U.S. GEOLOGICAL SURVEY 

CIRCU.LAR 601-F 

Hydrologic 

Implications of 

Solid-Waste Disposal 

HYDROLOGIC IMPLICATIONS OF 

SOLID-WASTE DISPOSAL 
Solid wastes, the byproduct of an afiluent society, accumulate at a rate of more than 1,400 million pounds per day. 
Hydrologic 

Implications of 

Solid-Waste Disposal 

By William J. Schneider 

WATER IN THE URBAN ENVIRONMENT 

U.S. GEOLOGICAL SURVEY CIRCULAR 601-F 

Washingt!'n 1970 
DEPARTMENT OF THE INTERIOR 

DONALD PAUL HODEL, Secretary 

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director 

First printing 1970 

Second printing 1971 

Third printing 1973 

Fourth printing 1985 

Free on application to Distribution Branch, Text Products Section, 

U.S. Geological Survey, 604 South Pickett Street, Alexandria, VA 22304 
FOREWORD 

Urbanization-the concentration of people in urban areas and the 

consequent expansion of these areas-is a characteristic of our time. It has 

brought with it a host of new or aggravated problems that often make new 

demands on our natural resources and our physical environment. Problems 

involving water as a vital resource and a powerful environmental agent are 

among the most critical. These problems include the maintenance of both 

the quantity and quality of our water supply for consumption, for 

recreation, and general welfare and the alleviation of hazards caused by 

floods, drainage, erosion, and sedimentation. 

A prerequisite to anticipating, recognizing, and coping intelligently with 

these problems is an adequate base of information. This series of reports is 

intended to show the relevance of water facts to water problems of urban 

areas and to examine the adequacy of the existing base of water information. 

E. L. Hendricks, 

Chief H_vdrologist 

v 

CONTENTS 

Page 

Fore"~rd ----------------------------------------------------------------- V 

Abstract ------------------------------------------------------------------ Fl 

Introduct~n ---------------------------------------------------------------

Types of solid wastes --------------------------------------------------------

Methods of solid-waste disposal --------------------------------------- ________ 3 

Hydrologic implications ----------------------------------------------------- 4 

Types of pollution ------------------------------------------------------ 4 

Relation to hydrologic regimen -------------------------------------------- 5 

Hydrologic controls ----------------------------------------------------- 6 

Hydrologic considerations in site selection --------------------------------------- 9 

Selected references ---------------------------------------------------------- 10 

ILLUSTRATIONS 

FRON"TISPIECE. Photograph of accm,mlated solid wastes in an open dump. 

Page 

FIGURE 1. Sketch showing generalized movement of leachate through the land phase 

of the hydrologic cycle ---------------------------------------- __ F6 

2. Drawings showing effects of solid-waste disposal on ground-water resources __ 8 

TABLES 

Page 

TABLE 1. Classification of refuse materials --------------------------- __________ F2 

2. Percentages of materials leached from refuse and ash -------------------- 5 

VII 

Water in the Urban Environment 

Hydrologic Implications of Solid-Waste Disposal 

By William J. Schneider 

ABSTRACT 

The disposal of more than 1,400 million pounds of solid 

wastes in the United States each day is a major problem. 

This disposal in turn often leads to serious health, esthetic, 

and environmental problems. Among these is the pollution 

of vital ground-water resources. 

Of the six principal methods of solid-waste disposal in 

general use today, four methods~open dumps, sanitary 

landfill, incineration, and onsite disposal~carry an inherent potential for pollution of water resources. Seepage of 

rainwater through the wastes leaches undesirable constituents which reach the ground water in the area. This leachate 

is generally both biologically and chemically contaminated. 

The extent of the pollution from this leachate is largely 

dependent upon the geologic environment in which the solid 

wastes are deposited. Pollution potential is highest in permeable areas with a shallow water table where the wastes are 

in direct contact with the ground water. In a relatively 

impermeable area, the pollution is generally confined locally 

to the vicinity of the waste-disposal site. 

Site selection for disposal of solid wastes must be based 

on adequate water-resources information if pollutional potential is to be minimized. This will require regional as well 

as localized data on the water resources of the area. Only 

through such an approach can adequate protection be 

afforded to the environment in general and the water 

resources in particular. 

INTRODUCTION 

The disposal of solid-waste material-principally 

garbage and rubbish-is primarily an urban problem. 

However, unlike liquid waste disposal of sewage and 

industrial effluents, the problem has received only 

limited recognition. It is common practice in many 

metropolitan areas to overlook or ignore the consequences of waste-disposal programs. The full scope of 

the problem, though, cannot be ignored. 

