1

Fact Sheet on Evapotranspiration 

Cover Systems for Waste Containment

INTRODUCTION

This fact sheet updates the Evapotranspiration 

Landfill Cover Systems Fact Sheet that was published in 2003. At that time evapotranspiration 

(ET) covers were more in a demonstration phase. 

Now they are increasingly being considered for 

use at waste disposal sites. These include 

municipal solid waste (MSW) landfills, hazardous waste (HW) landfills, and isolated arid waste 

sites when equivalent performance to conventional final cover systems can be demonstrated. 

Conventional cover system designs use barrier 

layers consisting of materials with low hydraulic 

conductivity (e.g., clay, geosynthetic clay liners, 

or geomembranes) to minimize the percolation 

of water from the cover to the waste. ET cover 

systems use water balance components to minimize percolation. These cover systems rely on 

This fact sheet is intended solely to provide general information about evapotranspiration covers. It is not intended, nor can it be 

relied upon, to create any rights enforceable by any party in litigation with the United States. Use or mention of trade names does 

not constitute endorsement or recommendation for use.

United States Office of Solid Waste and EPA 542-F-11-001

Environmental Protection Emergency Response February 2011

Agency (5203P) www.epa.gov

www.cluin.org

The alternative covers database contains 

222 project profiles. These project profiles 

include site background information, cover 

type and construction details, status (proposed, complete, under construction), cost 

information, and contacts. Sources of information include EPA and state websites, 

conference proceedings, studies, and individual contributions. Individuals wishing to 

have a cover they are familiar with listed 

can submit it online. The database is updated as new information becomes available.

Appendix A of this document contains a list 

of ET sites by EPA region and state.

http://cluin.org/products/altcovers

TABLE OF CONTENTS

INTRODUCTION......................................... 1

BACKGROUND........................................... 2

DESCRIPTION............................................ 3

LIMITATIONS .............................................. 6

DESIGN CONSIDERATIONS...................... 6

Climate.................................................. 6

Soil Type ............................................... 7

Soil Thickness....................................... 7

Vegetation Types................................... 7

Soil Fertility ........................................... 8

Control Layers....................................... 8

PERFORMANCE MONITORING ................ 8

Monitoring Systems .............................. 9

Numerical Models ................................. 9

COST ........................................................ 10

TECHNOLOGY STATUS........................... 11

REFERENCES ......................................... 11

GLOSSARY............................................... 13

APPENDIX A: Proposed, Approved, and 

Installed Sites Having Evapotranspiration 

Covers ....................................................... 15

APPENDIX B: Data From Two 

Comparison Demonstration Projects......... 24
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soil properties (e.g., soil texture and associated 

soil water storage capacity) to store water until it 

is either transpired through vegetation or evaporated from the soil surface. 

The fact sheet provides a summary of ET technical issues, including design considerations, 

performance monitoring, cost, technology status, 

and potential limitations on use. It is intended 

to provide basic information to site owners and 

operators, regulators, consulting engineers, and 

other interested parties about these potential 

design alternatives. Appendix A updates the 2003 

list of ET cover sites by adding over 130 new full 

scale examples. A separate on-line database provides more site specific information about these 

sites as well as other projects using ET covers.

Additional sources of information are also provided 

in the project specific references in the database.

The information contained in this fact sheet was 

obtained from currently available technical literature and from discussions with site managers. It 

is not intended to serve as guidance for actual 

design or construction, nor is it intended to suggest that ET final cover systems should be used 

at any particular site.1 The fact sheet does not 

address alternative materials for use in final cover 

systems, or other alternative cover system 

designs, such as asphalt covers.

BACKGROUND

Final cover systems often are used at landfills; 

abandoned dumps; some hazardous, low-level, 

and mixed low-level waste sites with conducive 

environmental conditions; hazardous waste containment facilities; sites with surface contamination; and other types of waste disposal sites. 

There are a number of reasons for using them, 

including to control moisture and percolation, 

manage surface water runoff, minimize erosion, 

prevent direct exposure to waste, control gas 

emissions and odors, prevent occurrence of 

disease vectors and other nuisances, and meet 

aesthetic and other end-use purposes. Final cover systems are intended to remain in place and 

maintain their functions for periods of many 

1

 For example, EPA’s Superfund remedy selection 

decisions are made on a site-specific basis. Thus, 

final cover systems are evaluated in a manner consistent with the overall framework established for remedy 

selection under CERCLA, the National Oil and Hazardous Substances Pollution Contingency Plan, and 

associated Superfund program guidance.

decades to hundreds of years. Cover systems 

may be used alone or, if warranted, in conjunction with other technologies (for example, slurry 

walls and groundwater pump and treat systems) 

to contain waste or leachate.

