized conditions it may be
necessary to determine the sedimentation fraction that passes through even
the finest sieves.
The cost of a particle size analysis can vary depending upon the particle
size range of interest. The average cost of an analysis of gravel through the
clay sizes is $25; the cost of an analysis is $40 if less than a 25-gram sam-
ple is available. The normal particle size analysis calls for a sand and
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gravel determination and this costs about $8 to $10. If an analysis of clay
sizes only is required, the cost is about $20 per sample. Volume discount
rates may be important in the costs of these tests.
SOIL-WATER CHARACTERISTIC CURVE. A knowledge of the water con-
tent versus pressure relationships of a soil is essential in calculating hy-
draulic conductivity and the rate of soil-water movement. A soil-water
characteristic curve is needed to transform water content data from neutron
logging into equivalent soil pressures.
The modified Haines method may be used to obtain the soil-water charac-
teristic curve up to suctions of about 1 atmosphere. This method employs
the equipment shown in Figure 29. Soil cores are carefully placed on the
fritted glass plate and saturated (Nielsen et al. , 1973). Excess water is
removed and the hanging water column is adjusted through a desired range
of negative pressure. A plot of water content versus soil pressure during a
drying cycle, which occurs during the Haines method, is usually different
from the curve during wetting, as evidenced in Figure 30. This hysteresis
phenomenon must be kept in mind during interpretation of field data. Since
the fritted glass membrane usually fails at about 0. 8 atmosphere negative
pressure, other methods are required to obtain the water content versus
soil pressure relationship for greater suction. Klute (1965) describes one
such method (the pressure-membrane method) which involves applying air
pressure to a soil sample in a weighable cell.
Estimates on the water content of a soil at field capacity may be obtained
by the so-called one-third atmosphere technique (Peters, 1965). Alterna-
tively, field capacity can be estimated in situ. A square plot of about 3 me-
ters per side is prepared with a raised border to permit ponding. Water is
applied until the desired soil depth is wetted. After recession of the water,
the soil surface is covered with polyethylene sheeting to prevent evaporation.
After allowing about 2 days for drainage, soil samples are obtained for grav-
imetric determination of water content. Incidentally, the test pond also can
be used to estimate infiltration rates into the soil.
The cost of developing a soil-water characteristic curve is a function of
the number of tests to be run. These tests are not routinely run in many
laboratories. The average cost of developing a soil-water characteristic is
about $30 to $40 per sample. Discounts of over 30 percent can be expected
for large numbers of samples. A series of 100 tests, for example, would
cost about $2000.
HYDRAULIC CONDUCTIVITY. Core samples obtained from the field may
be used to evaluate both the saturated and unsaturated hydraulic conductivity
for the soil depth sampled. For the saturated case a permeameter may be
used in which a constant positive head is applied to a soil sample, the dis-
charge rate is measured, and the hydraulic conductivity is calculated.
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ZERO
MARK
BUCHNER
FUNNEL
(PYREX)
SOIL
SINTERED
GLASS
PLATE
(POROUS)
RUBBER
TUBING
GRADUATED
PIPETTE
100cm MARK
Figure 29. Modified Haines Apparatus for obtaining soil-
water characteristic curves (after Day et al
1967).
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RELATIONSHIP BETWEEN WATER
CONTENT AND SUCTION FOR
QUARTZ SAND, 0.50-0.25 mm
50
g/cm
SUCTION
Figure 30. Soil-water characteristic curve/ showing hysteresis. ABC =
drying, CDA = wetting (after Day et al., 1967).
SPECIFIC SURFACE. The cation exchange capacity and specific surface
together govern the sorption characteristics of a soil. Unfortunately, the
mechanisms for adsorptions directly onto the surface of soil colloids are
imperfectly understood.
Mortland and Kemper (1965) discuss the principles of adsorption, relat-
ing to the specific surface of clays. In addition, a method for determining
specific surface based on sorption of ethylene glycol is presented. Specific
surface determinations are not routinely done and require a specific cost
quote.
In addition to the chemical analyses, further soil testing can include a
clay mineral identification that costs about $30 per sample. A simple min-
eral identification costs about $5 while a mineral separation and identifica-
tion can cost $25. A trace element determination such as zinc, manganese,
iron, or copper costs about $5.
The costs of soil-water chemical tests are approximately the same as the
costs of water sampling tests.
The range of tests that are performed in a hydrologic laboratory is var-
ied and usually quite unfamiliar to the field technician. For this reason an
example test schedule and cost quote is provided in Table 12.
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TABLE 12. HYDROLOGIC LABORATORY TESTS AND COST SCHEDULE,
SEPTEMBER 1974
Hydrologic loborotory tests Soil onalyses coifs (S)
Dry Unit Weight 6.00
Electrical Resistivity 20.00
Formation Factor (includes determination of conductivity of
interstitial water) 25.00
Hydraulic Conductivity
Saturation flow, undisturbed samples in standard cylinders at
effective stresses f90 psi; tested with formation water
Vertical flow 30.00
Horizontal flow 35.00
Nonstandard undisturbed samples, vertical or horizontal ffow 40.00
Saturated flow, undisturbed samples at simulated overburden
loads to 5000 psi and pore pressures to 3000 psi, vertical
or horizontal flow; tested with formation water 40.00
Unsafuroted flow, undisturbed samples (determination of
unsaturated hydraulic conductivity as a function of moisture
content over a range of negative heads to —2 atmospheres) 75.00
Moisture Content (as received) 6.00
Moisture-Tension Curve (water content as a function of negative
head, by the pressure-plate method) 40.00
Particle-Size Analysis
Complete (gravel through clay sizes) 25.00
Complete, if <25-gram sample available 40.00
Sand and gravel sizes only 10.00
Cloy sizes only (centrifuge method) 20.00
Permeability; single-phase flow of gas or liquid other than water;
undisturbed samples 40.00
Pore-Water Extraction — centrifuge, immiscible displacement, or
high-pressure (20,000 psi) squeeze methods 40.00
Porosity and "Specific Yield"
Total porosity (gravimetric method: includes granular specific
gravity and dry unit weight) 12.00
Pore-size distribution curve—cohesive samples
Mercury injection method: includes simulated moisture-
tension curve, approximate "specific yield, " effective
porosity at 2000 psi Hg pressure, total porosity, specific
gravity, dry unit weight 35.00
Pore-size distribution curve — friable samples
Moisture-tension method, see above: includes "specific
yield, " effective porosity at 2 atmospheres moisture
tension, total porosity, specific gravity, dry unit weight 50.00
"Specific Yield" (not including porosity)
Direct determination, using moisture-tension curve 40.00
Indirect methods
Centrifuge moisture equivalent (suitable for sands only) 25.00
Mercury-injection method, cohesive samples only (injected
porosities at 30 to 50 psi typically correspond to the- ap-
proximate range of "specific yield" 20.00
Thermal Conductivity 25.00
Specific Gravity (grain density) 8.00
Sample preparation and equipment modification for above tests, if
required by unusual sample conditions or test requirements 8.00/hr.
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Unsaturated hydraulic conductivity may also be measured in the labora-
tory using, for example, the steady-state method of Klute (1965). Soil is
placed in a cell containing a porous plate and two tensiometers. After sat-
urating the soil, air pressure is applied, the discharge rate of water leaving
the soil is measured, and the tensiometers are read. The hydraulic conduc-
tivity at the equivalent negative pressure is calculated from Darcy's equation,
"With this method a curve may be plotted depicting the relationship between
conductivity and negative pressure head. Using a soil-water characteristic
curve, the conductivity-pressure relationship may also be obtained.
Special equipment is required to conduct a hydraulic conductivity test in
the saturated state. The cost can vary with the effective stress required
from $30 to $50 for each test. These tests are also subject to large dis-
count rates. The expected cost for 100 tests is about $2400.
Chemical Analysis
SOLUBLE IONS, Soluble salts refer to the soil constituents of an inor-
ganic nature that are appreciably soluble in water. The following steps are
usually taken in an analysis for soluble salts: (1) preparing a sample by
bringing the soil-water content to some prescribed value; (2) extracting the
sample; and (3) measuring or analyzing the salt content of the extract.
The soil-water content at which the salt is extracted is a matter of con-
cern. The saturation extract, for example, is a technique used by agricul-
turists to relate soluble salts to field moisture range. A problem with dilut-
ing the sample, as done by the saturation extract, is that while the concen-
tration of some ions decreases on dilution, the concentration of others may
increase (Reitemeier, 1946). For example, as water is added to the soil,
precipitated calcium carbonate or gypsum may gradually dissolve, releas-
ing calcium and possibly magnesium ions into solution. Concurrently, the
additional concentrations of calcium and magnesium may displace sodium on
the exchange complex, thereby increasing the sodium level in the soil solu-
tion. Overall, calcium, magnesium, and sodium may increase in the soil
solution. In contrast, chloride and nitrate may decrease in concentration
because of dilution and negative adsorption. Reitemeier (1946) recommended
that for arid land soils, dissolved ions should be determined at or near the
water content at which the results are to be applied. Consequently, the soil
solutes of samples from deeper horizons of the vadose zone should be ex-
tracted at the prevailing soil-water pressure.
Pressure membrane apparatus may be used to extract soil solution sam-
ples in the dry range (Richards, 1954). Thus, if a soil-water characteristic
is available for the sample, together with gravimetric water content data,
the equivalent soil-water pressure can be determined. This Pressure is
then applied to the soil sample in the membrane. A problem wxth this tech-
nique is that solution is extracted from the larger pores which may not have
111
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the same chemical composition as that in the smaller interstices (Rhoades
and Bernstein, 1971).
A soil moisture extractor that uses the pressure membrane technique
costs about $400. These units, however, require a compressor that costs
about $650 and an independent pressure control manifold that costs from
$400 to $800 depending upon the number of outlets required.
For surface soils other factors should be examined in the determination
of soluble salts. For irrigated soils or land disposal operations subject to
wetting and drying, the water content of soils may range over large values
because of evaporation, so that conversion to the field water content value
may not be meaningful (Pratt, 1972). In this case, the saturation extract
technique is recommended (Rhoades and Bernstein, 1971), Water content by
this method represents about twice that at field capacity; therefore, the salt
content extracted from the saturated sample is about one-half the concen-
tration at field capacity. Bower and Wilcox (1965) explain in detail the pro-
cedure to obtain a saturated extract.
If detailed information is required on specific ionic constituents, chemi-
cal analyses using procedures presented in "Methods of Soil Analysis"
(Black, 1969) may be used. The principal ions of importance in most soil
studies are: calcium JCa++), magnesium (Mg++), potassium (K+), sodium
(Na+), carbonate (CO^), bicarbonate (HCOJ), sulfate (SO|), chloride (Cl~),
and boron, as well as the nitrogen series of ions. For soluble ions, the
procedures given in the water analyses section are applicable.
The cost of an electrical conductivity test on a soil sample is about $5 to
$6. The cost of conducting 10, 100, and 1000 tests is about $60, $500, and
$4000, respectively. The cost of determining soluble cations such as so-
dium, potassium, calcium, and magnesium, is about $3 for each chemical
parameter tested. To obtain the pH of soil a saturation extract costs about
$2 to $3.
CATION EXCHANGE CAPACITY. Methods for determining the sum of
individual exchangeable ions of a sample are given in Black (1969). This
sum is equal to the cation exchange capacity (CEC). Alternatively, the
CEC may be obtained directly using methods detailed by Chapman (1965).
Briefly, the exchangeable cations in a soil sample are replaced by either
ammonium acetate or sodium acetate, and the amounts of ammonium and
sodium ions adsorbed are determined. A problem may develop with the use
of ammonium ions because this ion becomes strongly adsorbed on some
clays. Cation exchange capacity is expressed as milliequivalents (meq) per
100 grams of sample.
The cost of determining the total cation exchange capacity is about $11.
The cost of determining the sodium, potassium, magnesium, and calcium
112
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exchangeable cations is about $12. The cost of conducting a base exchange
analysis which includes pH of saturated soil paste; electrical conductivity;
boron in soil extract; total cation exchange capacity; exchangeable percent
of exchange capacity for calcium, magnesium, potassium and sodium; lime-
stone content; calcium requirement; nitrates; bicarbonate exchangeable phos-
phorous; and exchangeable potassium; is about $20 per sample.
WATER
In addition to water sampling techniques and field determinations, the
sample containers, preservation technique, and method of analysis are key
factors in monitoring groundwater quality. The U.S. Environmental Protec-
tion Agency has published Manual of Methods for Chemical Analysis of Water
and Wastes (1974a) and Methods for Organic Pesticides in Water and Waste-
water (1971). The U.S. Geological Survey has published Methods of Collec-
tion and Analysis of Water Samples (Rainwater and Thatcher, I960) and is
currently updating and expanding this coverage through its series on Tech-
niques of Water Resources Investigations, Book 5, Laboratory Analysis
(Barnett and Mallory, 1971; U.S. Geological Survey, 1973).
The American Public Health Association (1971) has published the 13th
Edition of Standard Methods for the Examination of Water and Wastewater.
The major portions treating groundwater pollution monitoring are: Part
100 — "Physical and Chemical Examination of Natural and Treated Waters
in the Absence of Gross Pollution"; Part 200 - "Physical, Chemical, and
Bioassay Examination of Polluted Waters, Wastewaters, Effluents, Bottom
Sediments, and Sludges"; Part 300 — "Examination of Water and Wastewater
for Radioactivity"; and Part 400 — "Bacteriological Examination of Water
to Determine its Sanitary Quality".
Water testing laboratories can be found at Federal, State, county, and
municipal levels. Universities and private companies also provide analysis
capabilities. The cost of each analysis varies greatly with the degree of
automation, the number and kinds of tests required, and the accuracy of the
tests. The Corps of Engineers, the EPA, and other agencies require a cer-
tain sensitivity for the tests performed. The costs increase with the sensi-
tivity of the analysis. The costs presented in this section for water-quality
analysis represent an average cost for commercial laboratory services.
The costs do not include a sample preparation fee, which can vary from $3
to $25. Most commercial laboratories allow a 10 percent discount for in-
voices over $500 per month and a 20 percent discount for invoices of $1000
per month or more. In laboratory selection, factors such as location rela-
tive to the sampling area, time to complete analyses, and quality assurance
programs must be considered. In cost of analysis determinations, special
considerations should be given for group rates such as the following October
1974 values:
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Major Inorganic Chemicals
Group Rate $12
Calcium
Magnesium
Sodium
Potassium
Carbonate
Bicarbonate
Sulfate
Chloride
Nitrate
Total dissolved
solids
PH
Electrical conductivity
Drinking Water Trace Elements
Group Rate $50
Iron
Manganese
Arsenic
Barium
Cadmium
Hexavalent
chromium
Copper
Cyanide
Lead
Selenium
Silver
Zinc
Other Inorganic Chemicals
Group Rate $40
Silica
Boron
Fluoride
Nitrogen forms
Phosphorous forms
Hardness
Other Trace Elements
Vanadium
Molybdenum
Bromide
Iodide
Nickel
Group Rate $55
Aluminum
Cobalt
Lithium
Sulfide
Beryllium
Gases
Group Rate $30
Methane Carbon dioxide
Hydrogen sulfide Dissolved oxygen
Residual chlorine
Alopin
Chlordane
DDD
DDE
DDT
Insecticides
Group Rate $32
Dieldrin
Endrin
Heptachlor
Heptachlor Epoxide
Lindane
Toxaphene
Herbicides
Group Rate $45
2,4-D 2,4,5-T
Silvex
Radio chemical
Group Rate $100
Gross Alpha, Beta
dissolved and suspended
Radium-226 by Radon
Uranium Fluorometric
Determinations
The major constituents of water with respect to groundwater pollution
may be grouped into the following physical, inorganic chemical, organic
chemical, bacteriological, and radiological classifications:
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Physical
Temperature Odor
Density Turbidity
Color
Inorganic Chemical
Major constituents Trace elements
Other constituents Gases
Organical Chemical
Carbon Nitrogen
Biochemical oxygen Chemical oxygen demand
demand Phenolic materials
Methylene blue active Insecticides and herbicides
substances
Bacteriological
Coliform group Pathogenic microorganisms
Enteric viruses
Radiological
Gross alpha activity Strontium
Gross beta activity Radium
Tritium
Significant removals of the organic chemical, bacteriological, and radiologi-
cal constituents of percolated wastes ordinarily occur in the topsoil and va-
dose zone.