The urban population of the United States is now 

producing an estimated 1,400 million pounds of solid 

wastes each day. Disposal of these wastes is a major 

problem of all cities. In many instances, seemingly 

endless streams of trucks and railroad cars haul these 

wastes long distances-as much as hundreds of milesto disposal sites. Based on a volume estimate of 5. 7 

cubic yards per ton of waste, this refuse is suFcient to 

cover more than 400 acres of land per day to a depth 

of 10 feet. Local governments spend an estimated $3 

billion each year on collection and disposal, a sum 

exceeded in local budgets only by expenditures for 

schools and roads. 

The disposal of these solid wastes poses many problems to local government agencies. U nfortun~tely, the 

problem is handled by many governments on the basis 

of expediency without due regard to envircnmental 

considerations. Garbage and rubbish are collected, 

hauled minimum distances commensurate with public 

acceptance, and dumped. Occasionally, the waste is 

either burned or mixed with soil to provide landfill. 

As long as the procedure removes the refuse and as 

long as the disposal site is not a health hazard and 

does not offend esthetic values too greatly, th~ operation is considered successful. Overlooked or even 

ignored is the effect of the disposal on the total environment, including the water resources of the area. 

AI though the disposal of solid wastes can create many 

serious health, esthetic, and environmental problems, 

only the hydrologic implications-the effe:t upon 

water resources-are considered in this report. 

TYPES OF SOLID WASTES 

Our urban society generates many types of solid 

wastes. Each may exert a different influenct' on the 

Fl 
TABLE 1.-Classification of refuse materials 

[Adapted from American Public Works Association (1966)] 

Kind of refuse Composition 

Garbage ---------------Wastes from preparation, cooking, and serving of food; market 

wastes; wastes from handling, storage, and sale of produce. 

Household' restaurants, institution~. stores, and 

markets. 

Rubbish __ -------------Combustible: paper, cartons, boxes, barrels, wood, excelsior, tree 

branches, yard trimmings, wood furniture, bedding, and dunnage. 

Do. 

Noncombustible: metals, tin cans, metal furniture, dirt, glass, 

crockery, and minerals. 

Ashes _________________ Residue fro:n fires used for cooking and heating and from onsite Do. 

incineration. 

Trash from streets _______ Sweepings, dirt, leaves, catch-basin dirt, and contents of litter Streets, sidewalks, alleys, 

receptacles. vacant hts. 

Dead animals __________ Cats, dogs, horses, and cows ------------------------------ Do. 

Abandoned vehicles _____ Unwanted cars and trucks left on public property------------- Do. 

Demolition wastes _______ Lumber, pipes, brick, masonry, and other construction materials Demolitior sites to be used 

for new buildings, renewal projects, and expressway~. from razcJ buildings and other structures. 

Construction wastes _____ Scrap lumber, pipe, and other construction materials ---------- New construction and remodeling. 

water resources of an area. In order tc understand 

the effect of each type, it is necessary to identify the 

various types as to the principal constitutents. Table 1 

lists the various categories and sources of refuse material primarily generated by urban activities. Not included arc wastes from industries and processing 

plants; hazardous, pathological, or radioactive wastes 

from institutions and industries; solids and sludge 

from s~wage-treatment plants; and other special types 

of solid wastes. These items usually pose special handling problems and are usually not a part of normal 

municipal solid-waste-di&posal programs. The following descriptions of the categories of solid wastes are 

abbre\·iated from descriptions by the American Public 

\Yorks Association ( 1966). 

W astc refers to useless, unused, unwanted, or discarded materials including solids, liquids, and gases. 

Refuse refers to solid wastes which can be classified 

in se\·eral different ways. One of the most useful classifications is based on the kinds of material: garbage, 

rubbish, ashes, street refuse, dead animals, abandoned 

auton10biles, industrial wastes, demolition wastes, construction wastes, sewage solids, and hazardous and 

special vvastes. 

Garbage is the animal and vegetable waste resultF2 

ing from the handling, preparation, and cooking of 

foods. It is composed largely of putrescible organic 

matter and its natural moisture. It orighates primarily 

in home kitchens, stores, markets, re~taurants, and 

other places where food is stored, prepcred, or served. 

Rubbish consists of both combustible and noncombustible solid wastes from homes, stores, and institutions. Combustible rubbish is the organic component 

of refuse and consists of a wide variety of matter that 

includes paper, rags, cartons, boxes, wood, furniture, 

bedding, rubber, plastics, leather, tree branches, and 

lawn trimmings. Noncombustible rubl,;sh is the inorganic component of refuse and consi-::ts of tin cans, 

heavy metal, mineral matter, glass, crockery, metal 

furniture, and similar materials. 

Ashes are the residue from wood, coke, coal, and 

other combustible materials burned in homes, stores, 

institutions, and other establishments for heating, 

cooking, and disposing of other combustible materials. 

Street refuse is material picked up r:v manual and 

mechanical sweeping of streets and sidewalks and is 

the debris from public litter receptacl~s. It includes 

paper, dirt, leaves, and other similar materials. 

Dead animals a~e those that die nat·trally or from 

disease or are accidentally killed. Not included in this 
category are condemned animals or parts of animals 

from slaughterhouses which are normally considered 

as industrial waste matter. 

Abandoned vehicles include passenger automobiles, 

trucks, and trailers that are no longer useful and have 

been left on city streets and in other public places. 

METHODS OF SOLID-WASTE DISPOSAL 

The disposal of these solid wastes generated by our 

urban environment is generally accomplished by one 

or more of six methods. All are currently in use to one 

degree or another in various parts of the United 

States. To a large extent, the method of waste disposal 

in any particular area depends upon local conditions 

and, to some extent, upon public attitude. In many 

areas several methods are employed. Each has its 

unique relation to the water resources of the area. 

The six general methods of solid waste disposal are: 

1. Open dumps. 

2. Sanitary landfill. 

3. Incineration. 

4. Onsite disposal. 

5. Feeding of garbage to swine. 

6. Composting. 

Open dump.s.-Open dumps are by far the oldest 

ar.d most prevalent method of disposing of solid 

wastes. In a recent survey, 371 cities out of 1,118 

surveyed stated that this method was emphasized 

within their jurisdictions. In many cases, the dump 

sites are located indiscriminately wherever land can 

be obtained for this purpose. Practices at open dumps 

differ. In some dumps, the· refuse is periodically leveled 

and com~:..d.cted; in other dumps the refuse is piled as 

1-Iigh as equipment will permit. At some sites, the 

solid wastes are ignited and allowed to burn to reduce 

volurue. In general, though, little effort is expended 

to prevent the nuisance and health hazards that frequently accompany open dumps. 

Sanitary landfill.-As early as 1904, garbage was 

buried to provide landfill. Although in subsequent 

years, the practice was used by many cities, the technique of sanitary landfill as we know it today did not 

emerge until the late 1930's. By 1945, almost 100 

cities were using the practice, and by 1960 more than 

1,400 cities were disposing of their solid wastes by 

this method. 

Sanitary landfill consists of alternate layers of compacted refuse and soil. Each day the refuse is deposited, compacted, and covered with a layer of soil. 

Two types of sanitary landfill are common: area landfill on essentially flat land sites, and depression landfill 

in natural or manmade ravines, gulleys, or pits. Depth 

of the landfill depends largely on local conditions, 

types of equipment, availability of land, and oth~r 

such factors, but it commonly ranges from about 7 

feet to as much as 40 feet as practiced by New York 

City. 

In normal operation, the refuse is depos:ted and 

compacted and covered with a minimum of 6 inches 

of compacted soil at the end of each workirg period 

or more frequently, depending upon the depth of 

refuse compacted. Normally about a 1:4 cover ratio 

is satisfactory; that is, 1 foot of soil cover for each 

4-foot layer of compacted refuse. Ratios a5' high as 

1:8, however, have been used. Tl~e final ccver is at 

least 2 feet of compacted soil to prevent the problems 

associated with open dumps. 

lncineration.-Incineration is the process of reducing combustible wastes to inert residue by burning at 

high temperatures of about 1,700° to 1,8C'0°F. At 

these temperatures all combustible materials are consumed, leaving a residue of ash and noncombustibles 

having a volume of 5 to 25 percent of the original 

volume. 

Although incineration greatly reduces the volume 

and changes the material to inorganic matter, the 

problem of disposal is still present. Much of the re'iidue is hauled to disposal sites or is used for landfill, 

although the land required for disposal of the residue 

is about one-third to one-half of that required for 

sanitary landfill. Some cities require that combustible 

materials be separated from noncombustibles prior to 

collection, while others use magnetic devices to extract ferrous metal for salvage. 

The combination of urban growth, increasing percapita output of refuse, and the rising costs of land 

for sanitary landfills has stimulated the use of incineration for solid-waste disposal. Today, there are an 

estimated 600 central-incinerator plants in the United 

States with a total capacity of about 150,000 tons 

per day. 

Onsite disposal.-With the increasing rate of production of solid wastes in the urban environment, 

there is a growing trend toward handling tHs waste 

in the home, apartment, and institution. Onite disposal has become increasingly popular during the 

past decade as a way of minimizing the was·~ problem at its source. Most widely used devices fc r onsite 

disposal are incinerators and garbage grinders. 

Onsite incineration is used widely in ap~rtment 

houses and institutions. The incinerators do, h':lwever, 

require constant attention to insure proper operation 

F3 
and complete combustion. Domestic incinerators for 

use in individual homes are not a major factor in 

solid-waste disposal, nor are they likely to be a major 

factor in the near future. Maintenance and operating 

problems are usually considerable. 

Garbage grinders, on the other hand, are becoming 

increasingly prevalent in homes for disposal of kitchen 

food wastes. It is estimated that more than a million 

grinders are now in home use. The grinders are installed in the waste pipe from the kitchen sink; food 

wastes are simply scraped into the grinder, the grinder 

is started, and the water turned on. The garbage is 

ground and flushed into the sanitary-sewer system. In 

some local communities, garbage grinders have been 

installed in every residence as required by local ordinance. 

Swine feed.-The feeding of garbage to swine has 

been an accepted way of disposing of the garbage part 

of solid wastes from urban areas for quite some time. 

Even as late as 1960, this method was employed in 

110 American cities out of 1,118 cities surveyed on 

their solid-waste-disposal practices. In addition to the 

municipal practices of using garbage for swine feed, 

many cities and municipalities permit private haulers 

to service restaurants and institutions to collect 

garbage for swine feed. The feeding of raw garbage 

led to a wide-spread virus disease in the middle 1950's, 

which affected more than 400,000 swine. As a result~ 

all States now require that garbage be cooked before 

feeding to destroy contaminating bacteria and viruses. 

However, according to the American Public Works 

Association ( 1966) , more than 10,000 tons of food 

wastes-about 25 percent of the total quantity of 

garbage produced-is still used daily in the United 

States as swine feed. 

Composting.-Composting is the biochemical decomposition of organic materials to a humuslike material. As practiced for solid-waste disposal, it is the 

rapid but partial decomposition of the moist, solidorganic matter by aerobic organisms under controlled 

conditions. The end product is useful as a soil conditioner and fertilizer. The process is normally carried 

out in mechanical digesters. 

Although popular in Europe and Asia where intensive farming creates a demand for the compost, the 

method is not used widely in the United States at this 

time. Composting of solid-organic wastes is not practiced on a full-scale basis in any large city today. 

Although there are several pilot plants in operation, it 

does not seem likely that composting will be a major 

method of solid-waste disposal. 

F4 

The selection of one or more of thc~e methods of 

solid-waste disposal by a municipality C'epends largely 

on the character of the municipality. Geographic location, climate, standard of living, population distribution, and public attitudes play imp'lrtant roles in 

the selection. In general, the natural resources and 

environmental factors have been given only small 

recognition in this selection. Only recently has there 

been a considerable upsurge of scientific interest in 

the effects of solid-waste disposal on our water resources. 

HYDROLOGIC IMPLICATWONS 

TYPES OF POLLUTION 

The disposition of solid wastes in open areas carries 

with it an inherent potential for pollution of water 

resources, regardless of the manner of disposal or the 

composition of the waste material. Of the six principal 

methods of solid-waste disposal, only swine feeding 

and composting offer no direct possibiFty of pollution 

of water resources from the waste material itself. Quite 

the contrary: properly com posted garbage is a soil 

conditioner that improves the permeability of the 

soil and may actually assist in improv:ng the quality 

of water that percolates through it. Although the 

cooked garbage that is fed to swine does not directly 

contribute to pollution of water resources, the manure 

from the feedlots may cause serious r"'oblems if not 

managed properly. 

The type of pollution that may arise is directly related to the type of refuse and the manner of disposal. 

Leachates from open dumps and sanitary landfill 

usually contain both biological and chemical constituents. Organic matter, decomposing under aerobic 

conditions, produces carbon dioxide which combines 

with the leaching water to form carbC''1ic acid. This, 

in turn, acts upon metals in the refuse and upon 

calcareous materials in the soil and rocks, resulting in 

increasing hardness of the water. Und~r aerobic conditions, bacterial action decomposes organic refuse, 

releasing ammonia, which is ultimately oxidized to 

form nitrate. In both landfills and open dumps, where 

decomposition is accomplished by bacterial action, the 

leachate has a high biochemical o~ygen demand 

(BOD). 

Table 2 indicates the magnitude of the constituents 

leached from solid wastes under vari0us conditions. 

These data were compiled by Hughe'-' ( 1967) from 

various sources. 
TABLE 2.-Percentages of materials leached from refuse and ash, based on weight of refuse as received 

[Adapted from Hughes (1967)] 

Material leached 

Permanganate value ______ 30 min ---------------

Do ________________ 4 hr ----------------

Chloride ------------------------------------

Ammonia nitrogen ----------------------------

Biochemical oxygen demand --------------------

Organic carbon ------------------------------

SuHate -------------------------------------

Sulfide -------------------------------------

0.039 

.060 

.105 

.055 

.515 

.285 

.130 

.011 

Percentage leached under give:1 conditions • 

2 

0.037 

.127 

.037 

.249 

.163 

.084 

3 4 

0.11 

.036 

1.27 

.Oll 

0.087 

.22 0.30 

Albumin nitrogen ----------------------------- .005 --------------------------------------------------

Alkalinity (as CaC03) -------------------------------------------------------- 0.39 0.042 ________ _ 

Calcium --------------------------------------------------------------------

Magnesium -----------------------------------------------------------------

.08 

.015 

.075 

.09 

.01 

.021 2.57 

.014 .24 

Sodium ----------------------------------------------------------- 0.260 

Potassium --------------------------------------------------------- .135 

.078 .29 

.049 .38 

Total iron ------------------------------------------------------------------

Inorgan~ phosphate ---------------------------------------------------------- .0007 

Nitrate ------------------------------------------------------------------------------- .0025 

Organic nitrog-en ----------------------------- .0075 .0072 .016 

*Conditions of leaching: 

1. Analyses of leachate from domestic refuse deposited in standing water. 

2. Analyses of leachate from domestic refuse deposited in un- saturated environment and leached only by natural precipita- tion. 

RELATION TO HYDROLOGIC REGIMEN 

That part of the hydrologic regimen associated with 

pollution from solid-waste disposal begins with precipitation reaching the land surface and ends with the 

water reaching streams from either overland or subsurface flow. The manner in which this precipitation 

moves through this part of the cycle determines 

whether or not the water resource will become 

polluted. 

Precipitation on the refuse-disposal site will either 

infiltrate the refuse or run off as overland flow. In 

open dumps, there is little likelihood of di{._ect runoff 

unless the refuse is highly compacted. In sanitary 

landfills, the rate of infiltration is governed by the 

permeability and infiltration capacity of the soil used 

as cover for the refuse. A part of the water entering 

the refuse percolates downward to the soil zone and 

eventually to the water table. If the water table is 

above the bottom of the refuse deposit, the percolating 

water travels only vertically through the refuse to the 

water table. During the vertical-percolation process 

the water leaches both organic and inorganic constituents from the refuse. 

Upon reaching the water table, the leachate becomes part of and moves with the ground-water flow 

3. Material leached in laboratory before and after ignitio"'. 4. Domestic refuse leached by water in a test bin. 6. Leaching of incinerator ash in a test bin by wat<>r. 

6. Leaching of incinerator ash in a ~est bin by acid. 

system. As part of this flow system, the leachate may 

move laterally in the direction of the water-tal''<:> slope 

to a point of discharge at the land surface. In general, 

the slope of the water table is in the same direction as 

the slope of the land. The generalized move··nent of 

leachate in this part of the hydrologic cycle i~ shown 

in figure 1. 

There are several well-documented cases cf pollution caused by leachates from solid-waste--disposal 

sites, especially those compiled by the California 

Water Pollution Control Board ( 1961). 1-1ost of 

these studies, however, were able to determine only 

that the pollution originated from solid-waste-disposal 

sites; few, if any, data on the gross magnitud~ of the 

pollution and its fate in the hydrologic cycle are available. 

One well-documented case is that of polluti')n from 

about 650,000 cubic yards of refuse deposited in a 

garbage dump near Krefield, Germany, over a 15-

year period in the early 1900's. High salt co:"lcentrations and hardness were detected in ground water 

about a mile downgradient from the site w:thin 10 

years of operation. Concentrations up to 2ff) mgjl 

(milligrams per liter) of chloride and a hudness 

of 900 mg/1 were measured-an increase of more 

F5 
FrGURE !.-Generalized movement of leachate through the land 

phase of the hydrologic cycle. 

than sixfold in chloride concentration and fourfold in 

hardness. The pattern of pumping of wells in the area 

precludes detailed understanding of the course of the 

pollution in the ground water, but wells near the 

dumping site \vere still contaminated 18 years later. 

In Schirrhof, Germany, ashes and refuse dumped 

into an empty pit extending below the water table resulted in contamination of wells about 2,000 feet 

downstream. The contamination occurred 15 years 

after the dump was covered; measures of hardness 

up to 1,150 mgjl were recorded as compared with 

200 mg/1 prior to the contamination. 

In Surrey County, England, household refuse 

dumped into gravel pits polluted the ground water in 

the vicinity. Refuse was dumped directly into the 20-

foot-deep pits where water depth averaged about 12 

feet. 1faximum rate of dumping was about 100,000 

tons per year over a 6-year period, and this occurred 

during the latter part of the period of use ( 1954--60) . 

Limited observations on water quality extending less 

than a year after the closing of the pits showed 

chloride concentrations ranging from 800 mg jl at 

the dump site, through 290 mg/1 in downgradient 

adjacent gravel pits, to 70 mgjl in pits 3,500 feet 

a\vay. Organic and bacterial pollution were detected 

within half a mile of the dumping sites, but not beyond. Because of the limited study' period and the 

F6 

slow travel of the pollutants, the maximum extent of 

pollution was not determined. 

1'fore recently, a study was made of the ground-

\Vater quality associated with four sanitary landfill 

sites in northeastern Illinois (Hughes and others, 

1969) . At the DuPage County site, total solids of more 

than 12,500 mg jl and chloride contents of more than 

2,250 mg/1 were measured in samples collected about 

20 feet below land surface under the fll. These were 

by far the highest concentrations measured at any of 

the four sites. In general, total solid' ranged from 

2,000-3,000 mg/1 under the fill to as low as 223 

mg/1 adjacent to the fill. 

HYDROLOGIC CONTROLS 

The movement of leachate from a waste-disposal 

site is governed by the physical envirc~ment. Where 

the wastes are above the water table, both chemical 

and biological contaminants in the leachate move 

vertically through the zone of aeration at a rate dependent in part upon the properties of the soils. The 

chemical contaminants, being in solution, generally 

tend to travel faster than biological contaminants. 

Sandy or silty soils especially retard particulate biological contaminants and often filter them from the 

percolating leachate. The chemical contaminants, 

however, may be carried by the leachate water to the 
water table where they enter the ground-water flow 

system and move according to the hydraulics of that 

system. Thus, the potential for pollution in the hydrologic system depends upon the mobility of the contaminant, its accessibility to the ground-water reservoir, and the hydraulic characteristics of that reservoir. 

The character and strength of the leachate are dependent in part upon the length of time that infiltrated water is in contact with the refuse and the 

amount of infiltrated water. Thus, in areas of high 

rainfall the pollution potential is greater than in less 

humid areas. In semiarid areas there may be little or 

no pollution potential because all infiltrated water is 

either absorbed by the refuse or is held as soil moisture 

and is ultimately evaporated. In areas of shallow 

water table, where refuse is in constant contact with 

the ground water, leaching is a continual process producing maximum potential for ground-water pollution. 

The ability of the leachate to seep from the refuse 

to the ground-water reservoir is another factor in the 

degree of pollution of an aquifer. Permeable soils 

permi~ rapid movement; although some filtering of 

biological contamination may take place, the chemical 

contamination is generally free to move rapidly under 

the influence of gravity to the water table. Less permeable soils, such as clays, retard the movement of the 

leachate, and often restrict the leachate to the local 

vicinity of the refuse. Under such conditions, pollution is frequently limited to the local shallow groundwater reservoir and contamination of deeper lying 

aquifers is negligible. 

Leachate that does reach the water table and enters 

an aquifer is then subject to the hydraulic characteristics of the aquifier. Because the configuration of the 

water table generally reflects the configuration of the 

land surface, the leachate flows downgradient under 

the influence of gravity from upland areas to stream 

valleys, where it discharges as base flow to the stream 

systems. The rate of flow is dependent upon the permeability of the rock material of the aquifer and on 

the slope of the water table. In flat areas or areas of 

gentle relief, minor local topographic variations may 

have no effect on the configuration of the water table, 

and movement of ground water may be uniform over 

large areas. 

In some places dipping confined aquifers crop out 

in upland areas and thus are exposed to recharge. 

Contaminants entering the aquifer in these areas move 

downgradient into the confined parts of the aquifer. 

Although there is usually some minor leakage to confining beds above and below the aquifer, the 

contaminants in general will be confined to the particular aquifer, and water-supply wells tapping that 

aquifer will thus be subject to contamination to the 

extent that the contaminants are able to nnve from 

the outcrop to the wells. 

Optimum conditions for pollution of the groundwater reservoir exist where the water table. is at or 

near land surface, subjecting the solid wast~~ to continual direct contact with the water. Such conditions 

commonly exist where abandoned quarries that penetrate the ground-water reservoir are used as refusedisposal sites. The continual contact of the water with 

the refuse produces a strong leachate highly contaminated both biologically and chemically. Under 

hydrogeologic conditions of penneable materials and 

steep hydraulic gradients, the leachate may move 

rapidly through the ground-water system an-:l pollute 

extensive areas. The hydrologic effects of sclid-waste 

disposal in four geologic environments are shown in 

figure 2. 

Figure 2A illustrates a waste-disposal site in a permeable environment. The waste is shown in contact 

with the ground water in a permeable sand-and-gravel 

aquifer underlain by confining beds of relatively impermeable shale. In this case, the potential for pollution is high because conditions of both high infiltration 

and direct contact between wastes and ground water 

exist. Because of the permeability of the aquifer, the 

contaminants move downgradient with the water in 

the aquifer and are diffused and diluted during this 

movement. In areas where the water table is below 

the bottom of the waste material, the degm~ of contamination is lessened because the wastes are no 

longer in direct contact with the ground water. In 

this case, leachate from the wastes moves vertically 

through the zone of aeration to the water table. It 

then enters the ground water and moves downgradient 

as in the case of a shallow water table. 

Figure 2B illustrates a waste-disposal site in a relatively impermeable environment. In humid areas, the 

water table may be near land surface, and the disposed waste may or may not be in direct contact with 

the ground water. In the illustration, ground water is 

shown confined to the underlying limestone. aquifer. 

The relative impermeability of the overburden prevents significant infiltration of the rainfar; consequently there is only minor leaching of contaminants 

from the wastes. Pollution is confined locar-, to the 

vicinity of the waste-disposal site; moveme~t in all 

directions is inhibited by the inability of the water to 

F7 
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--~----_-_-:._-_-_-_-_-_-_-_-_-_-_-_-_-_-_---~----~--__:_-_:::-_-_-

B 

FrGL'RE 2 ( abn\·e and right) .-Effects on ground-water resources of solidwaste disposal at a site (A) in a permeable environment, (B) in a 

relatively impermeable environment, (C) underlain by a fractured-rock 

aquifer, and (D) underlain by a dipping-rock aquifer. Leachate shown 

in red. 

move through the tight soils. If significant amounts of 

rainfall penetrate the wastes, a local perched water 

table may develop in the \·icinity of the fill, and that 

water will likely be highly contaminated, both chemically and bacteriologically. 

Figure 2C illustrates a waste-disposal site abo\·e a 

fractured-rock aquifer. The position of the water table 

in the m·erburdcn rclati\·e to the waste-disposal site 

is dependent upon the amount of infiltration and the 

geometry of the ground-water How system. The water 

table shmvn here is belmv the boa y of \Vaste. In this 

case. the potential for pollution is not high because of 

limited vertical mo\·enlent of the leachate to the water 

table. However, the contawinants that reach the 

fractured-rock zone may mo\·e more readily in the 

general direction of the ground-water flow. Dispersion 

of the contaminants is limited because the flow is 

confined to the fracture zones. A thin, highly penneable overburden with a shallow \Vater table (similar 

to that shown in figure 2A) overlying the fractured 

F8 

rock would provide an ideal conditi')n for widespread ground-water pollution. 

Figure 2D illustrates a waste-disposal site in a geologic setting in which dipping aquifers are overlain by 

permeable sands and gravels. In this illustration, the 

waste-disposal site is shown directly above a permeable 

limestone aquifer. Here leachate from the landfill 

travels through the sand and enters the limestone 

aquifer as recharge. Again, the strength of the 

leachate depends in part upon whether the water table 

is in direct contact with the waste. Leachate will move 

downgradient \vith the ground-water flow in both 

the sands and gravels and the limestone, as shown in 

the illustration. If the waste-disposal site were located 

above the less permeable shale, most of the leachate 

would move downgradient through the sand and 

gra\·el, with very little penetrating the relatively impermeable shale as recharge. However, in its downgradient movement, it would enter any other 

permeable fom1ations as recharge. 
A high pollution potential exists also where wastedisposal sites are located on flood plains adjacent to 

streams. \rV ater-table levels generally are near land 

surface in flood-plain areas, especially during the 

usual period of high water in winter and spring 

throughout much of the humid areas of the United 

States. In such enviromnents the water may have 

contact with the refuse for extended periods, gi\'ing 

rise to concentrated leachate. The contaminated water 

moves through the flood-plain deposits and discharges 

into the stream during low-flo\v periods \vhen the 

bulk of the streamflow is from ground-water discharge. The degree of pollution of the stream depends 

upon the concentration of the leachate, the amount 

of leachate entering the stream, and the available 

streamfiovv for dilution. 

HYDROLOGIC CONSIDERATIONS IN SITE 

SELECTION 

It is obvious that our current national policy of 

pollution abatement and protection of our natural 

environment requires full consideration of the water 

resources in selection of sites for solid-waste disposal. 

c 

To date, vvith few exceptions, these considerations 

have been on a local scale, dealing primarily with the 

hydrological characteristics of the immediate site. 

The American Society of Civil Engineers in a 

manual on sanitary landfill (American Sxiety of 

Civil Engineers, 1959) discussed site selection from a 

hydrologic standpoint as follows: 

In choosing a site for the location of a sanitary landfill, 

consideration must be given to underground :1nd surface 

water supplies. The danger of polluting water supplies should 

not be o\·erlooked. 

The report states further that: 

Sufficient surface drainage ~hnuld be provided to assure 

minimum runoff to and into the fill. Als·), surfa::-e drainage 

should prevent quantities of water from causing erosion or 

\\·ashing of the fill * * * Although some apprehension has 

been expressed about the underground water supply pollutinn uf sanitary landfills, there has been little, if any, exp::>rience tu indicate that a properly located sanitary landfill will 

give rise to underground pollution problems. It is axiomatic, 

of course, that when a waste material is disposed of on land, 

the proximity of water supplies, both underground and surface, should be considered * * * Also, special attention 

should be given areas ha\'ing rock strata near the surface of 

the ground. For example, limestone strata may have solution 

channels or cre\·ices through which pollution contamination 

F9 
may travel. Sanitary landfills should not be located on rock 

strata without studing the hazards involved. In any case, 

refuse must not be placed in mines or similar places where 

resulting seepage or leachate may be carried to water-bearing 

strata or wells * * * In summary, under certain geological 

conditions, there is a real potential danger of chemical and 

bacteriological pollution of ground water by sanitary landfills. 

Therefore, it is necessary that competent engineering advice 

be sought in determining the location of a sanitary landfill. 

Consideration of hydrology in site selection is required by law in several States. Section 19-13-B24a 

of the Connecticut Public Health Code requires that: 

No refuse shall be deposited in such manner that refuse 

or leaching from it shall cause or contribute to pollution or 

contamination of any ground or surface water on neighboring 

properties. No refuse shall be deposited within 50 feet of 

the high water mark of a watercourse or on land where it 

may be carried into an adjacent watercourse by surface or 

storm water except in accordance with Section 25-24 of the 

General Statutes which require approval of the Water 

Resources Commission. 

The rules and regulations of the Illinois Department of Public Health require that: 

The surface contour of the area shall be such that surface 

runoff will not flow into or through the operational or completed fill area. Grading, diking, terracing, diversion ditches, 

or tilling may b-:! approved when practical. Areas having 

high ground water tables may be restricted to landfill operations which will maintain a safe vertical distance between 

deposited refuse and the maximum water table elevation. 

Any operation which proposes to deposit refuse within or 

near the maximum water table elevation shall include corrective or preventive measures which will prevent contamination 

of the ground-water stratum. Monitoring facilities may be 

required. 

Other States have similar regulations. 

A common denominator in these sets of recommendations is the general concern for the onsite pollutional 

aspect. This is characteristic of most current approaches, especially from the engineering and legislative viewpoints. Another characteristic is the restrictive 

approach to the problem. Hydrologic conditions 

are documented under which disposal of solid wastes 

is either discouraged or prohibited. In general, the 

pollutional problem is treated more in local than in 

regional context. These are, of course, important 

considerations and should be followed in any site 

selection. In fact, even stronger guidelines are desirable, to the extent of requiring detailed knowledge 

of the extent and movement of potential pollution at 

any site before the site is activated. 

The water resource, however, must be considered 

also as a regional resource, not just a localized factor. 

As such, it should be considered in a regional concept 

in its relation to solid-waste disposal. This, of course, 

FlO 

requires that adequate regional information on the 

water resource is available. Given sud' information, 

the planner can weigh all available alternatives and 

insure that the final site selection is co·npatiqle with 

comprehensive regional planning goals and environmental protection. The Northwestern Illinois Planning 

Commission followed this comprehensive approach in 

developing its recommendations on refuse-disposal 

needs and practices in northeastern lllhois (Sheaffer 

and other, 1963) . 

It is, of course, quite possible that, in the comprehensive approach, some otherwise opti-num sites for 

solid-waste disposal may be only marginally acceptable from a hydrologic viewpoint. Under such conditions detailed information on the hydro1ogy should be 

obtained and detailed evaluations made of the impact 

of the potential waste disposal before the site is put 

into use; the actual impact should then be monitored 

during and after use. In general, although such studies 

are desirable for all solid-waste-dispo,~l sites, they 

are essential where geologic, hydrologic, or other data 

indicate a possibility of undersirable pollutional effects. 

The problem of solid-waste disposal is one of the 

most serious problems of urban areas. The everincreasing emphasis on protection and preservation 

of natural resources though regional planning is evident today. The implementation of these commitments and goals can insure adequate protection •)f 

vital water resources from pollution by disposal of 

solid wastes. 

SELECTED REFERENC:"':S 

American Public Works Association, 1966, Hunicipal refuse 

disposal: Chicago, Ill., Public Adm. Service, 528 p. 

American Society of Civil Engineers, Committee on Sanitary 

Landfill Practices, 1959, Sanitary lan1fill: Am. Soc. 

Civil Engineers Eng. Practices Manual 39, 61 p. 

Anderson, J. R., and Dornbush, J. N., 1967, Influence of 

sanitary landfill on ground water quaFty: Am. Water 

Works Assoc. Jour., April 1967, p. 457-470. 

California Water Pollution Control Board, 1961, Effects of 

refuse dumps on ground water quality: California Water 

Pollution Control Board Pub. 24, 107 p. 

Hughes, G. M., 1967, Selection of refuse disposal sites in 

northeastern Illinois: Illinois Geol. Soc. Environmental 

Geology Note 17, 18 p. 

Hughes, G. M., Landon, R. A., and Farvold<O>n, R. N., 1969, 

Hydrogeology of solid waste disposal sites in northeastern Illinois: Washington, D.C., U.S. Public Health 

Service, 137 p. 

Sheaffer, J. R., von Boehm, B., and Hackett, J. E., 1963, 

Refuse disposal needs and practices in northeastern 

Illinois: Chicago, Ill., Northeastern Illinois Metropolitan Area Planning Comm. Tech. Rept. 3, 72 p. 

*u.s. GOVERNMENT PRINTING OFFICE: 1973-543-578/37