The design of cover systems is site specific and 

depends on the intended function of the final 

cover–cover designs can range from a single 

layer of soil to a complex multi-layer system that 

includes synthetic materials. To minimize percolation, conventional cover systems typically 

use low-conductivity barrier layers. These barrier 

layers are often constructed of compacted clay, 

geomembranes, geosynthetic clay liners, or combinations of these materials. Depending on the 

material type and construction method, the saturated hydraulic conductivities for these barrier layers 

are typically between 1x10-5 and 1x10-9 centimeters per second (cm/s). In addition, conventional 

cover systems generally include shallow-rooted 

plants and additional layers, such as surface 

layers to prevent erosion; protection layers to 

minimize freeze/thaw damage; internal drainage 

layers; and gas collection layers (Environmental 

Protection Agency [EPA] 1991; Hauser, Weand, 

and Gill 2001b).

The design, construction, and maintenance of 

cover systems may be subject to statutory and 

regulatory requirements under various federal 

and state programs; some of these requirements 

also may come into play in cleanup programs. 

For example, with regard to municipal solid waste 

facilities, regulations under the Resource Conservation and Recovery Act (RCRA) for the design 

and construction of final cover systems are based 

on using a low-conductivity barrier layer (conventional cover system). Under RCRA Subtitle D (40 

CFR 258.60), the minimum design requirements 

for final cover systems at municipal solid waste 

landfills (MSWLF) depend on the bottom liner 

system or the natural subsoils, if no liner system 

is present. The final cover system must have a 

permeability less than or equal to that of the bottom liner system (or natural subsoils) or a permeability no greater than 1x10-5 cm/s, whichever is 

less. This design requirement was established to 

minimize the “bathtub effect,” which occurs when 

the landfill fills with liquid because the cover 

system is more permeable than the bottom liner 

system. This bathtub effect greatly increases the 

potential for generation of leachate.
3

Until March 2004, the equivalent reduction language provided the statutory underpinning for 

proposing an alternative cover at an MSWLF. 

On March 22, 2004, 40 CFR 258 was amended 

to allow for research, development, and demonstration permits (40 CFR 258.4). These permits are issued for three years with up to three 

renewals (12 years total). The regulation states, 

“The director of an approved state may issue a 

research, development, and demonstration permit for a new MSWLF unit, existing MSWLF 

unit, or lateral expansion, for which the owner or 

operator proposes to utilize innovative and new 

methods which vary from the final cover criteria of §258.60(a)(1), (a)(2) and (b)(1), provided 

the MSWLF unit owner/operator demonstrates 

that the infiltration of liquid through the alternative cover system will not cause contamination of 

groundwater or surface water, or cause leachate 

depth on the liner to exceed 30 cm.” 

Figure 1 shows the minimum recommended 

requirements for a typical conventional Subtitle 

D landfill which consist of a 6-inch soil erosion 

layer, a geomembrane (when the landfill has a 

geomembrane liner), and an 18-inch barrier layer 

of soil that is compacted to yield a saturated 

hydraulic conductivity equal to or less than 1x10-5

cm/s (EPA 1992).

As another example, for hazardous waste landfills, 

RCRA Subtitle C (40 CFR 264 and 265) provides 

certain design specifications for final cover 

systems. These include the same provision for 

Subtitle D that the cover system have a permeability less than or equal to the permeability of any 

bottom liner system or natural subsoils present. 

To help implement these regulatory requirements, 

EPA has issued guidance for the minimum design 

of these final cover systems. Figure 1 shows an 

example of a RCRA Subtitle C cover at a hazardous waste landfill (EPA 1989). 

The design and construction requirements, as 

defined in the RCRA regulations, also may be 

applied under RCRA corrective action and other 

cleanup programs (e.g., Superfund or state 

cleanup programs). At Superfund remedial sites 

involving on-site disposal, the RCRA regulations 

for conventional covers usually are identified as 

applicable or relevant and appropriate requirements (ARARs) for the site.2

 Under RCRA, an 

alternative design, such as an ET cover, can 

be proposed in lieu of a RCRA design if it can 

be demonstrated that the alternative provides 

equivalent performance with respect to reduction 

in percolation and other criteria, such as erosion 

resistance and gas control.

Examples of sites that have proposed, approved, 

or installed ET covers and the regulatory program 

they are operating under are given in Appendix A. 

Details on these sites can be found in the alternative cover profiles database at http://cluin.org/

products/altcovers.