Physical
Measurements of water temperature and notes concerning odor are often
made at the sampling point. Density and turbidity determinations are Appli-
cable only in special situations. Density is important in the case of disposal
of fluids of high density compared to native groundwater, and turbidity is
important in well disposal or injection programs.
The cost of a density determination is about $5, and the cost of a tur-
bidity test is about $6. The cost of odor and color determinations are about
$1 to $5, respectively.
Inorganic Chemical
The primary divisions of inorganic chemical constituents with respect to
groundwater pollution are the following:
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1. Major — the major constituents of groundwater
2. Other — other common constituents of importance in water
use and waste disposal
3. Drinking Water Trace — trace constituents of concern for
drinking water quality
4. Other Trace — trace constituents of concern in waste disposal
5. Gases — common gases in groundwater and in, or generated
by, wastes.
The constituents within these divisions are:
Major
Calcium Sulfate
Magnesium Chloride
Sodium Nitrate
Potassium Total dissolved solids
Carbonate pH
Bicarbonate Electrical conductivity
Other
Silica Nitrogen forms
Boron Phosphorus forms
Fluoride Hardness
Drinking Water Trace
Iron Copper
Manganese Cyanide
Arsenic Lead
Barium Selenium
Cadmium Silver
Hexavalent chromium Zinc
Mercury
Other Trace
Vanadium Aluminum
Molybdenum Cobalt
Bromide Lithium
Iodide Sulfide
Nickel Beryllium
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Gases
Methane Carbon dioxide
Hydrogen sulfide Dissolved oxygen
Residual chlorine
The procedures for sample collection, treatment, and analytical determi-
nation vary widely from wastewaters and effluents to relatively unpolluted-or
natural ground-waters. This basic difference is recognized in APHA's Stand-
ard Methods (1971), wherein a major subdivision occurs between natural
waters and polluted waters. These differences arise because of factors such
as interference effects and biologic activity. In general, wastewaters, par-
ticularly those of industrial origin, may often require specialized sample
collection and analytical procedures.
CONTAINERS. Factors that are pertinent in selecting containers for col-
lecting and storing water samples are resistance to solution and breakage,
efficiency of closure, size, shape, weight, availability, and cost. Hard
rubber, polyethylene, teflon, and other types of plastics, and some types
of borosilicate glass are suitable based on experience within the U.S. Geo-
logical Survey and other agencies. Glass bottles may be a problem for anal-
ysis of boron, silica, sodium, and hardness. For dissolved oxygen determi-
nations, only glass containers should be used. For silica determinations,
only plastic containers should be used.
Before use, all new bottles should be thoroughly cleansed, filled with
water, and allowed to soak several days. The soaking removes much of the
water-soluble material from the container surface. The source of the sam-
ple and conditions under which it was collected should be recorded imme-
diately after collection. In the case of wells, this should include pumping
rate, duration of pumping if known, water level, temperature of water, and
electrical conductivity. Samples from wells near pollution sources should
be accompanied by a description of local conditions, such as "percolation
pond empty. "
Narrow-mouth 250-ml polyethylene bottles cost about 30 to 40 cents each.
The cost of a comparable size glass bottle is about 20 to 30 cents. If the
bottles are purchased by the case, the discount rate is about 10 percent for
1 to 4 cases, 15 percent for 5 to 19 cases, and 20 percent for 20 or more
cases. Shipping sleeves for use with plastic bottles cost about $18 per 100
sleeves. Glass mailers cost about $35 for a carton of 75.
PRESERVATION OF WATER AND WASTE SAMPLES. EPA's Manual of
Methods fnr Chemical Analysis of Water and Wastes {U.S. EPA 19?4a) is
—-—; - -rtrtnifnrinff water and wastes in compliance with the
a basac "^""^'"^"^ Pollution Control Act Amendments of
requirements of the Federal water ±-oj.j.unui
1972. Included is a detailed discussion of sample preservafcon techmques.
117
-------
Preservation techniques can only retard the chemical and biological
changes that inevitably continue after the sample is taken in the field. Cer-
tain changes occur in the chemical structure of the constituents that are a
function of physical conditions. Metal cations may precipitate as hydroxides
or form complexes with other constituents, cations or anions may change
valence states under certain reducing or oxidizing conditions, and other con-
stituents may dissolve or volatilize with the passage of time. Metal cations
may also adsorb onto surfaces (glass, plastic, quartz, etc. ). Biological
changes taking place in a sample may change the valence of an element.
Soluble constituents may be converted to organically bound materials, or
cellular material may be released into solution.
Methods of preservation are relatively limited and are intended generally
to (!) retard biological action, (2) retard hydrolysis of chemical compounds
and complexes, and (3) reduce volatility of constituents. Preservation meth-
ods are generally limited to pH control, chemical addition, refrigeration,
and freezing. Refrigeration at temperatures near freezing or below is the
best preservation technique available, but it is not applicable to all types of
samples. The preservative measures recommended by the EPA (U.S. EPA,
1974a) are given in Table 13. When the dissolved concentration is to be de-
termined, the sample is filtered immediately after collection through a 0.45-
micron membrane filter and the filtrate is analyzed by the specified proce-
dure. Specific techniques for monitoring wastewater are given in the EPA's
Handbook for Monitoring Industrial Wastewater (U.S. EPA, 1973), and
American Public Health Association (1971), Part 200.
SAMPLE COLLECTION AND TREATMENT FOR GROUNDWATERS.
Brown et al. (1970) present data that are applicable to groundwater sampling.
An analysis will more closely represent the water at the time of collection if
separate samples are taken for determination of certain groups of ions. The
test procedure should determine whether a given analytical determination
should be performed on a settled, filtered, or well-mixed sample.
On-site determinations are mandatory for temperature, pH, dissolved
oxygen, and specific conductance. For laboratory determinations the fol-
lowing procedures are recommended by Brown et al. :
One sample of about 1 liter volume should be collected and imme-
diately filtered through a 0.45-micron membrane filter. The fol-
lowing determinations are made on the filtrate: boron, chloride,
fluoride, lithium, nitrate, nitrite, dissolved solids, dissolved
phosphorous, potassium, selenium, silica, sodium, and sulfate.
A second sample of about 2 liters should be collected and imme-
diately filtered through a 0.45-micron membrane filter. The
filtrate should be acidified with double-distilled, reagent-grade
nitric acid to a pH of 3 or less. The following determinations
118
-------
TABLE 13. RECOMMENDED SAMPLING AND PRESERVATION TECHNIQUES
FOR INORGANIC CHEMICAL DETERMINATIONS
Measurement [Volume (ml)
Arsenic 1 100
Bromide TOO
Chloride 1 50
Cyanide
Dissolved oxygen
Fluoride
Hardness
Iodide
Metals, dissolved
Metals, total
Mercury, dissolved
Mercury, total
Ammonia nitrogen
Nitrate nitrogen
Nitrite nitrogen
pH
Dissolved orthophos-
phate
Hydro! yzable phosphorus
Total phosphorus
500
300
300
100
100
200
100
!00
100
400
100
50
25
50
50
50
——————
Preservative
HNO3 to PH<2
Cool to 4°C
None required
Cool to 4°C
NaOH to pH 12
On-site determ.
Cool to 4°C
Cool to 4°C
Cool to 4°C
Filter on site
HNO3 topH<2
HNO3 to PH<2
Filter
HNO3 to PH<2
HNO3 to pH<2
Cool to 4°C
H2SO4 to pH<2
Cool to 4°C
H2SO4topH<2
Cool to 4°C
Cool to 4°C
On-site determ.
Filter on site
Cool to 4°C
Cool to 4°C
HnSO, to pH<2
24
Cool to4°C
Holding time
6 months
24 hours
7 days
24 hours
none
7 days
'7 days
24 hours
6 months
6 months
38 days (glass)
13 days (hard
plastic)
38 days (glass)
13 days (hard
plastic)
24 hours
24 hours
24 hours
6 hours
24 hours
24 hours
24 hours
(continued)
119
-------
TABLE 13 (continued)
Measurement-
Total dissolved
phosphorus
Filterable residue
Non-filterable residue
Total residue
Volatile residue
Selenium
Silica
Specific conductance
Sulfate
Sulfide
Sulfite
Volume (ml)
50
100
100
100
100
50
50
100
50
50
50
Preservative
Filter on site
Cool to 4°C
Cool to 4°C
Cool to4°C
Cool to 4°C
Cool to 4°C
HNO3 to pH<2
Cool to 4°C
Cool to 4°C
Cool to4°C
2 ml zinc acetate
Coo! to 4°C
Holding time
24 hours
7 days
7 days
7 days
7 days
6 months
7 days
24 hours
7 days
24 hours
24 hours
are made on the acidified filtrate; aluminum, arsenic, barium,
cadmium, calcium, chromium, cobalt, copper, iron, lead, lith-
ium, magnesium, manganese, molybdenum, nickel, potassium,
silver, sodium, strontium, vanadium, and zinc.
A third sample of about 1 liter should be collected and not filtered.
The following determinations may be made on this sample: am-
monia, organic nitrogen, chemical oxygen demand, cyanide, phos-
phorus, and turbidity.
Collection of additional samples and individual treatment may
be necessary for the nitrogen forms, cyanide, dissolved oxygen,
organic phosphorus, and sulfide.
SELECTION OF SPECIFIC DETERMINATIONS. The major cations and
anions should usually be determined in a water analysis, along with pH,
electrical conductivity, and total dissolved solids at 25°C. The major cat-
ions are Ca++, Mg++, Na+, and K+. In areas of polluted groundwater, am-
monium ion (NHt) may also be a significant cation. The major anions are
CO|, HCO^, Cl", SO|, and possibly NOj. Another significant anion may be
fluoride (F~). If the major constituents are determined, then the cation-
anion balance in equivalents can be checked. Similarly, the calculated total
dissolved solids can be compared with the residue. Silicate (SiO?) is an un-
dissociated form found in many groundwaters that should be determined
prior to calculation of total dissolved solids. The electrical conductivity
120
-------
at 25 °C can be compared to the total dissolved solids. The chemical analy-
sis can thus be checked several ways for internal consistency. The deter-
mination of major ions also permits interpretation by the use of trilinear
diagrams as well as the application of physical chemistry to groundwater
quality problems. The cost of analyses of inorganic chemicals in water is
given in Table 14. Although costs for dissolved chemicals are of primary
interest in groundwater studies, the cost of analysis which includes sus-
pended chemicals (total) are also given for surface waste-water studies.
Specific uses dictate the items of interest in water supply monitoring.
In agricultural areas where irrigation water is pumped from groundwater,
boron is analyzed and sodium adsorption ratio and residual bicarbonate are
calculated from the analysis of major constituents. In municipal areas using
groundwater, fluoride, iron, and manganese, as well as selected trace me-
tals such as arsenic, are analyzed. Hardness is calculated. Many trace
metals occur in insignificant concentrations in groundwater and with careful
judgment can often be eliminated from the chemical analysis.
In monitoring near waste disposal sites, consideration should be given to
constituents in the wastewater or percolate. Judgment based on soil chem-
istry and geochemistry can then be used to predict what constituents should
be analyzed. Other forms of specific constituents may be important, such
as hydrogen sulfide (f^S) and nitrite ion (NO^)- Past groundwater quality
studies have often reflected a lack of sampling for constituents other than
those of interest. It should be remembered that other constituents can often
yield significant data. Also, no ion moves by itself; that is, a percolating
nitrate ion must be accompanied by some cation, for example. Similarly,
thermodynamic or kinetic studies of groundwater quality require knowledge
of concentrations of the major constituents, as well as pH and oxidation po-
tential. However, in some cases judgment can be used to effectively utilize
partial chemical analyses. In salt-balance studies in irrigated areas, for
example, electrical conductivity alone sometimes can be used quite
effectively.
Organic Chemical
Goerlitz and Brown (1972) discuss methods for analysis of organic sub-
stances in water. Before a proper sampling program for organic substances
can be initiated, the nature of the organic compounds must be considered.
Organic matter in a body of water may be distributed on the surface, in sus-
pension, adsorbed on suspended sediment, in bed materials, and in solution.
Because of this wide and generally unpredictable distribution of organic ma-
terial in a body of surface water, the collection of representative samples
requires care and often the use of specialized sampling equipment. In most
cases, samples for organic analysis are best collected with the same equip-
ment and technique used for the collection of samples for suspended-
sediment measurements (Guy and Norman, 1970). , Most surface water
121
-------
TABLE 14. COSTS OF INORGANIC CHEMICAL DETERMINATIONS FOR
GROUNDWATER POLLUTION,a OCTOBER 1974
Major parameters
(mg/A)
Calcium dissolved
Calcium total
Magnesium dissolved
Magnesium total
Sodium dissolved
Sodium total
Potassium dissolved
Potassium total
Carbonate
Bicarbonate
Sulfate
Chloride
Nitrate
Dissolved solids, fixed
Dissolved solids, total
Dissolved sol ids, volatile
PH
Electrical conductivity
Others (mg/£)
Silica
Boron dissolved
Boron total
Fluoride dissolved
Fluoride total
Nitrogen dissolved KJD
Nitrogen NH4 as N total
Nitrogen NH^ as N dissolved
Nitrogen NO? as N dissolved
Nitrogen NO2 as N total
Nitrogen NO3 as N dissolved
NO2 + NOs as N dissolved
NO2 + NO3 as N total
Nitrogen total KJD as N
Phosphate dissolved Ortho as PO4
Phosphate Ortho dissolved as P
Phosphate Ortho total as P
Phosphate dissolved as P
Phosphate total HYD as P
Water analysis cost ($)
o.x
5
10
5
5
5
5
5
8
10
5
5
5
2
5
1
5
3
3
5
10
15
10
15
10
5
5
5
5
5
5
5
10
3
3
3
5
10
o.ox
12
10
7
10
5
10
17
20
8
8
11
5
5
o.oox
20
10
15
15
20
(continued)
122
-------
TABLE 14 (continued)
Others (mg/je )
1 Phosphate total as P
Hardness/ calcium
Hardness, carbonate
Hardness, magnesium
Hardness, non-carbonate
Hardness, total
Drinking water trace (mg/fc)
Iron
Iron dissolved
Iron +2 and +3
Iron ferrous
Iron total
Manganese
Manganese dissolved
Manganese total
Arsenic dissolved
Arsenic total
Boron dissolved
Boron total
Cadmium dissolved
Cadmium total
Chromium dissolved
Chromium hexavalent
Chromium total
Copper dissolved
Copper total
Cyanide
Lead dissolved
Lead total
Selenium dissolved
Selenium total
Silver dissolved
Silver total
Lime dissolved
Lime total
Mercury dissolved
Mercury total
Water analysis cost ($)
o.x
10
3
3
3
1
3
5
5
5
5
10
5
5
5
10
15
10
10
10
10
8
8
8
5
5
10
10
13
15
15
10
10
5
10
10
10
o.ox
12
7
17
12
12
9
9
7
15
14
17
12
12
12
o.oox
15
10
20
15
15
10
10
10
15
20
15
15
1 C
15
(continued)
123
-------
TABLE 14 (continued)
Other traces (mg/A)
Vanadium dissolved
Vanadium total
Molybdenum dissolved
Molybdenum total
Bromine
Iodine
Nickel dissolved
Nickel total
Aluminum dissolved
Aluminum total
Cobalt dissolved
Cobalt total
Lithium dissolved
Lithium total
Sulfide dissolved
Sulfide total
Beryllium dissolved
Beryllium total
Gases (mg/jfc)
Hydrogen sulfide
Carbon dioxide
Methane
Dissolved oxygen
Residual chlorine
Water analysis cost ($)
o.x
10
10
10
10
10
10
10
10
10
10
10
10
12
12
5
5
10
10
5
5
5
5
8
o.ox
15
12
15
15
12
15
12
14
12
7
o.oox
20
15
15
20
15
15
15
Significance in reporting data is represented by o.x, o.ox, and o.oox. The
sensitivity provided is represented by:
o.x column with sensitivity down to 0. 1 milligram per liter (mg/t)
(0. 1 mg/JL = 0. 1 ppm = 100 jU/4),
o.ox column with sensitivity down to 0.01 mg/j£
(lOjL/A = 0.01 ppm) and
o.oox column with sensitivity down to 0.001 mg/A
124
-------
investigations are not concerned with surface or bottom material, but rather
with the body of the water. However, in groundwater pollution monitoring
where percolated water is the prime interest, the bottom material may be
of prime importance. The U.S. Environmental Protection Agency (1971)
also presents data on organic pesticides sampling analysis. The cost of
analysis of organic chemicals in groundwater is given in Table 15.
TABLE 15. COSTS OF ORGANIC CHEMICAL DETERMINATIONS FOR
GROUNDWATER POLLUTION,a OCTOBER 1974
Parameter (ma/&i
Carbon in suspension
Carbon dissolved
Carbon total
Biochemical oxygen demand
Immediate oxygen demand
Chemical oxygen demand
Methylene blue active substances
Nitrogen
Phenolic material
Pesticides {insecticides and herbicides),
each
Water analysis cost ($)
o.x
15
15
15
20
10
10
10
10
15
40
o.ox
25
15
11
17
42
o.oox
20
45
Significance in reporting data is represented by o.x, o.ox, and o.oox.
CONTAINERS. Organic substances tend to cling to sample containers
and special precautions are necessary. Glass bottles are the most accept-
able containers for collecting, transporting, and storing samples for organic
analysis. Glass appears to be inert relative to organic materials and can
withstand a rigorous cleaning procedure. Because organic materials are
so plentiful in the environment, it is extremely difficult to collect samples
free from extraneous contamination. Apparatus for containing samples
must be scrupulously clean. Boston round-glass bottles of 1-liter capacity
with sloping shoulders and narrow mouths are usually satisfactory. The
closure should be inert metal, lined with teflon.
All sample bottles must be cleaned prior to sample collection. The ac-
cepted procedure is to wash the bottles in hot detergent solution, rinse them
in warm tap water, then rinse them in dilute hydrochloric acid, and finally
rinse them in distilled water. The bottles are then put into an oven at 300«C
overnight. The teflon cap liners and metal closures are washed in deter-
gent. The cape are rinsed with distilled water and air dried. The liners
are rinsed in dilute hydrochloric acid, soaked in redistilled acetone for
several hours, and heated at 200'C overnight. When the heat treatments
125
-------
are completed, the bottles are capped with the closure and teflon liners.
The cost of glass bottles and mailers has been previously described.
SAMPLE PRESERVATION. Most water samples for organic analysis
must be protected from degradation. Icing is the most acceptable method
of preserving a sample. The U.S. Environmental Protection Agency (19?4a)
presents data for organic materials in water and wastes (Table 16). Goerlitz
and Brown (1972) also recommend preservation techniques for organic sub-
stances in water. The procedures are similar, with the following additions:
Chlorophylls
Herbicides
Insecticides
Refrigerate at 4°C
Acidify with concentrated t^SO^ at a rate of
2 ml per liter of sample and refrigerate at
4°C.
None required for chlorinated compounds.
TABLE 16. RECOMMENDED SAMPLING AND PRESERVATION TECHNIQUES
FOR ORGANIC CHEMICAL DETERMINATIONS
Measurement
Biological oxygen
demand
Chemical oxygen
demand
Methylene blue
active substances
(MBAS)
Nitrilotriacetic
acid (NTA)
OE 1 and grease
Organic carbon
Phenolics
Kjeldahl nitrogen
Volume (ml)
1000
50
250
50
1000
25
500
500
Preservative
Cool to 4°C
H9SO,, to pH < 2
£* *F
Cool to 4°C
Cool to 4°C
Cool to 4°C
H2SO4 to pH < 2
Cool to 4°C
H2SO4 to pH < 2
Cool to 4°C
H2SO4 to pH < 4
1.0 g/1 CuSO4
Cool to 4°C
H2SO4 to pH < 2
Holding time
6 hours
7 days
24 hours
24 hours
24 hours
24 hours
24 hours
24 hours
Source: U.S. EPA (1974a)
126
-------
Bacteriological
Coliform organisms have long been used as indicators of sewage pollu-
tion, although the group includes bacteria from diverse natural sources.
For example, members of the coliform group may come from soil, water,
and vegetation, as well as from feces. However, if a water sample contains
an appreciable coliform. count, the source of the sample is considered to
have a disease-producing potential in the absence of contrary information.
Standards for drinking-water quality provide criteria as to the number of
coliform organisms allowable per 100 ml of finished water.
The standard test for presence of members of the coliform group may be
carried out by the membrane filter technique or by the multiple-tube fer-
mentation technique described by American Public Health Association (1971).
Fecal coliforms are that fraction of the coliform group that is present in
the gut or the feces of warmblooded animals. They are capable of producing
gas from lactose in a suitable culture medium at 44. 5°C. Bacterial organ-
isms from other sources generally cannot produce gas in this manner
(American Public Health Association, 1971). The presence of fecal coli-
form organisms may indicate recent and possibly dangerous contamination.
The presence of other coliform organisms suggests less recent contamina-
tion or contributions from sources of nonfecal origin.
Fecal streptococci are being used increasingly as indicators of signifi-
cant contamination of water because the normal habitat of these organisms
is the intestine of man and animals. Fecal streptococcal data verify fecal
pollution and may provide additional information concerning the recency and
probable origin of pollution. In combination with data on coliform bacteria,
fecal streptococci are used in sanitary evaluation as a supplement to fecal
coliforms where more precise determination of sources of contamination is
necessary.
Samples for bacteriologic examination must be collected in bottles that
have been carefully cleansed and autoclaved for 20 minutes at 212'C at 15
psi. Sterilized milk dilution bottles are ideal sample containers. When
the sample is collected, ample air space must be left in the bottle to facili-
tate mixing of the sample by shaking. Care must be taken to avoid contam-
ination of the sample and sample bottle at the time of collection and in the
period prior to analysis.
As soon as possible after collection, preferably within 1 hour and not
more than 6 hours, the sample should be filtered and the membrane filter
placed on the growth medium. Samples must be kept cool during the time
between collection and filtration. If filtration is delayed, the sample should
be iced or refrigerated but not frozen.
127
-------
The costs of bacterial analysis for groundwater pollution are given in
Table 17.
TABLE 17. COSTS OF BACTERIAL ANALYSIS FOR GROUNDWATER
POLLUTION, OCTOBER 1974
Bacteria
Standard plate count
Coliform, fecal/100 pi
Coliform, total/100 pi
Enterococcus
Klebsiella - aerobacteria
Iron bacteria
Proteus
Pseudomonas aerceginosa
Staphylococcus
Salmonella
Sulfate reducing organisms
Streptococci, fecal
Streptococci, total
Bacteriological identification
(90 percent complete)
Cost ($)
7
10
10
10
10
9
10
10
10
9
10
10
10
35
Radiological
CONTAINERS. Radioactive elements are often measured in the sub-
microgram range and can therefore be influenced by any background or
residual material that may be in the sample container. Similarly, a radio -
nuclide may be largely or wholly adsorbed on the surface of suspended par-
ticles. Glass containers tend to have a higher background radioactivity
than polyethylene bottles. For most radiochemical analyses (excluding
tritium), a polyethylene bottle is recommended.
PRESERVATION. Radiochemical sample containers normally are
washed with nitric acid and allowed to fume for several hours before use.
After the sample has been taken and separated into suspended and dissolved
fractions, a preservative can be added. The kind of preservative is highly
dependent upon the kind of radiochemical to be analyzed. Formaldehyde or
ethyl alcohol has been suggested as a preservative for highly perishable
samples. Routinely in groundwater, however, hydrochloric and nitric acids
are used as general preservatives. Preservatives and reagents should be
tested for radioactivity prior to their use.
The costs of radiochemical analyses for groundwater pollution are given
in Table 18.
128
-------
TABLE 18. COSTS OF RADIOCHEMICAL ANALYSIS IN GROUND-
WATER POLLUTION, OCTOBER 1974
Radiochemical
Carbon-14 age date
Carbon 13/12 ratio
Cesium-137 diss.
Gamma-scan
Gross alpha and beta diss.
Gross alpha and beta susp-
Lead-210
Radium-226, by Radon
Strontium-90, diss.
Thorium-BTM colorimetric
Tritium, liq. scintillation
Uranium, diss.dir. fluorometric
Uranium, diss.extr. fluorometric
Cost ($)
160
55
22
70
25
25
25
30
35
25
20
18
26
129
-------
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APPENDIX
METRIC CONVERSION TABLE*
Non-Metric Unit
inch (in)
feet (ft)
miles
acres
grains
gallons (gal)
pounds per square inch (psi)
parts per million (ppm)
gallons per minute (gpm)
gallons per hour (gph)
Multiply by
25.4
0.3048
1.60934
0.404686
64.79891
3.7854
0.0680460
1
3.7854
3.7854
Metric Unit
millimeters (mm)
meters (m)
kilometers (km)
hectares (ha)
milligrams (mg)
liters (1)
atmospheres (atm)
milligrams per liter
(nag A)
liters (1) per minute
liters (1) per hour
# English units were used in this report because the data obtained were not
available in metric units.
140
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1 EPA°-R60N0/4 - 7 6 - 0 2 3
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
MONITORING GROUNDWATER QUALITY: METHODS AND
COSTS
5. REPORT DATE
May 1976
6. PERFORMING ORGANIZATION CODE
7'L.UTG°.R(SEverett, K. D. Schmidt, R. M. Tinlin,
and D. K. Todd
8. PERFORMING ORGANIZATION REPORT NO.
GE75TMP-69
9 PERFORMING ORGANIZATION NAME AND ADDRESS
General Electric Company-TEMPO
Center for Advanced Studies
p. 0. Drawer QQ
Santa Barbara, California 93102
10. PROGRAM ELEMENT
1HA326
NO.
11. CONTRACT/GRANT NO.
69-01-0759
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Monitoring & Support Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Las Vegas, Nevada 89114
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
3PA-ORD Office of Monitor
Lng and Technical Support
15. SUPPLEMENTARY NOTES
This is one of 5 final reports in a series of 11 documents prepared on
monitoring groundwater quality.
16. ABSTRACT
This report describes various groundwater monitoring methods and
provides a generalized cost breakdown of the major economic factors
for each method. All possible groundwater-related measuring techniques
applicable at the land surface, topsoil, vadose zone and zone of
saturation are presented. Each monitoring method is described,
referenced and illustrated. Estimates of itemized capital and opera-
tional costs are presented. The material is presented for in-depth
reference purposes without recommendation for least-cost techniques,
a least-cost mix of groundwater monitoring approaches, or an optimal
information system.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Cost analysis
Ground water
Monitors
Water pollution
Water quality
Water resources
Water wells
Aquifer characteris-
tics
Aquifers
Water monitoring
methods
Groundwater monitorir
costs
08H
13B
14A
8. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (This Report)'
UNCLASSIFIED
20. SECURITY CLASS (Thispage)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
6GPO 691-221-1976
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