### - - ------- - -- ~ . United States Robert S . Kerr Environmental Center for Environmental Environmental Protection Research Laboratory Research Information Agency Ada OK 74820 Cincinnati OH 45268 Technology Transfer EPA/625/6-87/016 

# EPA Handbook 06- 2 

### 2-06 

# Ground Water

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EPA/625/6-87/01 6 March 1987


# Handbook 

# Ground Water

U .S . Environmental Protection Agency Office of Research and Development Center for Environmental Research Informatio n

Cincinnati, OH 4526 8 Robert S . Kerr Environmental Research Laboratory

Ada, Oklahoma 74820

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Figure 1-2 Plume of leachate migrating from a sanita ry iandfili on a sandy aquifer using contours of chloride

Concentration ( from Freeze and Cherry , 1979) . 760 Landfill
. . .. : : ; . ., ; •, 230 740 225 

### - -, - ~ -I-- 720 6 220 m

° 10D 0 - . c 215 o > ~ 0~ t .8 /O 20o 210 I m s O 680 Sand 25 ~ ° `t?d5 E , Chloride concentration, mg/ I ~ n Standpipe tip 2(10 0 100 200 (meters) ° Piezometer ti p 640 ' . •• Multi-level sampling point 0 200 400 600 (feet) I 1 .1 1 T Water table Horizontal Scale ~ Clay -~ Flow direction
Figure 1-3 Vertical movement of contaminants along a n

old, abandoned, or improperly constructed 1 ,3.4 Recharge from Surface Water well (from Deutsch, 1961) . Normally, ground water moves toward or "discharges" to surface water bodies (see discussion, Abandoned Well Chapter 4) . Occasionally, however, the hydrauli c To Municipal gradient is such that surface water has a higher Disposal Pond (Corroded Casing) supply potential than ground water (such as during flood stages), causing a reversal in flow . Contaminanis in Water Tabie UP Per Aquifer . . . . ; . , - .%'
. •. . 

### the su rf

### ace water can then enter the ground-water • • : . . : , . Piezometric Surface System . Contaminated Water Reversal of flow can also be caused by pumping (Figure 1-4) . Lowering the ground-water level to a level near a surface water body can induce 'eanaQ e Aquiciude - through the stream or lake bed . Contamination of a glacial sand and gravel aquifer by organic compounds - _ = - - - -- - - - __7 

### present in an 

### adjacent river in such a manner has been documented (Schwarzenbach et al., 1983) . LowerAquifer
. : . .': .' ' . . 

### 1 

## .4 Sources of Ground-Wate r Contaminated Water 

## Contamination

. . .. . . . . . . .• . .• . . . . . . . : . . A wide variety of ground-water contamination : . . . : . . : : . : : . . . . .• . . . . . sources have been identified . As previously mentioned, contaminant releases to ground water can occur by design, by accident, or by neglect . The Office of Technology Assessment (OTA, 1984) grouped 33 types of ground-water contamination sources into six major categories (Table 1-2) based on the general nature of the contaminating activity . A number of these sources are depicted in Figure 1-5
. Category 1 includes sources that are intentionally designed to discharge substances . Subsurface percolation systems, such as septic tanks and cess pools, injection wells, and land application of wastewater or sludges fall within this category . Such
4

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Figure 1-4 Contaminated water induced to flow from a number of sources in this category are considered

surface water to g ro und water by pumping °waste" sources (e .g ., landfills, dumps, (from Miller, 1980) . impoundments, etc .), many others are "non-waste" related sources . Storage tanks, stockpiles, and a variety of containers with residues of commercial products have been found to contribute contaminants inal water Table - ~- to ground water
. Contaminated Orig --'- Surface Water PU Category III consists of sources designed to retain

---- ---mpin9 Water Level substances during transport or transmission . Such sources primarily consist of pipelines and material transport or transfer operations . Contaminant release s 

### ,Aquifer generally occur by accident or neglect ; for example, as a result of pipeline breakage or a traffic accident
. Screen Again, most substances which would be subject to

release from sources within this category are not wastes but raw materials or products to be used for some beneficial purpose

. Category IV includes those sources discharging systems are primarily designed to use the natural substances as a consequence of other planned capacity of the soil materials to degrade wastewaters . activities . This category contains a number of Injected wastewaters are often placed in unusable agriculturally related sources such as irrigation return zones to be assimilated with poor quality ground flows, feedlot operations, and pesticide and fertilizer water of natural origin . Septic tanks and cess pools applications . A number of sources related to urban have been estimated to discharge the largest volume activities such as highway desalting, urban runoff, and of wastewater into the ground and are the most atmospheric deposition are included . Surface and frequently reported source of ground-water underground mine-related drainage also fall within contamination (Miller, 1980) . this category . Injection wells are another major potential source of Category V comprises sources providing conduits or contamination . Although injection wells can be inducing discharge through altered flow patterns . For constructed and operated properly, contamination of the most part, such sources are unintentional ground water can occur in several ways (EPA, 1979) : ground-water contamination sources and include o Faulty well construction (e .g ., drilling and casing) water, oil, and gas production wells, monitorin ;; - :~i!s , exploration holes, and construction excavations . The o The forcing upward of pressurized fluids into potential to contaminate ground water from production nearby wells and aquifers, and faults and wells stems from poor installation and operation fractures of confining beds -methods, and incorrect plugging or abandonmen t o The migration of fluids into hydrologically procedures . Such practices create opportunitief for connected usable aquifers cross-contamination by vertical m,y : attun of contaminants
. o Faulty well closing
. Finally, Catego ry VI includes naturally occurring The depths and operating procedures used in waste sources whose discharge is created or made worse injection generally make monitoring and leak by human activity . Ground-water/surface water prevention very difficult to validate . interactions, described in the previous section, and Land application is a popular, inexpensive alternative salt-water intrusion or upconing (ground-water for wastewater and sludge treatment . The U .S . EPA movement upward as a result of pumpage) provide (1983) estimated that 40 to 50 percent of the the basis for this category . Withdrawals significantly in municipal sludge generated every year is applied to excess of recharge can affect ground-water quality
. the land . Salt water intrusion in coastal areas and brine-wate r 

### upconing from deeper formations in inland areas can Category 11 includes sources that are designed to occur when pumpage exceeds the aquifer's natural store, treat, or dispose of substances but are not recharge rate

. designed to release contaminants to the subsurface

. Landfills, open dumps, local residential disposal, Contaminant releases are also referred to as surface impoundments, waste tailings and piles, originating from point or nonpoint sources . Point materials stockpiles, graveyards, aboveground and sources are those which release contaminants from a underground storage tanks, containers, open burning discrete geographic location . Examples include sites, and radioactive disposal sites all fall into this leaking underground storage tanks, septic systems, broad category . It is important to note here that while and injection wells . Nonpoint contamination situations

5p . 5

Table 1-2 Sources of Ground-Water Contamination (from OTA, 1984) .
Category I-Sources designed to discharge substances Open burning and detonation sites Subsurface percolation (e .g ., septic tanks and cesspools) Radioactive disposal sites Injection Well s Hazardous waste Category III-Sources designed to retain substances during Non-hazardous waste (e .g ., brine disposal and drainage) transport or transmissio n Non-waste (e .g ., enhanced recovery, artificial recharge, solution Pipeline s mining, and in-situ mining) Hazardous waste Land application Non-hazardous waste Wastewater (e .g ., spray irrigation) Non-wast e Wastewater byproducts (e .g ., sludge) Materials transport and transfer operations Hazardous waste Hazardous wast e Non-hazardous waste Non-hazardous waste Non-waste Category II-Sources designed to store, treat, and/or dispose o f substances ; discharge through unplanned release Category IV-Sources discharging substances as consequence of other planned activitie s Landfills Irrigation practices (e .g ., return flow) Industrial hazardous waste Pesticide application s Industrial non-hazardous waste Fertilizer applications Municipal sanitary Animal feeding operations Open dumps, including illegal dumping (waste) De-icing salts applications Residential (or local) disposal (waste) Urban ruhnoff Surface impoundments Percolation of atmospheric pollutants Hazardous waste Mining and mine drainage Non-hazardous waste Surface mine-relate d Waste tailings Underground mine-related Waste piles Hazardous waste Category V-Sources providing conduit or inducing discharge Non-hazardous waste through altered flow pattern s Materials stockpiles (non-waste) Production wells Graveyards Oil (and gas) well s Animal burial Geothermal and heat recovery wells Aboveground storage tanks Water supply well s Hazardous waste Other wells (non-waste) Non-hazardous waste Monitoring wells Non-waste Exploration well s Underground storage tanks Construction excavation Hazardous waste Non-hazardous waste Category VI-Naturally occurring sources whose discharge is Non-waste created and/or exacerbated by human activity Containers , . Groundwater-surface water interactions Hazardous waste Natural leachin g Non-hazardous waste Salt-water intrusion/brackish water upconing (or intrusion and Non-waste other poor-quality natural water )

6F p . 6

Figure 1-5 Sources of ground-water contamination (from Geraghty and Miller, 1985) .

C`' r -,'~_ ~ ,~c ^, '~ ir~ f_~r-- • ~ 1 _ y_ d-, . ~t(F--~~>~ r^ ~~,1 Precipitation r Evapotranspiratio n , _ `_-•-•~- ~-• L r' ~--- ~.a ._ --~ ~_ S t'1~11 ~ ~\\ \ * i ~ ► . 1 11~~ ; ~ \, \~ . \ \~\ \ } Disposal or • I Injection Well 1 ~1t i ~ Pumping f Well Landfill, Dump a'• Pumping Well Land Spreading ~ Septic Tank/ or Refuse Pile Lagoon, Pit pm g Cesspool Sewe r or Irrigation or Basin i f Stream Water Table i--- ------- i -i-' ~------- Percolation , P . _ _ rcolation ag e

-Discharge i -I ~ i + + Leakage Water Table Aquifer Confining Zone Artesian Aquifer (Fresh) Leakage Confining Zona

Discharge or Injection Artesian Aquifer (Saline)

Intentional Unintentional Ground-Water Input Input Movemen t


### are more extensive in area and diffuse in nature . It is movement is governed by the hydraulic principles therefore difficult to trace contaminants from nonpoint discussed in Chapter 4

. sources back to their origin . Agricultural activities (i .e., For example, Darcy's Law states that the flow rate application of pesticides and fertilizers), urban runoff, through any porous medium is proportional to the and atmospheric deposition are potential nonpoint head loss and inversely proportional to the length of contaminant sources . the flow path : 

### 1 .5 Movement of Contaminants In Q= -K x A x h1/L (1 -1 ) Ground Water where : 1 .5.1 Contaminant Migration Q ground-water flow rate, in gal/d In broad terms, three processes govern the migration A cross-sectional area of flow, in ft2 of chemical constituents in ground water : (1 ) advection, movement caused by the flow of ground ht =head loss, in feet, measured between two water ; (2) dispersion, movement caused by the points L ft apart irregular mixing of waters during advection ; and (3 ) 

### retardation, principally chemical mechanisms which K hydraulic conductivity, a measure of the occur during advection . ability of the porous medium to transmit water, in gal/d/ft 2 1 .5.1 .1 Advection Equation 1-1 can be rearranged in the following Ground water n its natural state is constantly in . manner to produce the "bulk," or what is called motion (advection), although in most cases it is Darcian, velocity : 

### moving very slowly (Todd, 1980) . Ground-water

7