DESCRIPTION

ET cover systems are designed to rely on the 

ability of a soil layer to store the precipitation until 

it is naturally evaporated or is transpired by the 

vegetative cover. In this respect they differ from 

more conventional cover designs in that they rely 

on obtaining an appropriate water storage capacity in the soil rather than an as-built engineered 

low hydraulic conductivity. ET cover system 

designs are based on using the hydrological 

processes (water balance components) at a site, 

which include the water storage capacity of the 

soil, precipitation, surface runoff, evapotranspiration, and infiltration. The greater the storage 

capacity and evapotranspirative properties are, 

the lower the potential for percolation through the 

cover system. 

2

 In addition to compliance with ARARs, CERCLA Section 121 requires that remedial actions ensure protectiveness of human health and the environment.

Figure 1. Examples Subtitle D and C Cover 

Design.

Source EPA 1992a and 1989
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ET cover system designs tend to emphasize the 

following (Dwyer 2003; Hakonson 1997; Hauser, 

Weand and Gill 2001b): 

• Fine-grained soils, such as silts and clayey 

silts, that have a relatively high water storage 

capacity 

• Appropriate vegetation for long-term stability 

and evapotranspiration

• Locally available soils to streamline construction and provide for cost savings

Use of local soils allows the opportunity to utilize 

natural analogue data for speculating future performance.

In addition to being called ET cover systems, 

these types of covers have also been referred to 

in the literature as water balance covers, alternative earthen final covers, vegetative landfill covers, 

soil-plant covers, and store-and-release covers.

ET cover systems are constructed using a monolithic soil barrier. Monolithic covers, also referred 

Exhibit 1. Monolithic Cover at Lopez Canyon Sanitary Landfill

Site type: Municipal solid waste landfill 

Scale: Full scale 

Cover design: The ET cover was installed in 1999 and consists of a 3-foot silty sand/clayey sand layer, 

which overlies a 2-foot foundation layer. The cover soil was placed in 18-inch lifts and compacted to 95 

percent with a permeability of less than 3x10-5 cm/s. Native vegetation was planted, including artemesia, salvia, lupines, sugar bush, poppy, and grasses. In 2001, fifty 30-KW microturbines that use landfill 

gas as fuel were installed at the site. They provide sufficient electricity to power 1,500 homes. 

Regulatory status: In 1998, Lopez Canyon Sanitary Landfill received conditional approval for an ET 

cover, which required a minimum of two years of field performance data to validate the model used for 

the design. An analysis was conducted and provided the basis for final regulatory approval of the ET 

cover. The cover was fully approved in October 2002 by the California Regional Water Quality Control 

Board - Los Angeles Region. 

Performance data: Two moisture monitoring systems were installed, one at Disposal Area A and one at 

Disposal Area AB+ in May and November 1999, respectively. Each monitoring system has two stacks of 

time domain reflectometry probes that measure soil moisture at 24-inch intervals to a maximum depth 

of 78 inches, and a station for collecting weather data. Based on nearly 3 years of data, there is generally less than a 5 percent change in the relative volumetric moisture content at the bottom of the cover 

compared to nearly 90 percent change near the surface. This implies that most of the water infiltrating the 

cover is being removed via evapotranspiration and is not reaching the bottom of the cover. 

Modeling: The numerical model UNSAT-H was used to predict the annual and cumulative percolation 

through the cover. The model was calibrated with 12 months of soil moisture content and weather data. 

Following calibration, UNSAT-H predicted a cumulative percolation of 50 cm for the ET cover and 95 

cm for a conventional cover over a 10-year period. The model predicted an annual percolation of 

approximately 0 cm for both covers during the first year. During years 3 through 10 of the simulation, 

the model predicted less annual percolation for the ET cover than for the conventional cover. 

Maintenance activities: During the first 18 months, irrigation was conducted to help establish the vegetation. Once or twice a year, brush is cleared to comply with Fire Department regulations. Prior to the 

rainy season, an inspection is conducted to check and clear debris basins and deck inlets. No mowing 

activities or fertilizer applications have been conducted or are planned. 

Cost: Initial costs were estimated at $4.5 million, which includes soil importation, revegetation, quality control 

and assurance, construction management, and installation and operation of moisture monitoring systems. 

Sources: City of Los Angeles 2003, Hadj-Hamou and Kavazanjian 2003. More information available at 

http://cluin.org/products/altcovers
5

to as monofill covers, use a single fine-grained 

soil layer to retain water and support the vegetative community (Albright et al. 2010 and Hauser 

2009). Figure 2 shows an example of a monolithic ET cover. Exhibit 1 provides an example of a 

full-scale monolithic cover at a MSW landfill. 

A monolithic cover design can be modified by 

adding a capillary break. This entails placing 

a coarser grained material, usually a sand or 

gravel, under the monolithic fine-grained soil, as 

shown conceptually in Figure 3. The differences 

in the unsaturated hydraulic properties (i.e., soil 

matric potential) between the two layers minimize 

percolation into the coarser grained (lower) layer 

under unsaturated conditions (Stormont 1997). 

The finer-grained layer has the same function as 

the monolithic soil layer; that is, it stores water 

until it is removed from the soil by evaporation 

or transpiration mechanisms. The discontinuity 

in pore sizes between the coarser-grained and 

finer-grained layers forms a capillary break at the 

interface of the two layers. The break results in 

the wicking of water into unsaturated pore space 

in the finer grained soil, which allows the finergrained layer to retain more water than a monolithic cover system of equal thickness. Capillary 

forces hold the water in the finer-grained layer 

until the soil near the interface approaches saturation. If saturation of the finer-grained layer 

Vegetation

Fine-grained Layer

Interim Cover

Waste

Figure 2. Conceptual Design of a Monolithic 

ET Cover

Vegetation

Fine-grained Layer

Coarse-grained Layer

Interim Cover

Waste

Figure 3. Conceptual Design of a Capillary 

Barrier ET Cover

Exhibit 2. Capillary Barrier ET Cover at Rocky Mountain Arsenal Superfund Site

Site type: Consolidation area covers

Scale: Full scale

Cover design: These RCRA Subtitle C equivalent ET covers have been constructed for former waste 

disposal basins and manufacturing process areas that were contaminated during pesticide production. 

The design consists of a minimum of 16 inches of crushed concrete placed as a biota barrier, followed 

by a capillary barrier layer of pea gravel that provides a capillary break. The surface soil layer consists 

of at least 4 feet of soil seeded with a mix of cool and warm season native vegetation. 

Modeling: Construction parameters were developed using data from a four year RCRA equivalent demonstration study. The modeling was done using UNSAT-H.

Maintenance activities: Construction began in 2007 and finished in 2009. The covers are currently being 

monitored and maintained. 

Performance: The ET cover performance is monitored using a number of pan lysimeters (30 feet x 50 

feet) which have shown that the cover is performing as expected.

Cost: According to the responsible party, the total cost of constructing the ET covers was $69 million, 

and they cover approximately 450 acres.

Sources: Rocky Mountain Arsenal cleanup site: http://www.rma.army.mil/; and EPA Region 8 Superfund 

site: http://www.epa.gov/region8/superfund/co/rkymtnarsenal/index.html.
6

occurs, the water will move relatively quickly into 

and through the coarser-grained layer and to the 

waste below (Albright et al. 2010, Hauser 2009, 

and ITRC 2003). Exhibit 2 provides an example 

of a capillary barrier at a Rocky Mountain Arsenal 

hazardous waste site.

In addition to being potentially less costly to construct, ET covers have the potential to provide equal 

or superior performance compared to conventional 

cover systems, especially in arid and semi-arid 

environments (generally accepted as areas having less than 10 and 20 inches of precipitation, 

respectively). In these environments, they may 

be less prone to deterioration from desiccation, 

cracking, and freezing/thawing cycles. ET covers 

also may be able to minimize side slope instability, 

because they do not contain geomembrane layers, 

which can cause slippage (Albright and Benson 

2005, Benson et al. 2002; Dwyer et al. 1999).

LIMITATIONS

Although they have been approved in humid 

climates (e.g., Marine Corps Logistics Station 

Albany, GA and General Electric, Schenectady, 

NY), ET cover systems are generally considered 

more applicable in areas that have arid or semiarid climates like those found in parts of the Great 

Plains and West (e.g., North and South Dakota, 

Montana, Idaho, eastern Washington and Oregon, Utah, Colorado, West Texas, New Mexico, 

Arizona, Nevada, and southern California). 

Albright and Benson (2005) in their examination 

of data generated in EPA’s Alternative Cover 

Assessment Program (ACAP) found: “In humid 

locations with the abundant precipitation and 

typically lower potential evapotranspiration, the 

store-and-release mechanism used by ET covers does not provide sufficient hydraulic control 

to match the performance of conventional composite covers.” (emphasis added) However, the 

ACAP field data did show that in humid locations 

properly designed ET covers can provide performance comparable to that of the compacted clay 

covers in those locations. 

In addition, site specific conditions, such as site 

location (e.g., appropriate soil) and landfill characteristics, may limit the use or effectiveness 

of ET cover systems. Local climatic conditions 

(amount, seasonal distribution, and form of precipitation) also can limit the effectiveness of an 

ET cover at a given site. For example, snow 

often melts when vegetation is dormant, and without sufficient water storage capacity unacceptable percolation might occur (EPA 2000; Hauser, 

Weand, and Gill 2001b). However, if technically 

and financially feasible, this might be mitigated by 

thickening the ET layer.

Two federal research programs, the Department 

of Energy (DOE) sponsored Alternative Landfill Cover Demonstration (ALCD) and the ACAP, 

provide the best collection of data to describe 

the performance of ET cover systems in terms of 

minimizing percolation. Hauser (2009) also has 

some additional performance information; however, there are limited data on the ET covers’ ability to minimize erosion, resist biointrusion, and 

retain long-term effectiveness. On the other hand, 

erosion, effectiveness of biobarriers, and maintenance of vegetative cover over extended periods 

of time are issues faced by all conventional covers, and those design aspects are similar to ET 

covers. While the principles of ET covers and their 

corresponding soil properties have been understood for many years, their application as final 

cover systems for landfills has emerged only since 

the mid-1990s. Regulators in southern California 

initially required any landfill operator who wanted 

to deploy an ET cover to set up a demonstration 

project to prove equivalency. The success of these 

demonstrations has led to the regulators allowing 

an ET cover if the landfill owner shows that soil, 

design, and climatic conditions are similar to those 

of a landfill facility with a permitted ET cover.

DESIGN CONSIDERATIONS

The design of ET cover systems is based on 

providing sufficient water storage capacity and 

evapotranspiration to control moisture and water 

percolation into the underlying waste. The following considerations generally are involved in the 

design of ET covers.

Climate

The amount, form, and distribution of precipitation over a year, combined with factors that influence potential evapotranspiration, determine the 

total amount of water storage capacity needed for 

the cover system. This information can usually be 

found at nearby weather stations. The cover may 

need to accommodate a spring snowmelt event 

that causes the amount of water at the cover to 

be relatively high for a short period of time or con-
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ditions during cool winter weather with persistent, 

light precipitation. Storage capacity is particularly 

important if the event occurs when local vegetation is dormant, resulting in little or no transpiration. Other factors related to climate that are important to cover design are temperature, wind, 

and relative humidity (Benson 2001; EPA 2000; 

Hauser, Weand, and Gill 2001b).

Soil Type

Finer-grained materials, such as silts and clayey 

silts, are typically used for ET cover systems because they have a greater storage capacity than 

sandy soils. Sandy soils are typically used for the 

bottom layer of the ET capillary barrier cover system to provide a contrast in unsaturated hydraulic properties between the two layers. Many ET 

covers are constructed of soils that include clay 

loam, silty loam, silty sand, and sandy loam. The 

storage capacity of the soil varies among different soil types and requires laboratory analysis to 

quantify. One key aspect of construction is avoiding over-compaction (greater than 80-90%) during placement. Higher bulk densities from overcompaction may reduce the storage capacity of 

the soil and inhibit growth of roots (Chadwick et 

al. 1999; Hauser et al. 2001).

Soil Thickness

The thickness of the soil layer(s) depends on the 

required storage capacity, which is determined by 

the water balance at the site. The soil layers need 

to accommodate the design climate conditions, 

such as snowmelts and summer thunderstorms, 

or periods of time during which ET rates are low 

and plants are dormant. Monolithic ET covers 

have been constructed with soil layers ranging 

from 2 feet to 10 feet. Capillary barrier ET covers 

have been constructed with finer-grained layers ranging from 1.5 feet to 5 feet, and coarsergrained layers ranging from 0.5 feet to 2 feet.

In some arid to semiarid areas, when there is 

a lack of local precipitation data, the potential 

performance of an ET cover might be estimated 

by natural analog. This is done by trenching and 

examining the trench walls for a caliche layer. 

Caliche (CaCO3) is a precipitation product and 

when shallow generally indicates the level of 

deepest recent percolation. Also, an accumulation of soluble ions such as chloride can indicate 

the depth of recent percolation.

Vegetation Types

Vegetation for the cover system is used to promote transpiration and minimize erosion by stabilizing the surface of the cover. It can also be used 

for aesthetics or to promote habitat. Grasses, 

shrubs, and trees have all been used on ET covers. A mixture of native plants generally is planted, 

though not always, because native vegetation 

usually is more tolerant than imported vegetation 

to regional conditions, such as extreme weather 

and disease. A combination of warm- and coolseason species should provide water uptake 

throughout the entire growing season, which 

enhances transpiration. In addition, native vegetation species are less likely to disturb the natural 

ecosystem (Dwyer et al. 1999; EPA 2000). 

If deep rooting vegetation is considered for the 

cover, the designer should consider whether root 

penetration into the waste area will result in any 

transport of constituents into the above ground 

biomass. The presence of constituents such as 

heavy metals or radionuclides in leaf and stem 

tissue could present a hazard.

Summary of Key Design Considerations

• Climate—amount, form and timing of 

precipitation determines storage capacity need

• Soil Type—finer grained soils are preferred for fertility and storage capacity

• Soil Thickness—combined with soil 

type determines storage capacity of 

cover

• Vegetation Types—must be appropriate 

for location with well developed root 

systems to promote transpiration and 

provide long-term performance

• Soil Fertility—to sustain vegetation 

when plants are used

• Control Layers—biobarriers, gas collection, and drainage layers are used as 

needed
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Finally, consideration needs to be given to how long 

the selected vegetation will take to establish itself 

and how this will affect the cover’s performance.

Soil Fertility

When vegetation is a component of an ET cover 

system, the evaluation of the soil that is proposed 

for the cover (not the subgrade) should include a 

determination of whether the pH, cation exchange 

capacity, organic matter, and nitrogen, phosphorus, potassium, and micronutrient content are 

appropriate for the vegetation proposed for use 

on the cover (ITRC 2003b, Albright et al. 2010). 

Amendments, such as lime, biosolids, sawdust, 

or synthetic conditioners, can be worked into the 

soil to improve its suitability for planting and/or 

water storage capacity. These types of amendments, while adding to the cover construction 

cost, tend to be long-lived and should not need to 

be repeated. Fertilizers and amendments, such 

as manure, can be added at initial planting to help 

establish the cover; however, they are not longlived and must be reapplied in nutrient-poor soils 

on a regular basis. The need for reapplication of 

fertilizers will present an ongoing cost to the project and should be carefully evaluated in selecting 

an ET cover over a conventional cover. While it is 

not necessary that borrow soils be obtained onsite or locally, the cost of transporting them any 

distance should be considered (e.g., it could be 

prohibitively expensive). For a more complete 

discussion, see Section 5.2 Preconstruction Cover Material Specifications of ITRC 2003b. 

Control Layers

Control layers, such as those used to minimize 

animal intrusion, promote drainage, and control 

and collect landfill gas, are often included for 

conventional cover systems and may also be incorporated into ET cover system designs. For example, a capillary barrier ET cover for the mixed 

waste landfill at Sandia National Laboratories in 

New Mexico has a one-foot-thick crushed rock 

biobarrier located beneath the soil cover (about 

four feet bgs) to prevent animals from burrowing 

into the waste layer. Because of the difference 

in size between the soil and the rock, the rock 

layer also acts as a capillary break. At another 

site, Monticello Uranium Mill Tailings Site in Utah, 

an ET capillary barrier design has a cobble layer 

as an animal intrusion barrier located within the 

fine soil layer and above the 12-inch thick capillary barrier layer. 

PERFORMANCE MONITORING

Protection of groundwater quality often is a primary performance goal for all waste containment 

systems, including final cover systems. The 

potential adverse impact to groundwater quality 

can result from the release of leachate generated 

in landfills or other closed in-place waste disposal 

units such as unlined surface impoundments. 

The rate of leachate generation (and potential 

impact on groundwater) can be minimized by 

keeping liquids out of a landfill or contaminated 

source area of a remediation site. As a result, 

the function of minimizing percolation typically 

becomes a key performance criterion for a final 

cover system (EPA 1991).

Monitoring the performance of ET cover systems 

has generally focused on evaluating the ability 

of these designs to minimize water drainage into 

the waste. Percolation performance typically is 

reported as a flux rate (inches or millimeters of 

water that have migrated downward through the 

base of the cover in a period of time, generally 

considered as 1 year). Percolation monitoring 

for ET cover systems is measured directly using 

pan lysimeters or estimated indirectly using soil 

moisture measurements and soil matric potential, 

thereby allowing the calculation of a flux rate. A 

more detailed summary on the advantages and 

disadvantages of both approaches can be found 

in Benson et al. (2001) and EPA (2004).

Percolation monitoring can also be evaluated 

indirectly by using leachate collection and removal 

systems. For landfills underlain with these systems, the amount and composition of leachate 

generated can be used as an indicator of the 

performance of a cover system (the higher the 

percolation, the more leachate that will be generated) (EPA 1991).

Although the ability to minimize percolation is 

a performance criterion for final cover systems, 

limited data are available about percolation performance for final cover systems for both conventional and alternative designs. Most of the recent 

readily available data on flux rates have been 

generated by the ACAP and ALCD programs; see 

Appendix B for discussion and data presentation. 

From these programs, flux rate performance data 

are available for 14 sites with demonstrationscale ET cover systems (Dwyer 2003, Albright 

and Benson 2005).
9

Additional demonstration projects of ET covers conducted in the 1980s and early 1990s are 

discussed in the ACAP Phase I Report, which is 

available at http://www.dri.edu/acap-research. 

Monitoring Systems

Direct measurement of water flowing through the 

bottom of a cover can be done using a pan lysimeter. The lysimeters are installed underneath 

the cover system, typically as geomembrane liners backfilled with a drainage layer and shaped to 

collect water percolation. Water collected in the 

lysimeter is directed toward a monitoring point 

and measured using a variety of devices (for example, tipping bucket, pressure transducers). 

Pan lysimeters were used in the ALCD and ACAP 

programs for collecting performance data for ET 

cover systems and are part of the design for the 

Rocky Mountain Arsenal cover systems. They are 

the monitoring system of choice for equivalency 

demonstrations. Details of the ACAP lysimeters 

are in Albright et al. (2004).

Soil moisture monitoring can be used to determine moisture content at discrete locations in 

cover systems and to evaluate changes over time 

in horizontal or vertical gradients. Soil water properties are measured using a variety of methods 

and include methods for determining soil moisture (TDR, neutron attenuation, and resistivity), 

soil humidity (psychrometer), and soil matric potential (heat dissipation units or HDUs). Table 1 

presents examples of non-destructive techniques 

that have been used to assess soil moisture 

content of ET cover systems. A high soil moisture value indicates that the water content of the 

cover system is approaching its storage capacity, 

thereby increasing the potential for percolation. 

Soil moisture is especially important for capillary 

barrier ET cover systems; when the finer grained 

layer becomes saturated, the capillary barrier 

can fail resulting in water percolating through the 

highly permeable layer to the waste below (Hakonson 1997). Monitoring instruments have various configurations, costs, and accuracies. The 

choice of which one to use would depend on the 

site data quality objective.

Maintaining the effectiveness of the cover system 

for an extended period of time is another important performance criterion for ET covers as well 

as conventional covers. Some factors to consider in evaluating short-term and long-term performance monitoring of a final cover system include settlement effects, gas emissions, erosion 

or slope failure, and maintenance of vegetative 

cover. These factors can be monitored using a 

variety of methods including settlement gauges, 

erosion pins, TDR cables for subsidence, soil gas 

wells and associated sampling ports, and remote 

sensing (e.g., LIDAR).

Numerical Models

Models can be used to support the design of 

ET covers. Although models have strengths and 

weaknesses and none can accurately predict 

cover behavior in all environments, in their simplest application, a model can be used to test the 

assumptions made in the designer’s conceptual 

model. A good example of this is where model simulation shows a cover thickness that is clearly too 

thin or shows diminishing returns in adding more 

soil beyond an optimum thickness to achieve 

water storage capacity. Simulations by several 

models to test the conceptual model and design 

can be very useful in identifying critical assumptions where a small change can result in large 

performance deviations. Identifying sensitive assumptions allows for more conservative design 

specifications or the application of greater quality 

control checks. If such a procedure is desirable, a 

model using Richards’ equation (ITRC 2003b) is 

necessary to properly simulate the mechanisms 

important to cover function. At sites where ET engineered barriers are expected to last hundreds 

or thousands of years (e.g., DOE low-level radioactive burial grounds), the modeling should include extreme weather events and their resultant 

affects on engineered barrier design.

A number of models have been used for estimating water balances. Research reviewed for this 

fact sheet suggests that opinions differ among 

practitioners about how successful a given model 

will be in predicting cover performance. A model should only be selected after examining its 

strengths and weaknesses in simulating site-specific conditions. For example, if early snowmelt is 

a critical factor, how well does the model simulate it? For design purposes it might be prudent, 

though somewhat more expensive, to use two 

models, such as a water balance and a numerical model, to estimate cover performance (Khire 

et al. 1997). Table 2 in Chapter 3 of Albright et al. 

(2002) compares the processes and attributes of 

10 models.
10

COST 

Despite the large number of projects installed to 

date, limited cost data are available for the construction and operation and maintenance of ET 

cover systems. The available construction cost 

data indicate that these cover systems have the 

potential to be less expensive to construct than 

conventional cover systems, especially those 

requiring geomembranes. Factors affecting the 

cost of construction include soil layer thickness, 

availability of materials, placement methods, and 

The numerical model HELP is a widely used water 

balance model that is most appropriate for nonET landfill cover design. UNSAT-H, VADOSE/W 

and HYDRUS-1D/2D/3D are examples of numerical models that have been used frequently for 

the design of ET covers. Some models are in the 

public domain, others require purchase. Hauser 

(2009) recommends using the water balance 

Erosion Productivity Impact Calculator (EPIC), 

which is in the public domain, for ET cover modeling. EPIC is a water balance model and does 

not use Richards equation.

Table 1. Examples of Non-Destructive Soil Moisture Monitoring Methods

Method Description Instrumentation

Capacitance sensor Uses frequency domain induced polarization to measure the dielectric properties of 

the soil. The dielectric of dry soil is approximately 5, and the dielectric of water 

is approximately 80. When soil becomes 

moistened by water, its dielectric increases.

Consists of a probe connected to 

a coaxial cable and buried at 

appropriate depth

Electrical resistance blocks Measures resistance resulting from a gradient between the sensor and the soil; higher 

resistance indicates lower soil moisture

Consists of electrodes embedded 

in a gypsum, nylon, or fiberglass 

porous material

Gee lysimeter Wicks water from soil around a collection 

container and measures the resulting water 

level in the container directly

Consists of a small collector body 

and a wick. The water level in the 

collector body is measured by an 

electronic water level gauge.

Thermal dissipation unit Uses a heated ceramic block to determine 

soil moisture near the block. The rate of 

heat dissipation from the block is related to 

soil moisture—the quicker the dissipation 

the higher the soil moisture.

Consists of a small heater inside 

a porous block with a temperature 

sensor attached by cable to a 

surface meter

Neutron attenuation Emits high-energy neutrons into the soil that 

collide with hydrogen atoms associated with 

soil water and counts the number of pulses, 

which is correlated to moisture content

Consists of a probe inserted into 

access boreholes with aluminum 

or polyvinyl chloride casing

Psychrometer Measures relative humidity (soil moisture) 

within a soil

Generally consists of a thermocouple, a reference electrode, 

a heat sink, a porous ceramic 

bulb or wire mesh screen, and a 

recorder

Suction lysimeter Collects pore (unsaturated) water directly Constructed of a porous ceramic 

bulb with a cylindrical reservoir to 

store water. A tube to the surface 

allows water to be drawn and 

measured.

Tensiometer Measures the matric potential of a given 

soil, which is converted to soil moisture 

content

Commonly consists of a porous 

ceramic cup

Time domain reflectrometry Sends pulses through a cable and observes 

the reflected waveform, which is correlated 

to soil moisture

Consists of a cable tester (or 

specifically designed commercial 

time domain reflectrometry unit), 

coaxial cable, and a stainless 

steel probe
11

project scale. Locally available soils are typically 

used for ET cover systems. In addition, the use 

of local materials generally minimizes transportation costs (Dwyer 2003, EPA 2000). Also, when 

comparing the costs for ET and conventional 

covers, it is important to consider the types of 

components for each cover and their intended 

function. For example, it would generally not be 

appropriate to compare the costs for a conventional cover with a gas collection layer to an ET 

cover with no such layer. Additional information 

about the costs for specific ET cover systems is 

provided in some of the project profiles discussed 

under Technology Status.

TECHNOLOGY STATUS

EPA has developed and recently updated a 

searchable on-line database with information 

about ET cover systems, available at http://cluin.

org/products/altcovers. As of February 2011, the 

database contained 167 projects with full scale 

monolithic ET cover systems and 5 projects with 

capillary barrier ET cover systems; these systems have been proposed, tested, or installed 

throughout the United States. Full scale applications have primarily been in the Great Plains 

and western states. Where data are available, 

the database provides project profiles that include site background information (such as site 

type, climate, hydrogeology), project information 

(such as purpose, scale, status), cover information (such as design, vegetation, installation), performance and cost information, points of contact, 

and references. Appendix A provides a summary 

of key information from the database for projects 

with monolithic ET or capillary barrier ET covers.

In addition to this on-line database, several federal and state programs have demonstrated and 

assessed the performance of ET cover systems. 

The following programs provide performance 

data, reports, and other useful information to help 

evaluate the applicability of ET designs for final 

cover systems.

• Alternative Landfill Cover Demonstration: 

See Exhibit 3 in Appendix B for more information or http://www.sandia.gov/Subsurface/

factshts/ert/alcd.pdf.

• Alternative Cover Assessment Program: See 

Exhibit 4 in Appendix B for more information 

or http://www.dri.edu/acap-research. 

• Interstate Technology and Regulatory Council 

published two reports on ET covers: Technology Overview Using Case Studies of Alternative Landfill Technologies and Associated 

Regulatory Topics and Technical and Regulatory Guidance for Design, Installation, and 

Monitoring of Alternative Final Landfill Covers. For further information, see http://www.

itrcweb.org/guidancedocument.asp?TID=21.

In the initial stages of its program, California required any landfill that desired to employ an ET 

cover to conduct a demonstration project. The 

success of these demonstrations has led to the 

regulators allowing an ET cover if the landfill 

owner shows soil, design, and climatic conditions are similar to those of a landfill facility with 

a permitted ET cover. Texas has a similar program. Both of these states have seen a significant increase in the number of landfills using or 

proposing ET covers. 

REFERENCES 

Abichou, T., X. Liu, and K. Tawfiq. 2004. Design 

of Cost Effective Lysimeters for Alternative Landfill Cover Demonstrations Projects, Report #04-

0232007. Florida State University, College of Engineering. 88 pp. 

Albright, W., G. Gee, G. Wilson, and M. