United States Office of Ground Water EPA/816-R-99-014b
Environmental and Drinking Water (4601) September 1999
Protection Agency
The Class V Underground Injection
control Study
Volume 2
Agricultural Drainage Wells
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Table of Contents
Page
1. Summary 1
2. Introduction 4
3. Prevalence of Wells 6
3.1 States Where Relatively Large Numbers of ADWs Are
Known to Exist 10
3.2 States Where No or Few ADWs Are Documented, But Where
ADWs May Exist in Greater Numbers 10
4. Wastewater Characteristics and Injection Practices 12
4.1 Injectate Characteristics 12
4.1.1 Inorganic Constituents 12
4.1.2 Biological Constituents 15
4.1.3 Organic Chemical Constituents 16
4.2 Well Characteristics 21
4.3 Operational Practices 27
4.3.1 Location 27
4.3.2 Type of ADW 27
4.3.3 Economic Condition of the Landowner 27
4.3.4 Proximity to Potential Sources of Contamination 28
5. Potential and Documented Damage to USDWs 29
5.1 Injectate Constituent Properties 29
5.2 Observed Impacts 30
5.2.1 Nitrate in Ground Water 30
5.2.2 Septic Tank Contamination 33
5.2.3 Other Contamination Incidents and Studies 34
6. Best Management Practices 35
6.1 Closure and Alternatives to Agricultural Drainage Wells 35
6.1.1 Alternative Drainage Outlets 36
6.1.2 Temporary Storage 37
6.1.3 Return to Natural Drainage State 37
6.2 Erosion and Sediment Control 37
6.2.1 Conservation Tillage 38
6.2.2 Filter Strips 38
September 30, 1999
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Table of Contents (cont'd) Page
6.2.3 Water and Sediment Control Basins 39
6.2.4 Crop Rotation 39
6.3 Fertility Management and Nutrient Management 39
6.4 Integrated Pest Management 40
6.5 Irrigation Management 41
6.6 Livestock Waste Management 41
6.7 Improvement of Surface Drainage 44
7. Current Regulatory Requirements 44
7.1 Federal Programs 44
7.1.1 SDWA 45
7.1.2 CWA 46
7.1.3 CZMA and CZARA 48
7.2 State and Local Programs 49
Attachment A: State and Local Program Descriptions 51
References 60
September 30, 1999
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AGRICULTURAL DRAINAGE WELLS
The U.S. Environmental Protection Agency (USEPA) conducted a study of Class V
underground injection wells to develop background information the Agency can use to evaluate the risk
that these wells pose to underground sources of drinking water (USDWs) and to determine whether
additional federal regulation is warranted. The final report for this study, which is called the Class V
Underground Injection Control (UIC) Study, consists of 23 volumes and five supporting appendices.
Volume 1 provides an overview of the study methods, the USEPA UIC Program, and general findings.
Volumes 2 through 23 present information summaries for each of the 23 categories of wells that were
studied (Volume 21 covers 2 well categories). This volume, which is Volume 2, covers Class V
agricultural drainage wells.
1. SUMMARY
Agricultural drainage wells (ADWs) are used in many places throughout the country to drain
excess surface and subsurface water from agricultural fields, including irrigation tailwaters and natural
drainage resulting from precipitation, snowmelt, floodwaters, etc. ADWs may also receive animal yard
runoff, feedlot runoff, dairy runoff, or runoff from any other agricultural operation. In some cases, these
fluids are released into ADWs in order to recharge aquifers that are used as sources of irrigation water.
The water that drains into ADWs may contain high levels of naturally occurring minerals or may
be contaminated with fertilizers, pesticides, or bacteria and other microorganisms. Available sampling
data show that the primary constituent in ADW injectate that is likely to exceed health-based standards
is nitrate. The data also indicate that boron, sulfate, coliforms, and certain pesticides (cyanazine,
atrazine, alachlor, aldicarb, carbofuran, 1,2-dichloropropane, and dibromochloropropane) in
agricultural drainage have exceeded primary, or health-based, drinking water maximum contaminant
levels (MCLs) or health advisory levels (HALs). Total dissolved solids (TDS) and chloride in some
ADWs also have been measured above secondary MCLs, which are designed to protect against
adverse aesthetic effects such as objectionable taste and odor.
Concerns about high concentrations of contaminants entering ADWs are compounded by the
recognition that the point of injection for many ADWs is within a permeable coarse-grained unit, karst,
or a fractured unit (some ADWs are in fact nothing more than improved sinkholes in areas with karst).
Such hydrogeologic settings usually allow contaminants to migrate readily without significant attenuation.
A number of studies and incidents have shown that ADWs have in fact contributed to or caused
ground water contamination. In particular, ten studies reviewed for this report document nitrate
contamination of ground water in agricultural areas. Six of these studies clearly link the nitrate
contamination to ADW use. For example, one study in north central Iowa between 1981 and 1983
found that areas with the highest density of ADWs also had the highest average concentrations of nitrate
in ground water samples (37 percent of the farm wells sampled in an area with a relatively large number
of ADWs had nitrate concentrations above the MCL). Four other studies, however, do not clearly
September 30, 1999 1
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distinguish nitrate contamination from ADWs versus more general sources of nonpoint source pollution
associated with agriculture. In addition to these nitrate studies, there are two known contamination
incidents in Iowa (in 1977 and 1997) involving direct discharges from septic tanks to ADWs. In one of
these incidents, the ADW was also contaminated by runoff from the field application of hog manure.
Other contamination incidents include ground water and drinking water contamination linked to 15
drainage wells in Mnidoka County, Idaho in 1979, and a community supply well in Dane, Wisconsin
being contaminated around 1988 by atrazine that likely drained into an improperly abandoned water
well that had been illegally modified to receive surface runoff from an agricultural area.
A further concern associated with ADWs is the potential for some wells to be vulnerable to
spills or illicit discharges. The close proximity of ADWs to large earthen lagoons for storing manure at
large-scale confined animal feeding operations is a particular issue that has been recognized for some
wells in Iowa; the growth of such operations nationwide may also make it an issue in other locations.
The two cases cited above involving septic tank discharges to ADWs in Iowa may also illustrate a
practice that is not uncommon in other states. Following one of those incidents, it was estimated that as
many as 30 percent of the rural septic tanks in one Iowa township may be directly connected to
ADWs. Separately, some ADWs may occasionally receive accidental releases of materials during
farming operations, such as spills of motor oils used in equipment or bulk releases of pesticides during
storage or handling. Moreover, if not carefully managed, the land application of manure in areas
drained by ADWs can cause contamination, as illustrated by one of the incidents reported in Iowa.
According to the state and USEPA Regional survey conducted for this study, there are at least
1,069 documented ADWs and more than 2,842 ADWs estimated to exist in the U.S. Although
believed to exist in at least 20 states, more than 95 percent of the documented wells are in just five
states: Idaho (303), Iowa (290), Ohio (>200), Texas (135), and Minnesota (92). In truth, there may
be thousands more ADWs than these results suggest, recognizing the significant uncertainties in the
current inventory. For example, it is likely that more ADWs exist than have been counted because (1)
there is often a lack of public records on such wells, (2) public officials are unable to document the
locations of ADWs in remote areas on private land without the cooperation of the landowner, (3) some
ADWs are hard to find or not even known to exist because they consist of tile drainage lines and
cisterns entirely below ground, and (4) ADWs have been grouped with storm water drainage wells in
some state inventories. Looking forward, the number of ADWs should decrease as the risk to USDWs
becomes known and ADWs that cause or threaten contamination are discovered and closed.
However, the known number of ADWs may actually increase as the existing wells are actively looked
for and discovered.
States with the majority of known ADWs are developing and implementing regulatory
programs to address these wells. Specifically:
• In Idaho, wells >18 feet deep are individually permitted, while shallower wells are permitted by
rule.
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• All ADW owners in Iowa are required to have applied for a permit by July 1, 1999. The only
exception to this is ADW owners who can demonstrate that their ADW will be closed prior to
December 31, 2001. New wells in Iowa are generally prohibited, although they may be
permitted under very strict conditions (these conditions are so stringent that new ADWs in
Iowa are unlikely to receive a permit).
• The regulations in Ohio authorize ADWs by rule as long as inventory information is submitted.
All existing ADWs in the state are considered out of compliance (not rule authorized) because
their owners or operators did not submit required inventory information by the applicable
deadline. Any new ADWs would be examined individually by the state and subjected to
conditions believed necessary to protect USDWs.
• All of the known ADWs in Texas received individual authorizations for construction of the
wells. Owners or operators of any new wells would have to submit basic information to the
state, which would either disapprove the well or authorize it subject to conditions deemed
necessary to protect USDWs.
• Minnesota rules, which became effective on July 15, 1974, prohibit injection or disposal of any
materials into a well. State staff, however, acknowledge that some ADWs continue to exist and
require them to close when they are found. The prohibition relates to wells that reach ground
water. Horizontal drain tiles are not included in the definition of a "well" in Minnesota.
The regulatory picture in other states with few or no ADWs in the current inventory is varied.
In particular, Georgia, North Carolina, and North Dakota have banned new ADWs and require
existing ADWs to close when they are found. Oregon, Washington, and Wisconsin also have a ban,
but recognize that some ADWs continue to exist. Most other states authorize ADWs by rule,
consistent with the existing federal UIC requirements.
These regulatory programs in the states are supplemented somewhat by non-regulatory
programs and guidance at the federal level. Namely, under the authority of the Clean Water Act, the
U.S. Department of Agriculture and USEPA released a draft Unified National Strategy for Animal
Feeding Operations on September 11, 1998. Once finalized, the goal of this strategy will be for
owners and operators of animal feeding operations to take actions to minimize surface and ground
water pollution from confinement facilities and land application of manure. In addition, under the
Coastal Zone Act Reauthorization Amendments, 29 coastal states are required to develop and
implement Coastal Nonpoint Pollution Control Programs addressing nonpoint pollution from agriculture
and other sources. Although these programs are aimed primarily toward surface water protection, they
also will benefit ground water by emphasizing contaminant source reduction and conservation measures
such as nutrient, integrated pest, and irrigation management. To support the development and
implementation of these programs, USEPA issued Guidance Specifying Management Measures for
Sources of Nonpoint Pollution in Coastal Waters. Much of this guidance is relevant to Class V
ADWs because it presents techniques for minimizing seepage to ground water.
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2. INTRODUCTION
Agricultural practices throughout the United States vary considerably by soil type, crops grown,
cultural practices, climate, and historical precedent. There is one attribute, however, that is the same all
over: crops need water to grow. Sometimes there is too much water and fields must be drained before
the crops can be planted (or harvested). This situation, of course, is highly dependent upon the type of
crop, some needing significantly more water (such as rice) and others needing less (such as corn).
Sometimes natural precipitation is insufficient and water must be added through irrigation. This situation
can vary from year to year and from region to region. When excess water is removed from a field it
needs to go somewhere. Often the water is discharged to surface streams or rivers, but water can also
be drained to the subsurface through the use of an ADW. An ADW helps to manage the water level in
the soil so crops can be grown (USEPA, 1987 and 1997). In some areas, ADWs may be used to
recharge an aquifer that provides irrigation water for crops. In other areas, ADWs are used for a
combination of purposes. For example, in Idaho "[they] are used primarily for draining snow melt and
storm water,... with only minor irrigation tail water components" (Slifka, 1997).
According to the existing UIC regulations in 40 CFR 146.5(e)(4), "drainage wells used to drain
surface fluid, primarily storm runoff, into a subsurface formation" are considered Class V injection
wells. This type of well includes ADWs.
It is important to define exactly what is and what is not considered an ADW for the purpose of
this study. ADWs are wells that receive fluids such as irrigation tailwaters or return flow, other field
drainage (i.e., resulting from precipitation, snowmelt, floodwaters, etc.), animal yard runoff, feedlot
runoff, or dairy runoff. As described in more detail in Section 4.2 below, ADWs are generally part of a
system consisting of a buried collection basin or cistern, one or more tile drainage lines buried a few feet
beneath the land surface to collect water and channel it to the cistern, and a drilled or dug well typically
located near low-lying areas of fields. The cistern collects drainage water that is released into the well.
Some ADWs are open at the land surface or have surface intakes, allowing surface runoff to enter the
well directly, either by design or as a result of poor repair. Others collect only subsurface drainage
(percolated water) by a network of tiles. Many ADW systems receive both surface runoff and
subsurface drainage.
In order to qualify as an ADW, a system must have a "well." As currently defined in the UIC
regulations (40 CFR 144.3), a "well means a bored, drilled or driven shaft, or a dug hole, whose depth
is greater than the largest surface dimension." Therefore, any hole that is deeper than it is wide qualifies
as a well. This includes relatively sophisticated designs in which holes are drilled and cased with metal
or plastic pipe. However, it also includes simple systems designed to drain fluids to the subsurface.
For example, an improved sinkhole, defined as a surface depression altered to direct fluids into the
opening (USEPA, 1987), qualifies as an injection well, as does an abandoned drinking water well that
has been adapted to convey fluids to the subsurface. If improved sinkholes or abandoned drinking
water wells accept surface and/or subsurface drainage from agricultural activities, they qualify as
ADWs.
September 30, 1999
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"Infiltration galleries" are also considered injection wells. These galleries consist of one or more
vertical pipes leading to a horizontal, perforated pipe laid within a trench, often backfilled with gravel or
some other permeable material. Such a design is commonly used to return treated ground water at
aquifer remediation sites, but conceivably could be used to facilitate agricultural drainage at some sites.
Each of the vertical pipes in such a system, individually or in a series, should be considered an injection
well subject to UIC authorities (Elder and Lowrance, 1992).
Other kinds of systems with a drainfield type of design are also likely to be considered shallow
injection wells, as long as they release fluids underground as opposed to a surface water body or the
land surface. These may include french drains, tiles drains, infiltration sumps, and the like.
Injection wells, however, do not include surface impoundments or ditches that are wider than
they are deep. Therefore, although such features are commonly used to direct or retain surface and/or
subsurface drainage at farms, they do not qualify as wells themselves.
A number of wells on agricultural cropland in the Southwest and Central California pump
ground water in order to lower the water table, and then release the water to surface outlets. These
systems may be collector sumps, usually 10 to 20 feet deep, that are fed by a system of underground
drainage tiles. Alternatively, unconfmed aquifers may be pumped to lower the water table by creating a
cone of depression, as occurs in Southern California and in Yuma and other locations in Arizona. In
neither case, however, is the water injected back into the ground; to the contrary, water is removed
from the ground by pumping to surface water outlets. Similar systems are found in other areas of the
nation, although they may not be as prevalent as in the Southwest (Smith, 1998). When all of the water
is discharged to the surface and there is no subsurface emplacement of fluids through a well, then there
is no "well injection" under the UIC regulations (as defined in 40 CFR 144.3). Therefore, even though
these systems are commonly used in the Southwest to drain agricultural fields, they do not qualify as
ADWs for the purpose of this study and are not considered further. Similarly, the drains and wells used
to pump ground water up for the purpose of dewatering a field are not injection wells and are not within
the scope of this study.
Some ADWs receive other fluid that technically is not agricultural drainage. For example, as
discussed in later sections, there are known instances in which septic tanks without leachfields discharge
directly to tiles that drain to ADWs. This is a common practice in rural areas of Iowa where ADWs
are used (Heathcote, 1998). In addition, many ADW systems located near roads have surface inlets
for roadway and ditch drainage (USEPA, 1998). These systems, therefore, can receive both
agricultural and more general storm water runoff. For the purpose of this volume, wells that receive
multiple kinds of fluids are considered ADWs as long as some fraction of the injectate consists of
agricultural drainage.
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3. PREVALENCE OF WELLS
For this study, data on the number of Class V ADWs were collected through a survey of state
and USEPA Regional UIC Programs. The survey methods are summarized in Section 4 of Volume 1
of the Class V Study. Table 1 lists the numbers of Class V ADWs in each state, as determined from
this survey. The table includes the documented number and estimated number of wells in each state,
along with the source and basis for any estimate, when noted by the survey respondents. If a state is
not listed in Table 1, it means that the UIC Program responsible for that state indicated in its survey
response that it did not have any Class V ADWs.
Many states and USEPA Regions administering the UIC program acknowledge that agricultural
drainage wells probably exist in different areas, but they have not been able to determine exactly how
many for a variety of reasons. Chief among these reasons is the fact that ADWs exist on rural private
property, and often in a very remote area such as the middle of a field that cannot be located by public
officials without the cooperation of the landowner. Moreover, some ADW designs are completely or
almost completely below the ground, making them virtually invisible at the land surface. In cases where
ADWs were constructed many years ago without any record, which is a common occurrence, it is not
unusual for the current landowner to not even know that they exist. Another complication is that
ADWs have been grouped together with storm water drainage wells in some state inventories. As a
result, there is no way to tell based on current records which wells qualify under today's definition as
ADWs versus storm water drainage wells or perhaps some other kind of injection well.
It is also a very difficult, if not impossible, task to develop a reasonable estimate of the number
of ADWs nationwide based on the possible co-occurrence of ADWs with certain other known
conditions, such as soil and geological characteristics and land use patterns. In a very general sense,
current patterns suggest that ADWs are used in areas where crop land has inadequate natural drainage
or poorly drained soils, and the crop land is coincident with underlying geologic formations that are
capable of receiving and removing large volumes of excess drainage water. The areas where wells are
likely to be located are characterized by poor internal soil drainage or a high water table, related to soil
properties or an impermeable substrate, and/or flat topography or poorly integrated natural drainage
through waterways. Suitable subsurface geologic formations often include areas with shallow, fractured
bedrock formations, or limestone bedrock, particularly where affected by karst development that
provides solution channels and sinkholes that allow rapid transmission of water.
For example, ADWs in Iowa discharge into limestone bedrock aquifers with karst features,
including solution channels and sinkholes. In Idaho, ADWs discharge into basaltic lava flows that have
many large fractures, pores, and tubes. These settings allow the intermittent and rapid transmission of
large volumes of water over long periods of time (i.e., they do not plug up in the short term). These
geologic formations also are usually located close to the surface, which eases and reduces the cost of
drilling an ADW. They are also conducive to the formation of sinkholes that can be widened or
otherwise "improved" to accept agricultural drainage.
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Table 1. Inventory of Agricultural Drainage Wells in the U.S.
State
Documented
Number of Wells
Estimated Number of Wells
Number
Source of Estimate and Methodology1
USEPA Region 1 - None
USEPA Region 2
NY
PR
1
NR
200
NR
Discussions with farmers in state.
N/A
USEPA Region 3
DE
PA
0
NR
50
NR
Best professional judgment.
N/A
USEPA Region 4
FL
KY
Unknown
NR
Unknown
NR
N/A
State officials indicated that agricultural drainage wells do exist
in KY, but none are reported.
USEPA Region 5
IL
IN
MI
MN
OH
WI
Tribal Program
6
6
14 or 15
92
>200 in Seneca
County
0
NR
NR
NR
NR
>100
1,000-1,500
(including improved
sinkholes)
<25
NR
Best professional judgment. State officials suspect more than
6 wells exist. Local public health official used best
professional judgment and personal observations to guess that
maybe thousands of improved sinkholes may exist.
N/A
USEPA Region suspects more wells exist.
Several hundred wells may exist. Survey could not find basis
for estimate but it might be an extrapolation of results from
Quade (1990), using best professional judgment.
Best professional judgement. Ohio EPA derived the estimate
from a combination of interviews with local officials,
inspection, knowledge of north-central and northwestern
Ohio's geology, and the results of the 319 grant study
conducted in the Thompson Township of Seneca County.
Best professional judgment. State officials assume 1 per
county.
N/A
USEPA Region 6
OK
5
NR
N/A
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Table 1. Inventory of Agricultural Drainage Wells in the U.S. (continued)
State
TX
Documented
Number of Wells
135
Estimated Number of Wells
Number
>135
Source of Estimate and Methodology1
As documented in an existing UIC database, authorizations to
construct have been issued for 135 ADWs. State officials,
however, recognize that there may be many more unregistered
wells located on private property.
USEPA Region 7
IA
290
290
State registration and field inspections.
USEPA Region 8 - None
USEPA Region 9
CA
1 (USEPA Region)
0(SiskiyouCo.)
1 (USEPA Region)
3,000
(Siskiyou Co., see
note to right)
Best professional judgment. The estimate for Siskiyou
County is made up mostly of surface impoundments or basins
that allow fluids to seep to the subsurface through their base,
but probably not through a "well" (Barber, 1999). An initial
survey response provided by the Division of Environmental
Health in Yolo County estimated several thousand wells, but
county staff have since stated that this estimate was based on
a misunderstanding of what qualifies as an ADW, and a more
accurate estimate is zero (Taniguchi, 1999).
USEPA Region 10
ID
OR
WA
Tribal Program
303
7
2
6
303
100
100
6
Based on original statewide screening by hydrogeologic basin
to identify all ADWs at the time of initial permitting, plus
regular field inspections allowing status updates and
identification/investigation of unpermitted injection wells.
Best professional judgment, based on discussion with the
Oregon Department of Agriculture and Oregon State
University Extension Service Staff. Confirmed by February
24, 1999 update from Calvin Terada of USEPA Region 10
(Terada, 1999).
Calvin Terada of USEPA Region 10 (Terada, 1999).
N/A
All USEPA Regions
All States
>1,069
>2,842
Total estimated number counts the documented number when
the estimate is NR. The total does not count the estimated
3,000 in Siskiyou County, California, which appear to be
drainage impoundments or basins as opposed to "wells"
within the scope of this study.
1 Unless otherwise noted, the best professional judgment is that of the state or USEPA Regional staff completing the survey
questionnaire.
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N/A Not available.
NR Although USEPA Regional, state and/or territorial officials reported the presence of the well type, the
number of wells was not reported, or the questionnaire was not returned.
Unknown Questionnaire completed, but number of wells is unknown.
Despite this tendency for ADWs to be located in certain kinds of geologic settings, the number
of ADWs nationwide cannot be estimated simply by assuming some density of ADWs in agricultural
areas underlain by favorable soil and geological conditions, because there are many other factors
involved. In particular, available inventory information indicates that historical farming and/or cultural
practices strongly influence the occurrence of ADWs, with such wells being readily used by some
farming families in a given area but not used at all by others in the same area. The water supply
available to meet demands, which varies from place to place and often from season to season in the
same place, also influences the occurrence and use of ADWs. For example, ADWs tend not to be
used to drain water to the subsurface in arid areas where water is in short supply. This gives rise to the
situation in the Southwest discussed above, where water is pumped from the ground to dewater a field
and then released to surface outlets where the water can be used for other purposes. Alternatively, in
locations where ground water is pumped and used for irrigation, the excess water may be drained back
into ADWs for the purpose of recharging an aquifer. Because of these complicating factors, which are
independent of geologic patterns and are very difficult to predict, USEPA has not attempted to develop
a mathematical model for estimating the number of ADWs nationwide, as developed for storm water
drainage wells and large-capacity septic systems (see Volumes 3 and 5, respectively, along with
Appendix C). Such a model for ADWs is unwarranted based on the high level of effort that would be
required relative to the likely accuracy that would be achieved.
Therefore, the current understanding of the prevalence of ADWs is based on data reported in
the literature and on the results of the state and USEPA Regional survey, which many of the survey
respondents acknowledge are based on incomplete knowledge. According to this information, there is
now a total of at least 1,069 ADWs known to exist in the U.S. and more than 2,842 ADWs wells are
estimated. The true number of ADWs in the nation, however, may be much larger. These wells appear
to be concentrated primarily in Idaho, Iowa, Minnesota, Ohio, and Texas (a relatively large number are
also estimated, but not documented, to exist in New York). ADWs are substantially less prevalent in
other states where new and existing ADWs have been banned (e.g., Georgia, North Carolina, North
Dakota) or where ADWs are not widely used as a matter of practice (e.g., California and Arizona).
This information is discussed in more detail below for different states, based on the likely prevalence of
ADWs and the certainty with which they are known to exist.
Looking forward, the number of ADWs should decrease as the risk to USDWs becomes
known and ADWs that cause or threaten contamination are discovered and closed. However, the
known number of ADWs may actually increase as the existing wells are actively looked for and
discovered.
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3.1 States Where Relatively Large Numbers of ADWs Are Known To Exist
Idaho now inventories 285 active ADWs in the state. This inventory is based on a concerted
effort to locate ADWs using topography and land use maps and after several years of regular field
inspections (Slifka, 1998). A total of 303 ADWs are currently registered in Idaho (Tallman and Slifka,
1998).
Current registration information for Iowa shows 290 active ADWs, mostly in north-central
Iowa (Humboldt, Pocahontas, Floyd, and Wright Counties), according to the Class V UIC survey
(Cadmus, 1999). These wells currently drain an estimated minimum of 40,000 acres. Construction of
new ADWs has been prohibited in Iowa since 1957, but existing ADWs have been allowed to remain
functional because of their important role in draining some of the most productive crop land in the world
(Heathcote and Appelgate, 1998).
A study conducted in Thompson Township of Seneca County, Ohio indicates that there may be
more than 200 ADWs in that county alone. Officials with the Ohio EPA estimate that, statewide, there
are at least 1,000-1,500 ADWs, including improved sinkholes. The widespread occurrence of
sinkholes make ADWs an attractive option for handling drainage in some areas of Ohio (Cadmus,
1999). In fact, in many areas in Ohio where improved sinkholes are used for drainage, the soil does
not drain well and there are often no other drainage alternatives than the sinkholes if the fields are to be
used for agriculture (Micham, 1999).
A total of 135 ADWs are currently in the Class V inventory in Texas, although officials with the
Texas Natural Resource Conservation Commission recognize that there could be many more on private
property. These wells are primarily located in the Pan Handle and the Lower Rio Grande Valley,
where conditions of severely limited surface drainage, soil characteristics, and agricultural practices
combine to create a need for ADWs. Of the 135 ADWs on record, 114 (84 percent) are in Hidalgo
County. The rest are in Hudspeth County (11 wells), Runnels County (9 wells), and Oldham County
(1 well).
Although Minnesota bans new ADWs and requires existing ADWs to close when found, it has
92 documented ADWs and estimates that greater than 100, possibly several hundred, wells may
continue to exist. This estimate is based on a 1992 study by Quade of ADWs in three south-central
Minnesota counties (Brown, Blue Earth, and Faribault Counties).
3.2 States Where No or Few ADWs Are Documented, But Where ADWs May
Exist in Greater Numbers
Georgia, North Carolina, and North Dakota have banned new ADWs and require existing
ADWs to close when they are found. Officials in these states, therefore, have reported that no ADWs
currently exist within their borders. In contrast, Oregon, Washington, and Wisconsin also have a ban,
but as described below, recognize that some wells continue to exist:
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• Oregon has seven documented ADWs, but USEPA Region 10 and state staff estimate that
there may be 100 ADWs in Oregon (Cadmus, 1999)
• Washington has two documented wells, but USEPA Region 10 officials, through discussion
with state personnel, estimate that there may be 100 ADWs in the state.
• Wisconsin has no documented ADWs, but the state has closed 3 wells in the 10 years following
the ban, indicating that wells exist regardless of the ban. Officials assumed that each county is
likely to have one ADW, resulting in an estimate of less than 25 wells in the state.
A few states that do not officially ban ADWs have provided survey responses stating that none
or very few are documented to exist within their borders. However, they estimate that many wells may
exist, as outlined below:
• California has one documented well according to USEPA Region 9's survey response. Staff
with the Bureau of Environmental Health in Siskiyou County are aware of roughly 3,000
seepage impoundments or ponds that are used to capture and remove excess water from
agricultural fields, but it is unknown how many (if any) of these drain into a "well" (Barber,
1999). In addition, Braun and Hawkins (1991) described the existence of dry wells in and
around citrus groves in Tulare County, and Hoi den (1986) reported that there were about
5,000 abandoned dry wells in the Central Valley. No information is available, however, on
whether any of these wells can be counted as active ADWs in the current inventory.
• Delaware has no documented ADWs, but estimates that 50 may actually exist.
• According to USEPA Region 2 officials, New York has only one documented well, but
discussions with farmers in the state have led to an estimate of possibly 200 ADWs in the state.
• Six ADWs are documented and in the inventory in Illinois, though it is unclear if any of these
have been plugged or abandoned. State officials suspect more wells exist than are
documented, with one local public health official speculating that there could be thousands of
improved sinkholes accepting agricultural drainage.
The documented and estimated number of ADWs in Puerto Rico, Pennsylvania, Florida,
Kentucky, and the USEPA Region 5 Tribal Program is either unknown or not reported. However,
because ADWs are not banned in these locations, it is quite possible that some do exist there.
In all of the other states not mentioned above, ADWs are not banned but survey responses
indicate that none or few ADWs are estimated to exist. For example, there are six ADWs in the 1997
UIC program inventory in Indiana, but there is a strong suspicion that this number is outdated (it is
based on a 1988 study). There are also six documented ADWs existing on USEPA Region 10 Tribal
Lands (encompassing the States of Alaska, Idaho, Oregon, and Washington). Michigan confirms that it
has approximately 15 ADWs. The USEPA Region 5 UIC program, however, suspects that this
September 30, 1999 11
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documented inventory is lower than the true number. Although the exact location of all of these wells is
unknown, some of the wells in Michigan are known to be in Monroe, Lenawee, and southern
Washtenaw Counties. Survey responses suggest that the number of ADWs in all other states is zero.
4. WASTEWATER CHARACTERISTICS AND INJECTION
PRACTICES
4.1 Injectate Characteristics
Water is the principal component of any injectate in an ADW, but the chemicals in that water
may be a source of concern if they contaminate USDWs. Some chemicals are naturally occurring
minerals, such as calcium, sodium, aluminum, and the like. Although naturally occurring, the levels of
these minerals can often be altered (usually increased) by human activities. Other chemicals are the
result of man-made practices, including general farming practices. These include pesticides, fertilizers
(both natural and artificial), and biological contaminants (such as bacteria and other microorganisms).
The constituents that may be released into ADWs can be broadly categorized into inorganic
constituents, biological contaminants, and organic chemical constituents. Sampling results from various
studies that address the occurrence of these chemical groups in ADW injectate are summarized below.
Some of these studies include subsurface drainage or ground water quality data that reflect aggregate
agricultural practices, not just contaminant migration via ADWs. Additional studies that focus on nitrate
and other chemicals measured in ground water around ADWs are discussed in Section 5.2.
4.1.1 Inorganic Constituents
The most common inorganic constituents in ADW injectate are nitrates, TDS, sediment, salts,
and metals. Nitrogen compounds that are regularly applied to crop land for nutrients usually oxidize to
nitrate, which is a highly mobile chemical in ground water.1 As such, nitrate is a pervasive contaminant
in both surface and subsurface flows entering ADWs. TDS is a collective term for solid salts,
organometallic compounds, and other non-specific inorganic compounds that are dissolved in water.
Dissolved solids do not function as a medium for transporting other materials in water. Sediment
suspended in water, on the other hand, can transport other potential contaminants such as pesticides,
bacteria, and metals. These contaminants are capable of sorbing onto the surfaces of suspended solids
and eventually may desorb, contributing to the degradation of ground water quality. The addition of
nutrients and soil conditioners often contribute to concentrations of major salt-forming ions, such as
1 Phosphorus compounds are also commonly applied to crops for nutrients. However, phosphorus is
not toxic to humans or animals in the forms commonly found in water, so its presence does not appear to
be a significant health concern with regard to ground water contamination by ADWs. The main concern
associated with phosphorus-rich ground water is if it discharges to surface water, where it may induce
eutrophication and other undesirable changes to aquatic ecosystems.
September 30, 1999 12
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calcium, magnesium, sodium, potassium, chloride, and sulfate. These ions can become concentrated in
ADW injectate through natural processes, including evaporation and transpiration, as well as through
man-made processes such as recycling of irrigation waters.
Nitrate
Nutrients, essential for plant and crop growth, are commonly applied to agricultural land as
chemical fertilizers, manure, or in some cases, sewage sludge. Nine studies summarized below illustrate
the occurrence of nitrate in agricultural drainage, especially for ADWs in Iowa. These studies show a
wide range of nitrate concentrations in ADW injectate that commonly exceed the primary MCL of 10
mg/1 for nitrate measured as nitrogen (NO3-N). Fertilization rates, crop rotation, soil characteristics,
and stratigraphy contribute to these variations.
In Iowa, the concentration of nitrogen compounds (NO3-N) found in subsurface drainage
systems commonly exceeds the MCL of 10 mg/1. For example, Austin and Baker (1983) observed
NO3-N concentrations as high as 100 mg/1 as fertilization rates and precipitation increased. In a
statistical survey of private drinking water wells in Iowa, Kross et al. (1990) found that the average
concentration of nitrate-N in drainage water was between 10 and 20 mg/1. In an Iowa Department of
Natural Resources study of ground water quality in Floyd County, NO3-N concentrations in tile water
injectate ranged from 2 to 35 mg/1 (Quade and Seigley, 1997).
Baker et al. (1985) monitored water draining into four ADWs in Humboldt County Iowa during
periods of flow in 1981 and 1982. Results of this monitoring showed that during periods between
runoff events when all the drainage to the ADWs was subsurface flow, NO3-N concentrations were the
highest, commonly in the range of 10-30 mg/1. When the ADWs received surface and subsurface
drainage during periods of snowmelt or rainfall runoff, concentrations often dropped below 10 mg/1.
Because nitrate is formed by oxidation in the soil, overland runoff typically has low concentrations
compared to the subsurface drainage from cropland. Overall, Baker et al. (1985) found that nitrate-N
concentrations ranged from 1.5 to 34.0 mg/1 in the ADWs tested. Some 85 percent of the samples of
drainage water analyzed exceeded the 10 mg/1 MCL.
In Iowa's Agricultural Drainage Well Project, NO3-N concentrations in drainage water ranged
from 4.0 mg/1 to 29.0 mg/1 over the course of the 4-year study (Iowa Dept. Of Agriculture and
Stewardship, 1994). The study concluded that NO3-N concentrations in subsurface drainage water
are related to crop rotation, plus rate and timing of nitrogen fertilizer application. Citing research
performed in Floyd County Iowa by Cherryholmes in 1986, USEPA Region 7 noted that nitrate-nitrite
concentrations ranged from 0.2 to 31.0 mg/1 for injectate water sampled from ADWs studied in Iowa
(Langemeier and Marre, 1987).
In addition to the above Iowa studies, studies in Idaho and Texas provide data on the nitrate
concentration of ADW injectate. In 1977, the U.S. Geological Survey (USGS) conducted a study in
Idaho that found nitrate concentrations up to 9.8 mg/1 in drainage water (Seitz, 1977). More recently,
in 1995, the State of Idaho has found nitrate concentrations in ADW injectate ranging from 0.001 mg/1
September 30, 1999 13
-------
to 6.8 mg/1, with the majority of samples below 1 mg/1 (Slifka, 1998). A 1983 study in Texas by
Knape reported NO3-N levels ranging from 15 to 45 mg/1 in agricultural drainage water (Knape,
1983).
TDS and Sediment
Five available studies address TDS or sediment levels in ADW fluids. In the Texas study
mentioned above in the nitrate section, Knape (1983) found that agricultural drainage waters in Texas
contained 1,754 to 6,510 mg/1 of TDS. The Idaho study by the USGS in 1977 found TDS levels
between 1.0 and 4,575 mg/1 (Seitz, 1977). In 1994, Skaggs et al. found that sediment loads in
subsurface drainage were less than that of surface runoff for agricultural land, but admitted that sediment
loading could be a problem (Skaggs et al., 1994). In an Iowa study, Austin and Baker (1983) found
that after a snowmelt, TDS exceeded 1,000 mg/1 in drainage water, suggesting that runoff was entering
ADWs via surface intakes to tile drains or an uncapped or open drainage well. Finally, a study in the
San Joaquin Valley in California found TDS concentrations as high as 11,600 mg/1 in drainage water
(Lee, 1993).
These results show that TDS levels in agricultural drainage are likely to greatly exceed the
secondary MCL of 500 mg/1. This secondary MCL is not health-based, but rather was established to
represent a goal that would prevent most adverse taste effects.
Salts and Metals
Other common inorganic constituents found in ADW injectate include salts and metals. Excess
salt concentrations, including calcium, magnesium, sodium, potassium, chloride, sulfate, and carbonate
are often found in agricultural drainage waters.
One study in the San Joaquin Valley in California found a maximum sodium level of 2,820 mg/1
in drainage water. Measured concentrations of boron were as high as 18,000 mg/1 (Lee, 1993). For
comparison, the draft health advisory for boron is 0.6 mg/1 (there is no health advisory for sodium).
In addition, there is information on salt-forming metals and ion complexes from the 1977 USGS
Idaho study, Knape's Texas study, and Baker et al.'s work in Iowa. These data are summarized in
Table 2, along with available standards for the purpose of comparison (NA means no standard is
available). As shown, the concentrations of sulfate, chloride, and boron in Texas exceeded the
standards, and the maximum iron concentration in Iowa exceeded the standard. None of the observed
concentrations in Idaho exceeded the available standards.
September 30, 1999 14
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4.1.2 Biological Constituents
Pathogens such as bacteria, viruses, and parasites may be transported by surface runoff and
can be found in drainage water and ground water near animal feedlots, or improperly constructed,
leaking manure tanks or earthen material storage basins (USEPA, 1997). Three Idaho studies,
summarized below, address biological constituents in agricultural drainage water.
Table 2. Inorganic Contaminant Concentrations from Selected ADW Studies
Contaminant
Ca
Mg
Na
K
HCO3
SO4
Cl
F
Fe
B
SiO2
P
Standard (mg/l)
NA
NA
NA
NA
NA
500 (proposed primary
MCL)
250 (secondary MCL)
4 (primary MCL under
review)
0.3 (secondary MCL)
0.6 (draft health advisory)
NA
NA
Range of Concentrations (mg/l)
Idaho*
35-76
9.2-30.0
9.1 -53.0
2.9-15.0
138-278
7.2-110.0
2-86
0.4-0.9
0.4-35.0
0.06 ->4.6
Iowa**
13-150
1 -120
0.01 -2.6
0.01 -1.99
Texas***
206 - 430
38-130
354-1659
4-10
294-366
571 -1361
371 -1999
0.9-2.2
2.7-15.0
41 -61
Sources:* Seitz et al., 1977.
**Bakeretal., 1985.
***Knape, 1983.
In 1979 in Minidoka County, Idaho, domestic drinking water wells and ADW drainage water
were tested for coliform bacteria. Turbidity and fecal coliform bacteria in the sampled drainage water
exceeded acceptable limits. Coliform levels in 31 percent of domestic wells exceeded drinking water
standards during the irrigation season. Turbidity levels in sampled drainage water from both the study
and control area were known to exceed drinking water standards regularly throughout the year.
Coliform concentrations in the study area were significantly higher than in control areas throughout the
year (Graham, 1979).
September 30, 1999
15
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The USGS conducted a study of irrigation drainage wells in the western Snake River- Plain
Aquifer area of Idaho (Seitz et al., 1977). The study area is underlain by basalt flows and interbedded
pyroclastic and sedimentary rocks. The volcanic members are extensively fractured and vesicular,
providing conduits for movement of water to the subsurface. The quality of the irrigation waste water is
highly variable, depending upon the original source of the irrigation water, amount of nutrient added to
crops, dilution by precipitation, and numerous other factors. Researchers found that nearly all the
irrigation waste water entering drainage wells contained significantly higher concentrations of indicator
bacteria than either surface or ground water. Specifically, the research showed that injectate contained
30 to >200,000 colonies/100 ml of total coliform, 4 to 20,000 colonies/100 ml of fecal coliform, and
>160 to 80,000 colonies/100 ml of fecal streptococci.2
More recent investigations of injectate quality in Idaho generally found biological contaminants
in the lower range of the above concentrations. These recent investigations show very few cases of
high concentrations of bacterial contaminants (Slifka, 1997).
In addition to these Idaho studies, two contamination incidents in Iowa provide information on
the levels of microbiological contamination that may enter ADWs in mismanagement scenarios. In once
incident, hog manure runoff draining into an ADW resulted in fecal coliform levels as high as 4,000
colonies per 100 ml in water in tile lines draining into an ADW collection cistern (USEPA Region 7,
1997a). In the other incident, an ADW that received discharge directly from septic systems contained
water with 830,000 colonies of fecal coliforms per 100 ml (Stone, 1979). These two contamination
incidents are discussed further in Section 5.2.2.
4.1.3 Organic Chemical Constituents
Pesticides in agricultural drainage water may also pose a threat to ground water quality and
human health. Pesticides that may be found in drainage water, drainage wells, and ground water
include bactericides, fungicides, insecticides, nematocides, rodenticides, and herbicides. Other
incidental organic contaminants may also be a problem if hazardous materials, such as fuel or solvents
used for cleaning, are accidentally or intentionally allowed to enter ADWs. The likelihood of such
events increases when ADWs are located near roads, equipment preparation or maintenance areas, or
other trafficked areas.
Seven studies are summarized below addressing organic constituents in agricultural drainage
water or ground water associated with ADWs. Tables presenting concentration information are also
included.
2 For comparison, the primary MCL that community water systems have to meet for total coliforms
(including fecal coliform and E. Co/;') states that no more than 5.0% of samples can test positive for total
coliform in a month. For water systems that collect fewer than 40 routine samples per month, no more
than one sample can be total coliform-positive. Every sample that has total coliforms must be analyzed
for fecal coliforms. There cannot be any fecal coliforms.
September 30, 1999 16
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Baker et al. (1985) monitored water draining from row-cropped areas into four drainage wells
in Iowa during periods of flow in 1981 and 1982. The researchers detected several different pesticides
in the water draining to the wells, but usually at levels below 0.001 mg/1. Pesticide levels were highest
in samples taken soon after rainfall of at least 20 mm, when surface runoff or ponding would be
expected. The following concentrations of pesticides were found: alachlor, 0 - 0.055 mg/1; atrazine, 0
- 0.0005 mg/1; carbofuran, 0 - 0.0006 mg/1; chlordane, 0 - 0.0018 mg/1; cyanazine, 0 - 0.08 mg/1; 2,4-
D, 0 - 0.0004 mg/1; dicamba, 0 - 0.012 mg/1; dieldrin, 0 - 0.000028 mg/1; and metribuzin, 0 - 0.00041
mg/1. For the pesticides with standards set, alachlor and cyanazine exceeded the MCL.
USEPA Region 8 compiled research for a 1987 symposium on Class V Injection Well
Technology (Langemeier and Marre, 1987). Citing a 1986 Cherryholmes publication, the authors
showed maximum concentrations of several pesticides found in eight ADWs in Floyd County, Iowa
between June and September 1986. These include atrazine, 0.0052 mg/1; cyanazine, 0.0028 mg/1;
metolachlor, 0.0059 mg/1; alachlor, 0.00029 mg/1; metribuzin, 0.00073 mg/1; and carbofuran, 0.0002
mg/1. Concentrations of atrazine and cyanazine exceeded MCLs. Also, The Floyd County Iowa Soil
and Water Conservation District sampled private drinking water wells from 1990 to 1996 as part of its
Groundwater Protection Project (Moore, 1997). Investigators monitored for atrazine at 12 different
locations throughout the county. Concentrations ranged from less than method detection level (
-------
Table 3. Iowa Herbicide Concentrations in Subsurface Drainage Water, 1990-1993
Herbicide
atrazine
cyanazine
metolachlor
dicamba
pendimethalin
butyl ate
2,4-D
bentazon
chloramben
metribuzin
acifluorfen
clomazone
fluazifop-butyl
alachlor
trifluralin
Range of Maximum Concentration (mg/l)
0.00029-0.0012
0.00046-0.005'
0.00016-0.0019
< MDLa - 0.00056
-------
Table 4. Pesticides in Snake River-Plain Aquifer Irrigation Waste Water (Idaho)
Pesticide
aldrin
chlordane
ODD
DDE
DDT
diazinon
dieldrin
dyfonate
endrin
heptachlor
heptach lor-epoxide
lindane
malathion
methylparathion
parathion
PCB
2,4-D
2,4,5-T
Silvex
Range of Concentrations (mg/l)
-------
Table 5. Pesticide Concentrations in Drainage Water or Ground Water'
Pesticide
(source)
alachlor(USEPA, 1990)
aldicarb (USEPA, 1990)
aldrin (Knape, 1983)
atrazine (USEPA, 1990)
bromacil (USEPA, 1990)
carbofuran (USEPA,
1990)
cyanazine (Libra et al.,
1994; USEPA, 1990)
1,2-DCP (USEPA, 1990)
DCPA (USEPA, 1990)
DBCP (USEPA, 1990)
diazinon (Knape, 1983)
dinoseb (USEPA, 1990)
dyfonate (USEPA, 1990)
EDB (USEPA, 1990)
endrin (Knape, 1983)
heptachlor epoxide
(Knape, 1983)
metolach lor (USEPA,
1990)
metribuzin (USEPA,
1990)
oxamyl (USEPA, 1990)
simazine (USEPA, 1990)
1 ,2,3-trichloropropane
(USEPA, 1990)
Concentration Ranges
(mg/l)
0.0001-0.01
0.001-0.05
< 0.00002
0.0003-0.003
0.3
0.001-0.05
0.001-0.0028
0.001-0.05
0.05-0.7
0.0002-0.02
< 0.0003
0.001-0.005
0.0001
0.00005-0.02
< 0.0002
< 0.00006
0.0001-0.0004
0.001.0-0.004
0.005-0.065
0.0002-0.003
0.0001-0.005
Proposed (P) or
Actual (A) MCL
(mg/l)
0.002 (A)
0.007 (P)
0.003 (A)
0.04 (A)
0.001 (DHAL)b
0.005 (P)
0.0002 (P)
0.007 (A)
0.00005 (A)
0.002 (A)
0.0002 (A)
0.2 (A)
0.004 (A)
Found in Drainage Water
(DRAIN) or Ground Water
(GW)
GW
GW
DRAIN & GW
GW
GW
GW
GW
GW
GW
GW
DRAIN & GW
GW
GW
GW
DRAIN & GW
DRAIN & GW
GW
GW
GW
GW
GW
a Please note that the original table provided in a prior USEPA review (USEPA, 1990) cited pesticide
concentrations in mg/l (parts per million) when the values should have been cited as • g/L (parts per billion).
All values taken from this USEPA report have been converted to mg/l.
" DHAL stands for draft health advisory level (see Appendix D).
September 30, 1999
20
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4.2
Well Characteristics
ADWs often consist of a buried cistern or collection basin that is fed by fluids from subsurface
drainage lines ("tile lines"), as illustrated in Figure 1. The cisterns may also collect surface water. The
cistern or collection basin sits atop a cased, drilled, or dug well that releases fluid into the subsurface.
Figure 1. Schematic Diagram of an ADW
Designed to Accept Tile Drainage Water
Source: Pat Lohmann, Iowa
DNR
Drain tile lines are typically just a few feet below the surface and are used to draw down excess
soil water and move it laterally to an outlet. The outlet may discharge directly to an ADW, or it may
discharge to a surface depression or waterway that leads to an ADW. Most drain lines are constructed
of plastic, concrete, or clay, and may be perforated and gravel-packed to encourage percolation
(Knape, 1983). In addition to accepting subsurface drainage, many tile line systems use surface intakes
to provide more rapid drainage from low areas.
ADWs range in diameter from 3 to 36 inches and may be constructed in various ways related
to their age. Some use steel casing, while others may use brick or concrete pipe. They
may range in depth from 20 to hundreds of feet, typically injecting drainage water into the shallowest
permeable zone (USEPA, 1990). Although the majority of ADWs in Iowa are less than 100 feet deep,
many are deeper, with the deepest ADW in Iowa reported to be 400 feet deep (Heathcote, 1999).
Figure 2 shows a schematic of a typical ADW in Iowa where a buried basin or cistern collects
drainage from surface and subsurface inlets (Iowa Dept. of Agriculture and Land Stewardship, 1994).
In this type of system, the cistern does not have a silt storage area where particles will settle and remain
outside the drainage well; as a result, any silt contained within the drainage is washed down the well.
Subsurface outlets may be located in the cistern, or adjacent to the cistern, depending on the system
design. In many cases, the top of the cistern has been left open to receive surface runoff in addition to
September 30, 1999
21
-------
subsurface agricultural drainage. The drain lines often run parallel to each other at varying intervals from
75 to 225 feet. Many tile line systems also have surface inlets as shown in Figure 2. A law passed in
Iowa in 1997, however, requires that surface intakes be removed and repairs made to prevent surface
water from entering ADWs by December 31, 2001.
Figure 2. ADW Typically Used in Iowa
@ "Quasi" surface flow
(3) Subsurface flow
Source: Iowa Department of Agriculture and Land Stewardship, 1994.
Figures 3 and 4 are photographs of the top of the cisterns of two ADWs in Iowa. The well in
Figure 3 is located in Weaver Township (Section 1), Humboldt County, Iowa. The hole and missing
bricks shown at the bottom, which reflect the common state of repair of ADWs in the state, provide a
ready opening for surface runoff to drain directly into the well. The well in Figure 4 is located in Corinth
Township (Section 6), also in Humboldt County. The cistern for this well is covered simply by a board
with a rock on top of it.
September 30, 1999
22
-------
Figure 3. ADW in Weaver Township, Humboldt County, Iowa
Source: Iowa Environmental Council
Figure 4. ADW in
Humboldt County
Corinth Township,
Iowa
Source: Iowa Environmental Council
September 30, 1999
23
-------
Figure 5. ADW Typically Used in Texas
.Concrete Cover
Free Fa|L
1 Foot Maximum
Land Surface
. 20nnch Concrete Pipe
,4 Foot |.D >
Minimum
, Reinforced
Concrete
Top
Concrete
or Brick
0)
LJ_
00
o
-------
placed at the top of the cistern and is activated when the water in the cistern rises to a certain level. A
float that hangs from a switch on the pump rises with the water level, activating the pump. Fluids are
transferred from the cistern via a plastic pump and subsequently injected under pressure into the
drainage well. This design is more costly than the older designs, and is rarely used (Knape, 1983).
In Idaho, most injection wells are steel cased wells drilled into subsurface porous formations
(see Figure 6). Many wells have uncased rock (lava) holes in the lower sections. The top of the
cistern, or the actual well, is left open to receive surface runoff in addition to subsurface agricultural
drainage (USEPA, 1997). In these systems, the well head has a screen and/or syphon attached to the
casing to keep larger debris from entering the well. Catchment basins are constructed near the well
inlets to reduce sediment in the injectate (Slifka, 1998).
Figure 6. ADW Typically used in Idaho
.Inverted Wetieod
Source: State of Idaho, Department of Water Resources.
As noted in Section 2, some abandoned drinking water wells are used for ADWs. Abandoned
drinking water wells may be constructed with a variety of materials and design specifications, depending
on the age of the well and the hydrogeological conditions at the site. There are three types of drinking
water wells: hand dug or bored, driven, and drilled wells. Hand dug or bored wells are usually less than
100 feet deep and range in diameter from 1 to 6 feet, although some wells are reported to be greater
than 10 feet in diameter (Alabama Cooperative Extension Service, 1995; Black et al., 1989; Brichford
and Matzat, 1995; Derickson, 1996; Eversoll et al., no date; Glanville, 1995; Zahniser and Gaber,
1993). They are typically cased with brick, rock, concrete (Black et al., 1989; Brichford and Matzat,
1995), stone tile, or other curbing material to hold the soil back from the well (Alabama Cooperative
September 30, 1999
25
-------
Extension Service, 1995; Zahniser and Gaber, 1993). Driven wells usually range from 1 to 6 inches in
diameter and are 10 to 50 feet deep (Alabama Cooperative Extension Service, 1995; Black et al.,
1989; Brichford and Matzat, 1995; Eversoll et al., no date; Glanville, 1995; Zahniser and Gaber,
1993). They are driven down into an aquifer and made from steel piping, typically with a short, pointed
sandpoint and well screen on the leading end. Drilled wells are the most common type of water well in
use today (Brichford and Matzat, 1995). Most domestic water supply wells range from two to eight
inches in diameter (Black et al., 1989, Glanville, 1995) and are drilled to various depths, depending on
the depth to the aquifer. Wells have been drilled from 30 to more than 1,000 feet deep (Alabama
Cooperative Extension Service, 1995).
Finally, some ADWs are simply improved sinkholes, where a surface depression has been
altered to direct fluids into the opening. In order to qualify as an injection well, an improved sinkhole
has to be deeper than it is wide. This type of ADW is often found near roadways and culverts to drain
not only excess irrigation water, but also storm water runoff. Figure 7 provides a photograph of an
improved sinkhole north of Madison, Wisconsin.
Figure 7.
North of
Wisconsin
Improved Sinkhole
Madison,
?$f£J
S-"*- -J*T3*1.i£*-n*A
rff .j ^, i .
'^*i^.V
i -"• V* "
'«*% *
* ISegi
' .^MJfivSj
fw^^^T '• •:. '^;^;
»^'v?ic-''i-S*2ss^SflE1';':-'" '"'^
l^.^^^^^t^'"'^^-; *.'.*<'
Source: USEPA Region 5
September 30, 1999
26
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4.3 Operational Practices
The operational practices for ADWs can be quite varied, depending on the well location (both
the state and the location within the state), the type of ADW, the age and economic situation of the
landowner, and the proximity to potential sources of contamination, among other factors. Each of these
factors is briefly discussed below.
4.3.1 Location
As discussed in Section 7 below, there is a range of different state and local programs designed
to address ADWs. There is a heightened awareness of the importance of this issue in certain states,
such as Iowa, Idaho, and several others that have specific regulatory programs to address ADWs. In
other instances, there may be little or no data available on ADWs within a state, especially if the wells
are not officially recognized and counted as an ADW in the state. For example, though improved
sinkholes and abandoned irrigation and drinking water wells are considered ADWs if they receive
agricultural drainage, they may not be identified as such by the state UIC program and their locations
are most likely unknown.
As previously discussed, cultural practices of the various landowners may significantly affect the
operational practices associated with ADWs. In one region of a state, ADWs may all be constructed
according to a single type (having been constructed during roughly the same points in time), while other
regions may not have ADWs or have ADWs of a different type and using different operational
parameters.
4.3.2 Type of ADW
For ADWs constructed to drain land of natural water that occurs either through a high water
table or precipitation, the operational characteristics are often quite similar. That is, they are fed
through surface flow, subsurface flow, or a combination of the two and the farmer often has little or no
activity to perform (other than cleaning any screens that exist).
In contrast, ADWs used to drain irrigation water may have different operational characteristics.
If the landowner is aware of the ADW (which is not always the case, especially with abandoned wells),
then he or she will endeavor to maintain the ADW to continue to operate. Irrigation is a principal
source of injectate water in some states.
4.3.3 Economic Condition of the Landowner
This factor can often play the most significant role in the operation and control of ADWs. A
study in Iowa (Huber, 1988) found that many owners of ADWs have little financial incentive for
mitigating problems associated with their ADWs. Also a number of complicating factors, such as debt
outstanding, availability of Conservation Reserve Program easements (which make income tax credits
available for land taken out of cultivation), and inheritance tax obligations, affect the likelihood of
September 30, 1999 27
-------
activities being undertaken. Changing the use of the land from crops to forage (for livestock) can be a
sound way of avoiding drainage problems, but such a change may not be made by the landowner for a
variety of reasons. Obviously, changing the way people operate their land and businesses is difficult for
an outsider to force.
4.3.4 Proximity to Potential Sources of Contamination
It is not always easy to identify the origin of a chemical detected in an ADW or receiving
ground water. The data shown in Section 4.1 above indicate a wide variety of contaminants may enter
ADWs. The logical source of these contaminants is the land that the ADW is designed to drain, but
that is not always the case. Direct discharges from human septic tanks, subsurface plumes from septic
systems, nearby feedlot and manure storage operations, accidental releases of materials during farming
operations (e.g., spills of motor oils used in equipment or bulk releases of pesticides during storage or
handling), and other sources can contaminate an ADW with a variety of the same contaminants, such as
nitrate. Moreover, simply identifying nitrate or pesticides in a well does not tell you which field it came
from, particularly when the tile lines (subsurface drain lines) cross over property lines. If farmer A uses
pesticide X, while farmer B uses pesticides X, Y, and Z, and both their properties drain into an ADW,
then whose pesticide X is being detected in the well? Likewise, for ADWs that receive storm water
runoff from roads or suburban areas, metals, hydrocarbons, and household pesticides could
contaminate the ADW, even if the ADW is in a rural area. Short of accurately identifying each source
of contaminant, its individual mobility characteristics and modeling each well, there is no simple means
of identifying where a particular contaminant originated.
The close proximity of ADWs to large-scale confined animal feeding operations (CAFOs) is a
particular concern, as illustrated by recent developments in Iowa. In the mid-1990s, large-scale
CAFOs began expanding in Iowa and with them came multi-million gallon earthen manure storage
structures. Many of the largest facilities are located in the area of north-central Iowa where ADWs are
concentrated. For example, in Wright County there are 46 large-scale permitted livestock facilities and
38 active ADWs. In Lincoln Township, just southeast of the town of Clarion, there are 12 permitted
hog confinements and 28 ADWs. Including the area surrounding Lincoln Township, there are 27
ADWs within one mile of a permitted hog confinement facility. In some cases, the ADWs are very
close (hundreds of meters) to the facilities and their manure storage structures. A recent paper by the
Iowa Environmental Council presents photographs of wells in close proximity to a large earthen lagoon
of a hog confinement facility, a facility that houses 950,000 chickens and 24,000 finishing hogs, and a
swine nursery facility (Heathcote and Appelgate, 1998).
Although similar data are not available for other states, it appears likely that some ADWs in
other locations are also in close proximity to animal feeding operations (AFOs). It is estimated that
there are 450,000 AFOs in the United States. An AFO is a "lot or facility" in which livestock "have
been, are, or will be stabled or confined and fed or maintained for a total of 45 days or more in any 12
month period and crops, vegetation, forage, growth or post harvest residues are not sustained in normal
growing season over any portion of the lot or facility" (U.S. Dept. of Agriculture, 1998).
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The close proximity of large livestock confinement facilities to ADWs presents at least two
concerns: (1) possible impact to aquifers from runoff after land application of manure, and (2) risk of a
catastrophic spill from a manure storage basin or lagoon entering an ADW. These risks have been
particularly evident in Wright County Iowa, where the Mississippian aquifer into which ADWs near
feedlots drain is the main water supply for public and private waters supplies for much of north-central
Iowa (Heathcote and Appelgate, 1998).
5. POTENTIAL AND DOCUMENTED DAMAGE TO USDWs
5.1 Injectate Constituent Properties
The primary constituent properties of concern when assessing the potential for Class V ADWs
to adversely affect USDWs are toxicity, persistence, and mobility. The toxicity of a constituent is the
potential of that contaminant to cause adverse health effects if consumed by humans. Appendix D of
the Class V Study provides information on the health effects associated with contaminants found above
drinking water MCLs or HALs in the injectate of ADWs and other Class V wells. As discussed in
Section 4.1, the contaminants that have been observed above primary (health-based) drinking water
standards or health advisory levels in ADW injectate are nitrate, boron, sulfate, coliforms, and certain
pesticides (cyanazine, atrazine, alachlor, aldicarb, carbofuran, 1,2-dichloropropane (DCP), and
dibromochloropropane (DBCP)). TDS and chloride have been measured above secondary MCLs in
some ADWs, but these standards are designed to minimize aesthetic (taste) effects not adverse health
effects (health-based standards do not exist for these parameters).
Persistence is the ability of a chemical to remain unchanged in composition, chemical state, and
physical state over time. Appendix E of the Class V Study presents published half-lives of common
constituents in fluids released in ADWs and other Class V wells. All of the values reported in
Appendix E are for ground water. Caution is advised in interpreting these values because ambient
conditions have a significant impact on the persistence of both inorganic and organic compounds. The
primary inorganics of concern in ADW injectate are, in general, highly persistent in ground water. As
for the organic constituents of concern, atrazine, aldicarb, carbofuran, and 1,2-dichloropropane are
highly persistent in ground water.3 A wide range of values for bacterial die-off rates are reported in the
literature, as presented in Appendix E.
Appendix E also provides a discussion of mobility of certain constituents found in the injectate
of ADWs and other Class V wells. Because the point of injection for ADWs is within a permeable
coarse-grained unit, karst, or a fractured unit in many areas (because substantial void space is needed
to accept large quantities of drainage), conditions are often present that would allow constituents in
ADW injectate to be highly mobile.
3 Published half-lives are not available for the other organics in ADW injectate observed above
MCLs, including cyanazine, alachlor, and dibromochloropropane.
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5.2 Observed Impacts
This section summarizes known contamination incidents involving ADWs and other studies on
ground water impacts associated with agricultural drainage. The discussion is organized into three main
sections, first dealing with nitrate in ground water, then contamination incidents involving the direct
discharge of septic tank contents to ADWs, and then finally other contamination incidents and studies.
5.2.1 Nitrate in Ground Water
Nitrate is a widespread contaminant of ground water, and high concentrations of nitrate in
ground water are often linked to agricultural practices, including, but not limited to, the use of ADWs
(Hallberg and Keeney, 1993). Large amounts of nitrogen are added to the soil in many agricultural
systems providing the opportunity for large leaching losses of nitrate into ground water (Hallberg and
Keeney, 1993), but not necessarily a correlation to injection wells. Much research shows background
nitrate-N concentrations are low, often less than 2.0 mg/1, in ground water moving from forested,
pasture, or grassland areas to agricultural areas (Hallberg, 1989).
There are numerous factors that affect the fate and transport of nitrate in ground water,
including hydrogeologic factors, agricultural land use and practices, local features, and water chemistry.
Among the most important of these controlling factors are the amount of nitrogen source available, the
amount of infiltrating or percolating water, the hydraulic conductivity of the subsurface, depth to the
water table, and the potential for nitrate-reduction and/or denitrification (Hallberg, 1989). Several
studies, discussed below, illustrate the interplay of these various controlling factors with respect to
ADW use and nitrate contamination of ground water.
A compilation of data from the Big Spring Basin in northeastern Iowa provides qualitative
evidence of the link between the amount of nitrogen source available and increased concentrations of
nitrate in ground water. The data indicate that in the 1930s, nitrate-N concentrations in an aquifer were
less than 1 mg/1. In the 1950s and 1960s, the nitrate-N concentration in the aquifer averaged about 3
mg/1 and by 1983, the average concentration was 10.1 mg/1. The increases in nitrate concentrations
were reported to directly parallel increases in the amount of nitrogen fertilizer applied (Hallberg, 1986).
Thus, these data suggest that nitrogen source availability directly influences nitrate contamination of
ground water.
Similarly, a study in Idaho conducted by the Idaho Department of Water Resources based on
nitrate data collected by the U.S. Bureau of Reclamation showed nitrate levels in ground water
increasing from 1980 to 1995. The largest increases were in areas of gravity or flood irrigation. The
highest level of nitrate in ground water was measured at 8.0 mg/1 in 1995. At this same time, the highest
level of nitrate contamination in the fluids entering ADWs in the area was measured at 6.8 mg/1. Much
of the irrigation water in the area is pumped from ground water and is the source of much of the
injectate placed back into the aquifer. Many agricultural areas along the Snake River Plain that show
high levels of nitrates in ground water have few ADWs (Slifka, 1998).
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Scientists made stronger connections between ADW use and nitrate in ground water from a
study in north central Iowa between 1981 and 1983 (Baker et al, 1985; Baker and Austin, 1984).
Investigation of farm water supply wells in three study areas showed nitrate ground water contamination
of the local carbonate aquifer studied. The results showed that areas with the highest density of ADWs
had the highest average concentrations of nitrate in ground water samples. Further, the percent of
drinking water wells in the study areas whose average concentration exceeded the MCL of 10 mg/1
was highest in the areas with the greatest concentration of ADWs.4 Baker et al. (1985) also related
nitrate concentrations in farm drinking water wells to their distance from an ADW, and found that
drinking water wells within 0.3 to 1.2 miles of an ADW showed the highest nitrate concentrations.
Finally, the study showed that farm wells in areas with greater than 50 feet or more of overlying earth
material (overburden) had significantly higher nitrate concentrations than areas with less overburden.
This suggests that nitrate in the recharge to drainage wells, rather than the nitrate in normal infiltration,
had increased nitrate concentrations in the aquifer. The authors pointed to prior research that shows
that areas with 50 feet or more of overburden are more confined, and typically show low nitrate levels.
In these settings recharge from the surface, carrying nitrate, typically has not penetrated the protective
confinement and affected this deeper ground water.
The Baker et al. (1985) results highlight several key factors affecting nitrate in ground water. In
particular, the results indicate the importance of hydrogeological factors on nitrate contamination. The
type of terrain and the amount of overburden influenced nitrate concentrations in ground water. The
study also suggests that areas with a confined bedrock aquifer may have higher nitrate concentrations
than normal with ADW use. The ADWs allow nitrate easy access into these aquifers. Additionally, in
areas with high densities of ADWs, drinking water wells may show increased nitrate contamination from
ADW use.
Further illustrations of the factors influencing nitrate contamination of ground water are found in
a 1994 review of hydrologic and water quality impacts of agricultural drainage (Skaggs et al., 1994).
Researchers reviewed evidence that showed nitrate contamination of ground water from areas with
improved subsurface drainage in California, Georgia, Illinois, Indiana, Iowa, Michigan, Minnesota,
North Carolina, Ohio, and Vermont. In general, the research reviewed showed that intensive
subsurface drainage will increase outflows of mobile constituents, such as nitrate-nitrogen and certain
salts, but decrease overland runoff and the loss of sediment, phosphorous, organic nitrogen, and other
pollutants that are typically contained in runoff water. Most of the studies reviewed attributed increased
nitrate levels to increases in nitrification with decreases in denitrification caused by deeper water table
depths with subsurface drainage. Nitrification is the microbial oxidation of ammonium to nitrate; it is the
4 Specifically, samples take from one area, with the most ADWs, averaged the highest N03-N
concentration at 10.9 mg/1 with 37 percent of the farm wells having an average greater than or equal to
the MCL of 10 mg/1; samples taken from a second area, with less ADWs than the first area, averaged
slightly less at 8.7 mg/1 with 30 percent of the wells greater than or equal to 10 mg/1; and samples taken
from a third area, with no ADWs, averaged much less than the first two areas at 3.0 mg/1 with only 9
percent of the wells greater than or equal to 10 mg/1 (Baker and Austin, 1984).
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principal natural source of nitrate to the biosphere. Denitrification refers to the removal of nitrate
through microbial respiratory processes in anaerobic, reducing environments, such as those found in
wetlands, saturated soils, and some confined and/or deeper aquifers. ADWs that accept subsurface
drainage water may increase nitrate levels by deepening the water table, thus eliminating the denitrifying
environment, and in turn allowing nitrification processes to act on water filtering through the subsurface.
The review found that nitrate losses from similarly cropped soils varied from 3 Ibs/acre/year for low
intensity subsurface drainage to 14 Ibs/acre/year for medium intensity subsurface drainage to 29
Ibs/acre/year for high intensity drainage. This review illustrates the importance of
nitrification/denitrification, and the relationship of soil drainage water on nitrate contamination.
Noting that tile-drainage water is shallow ground water, Hallberg reports that leaching losses of
nitrate to subsurface drainage water are directly proportional to the nitrogen fertilizer applied for
agricultural purposes (Hallberg, 1986). The author presents additional evidence of the impact that
nitrogen source availability has on nitrate contamination. In doing so, he notes many studies showing a
linear relationship between nitrate losses with subsurface drainage (increased nitrate levels in injectate)
to nitrogen application rates exceeding 45 pounds per acre. The author presents evidence from several
studies that show this same general trend, including studies of an Iowa carbonate aquifer system and an
Iowa alluvial aquifer. The report notes that a considerable amount of applied nitrogen is left in the soil
and lost through leaching into tile effluents. According to the report, nearly half of the applied fertilizer
nitrogen may be discharged with tile drainage water at rates commonly applied to corn. Large leaching
losses can be expected to continue as farmers continue to rely on increased fertilizer use.
Another study, conducted by the Iowa Department of Natural Resources (DNR) in 1994,
examined the effects of ADWs on water quality in Floyd and Mitchell Counties, Iowa (Libra et al,
1994). Among other issues, scientists studied the effects of ADW effluent on ground water and related
the results to the hydrogeologic setting in the two counties. Results of the study showed that the study
area strata form a three-part aquifer system in these counties, and that ADWs did deliver agricultural
contaminants, most notably nitrate, to ground water. Results were mixed; monitoring at a well nest
located 500 feet from a 300 foot-deep ADW showed significant ADW contamination at some depths,
and negligible contamination at other depths. For instance, samples from the middle and lower aquifer
piezometers were generally below 1 mg/1, although occasional samples showed up to 7 mg/1 NO3-N.
Similarly, large increases in nitrate-N concentration (some as high as 22 mg/1) were observed in some
deep bedrock aquifer areas during wet periods, yet other deep bedrock sampling areas with similar
potentiometric response to the wet conditions did not show this same result. The researchers could not
explain all the variations, but differences in the sampling results were attributed to different depths of
ADWs and bedrock saturation conditions. Additionally, some private wells located within one to two
miles of clusters of ADWs were affected by the drainage wells, while others were not. Factors
affecting these results are the interplay between private well depth and construction, ADW depth, and
stratigraphy. Overall, the study found that clearly discernable effects of ADWs on ground water are
limited to areas that have a low natural susceptibility to agricultural contamination, including deep
bedrock areas overlain by more than 50 feet of low-permeability glacial deposits and/or shales. These
results further illustrate the importance of aquifer depth and hydraulic conductivity. In areas with less
September 30, 1999 32
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confinement, the effects of ADWs cannot be clearly discerned from the general level of nonpoint source
contamination that is affecting the bedrock aquifers in the area.
Iowa DNR researchers studied the effects of ADW closure on ground water quality in Floyd
County, Iowa (Quade and Seigley, 1997). The project, beginning in 1994, sought to monitor the
effects of ADW closure on the water quality of the carbonate aquifer system in Floyd County. Results
showed an increase in nitrate concentration in the shallow water table (29 feet). None of the closed
ADWs injected into this shallow zone, so researchers did not expect to see improvement. However,
they also did not expect to see an increase in nitrate concentration; they attributed the increase to
various factors, including climate, farming practices, and fertilization rates. Mean nitrate-N
concentration in the shallowest bedrock well (103 ft.) showed a decrease from 19 to 12 mg/1.
Similarly, post closure mean nitrate concentrations declined to "negligible" values for bedrock wells at
207 ft., 297 ft., and 360 ft. The decrease in mean nitrate concentration at these three wells was
statistically significant, suggesting that ADW closure had a causal impact on improved ground water
quality at these sites.
Kross et al. (1990) found nitrate levels in ground water in Floyd, Wright, Humboldt, and
Pocahontas counties in Iowa (counties with ADWs) to range between 0.5 to 7.0 mg/1, below the MCL.
From the statewide survey they could not discern a water-quality impact attributable to ADWs, but the
survey was not designed to detect such localized effects in relation to the wider-scale nonpoint source
problems in adjacent karst and shallow bedrock aquifer regions. These results suggest that nitrate
contamination of ground water from ADW use may be localized in areas adjacent to the wells, and that
over an entire region, contamination effects may be hard to distinguish from other sources.
Finally, the Floyd County Iowa Soil and Water Conservation District found nitrate-N levels in
private drinking water wells that ranged from <0.1 to 26 mg/1 in their ADW test program from 1991 to
1995 (Moore, 1997).
Results from these studies suggest that nitrate ground water contamination from ADWs is
influenced strongly by nitrogen source availability, amount of percolating water, depth to water table or
zone of injection, and nitrate reduction/denitrification. Increased ground water nitrate concentrations
can be expected in areas with densely spaced ADWs and is most evident in settings where the local
aquifer would not otherwise exhibit high nitrate levels.
5.2.2 Septic Tank Contamination
There are at least two known incidents involving septic tank contamination of an ADW. Both
of these cases are reported in Wright County, Iowa.
In the first case, an investigation conducted in 1977 made it apparent that raw sewage was
entering a drainage well in the Lake Cornelia area. It was further evident that this waste originated from
at least seven homes located in the area that were discharging their waste to a drain tile system leading
to an ADW associated with some cropland (Choquette, 1977a).
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The other incident was associated with the field application of wastewater from a hog manure
lagoon in Lincoln Township. Between April 2, 1997 and April 18, 1997, approximately 1,556,376
gallons of manure were applied to 72 acres of land surrounding an ADW. The addition of manure to
the croplands already saturated with excess water from snow melt caused rapid infiltration of the liquid
manure. The liquid manure then leached into tile lines leading to the ADW. All fluids received by the
well discharged into the Mssissippian Aquifer that is used as an underground source of drinking water
for public and private water supplies.
Upon investigation of the incident by USEPA and the Iowa DNR, it was determined that fluids
containing fecal coliform entered the ADW as a result of not only the manure runoff and infiltration, but
also direct discharges from a septic tank hooked to a tile line leading to the ADW. On May 18, 1998,
USEPA Region 7 issued a consent agreement and consent order requiring the farm that applied manure
to pay $7,000 in civil penalties and to locate and eliminate all surface openings in tiles located on land to
which manure is applied (USEPA Region 7, 1998).
In this latter incident, contamination from the septic tank was small compared to the large
volume of the manure application. However, when examined on a regional basis, contamination from
septic tanks can be a significant source of aquifer contamination. Direct discharges from septic tanks to
ADWs in the area may create an equal or greater impact on ground water than manure application. It
was estimated that about 30% of the individual rural septic tanks in Lincoln Township were directly
connected to agricultural drainage tiles/wells. If this is true, an estimated one million gallons per year of
sewage from septic tanks may be entering drainage tiles and ADWs (Choquette, 1997b).
5.2.3 Other Contamination Incidents and Studies
In 1979, the Idaho Department of Water Quality conducted a study to assess evidence of
ground water contamination from ADWs. In 3 areas of Minidoka County, Idaho, 15 drainage wells
were monitored for 1 year. Turbidity levels exceeded MCLs almost 78 percent of the time, while other
contaminants found in drainage water seasonally exceeded MCLs or safe levels. Coliform bacteria
were found in unusually high concentrations in 31 percent of domestic drinking water wells, while levels
of nitrate-nitrogen, chloride, and specific conductance were much higher in the test areas than the
control areas during the agricultural season. This suggests that contamination resulted from ADW use
(Graham, 1979).
Around 1988 (approximately 10 or 11 years ago), a water supply well for the Village of Dane,
in Dane County, Wisconsin, was discovered to be contaminated by atrazine. A survey of the area
found that the source of this contamination was likely to be an improperly abandoned drinking water
well that had been illegally modified to receive surface runoff from an agricultural area. The drainage
well was subsequently sealed in accordance with applicable requirements, and the atrazine
contamination in the water supply well disappeared (Roth, 1999).
A 1987 survey by the California Department of Food and Agriculture (Troiana and Segawa,
1987) revealed that 49 percent of 122 ground water wells sampled in Tulare County, California were
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contaminated with detectable levels of one or more herbicides, including simazine, diuron, atrazine,
bromacil, and prometon. A followup study in 1991 (Braun and Hawkins, 1991) detected bromacil,
diuron, and simazine in surface runoff water from agricultural fields (citrus groves) and non-crop sites
following a rain or irrigation event. Samples of rain runoff collected within orange groves and near
suspected dry wells contained high concentrations of diuron and simazine, but significantly lower
concentrations of bromacil. Water was observed running into suspected dry wells at the time of the
sampling, but Braun and Hawkins (1991) concluded that the extent to which this runoff was
contributing to ground water contamination was unknown and needed to be investigated further.
Other cases involving the cross-contamination of aquifers by abandoned water wells are
documented in a fact sheet published by Nork (1992). Cross-contamination occurs when two aquifers
are penetrated by one abandoned well without a seal placed between the zones that would prevent the
water from mixing. This allows contaminated water in one aquifer to mix with and contaminate water in
another aquifer. The fact sheet, however, provides no specific information on these cases and whether
they were caused by ADWs.
6. BEST MANAGEMENT PRACTICES
Only a few physical alterations to ADWs themselves will avoid or reduce their potential to
contaminate ground water. Therefore, aside from closing ADWs and getting rid of excess water by
other means, the only way to reduce the potential for contamination from agricultural drainage while
minimizing adverse economic impact is to follow best management practices (BMPs).
The following discussion relies on developing and existing USEPA guidance to protect ground
water and surface water from risks posed by contaminants from agricultural sources. In particular, it
draws primarily from draft Agricultural Drainage Wells Interim Guidance (USEPA, 1999). This
draft interim guidance relied heavily on Chapter 2 of USEPA's Guidance Specifying Management
Measures for Sources ofNonpoint Pollution in Coastal Waters., issued under the authority of
section 6217(g) of the Coastal Zone Act Reauthorization Amendments (CZARA) of 1990. The
CZARA guidance document also presents techniques for minimizing seepage to ground water and
describes in great detail the nutrient and pesticide management measures summarized below.
6.1 Closure and Alternatives to Agricultural Drainage Wells
Often, closing ADWs is the best solution to the problems associated with such wells when
feasible alternatives exist. States like Iowa are taking steps in that direction. In 1997, Iowa passed a
law requiring all ADWs in the drainage area of a large permitted earthen manure lagoon to be closed.
As a result, ADWs identified as located in the most critical areas will be closed first (over the next 2
years). The Iowa law also requires permits for all remaining ADWs in operation. To qualify for a
continued use permit, all of a well's surface intakes must be removed and cisterns must be water tight
and have raised sidewalls to prevent surface water from flowing directly into the wells. All cisterns must
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have locked covers to prevent unauthorized access. Also, all septic tank connections must be removed
from the ADW system. Rules for the continued use provisions of the 1997 Legislation were approved
in December 1997 and became effective in June 1998 (Heathcote and Appelgate, 1998). Other
ADWs in Iowa are being closed voluntarily, with financial assistance from the state for closure costs
and the construction of alternative drainage outlets. Separately, U.S. Department of Agriculture
(USDA) Natural Resources Conservation Service cost-share money from the Environmental Quality
Incentives Program (EQIP) can be used for ADW repairs and removal of surface intakes.
Wells must always be closed in compliance with state and federal requirements related to well
closure and plugging and in compliance with other regulations (e.g., wetland protection). Some states
offer both technical and financial assistance to address well closure and drainage alternatives.
Temporarily and permanently abandoned agricultural drainage wells have to be properly
managed to prevent accidents or misuse, which could pose a hazard to farmers, farm equipment, and
vulnerable aquifers. Proper management activities include installing locked covers on drainage well
cisterns to prevent contamination from unauthorized disposal and to prevent accidental entry by children
or small animals, closing (i.e., plugging or filling) permanently abandoned wells in accordance with state
and federal regulations, marking abandoned wells or wells hidden beneath the soil surface, and keeping
inventories of well locations and records of their past use.
There are three possible alternatives to letting agricultural drainage flow down ADWs:
• Provide other drainage outlets where appropriate, such as open ditches or tile mains, to route
the drainage water to the closest natural outlet.
Construct seepage ponds or storage reservoirs for temporary water retention or reuse in
irrigation.
Allow part or all of the land to return to its natural drainage state (e.g., conversion of some or
part of the land to wetland).
6.1.1 Alternative Drainage Outlets
Maintaining land in production after ADWs are closed may require the construction of alternate
drainage outlets. The typical alternate outlet is a surface water body connected to agricultural land by a
network of open ditches or tile mains. Using alternate outlets is often complex, mainly because ADWs
are typically outside of existing drainage districts and constructing drainage routes to the outlets involves
contending with adverse geological and terrain conditions, other engineering difficulties, and
socioeconomic and legal constraints. The use of alternate outlets also may lead to pollution problems in
areas formerly not directly affected by ADWs (e.g., surface water bodies such as lakes and rivers). It
is appropriate to use drainage outlets only if monitoring indicates that drainage waters will not adversely
affect surface water and associated ecosystems.
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6.1.2 Temporary Storage
Excess irrigation water may be collected in ponds for temporary storage, then reused through a
sprinkler system on other land. Sand and gravel-filled seepage ponds allow water to both evaporate
and seep into the ground. This alternative to ADWs generally allows nonpersistent contaminants, such
as bacteria, to degrade at the surface or to be filtered out as the water percolates downward. For
these reasons, storage and seepage ponds are generally considered preferable to the alternative of
diverting agricultural water to natural outlets. However, it is important to adequately demonstrate that
the design of a pond will prevent contaminants from migrating to ground water. Bottom liners may be
necessary to prevent seepage and ground water monitoring may be necessary to provide early
detection of any seepage that does occur.
6.1.3 Return to Natural Drainage State
Eliminating drainage systems from cropland without providing alternative and efficient water
outlets could interfere with routine farming activities. The effects of closing ADWs depend on site
characteristics including climate, soils, land use and cover, and topography. In general, closure of
ADWs could lead to ponding in low-lying areas and on poorly drained soils, creating wetlands that are
unsuitable for crop production. In addition, crop yields in dry areas may be affected due to isolation of
better drained soils, variable wetness conditions, small or irregular field patterns, short row length, and
less efficient use of large equipment. Reverting drained agricultural land to wetland requires careful
land-use planning to prevent economic and environmental damage (such as flooding and decreased
ground water recharge).
6.2 Erosion and Sediment Control
Erosion controls can reduce the threat of ground water contamination by improving the quality
of surface runoff flowing into ADWs. In general, erosion control practices are intended to minimize the
impact of precipitation on the soil surface by reducing the velocity of surface runoff and the
channelization it causes. These practices are especially useful during periods when vegetation cover is
sparse and the potential for erosive rainfalls is high. USEPA and the U.S. Department of Agriculture
have evaluated numerous erosion control practices that address the problem agricultural erosion poses
for ground water quality in the joint USEPA-USDA publication, Control of Water Pollution from
Cropland, Volume 1: A Manual for Guideline Development (USEPA/USDA, 1975).
BMPs for erosion control are designed to allow suspended solids and associated pollutants to
settle out of runoff. The most desirable BMP strategy involves implementing farming practices that
prevent erosion and transport of sediment from the field, including conservation tillage, contour strip
cropping, terraces, and critical area planting. Another BMP strategy involves routing runoff from fields
through structures that remove sediment, such as filter strips, field borders, grade stabilization
structures, sediment retention ponds, water and sediment control basins, and terraces. Site conditions
will dictate the appropriate combination of practices for any given situation (USEPA, 1993).
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USEPA recognizes the possibility that implementing some of these measures may increase the
potential for movement of water and soluble pollutants through the soil profile to ground water. It is
not, however, USEPA's intent for these BMPs to avoid surface water problems at the expense of
ground water or vice versa. It is necessary to design erosion and sediment control systems to protect
against the contamination of both ground water and surface water.
6.2.1 Conservation Tillage
Conservation tillage is any tillage or planting system that leaves at least 30 percent of the soil
surface covered with residue after planting; or, where soil erosion by wind is the primary concern,
maintains at least 1,000 pounds of flat, small-grain residue equivalent on the surface during the critical
erosion period. Ordinarily, water tends to remain in the upper soil profile, promoting surface runoff
and, consequently, soil erosion. Studies have shown, however, that conservation-tillage practices
channel soil moisture downward through undisturbed soil macro pores, thus reducing erosion. By
slowing the flow of surface runoff, conservation tillage reduces the material-carrying capacity of runoff
water. It also shields soil from the impact of rainfall, thus protecting the soil surface from detachment
and erosion during highly vulnerable crop-establishment periods. This, in turn, may reduce the potential
for USDW contamination by ADWs that receive surface flows.
A potential drawback of conservation tillage is that residue left on farm fields can intercept
pesticides before they reach the soil, making greater, or more frequent, pesticide applications
necessary. This problem can be compounded by the greater infiltration capacity (from cracks, root
channels, worm holes, and decreased runoff velocities) in conservation- or reduced-tillage soils; this
greater infiltration capacity promotes the leaching of agrichemicals. (That is why nutrient and pest
management plans must be part of a complete system of BMPs - to reduce the nutrient and pesticide
loads on ground water and surface water.) At times, some reduced-till systems must also rely heavily
on herbicides to control weeds that conventional tillage normally buries (USEPA, 1993).
The overall positive effect of conservation tillage on surface water quality is well documented
but its effect on ground water quality is still being studied and evaluated by agricultural scientists.
Currently, there is a difference of opinion on the usefulness and effectiveness of this BMP. It is
recommended that conservation tillage practices be implemented only after consulting with tillage
experts who understand the impact of such site conditions as climate, soil properties, depth to ground
water, and the physical characteristics of the aquifer. In circumstances where any tillage method can be
employed, conservation tillage is usually chosen because it conserves soil, saves fuel, and reduces labor
and material costs, all of which are important concerns to farmers (NRC, 1989; USEPA, 1993).
6.2.2 Filter Strips
Filter strips are bands of planted or indigenous vegetation situated downslope of cropland or
animal production facilities to provide localized erosion protection and to filter nutrients, sediment, and
other pollutants from agricultural runoff. Due to their low installation and maintenance costs and
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effectiveness in removing a variety of pollutants, many conservation and regulatory agencies encourage
the use of vegetated filter strips (Dillaha et al, 1989).
Filter strips are often coupled with practices that reduce nutrient inputs, minimize soil erosion, or
collect runoff. Filter strips can also enhance wildlife habitat by providing wildlife nesting and feeding
sites, in addition to serving as a pollution control measure. Some filter strips need maintenance such as
mowing of grass or removal of accumulated sediment. Filter strips may be effective for controlling
particulate and soluble pollutants, where sedimentation is not excessive. Thus, in many cases, filter
strips are used as pretreatment or supplemental treatment for other practices within a management
system, rather than as an entire solution to a sedimentation problem (USEPA, 1993). In general, filter
strip effectiveness is dependent on factors such as incoming sediment and nutrient load, flow velocity
and depth, vegetation height and density, and the slope and width of the filter strip (Dillaha et al., 1989).
6.2.3 Water and Sediment Control Basins
Water and sediment control basins may be constructed at the lower end of a field to impound
runoff and retain sediment. Retention ponds or sediment basins help reduce the volume of direct runoff
that causes surface erosion. This, in turn, may help improve the quality of surface water entering
drainage wells. Control basins also allow sediment and adsorbed agricultural chemicals time to settle
and degrade prior to entering an ADW. Consequently, control basins afford the ground water below
them some protection against contamination. Waste treatment lagoons can also be used to retain
agricultural runoff. There is debate, however, about inadequate seals in lagoons, causing seepage
through the lagoon sidewalls and bottom. Usually the long-term seepage rate is low enough that the
concentration of contaminants transported into the ground water does not reach an unacceptable level
(USEPA, 1993).
6.2.4 Crop Rotation
Crop rotation is the successive planting of different crops in the same field. It can break pest
cycles and disrupt weed life cycles, reducing the need for agrichemicals and, thus, helping protect
ground water from contamination. Crop rotation can also increase harvests and provide other benefits.
By improving tillage, it may disrupt disease, insect, and weed reproduction cycles, and, therefore,
increase grain yields beyond those achieved with continuous cropping under similar conditions. The
practice also promotes crop diversification, which provides an economic buffer against price
fluctuations associated with crops and production inputs, pest infestations, and damaging weather
(NRC, 1989). Planting legumes as part of a crop rotation plan can also provide nitrogen for
subsequent crops, thus aiding nutrient management.
6.3 Fertility Management and Nutrient Management
Fertility management and nutrient management are interchangeable terms. Proper fertilizer
application and management can reduce the quantity of nutrients used in agricultural production.
Fertility management helps protect ground water from contamination by reducing the excess nutrients
September 30, 1999 39
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that may be lost to surface runoff and leachate. A fertility management plan helps farmers (1) apply
nutrients at rates necessary to achieve realistic crop yield goals, (2) improve the timing of nutrient
application, and (3) use agronomic crop production technology to increase nutrient use efficiency.
Fertility management involves testing soil, manure, and plant tissue; using manure and
composted agricultural wastes where possible; properly timing nutrient applications; applying nutrients
to obtain realistic yields; and calibrating application equipment. The application of nutrients during
periods conducive to surface water runoff and soil leaching is discouraged.
It is necessary to consider realistic crop needs when determining the amount of nutrients to be
applied and the timing of nutrient applications. Testing is needed at a point in the growing cycle when
the farmer is able to predict nutrient need (keeping in mind proper crop yield goals), while allowing
enough time for application and for crops to respond to the application. Premature application can
result in greater loss of fertilizer to the environment. Accounting for all sources of nitrogen in soil (newly
applied sources, residual nitrate in the soil, nitrate mineralized from soil organic matter, and nitrate in
precipitation and irrigation water) will provide a safeguard against excess fertilizer application.
Furthermore, slow-release fertilizers and nitrification inhibitors may enhance fertilizer effectiveness.
Proper calibration and operation of equipment is needed to ensure accurate application rates.
6.4 Integrated Pest Management
Integrated pest management (IPM) is a mixture of chemical and other, nonpesticide, methods
to control pests. Pesticides protect food and fiber crops from losses caused by weeds, diseases,
insects, and other pests. However, the potential for pesticides to contaminate surface water and
ground water has caused farmers and the public to re-evaluate pesticide use. Keeping a crop free of
pests is usually not possible, and attempting to do so can be prohibitively expensive - not only in
monetary terms, but in terms of environmental quality.
IPM combines chemical, cultural, and biological control practices into a single program to
manage pest populations, while minimizing the potential to contaminate surface water and ground water.
Its goal is to keep pest numbers and crop losses from pests below economically damaging levels. IPM
emphasizes preventive and remedial practices that make crops less attractive, more competitive, or
more resistant to pests. IPM practices also reduce opportunities for pests to survive near a crop. They
include timely planting, crop rotation, use of resistant cultivars, and fertility/nutrient management, all of
which contribute to long-term control of pest populations.
IPM practices help attain the goal of preventing ground water contamination from ADWs. This
is accomplished primarily through the reduced use of pesticides, which can contaminate agricultural
drainage water. Significant reductions in pesticide use on some crops can be achieved in IPM
programs while providing maximum protection to humans and the environment, with minimal disruption
of food and fiber production (CAST, 1982). In addition, farmers may select pesticides that are less
persistent, bioaccumulative, or toxic. Predicting pest intensities and calculating crop losses and
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economic injury associated with various pest intensities can provide information useful for improving
application rates and timing.
6.5 Irrigation Management
Irrigated cropland accounts for approximately 15 percent of the harvested U.S. cropland and
approximately 38 percent of the total value of crops produced (Rajinder et al., 1992). The potential
impact of irrigation on ground water quality varies depending on the method of irrigation. ADWs are
sometimes used to return excess irrigation water to an aquifer; this practice can directly inject
contaminants into a USDW. Excessive application or uneven distribution of irrigation water may cause
runoff or deep percolation of water contaminated with agrichemicals and other dissolved matter, which
may eventually reach and contaminate ground water.
Irrigation management involves managing water, soil, and plant resources to optimize
precipitation use and applied irrigation water according to plant water needs. This includes:
Measuring water needs of soil.
• Applying the correct amount of water at the proper time (irrigation scheduling) without
significant soil erosion and translocation of applied water.
Applying the predetermined amount of water (includes measurement).
• Adjusting irrigation system operations to maximize irrigation application uniformity.
• Performing necessary irrigation system maintenance.
Chemigation operations, which add chemicals to irrigation water, need additional management
measures, including:
• Use of backflow preventers for wells.
• Minimizing the harmful amounts of contaminated water that discharge from the edge of the field.
• Controlling deep percolation.
Using a tailwater management system for furrow irrigation.
6.6 Livestock Waste Management
Livestock waste includes fecal and urinary wastes; process water (such as that from a milking
parlor); and the feed, bedding, litter, and soil with which they become intermixed.
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Contaminants from livestock production can be transported to ADWs both through-surface
runoff and leaching into subsurface drainage and ground water. An objective of livestock waste
management is to minimize the amount of solid material transported by surface runoff and reduce the
amount of dissolved substances that contaminate surface runoff and ground water. The BMPs outlined
in the box below can be used to control potential contamination of surface and ground water by animal
wastes. These BMPs can be used in an approved livestock waste management plan.
Livestock Waste Management BMPs
• Annual soil testing to determine nutrient content and evaluation of efficiency of nutrient use in
the production system.
• Nutrient analysis of the waste prior to application to match with crop requirements.
• Determination of application rates based on crop needs and soil hydraulic conditions.
• Timing of application to match maximum crop uptake such as spring or summer.
• Incorporation into soil to avoid volatilization or loss in runoff.
• Installation of vegetative filter strips to control sediment and nutrient losses in feedlot and dairy
runoff.
• Livestock access restrictions to streams, lakes, and other impoundments, and rotational
grazing to maintain sufficient vegetative cover on pasture land.
• Neutralization of waste streams, or waste strength reduction.
• Erosion and runoff control methods and buffer zones.
• Burial or disposal of animal carcasses away from drainage wells and conduits to ground water
and surface water.
Source: North Carolina State University, 1982.
As discussed in Section 4.3.4, there is a risk of contamination when subsurface tile lines and
ADWs are located downhill or downgradient from earthen lagoons used to store manure.
Contamination could result from overland spills due to overtopping or a breach of surrounding surface
berms, from seepage leaving the bottom of the lagoon, and from a subsurface breach that can allow
fluids from a lagoon to directly enter a tile line and flow to an ADW (like pulling a plug out of a full bath
tub). There have been several subsurface "spills" of this latter kind in Iowa where lagoons emptied
through a breach to a tile line and traveled through the tile to a surface outlet. In these instances, no spill
was evident at the surface but it was discovered either through the observation of a sudden drop in the
liquid level or through the report of a large volume spill in a nearby river or stream. To date, there has
not been a documented case in which a subsurface spill of this magnitude has entered tiles connected to
an ADW, but the potential continues to exist (Heathcote, 1999).
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Therefore, it is important to never locate earthen manure storage lagoons where a surface or
subsurface breach could cause wastes to reach an ADW. Precisely because of the risk of spills
entering tiles and traveling through the tile system to an ADW possibly a mile or more away, Iowa has a
new law that prohibits earthen lagoons in the drainage basin of an ADW. However, if earthen manure
storage lagoons are located in the vicinity of an ADW in other states, strict precautions are necessary to
prevent releases. For example, it would be necessary to line such lagoons with compacted clay (at
least three-feet thick) and/or synthetic materials. The sides and bottom of livestock waste treatment
lagoons have been found to seal somewhat, but this layer by itself only reduces seepage and does not
prevent fluid movement altogether.
In addition to the above concerns associated with earthen manure storage lagoons, ground
water may become contaminated by leachate from feedlots, runoff holding ponds, manure stockpiles,
and silos. ADWs may be a direct conduit for such leachate to reach ground water. To minimize the
potential threat posed by removal of manure from feedlot surfaces, it is necessary to exercise caution to
preserve the integrity of the "surface-seal layer." Formed on active feedlots, this layer is normally 2 to
4 inches thick and may reduce water movement downward (US Congress, 1990).
On some farms, an applicable BMP involves applying liquid manure to agricultural land in an
environmentally acceptable manner while maintaining or improving soil resources. This includes
carefully managing the land application of manure in areas that drain to ADWs. In particular, nutrient
loading needs to be carefully managed to prevent subsurface leaching and hydraulic loading needs to be
controlled to prevent overloading and rapid soil infiltration that can drain directly into an ADW. Such
overloading was the primary cause of one of the contamination incidents in Iowa described in Section
5.2.2. Moreover, in the vicinity of ADWs, land application of manure needs to be prohibited on frozen
or snow-covered ground and spray application needs to be either prohibited altogether or allowed only
under closely managed circumstances that ensure incorporation into the soil and avoid loss in runoff.
In conjunction with livestock waste management BMPs, grazing management practices can
maintain enough live vegetation and litter cover to protect the soil from erosion and help prevent ground
water contamination. Appropriate systems adjust grazing intensity and duration to reflect the availability
of forage and feed designated for livestock uses and control animal movements through the operating
unit of range or pasture. Practices that accomplish this are:
• Deferred grazing: Postponing grazing or resting grazing land for prescribed periods.
• Planned grazing system: A practice in which two or more grazing units are alternately rested and
grazed in a planned sequence for a period of years, and rest periods may be throughout the
year or during the growing season of key plants.
• Proper grazing use: Grazing at an intensity that will maintain enough cover to protect the soil and
maintain or improve the quantity and quality of desirable vegetation.
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• Proper woodland grazing: Grazing wooded areas at an intensity that will maintain adequate
cover for soil protection and maintain or improve the quantity or quality of trees and forage
vegetation.
• Pasture and hay land management: Proper treatment and use of pasture or hay land.
6.7 Improvement of Surface Drainage
Both surface drainage (runoff) and subsurface drainage deliver water and contaminants to
ADWs. Subsurface drainage systems consist of buried drainage tiles or corrugated plastic piping
systems installed to lower the water table and drain soil with poor natural drainage. Studies have
shown that nitrate and pesticides may be found in waters of subsurface drainage systems (Ritter et al,
1995). As discussed, however, surface waters carry most of the suspended solids (sediments),
microbes, animal wastes, and the highest concentrations of most pesticides to ADWs. Hence,
improvements in the design and management of drainage waters reaching an ADW can help to reduce
the threat to ground water.
Examples of such improvements include the elimination of surface water inlets on a drainage
well or within the tile system connected to such a well to prevent direct entry of surface water runoff.
This might include making the cisterns water tight, raising the inlets (sidewalls) above maximum ponding
levels, and marking drainage well locations so they are not damaged by plows or other farm equipment.
Similarly, some subsurface drainage systems have surface water inlets upslope from ADWs. It is
important to also close these inlets to ensure no surface water entry. The removal of direct surface
water runoff from ADW systems will significantly reduce most contaminants including pesticides and
bacteria, but this is not the case for nitrate. Research in Iowa has shown that concentrations of nitrate
will increase in drainage water when surface water intakes are removed because all drainage is forced
to infiltrate through the soil profile where additional nitrate is leached from the soil. Current Iowa
research shows that other innovative approaches such as processing drainage water through wetland
areas holds some promise in helping remove nitrate prior to injection of drainage water in ADWs
(Heathcote, 1999).
7. CURRENT REGULATORY REQUIREMENTS
As discussed below, several federal, state, and local programs exist that either directly manage
or regulate ADWs, or impact them indirectly through broad based water pollution prevention initiatives.
7.1 Federal Programs
On the federal level, management and regulation of agricultural drainage falls primarily under the
UIC program authorized by the Safe Drinking Water Act (SDWA). Some states and localities have
used these authorities, as well as their own authorities, to extend the controls in their areas to address
endemic concerns associated with ADWs. Other federal programs that address ADWs indirectly are
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implemented under the Clean Water Act (CWA), the Coastal Zone Management Act (CZMA), and
the Coastal Zone Reauthorization Amendments of 1990 (CZARA).
7.1.1 SDWA
Class V wells are regulated under the authority of Part C of SDWA. Congress enacted the
SDWA to ensure protection of the quality of drinking water in the United States, and Part C specifically
mandates the regulation of underground injection of fluids through wells. USEPA has promulgated a
series of UIC regulations under this authority. USEPA directly implements these regulations for Class
V wells in 19 states or territories (Alaska, American Samoa, Arizona, California, Colorado, Hawaii,
Indiana, Iowa, Kentucky, Michigan, Minnesota, Montana, New York, Pennsylvania, South Dakota,
Tennessee, Virginia, Virgin Islands, and Washington, DC). USEPA also directly implements all Class
V UIC programs on Tribal lands. In all other states, which are called Primacy States, state agencies
implement the Class V UIC program, with primary enforcement responsibility.
ADWs currently are not subject to any specific regulations tailored just for them, but rather are
subject to the UIC regulations that exist for all Class V wells. Under 40 CFR 144.12(a), owners or
operators of all injection wells, including ADWs, are prohibited from engaging in any injection activity
that allows the movement of fluids containing any contaminant into USDWs, "if the presence of that
contaminant may cause a violation of any primary drinking water regulation ... or may otherwise
adversely affect the health of persons."
Owners or operators of Class V wells are required to submit basic inventory information under
40 CFR 144.26. When the owner or operator submits inventory information and is operating the well
such that a USDW is not endangered, the operation of the Class V well is authorized by rule.
Moreover, under section 144.27, USEPA may require owners or operators of any Class V well, in
USEPA-administered programs, to submit additional information deemed necessary to protect
USDWs. Owners or operators who fail to submit the information required under sections 144.26 and
144.27 are prohibited from using their wells.
Sections 144.12(c) and (d) prescribe mandatory and discretionary actions to be taken by the
UIC Program Director if a Class V well is not in compliance with section 144.12(a). Specifically, the
Director must choose between requiring the injector to apply for an individual permit, ordering such
action as closure of the well to prevent endangerment, or taking an enforcement action. Because
ADWs (like other kinds of Class V wells) are authorized by rule, they do not have to obtain a permit
unless required to do so by the UIC Program Director under 40 CFR 144.25. Authorization by rule
terminates upon the effective date of a permit issued or upon proper closure of the well.
Separate from the UIC program, the SDWA Amendments of 1996 establish a requirement for
source water assessments. USEPA published guidance describing how the states should carry out a
source water assessment program within the state's boundaries. The final guidance, entitled Source
Water Assessment and Programs Guidance (EPA 816-R-97-009), was released in August 1997.
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States must conduct source water assessments which are comprised of three steps. First, a
state must delineate the boundaries of the assessment areas in the state from which one or more public
drinking water systems receive supplies of drinking water. In delineating these areas, states must use
"all reasonably available hydrogeologic information on the sources of the supply of drinking water in the
state and the water flow, recharge, and discharge and any other reliable information as the state deems
necessary to adequately determine such areas." Second, the state must identify contaminants of
concern, and for those contaminants, the state must inventory significant potential sources of
contamination in delineated source water protection areas. Class V wells, including ADWs, should be
considered as part of this source inventory, if present in a given area. Third, the state must "determine
the susceptibility of the public water systems in the delineated area to such contaminants." States
should complete all of these steps by May 2003 according to the final guidance.5
7.1.2 CWA
In February 1998, President Clinton released the Clean Water Action Plan (CWAP), which
provides a blueprint for restoring and protecting water quality across the nation. The CWAP describes
over 100 specific actions to expand and strengthen existing efforts to protect water quality. As part of
these efforts, the CWAP calls for the development of a USD A and USEPA unified strategy to minimize
the water quality and public health impacts of animal feeding operations (AFOs). For the purpose of
this strategy, AFOs are agricultural enterprises where animals are kept and raised in confined situations.
AFOs congregate animals, feed, manure and urine, dead animals, and production operations on a small
land area. Feed is brought to the animals rather than the animals grazing or otherwise seeking feed in
pastures or fields.
The USDA and USEPA released a draft Unified National Strategy for Animal Feeding
Operations on September 11, 1998 (http://www.nhq.nrcs.usda.gov/cleanwater/afo/index.html). USDA
and USEPA's goal is for AFO owners and operators to take actions to minimize surface and ground
water pollution from confinement facilities and land application of manure. To accomplish this goal, the
draft unified strategy establishes a national performance expectation that all AFOs should develop and
implement technically sound and economically feasible Comprehensive Nutrient Management Plans
(CNMPs) to minimize impacts on water quality and public health.
In general terms, a CNMP identifies actions or priorities that will be followed to meet clearly
defined nutrient management goals at an agricultural operation. CNMPs should address, at a minimum,
feed management, manure handling and storage, land application of manure, land management, record
keeping, and management of other utilization options (e.g., sale of manure to other farmers, composting
and sale of compost to home owners, and using manure for power generation). The draft Unified
Strategy provides guidance on each of these components of a CNMP and discusses opportunities for
technical and financial assistance for the development of CNMPs.
5 May 2003 is the deadline including an 18-month extension.
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The draft Unified Strategy also outlines a two-pronged approach for providing AFO owners
and operators and the animal agricultural industry with necessary assistance and ensuring protection of
water quality and public health. That approach consists of: (1) voluntary programs for most AFOs; and
(2) regulatory programs for some AFOs.
For the vast majority of AFOs, voluntary efforts will be the principal approach to assist owners
and operators in developing and implementing CNMPs and in reducing water pollution and public
health risks associated with AFOs. While CNMPs are not required for AFOs participating in voluntary
programs, they are strongly encouraged as the best possible means of managing potential water quality
and public health impacts from these operations. The draft Unified Strategy proposes incentives to
further the voluntary development and implementation of CNMPs through locally led conservation,
environmental education, and technical and financial assistance programs.
The primary means for regulating AFOs is through National Pollutant Discharge Elimination
System (NPDES) permits, which have been written to limit discharges to surface waters from certain
AFOs. Such permits have been reserved for relatively large operations defined as "concentrated
animal feeding operations" (CAFOs), where more than 1,000 "animal units" are confined at the facility.
CAFOs that may be subject to NPDES permit requirements also include operations where more than
300 animal units are confined at the facility and: (1) pollutants are discharged into navigable waters
through a manmade ditch, flushing system, or other similar manmade device; or (2) pollutants are
discharged directly into waters that originate outside of and pass over, across, or through the facility or
come into direct contact with the confined animals. In addition, the NPDES permitting agency may,
after conducting an on-site inspection, designate an animal feeding operation of any size as a CAFO
based on a finding that the facility "is a significant contributor of pollution to the waters of the United
States." This may include facilities with 300 animal units or less in certain situations.
While the addition of pollutants from a discrete conveyance (e.g., natural channel or gullies) to
surface waters is regulated under the NPDES program as a "point source" discharge, the CWA
exempts "agricultural stormwater discharges" from the definition of a point source. USEPA has in the
past, and will in the future, assume that discharges from the vast majority of agricultural operations are
exempted from the NPDES program by this provision. The agricultural storm water exemption,
however, does not apply in a small number of circumstances that meet the following criteria:
• The discharge is associated with the land disposal of animal wastes (e.g., manure or other
animal waste) originating from a CAFO (which is defined as a point source within the CWA
and is regulated as a point source); and
• The discharge is not the result of proper agricultural practices (i.e., in general, the disposal
occurred without a CNMP developed by a public official or a certified private party or on a
manner inconsistent with the CNMP).
Finally, the draft Unified Strategy describes the desired outcomes and specific actions that will
be undertaken in coming months and years with respect to seven major strategic issues. These issues
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are: (1) building capacity for CNMP development and implementation; (2) accelerating voluntary,
incentive-based programs; (3) implementing and improving the existing regulatory program; (4)
coordinated research, technical innovation, compliance assistance, and technology transfer; (5)
encouraging industry leadership; (6) data coordination; and (7) performance measures and
accountability. Actions planned under Strategic Issue #3 (implementing and improving the existing
regulatory program) include USEPA coordination with the states to establish a two-phase approach to
issuing NPDES permits to CAFOs, development of NPDES permitting guidance and model permits,
development of state-specific CAFO permitting strategies, review and revision of effluent limitations
guidelines for feedlots, revision of the NPDES permit regulations regarding CAFOs, and improved
implementation of the existing CWA compliance and enforcement program.
7.1.3 CZMA and CZARA
The 1990 CZARA included a new requirement (found in § 6217 of CZARA) that coastal
states with coastal zone management programs under § 306 of the CZMA develop and implement
Coastal Nonpoint Pollution Control Programs. Twenty-nine states were required to submit plans to
USEPA and the National Oceanic and Atmospheric Administration (NOAA) by July 1995, and to
implement the management measures by January 1999. The plans are required to establish specific
management measures to control nonpoint pollution from several different types of sources, including
urban runoff, hydromodification, marinas, silviculture, and agriculture. States may apply the
management measures in their § 6217 CZARA plans to both point and nonpoint sources in the
management area, as long as NPDES requirements also are met for point sources subject to CWA
NPDES permitting requirements.
The coastal nonpoint program must be based on the impact of land and water uses on coastal
waters. Identification and mitigation of such impacts is a five-step process. First, each state must
identify its impaired and threatened coastal waters. Second, states must identify the land uses that
individually or cumulatively cause or contribute to coastal water quality impairments. Third, the critical
coastal areas that need additional measures to protect against current and anticipated nonpoint pollution
problems must be identified and established. A state, for example, could specify a land area along a
shoreline and extending inland a specified distance. Fourth, once the land uses and critical coastal areas
have been identified, states must describe the management measures applicable to those areas and land
uses to address the sources of nonpoint pollution. Finally, the state selects the additional management
measures to be implemented.
In practice, the critical coastal area in which the management measures called for by the
program are implemented is usually the coastal watershed, although NOAA reviews the state's §6217
management area, and when necessary will recommend that the management area extend inland of the
coastal watershed (NOAA/USEPA, 1993).
The statute defines management measures as the following:
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"economically achievable measures for the control of the addition of pollutants from
existing and new categories and classes of nonpoint sources of pollution, which reflect
the greatest degree of pollutant reduction achievable through the application of the best
available nonpoint pollution control practices, technologies, siting criteria, operating
methods, or other alternatives."
Guidance prepared by USEPA in 1993 specifies management measures for sources of
nonpoint pollution from agricultural sources, as well as management measures for other types of sources
(USEPA, 1993). The management measures are grouped into six major categories: (1) Erosion and
sediment control management measures; (2) Management measures for facility wastewater and runoff
from confined animal facility management; (3) Nutrient management measures; (4) Pesticide
management measures; (5) Grazing management measures; and (6) Irrigation water management
measures. Most of these measures are summarized in Section 6 above.
7.2 State and Local Programs
As discussed in Section 3 above, more than 95% of the documented ADWs in the nation exist
in five states: Idaho, Iowa, Ohio, Texas, and Minnesota. Idaho, Ohio, and Texas are UIC Primacy
States for Class V wells. Attachment A to this volume describes how each of these states currently
regulate ADWs. In brief:
• In Idaho, wells >18 feet deep are individually permitted, while shallower wells are permitted by
rule.
• In Iowa, all ADWs that existed before February 18, 1998 must close or get a permit by
December 31, 2001. New wells in Iowa are generally prohibited, although they may be
permitted under strict conditions.
• The regulations in Ohio authorize ADWs by rule as long as inventory information is submitted.
All existing ADWs in the state are considered out of compliance (not rule authorized) because
their owners or operators did not submit required inventory information by the applicable
deadline. Any new ADWs would be examined individually by the state and subjected to
conditions believed necessary to protect USDWs.
• All of the known ADWs in Texas received individual authorizations for construction of the
wells. Owners or operators of any new wells would have to submit basic information to the
state, which would either disapprove the well or authorize it subject to conditions deemed
necessary to protect USDWs.
• Minnesota bans new ADWs and requires existing ADWs to close when found, but
acknowledges that some continue to exist.
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The regulatory picture in other states with few or no ADWs in the current inventory is varied.
In particular, Georgia, North Carolina, and North Dakota have banned new ADWs and require
existing ADWs to close when they are found. Oregon, Washington, and Wisconsin also have a ban,
but recognize that some ADWs continue to exist. Most other states authorize ADWs by rule,
consistent with the existing federal UIC requirements.
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ATTACHMENT A
STATE AND LOCAL PROGRAM DESCRIPTIONS
This attachment does not describe every state's program; instead it focuses on the five states
where relatively large numbers of ADWs are known to exist: Idaho, Iowa, Minnesota, Ohio, and
Texas. Altogether, these five states have a total of 1,020 documented ADWs, which is slightly more
than 95% of the documented well inventory for the nation.
Idaho
Idaho is a UIC Primacy State for Class V wells and has promulgated regulations for the UIC
program in the Idaho Administrative Code (IDAPA), Title 3, Chapter 3. Deep injection wells are
defined as more than 18 feet in vertical depth below the land surface (37.03.03.010.11 IDAPA).
Wells are further classified, with Class V Subclass 5F1 defined as agricultural runoff waste wells
(37.03.03.01.e.j IDAPA).
Authorization
Construction and use of shallow injection wells is authorized by rule, provided that inventory
information is provided and use of the well does not result in unreasonable contamination of a drinking
water source or cause a violation of water quality standards that would affect a beneficial use
(37.03.03.03.d. IDAPA). Construction and use of Class V deep injection wells may be authorized by
permit (37.03.03.03 c IDAPA). The regulations outline detailed specifications for the information that
must be supplied in a permit application (37.03.03.035 IDAPA).
Operating Requirements
Standards for the quality of injected fluids and criteria for location and use are established for
rule-authorized wells, as well as for wells requiring permits. The rules are based on the premise that if
the injected fluids meet MCLs for drinking water for physical, chemical, and radiological contaminants
at the wellhead, and if ground water produced from adjacent points of diversion for beneficial use
meets the water quality standards found in Idaho's "Water Quality Standards and Wastewater
Treatment Requirements" (16.01.02 IDAPA), then the aquifer will be protected from unreasonable
contamination. The state may, when it is deemed necessary, require specific injection wells to be
constructed and operated in compliance with additional requirements (37.03.03.050.01 IDAPA (Rule
50)). Rule-authorized wells "shall conform to the drinking water standards at the point of injection and
not cause any water quality standards to be violated at the point of beneficial use" (37.03.03.050.04.d.
IDAPA).
Monitoring, record keeping, and reporting may be required if the state finds that the well may
adversely affect a drinking water source or is injecting a contaminant that could have an unacceptable
effect upon the quality of the ground waters of the state (37.03.03.055 IDAPA (Rule 55)).
September 30, 1999 51
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Plugging and Abandonment
The Idaho Department of Water Resources (IDWR) has prepared "General Guidelines for
Abandonment of Injection Wells," which are not included in the regulatory requirements. IDWR
expects to approve the final abandonment procedure for each well. The General Guidelines
recommend the following:
• Pull casing, if possible. If casing is not pulled, cut casing a minimum of two feet below land
surface. The total depth of the well should be measured.
• If the casing is left in place, it should be perforated and neat cement with up to 5% bentonite
can be pressure-grouted to fill the hole. As an alternative, when the casing is not pulled,
owners/operators may use course bentonite chips or pellets. If the well extends into the aquifer,
the chips or pellets must be run over a screen to prevent any dust from entering the hole. No
dust is allowed to enter the bore hole because of the potential for bridging. Perforation of
casing is not required under this alternative.
• If a well extends into the aquifer, a clean pit-run gravel or road mix may be used to fill bore up
to ten feet below top of saturated zone or ten feet below the bottom of casing, whichever is
deeper, and cement grout or bentonite clay used to surface. The use of gravel may not be
allowed if the lithology is undetermined or unsuitable. A cement cap should be placed at top of
casing if not pulled, with a minimum of two feet of soil overlying filled hole/cap.
• Abandonment of well must be witnessed by IDWR representative.
Financial Responsibility
No financial responsibility requirement exists for rule-authorized ADWs. Permitted wells are
required by the permit to demonstrate financial responsibility through a performance bond or other
appropriate means to abandon the injection well according to the conditions of the permit.
(37.03.03.35.03.6 IDAPA).
Iowa
Iowa is a Direct Implementation State. However, the State Department of Natural Resources
(DNR) has promulgated regulations for ADWs in 567 Iowa Administrative Code (IAC) Chapters 50
and 51. In 1997, ADWs in designated drainage areas (areas where there are anaerobic lagoons or
earthen manure storage structures that require permits under 567-65 IAC) were required to be closed
and BMPs were required for all other ADWs (Senate File 473).
September 30, 1999 52
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Authorization
All owners of ADWs that existed prior to February 18, 1998 are required to have applied for a
permit by July 1, 1999 or close their well by December 31, 2001 (567-50.4(1) IAC). In particular, a
permit is required for diversion of water or any other material from the surface directly into any aquifer,
including diversion by means of an ADW. Diversion by tile or ditch into a sinkhole or quarry excavated
in carbonate rock is presumed to be a diversion from the surface directly into an aquifer in the absence
of convincing evidence to the contrary (567-51.3 IAC). Water in drain tile lines is considered surface
water (567-51.4 IAC). Any person who proposes to pump or divert by gravity more than 25,000
gallons of water during a period of 24 hours or less from any source of ground water or surface water,
including streams bordering the state, impound surface water, divert surface runoff into a well, sinkhole,
or excavation, or inject water or any material into a well is required to clarify with DNR if a permit is
required under 567-51 (567-50.1 IAC). If the ADW is located in a legally organized drainage district,
the drainage district is a joint applicant for the permit (567-50.4(1) IAC).
All supporting information necessary to allow the DNR to investigate the permit application
must be supplied, including certain specified information:
• Location of the ADW to at least the nearest quarter-quarter section, township, and range;
• Diameter and depth of the ADW, if known;
• Description and ownership of the lands that are drained by the ADW and associated drainage
system;
Location of tiles that drain to the ADW, if known, and the existence of any existing surface
water intakes;
The location and description of any earthen storage structures, confinement feeding operations,
or open feedlots within the agricultural drainage area;
• Information regarding any known connections between the ADW or its drainage system and
wastewater disposal or storage systems such as septic tanks and the location of such
connections;
• The nature and extent of any agreements between the well owner and adjacent landowners
who have lands that are drained by the ADW and associated tile drainage system; and
• Any available information regarding the economic and physical feasibility of closing the ADW
(567-50.6 and 50.6(7) IAC).
The Iowa rules specify criteria for issuance of permits. A permit may not be issued if (1) the
ADW is located within a designated drainage area (i.e., within the drainage basin of a permitted
September 30, 1999 53
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anaerobic lagoon or earthen manure storage structure); or (2) if the ADW would be constructed after
February 18, 1998. A permit may be issued if there is reasonable assurance that the applicant(s) can
minimize the contamination potential to the aquifer through closure of surface water intakes, elimination
of any septic system connections, and other appropriate management practices including nutrient and
pesticide management as required under 567-52.21(2) IAC. In addition, there must be no
economically and physically viable alternatives to the use of the ADW. The DNR will consult with the
Division of Soil Conservation, Department of Agriculture, and other parties with drainage expertise as
necessary. In determining if a viable drainage alternative exists, the DNR will consider the impact that
closure of the ADW would have on lands drained by the ADW if an alternative drainage system is not
provided; the cost and feasibility of providing an alternative outlet, including systems constructed by the
Division of Soil Conservation; the availability of public assistance for constructing an alternative outlet or
for compensation for loss of productivity on lands drained by the ADW; and the results of engineering
studies under 567-52.21(2) IAC.
New wells in Iowa are generally prohibited, although they may be permitted under the same set
of strict conditions outlined above. In general, these conditions are so stringent that it is unlikely that
new ADWs in Iowa will receive a permit.
Operating Requirements
A permitted ADW may be subject to restrictions related to its potential effects on ground water
or surface water. These restrictions are specified in 567-52.2 IAC. These provisions are unlikely to
be pertinent to many ADWs.
The following permit conditions are also specified for ADWs in 567-39.7 and -39.8 IAC:
• All surface water intakes must be removed by December 31, 2001. Additional tile lines may
be added to compensate for removal of surface water intakes provided that the additional tiles
do not increase the size of the ADW area. Replacement tiles must conform to specified
standards.
• Cisterns must be sealed or otherwise modified as necessary by December 31, 2001 to prevent
direct entry of surface water. Compliance with state-specified wellhead protection Interim
Standard 981 is considered compliance.
• The ADW or cistern must be provided with a locked cover to prevent unauthorized access.
Ventilation must not allow surface water to enter the ADW.
• Repair and maintenance must be conducted as necessary. The ADW and associated tile
drainage system must be maintained in a condition so as to prevent surface water which has not
filtered through the soil profile from entering the drainage well.
September 30, 1999 54
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DNR approval is required for modification of the ADW. Construction of new surface water
intakes is not allowed. The drainage system may be modified without DNR approval if the
modifications do not enlarge the ADW area.
If use of the ADW is discontinued, DNR must be notified and closure made in accordance with
567-Chapter 39 I AC or by an alternative method approved by DNR.
• DNR may modify or cancel permits, or require other actions to protect the public health and
safety, protect the public interest in lands and waters, or prevent any substantial harm to
persons or property.
• Effluent from wastewater treatment or storage systems, including septic systems, may not be
allowed to go directly into the ADW or associated drainage system. Runoff controls may be
required for feedlots that discharge across lands drained by an ADW.
• Nitrogen application on lands within an ADW drainage area is limited to the levels necessary to
obtain optimum crop yields.
• Liquid animal wastes to lands drained by an ADW may not result in a discharge of waste to the
ADW or associated drainage system.
Pesticide application within the ADW drainage area must conform to state standards in Iowa
Code Chapter 206.
Prior to issuance of a permit, the applicant must conduct an engineering study of the physical
and economic feasibility of alternatives to the continued use of the ADW.
Plugging and Abandonment
Closure is required to satisfy the requirements of 567-Chapter 39 IAC on plugging of
abandoned wells or alternative means approved by DNR. Cisterns must be filled in or removed and
any tile lines must be removed for a distance of 10 feet around the wellhead or be replaced with non-
perforated pipe. Under Chapter 39, approved sealing materials are bentonite products and cement.
Filling materials also are specified. The plugging procedures specified vary according to the depth and
diameter of the well (567-39.7 and -39.8 IAC).
Minnesota
Minnesota is a Direct Implementation State. It currently has no separate Class V rules for
ADWs. The 1989 Minnesota Ground Water Protection Act (Minn. Laws ch. 326), however,
establishes that it is the goal of the state that ground water be maintained in its natural condition, free
from any degradation by human activities. The state's regulations implementing the Act also specify that
"for the conservation of underground water supplies for present and future generations and prevention
September 30, 1999 55
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of possible health hazards, it is necessary and proper that the Minnesota Pollution Control Agency
(MFC A) employ a nondegradation policy to prevent pollution of the underground waters of the state"
(7060.0200 Minnesota Rules (MR) and 7060.0500 MR).
Consequently, the state prohibits discharge into both the saturated and the unsaturated zones by
means of injection wells or other devices (7060.0600 Subparts 1 and 2, MR). No sewage, industrial
waste, or other wastes shall be discharged directly into the zone of saturation; no sewage, industrial
waste, other waste, or other pollutants shall be allowed to be discharged to the unsaturated zone or
deposited in such place, manner, or quantity that the effluent or residue therefrom, upon reaching the
water table, may actually or potentially preclude or limit the use of the underground waters as a potable
water supply; and no discharge or deposit shall be allowed that may pollute the underground waters.
In addition, the Department of Health has promulgated regulations pertaining to wells and
borings that provide that a well or boring must not be used for disposal of surface water, ground water,
or any other liquid, gas or chemical (4725.2050 MR). Wells are defined as drilled, dug, or bored
excavations that end below the water table (4725.0100 Subpart 51 MR and 1031.005 Subdivision 21
Minnesota Statutes). This prohibition therefore does not address injection into the unsaturated zone.
Although ADWs may exist that predate the ban, the rules in 7060.0600 and 4725.2050 MR
are considered by the MFC A to ban all new ADWs in the state, including wells that do not inject
directly into a USDW.
Ohio
Ohio is a UIC Primacy State for Class V wells. Regulations establishing the UIC program are
found in Chapter 3745-34 of the Ohio Administrative Code (OAC).
Authorization
Any underground injection, except as authorized by permit or rule, is prohibited. Injection into
Class V wells is authorized by rule (3745-34-13 OAC). The permit-by-rule provision requires owners
or operators of Class V wells to supply information on the facility name and location, legal contact,
ownership of the facility, nature and type of well, and operating status.
According to an official with the Ohio EPA, owners or operators of existing ADWs in the state
did not submit required inventory information within the applicable deadline, and thus are technically out
of compliance, as opposed to currently rule authorized. However, given the current priorities and
limited funding of the state UIC program, these wells are not being called in for a permit and are not
being subject to any enforcement action. If a new ADW were identified, the state would investigate its
particular circumstances and impose conditions to ensure that it did not endanger USDWs (Orr, 1999).
September 30, 1999 56
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Operating Requirements
ADWs are not considered to be subject to the conditions applicable to all permits in 3745-34-
26 OAC. An ADW, however, could be subject to the requirements for corrective action, monitoring
and reporting, or operation, if required for the protection of USDWs (3745-34-14 OAC).
Texas
Texas is a UIC Primacy State for Class V wells. The Injection Well Act (Chapter 27 of the
Texas Water Code) and Title 3 of the Natural Resources Code provide statutory authority for the UIC
program. Implementing regulations are found in Title 30, Chapter 331 of the Texas Administrative
Code (TAC).
Authorization
Underground injection is prohibited unless authorized by permit or rule (331.7 TAC). In
general, injection into a Class V well is authorized by rule, although the Texas Natural Resource
Conservation Commission (TNRCC) may require the owner or operator of a well authorized by rule to
apply for and obtain an individual permit (331.9 TAC). No permit or authorization by rule is allowed
where an injection well causes or allows the movement of fluid that would result in the pollution of a
USDW. A permit or authorization by rule must include terms and conditions reasonably necessary to
protect fresh water from pollution (331.5 TAC).
All of the 135 ADWs presently on record with the TNRCC are authorized by rule. All of these
wells were constructed several years ago, when it was only necessary to receive authorization to
construct a well. Today, a well owner or operator would need both authorization to construct and
operate the well. Although TNRCC has not received an application for a new ADW in at least three
years, the process would start with the proposed well owner or operator submitting a form to get the
state's approval. If approved, the state would then grant authorization in the form of a letter that would
include any conditions believed necessary to protect USDWs. This process and the resulting
conditions would be simpler than those associated with an individual permit (Eyster, 1999).
Siting and Construction
All Class V wells are required to be completed in accordance with explicit specifications in the
rules, unless otherwise authorized by the TNRCC. These specifications are:
• A form provided either by the Water Well Drillers Board or the TNRCC must be completed.
• The annular space between the borehole and the casing must be filled from ground level to a
depth of not less than 10 feet below the land surface or well head with cement slurry. Special
requirements are imposed in areas of shallow unconfmed ground water aquifers and in areas of
confined ground water aquifers with artesian head.
September 30, 1999 57
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In all wells where plastic casing is used, a concrete slab or sealing block must be placed above
the cement slurry around the well at the ground surface; the rules include additional
specifications concerning the slab.
In wells where steel casing is used, a slab or block will be required above the cement slurry,
except when a pitless adaptor is used, and the rules contain additional requirements concerning
the adaptor.
All wells must be completed so that aquifers or zones containing waters that differ significantly
in chemical quality are not allowed to commingle through the borehole-casing annulus or the
gravel pack and cause degradation of any aquifer zone.
The well casing must be capped or completed in a manner that will prevent pollutants from
entering the well.
When undesirable water is encountered in a Class V well, the undesirable water must be sealed
off and confined to the zone(s) of origin (331.132 TAG).
Operating Requirements
None specified. Chapter 331, Subpart H, " Standards for Class V Wells" addresses only
construction and closure standards (331.131 to 331.133 TAG).
Mechanical Integrity Testing
Injection may be prohibited for Class V wells that lack mechanical integrity, although this
requirement would be unlikely to be applied to ADWs (because they do not have mechanical integrity
like Class I or n wells). The TNRCC may require a demonstration of mechanical integrity at any time if
there is reason to believe mechanical integrity is lacking. The TNRCC may allow plugging of the well
or require the permittee to perform additional construction, operation, monitoring, reporting, and
corrective actions that are necessary to prevent the movement of fluid into or between USDWs caused
by the lack of mechanical integrity. Injection may resume on written notification from the TNRCC that
mechanical integrity has been demonstrated (331.4 TAG).
Plugging and Abandonment
Plugging and abandonment of a well authorized by rule is required to be accomplished in
accordance with §331.46 TAG (331.9 TAG). In addition, closure standards specific to Class V wells
provide that closure is to be accomplished by removing all of the removable casing and filling the entire
well with cement to land surface. Alternatively, if use of the well is to be permanently discontinued, and
if the well does not contain undesirable water, the well may be filled with fine sand, clay, or heavy mud
followed by a cement plug extending from the land surface to a depth of not less than 10 feet. If the use
September 30, 1999 58
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of a well that does contain undesirable water is to be permanently discontinued, either the zone(s)
containing undesirable water or the fresh water zone(s) must be isolated with cement plugs and the
remainder of the wellbore filled with sand, clay, or heavy mud to form a base for a cement plug
extending from the land surface to a depth of not less than 10 feet (331.133 TAG).
Financial Responsibility
Chapter 27 of the Texas Water Code, "Injection Wells," enacts financial responsibility
requirements for persons to whom an injection well permit is issued. A performance bond or other
form of financial security may be required to ensure that an abandoned well is properly plugged (§
27.073). Detailed financial responsibility requirements also are contained in the state's UIC regulations
(331.141 to 331.144 TAG). A permittee is required to secure and maintain a performance bond or
other equivalent form of financial assurance or guarantee to ensure the closing, plugging, abandonment,
and post-closure care of the injection operation. However, the requirement, unless incorporated into a
permit, applies specifically only to Class I and Class m wells and is unlikely to be applied to ADWs
(331.142 TAG).
September 30, 1999 59
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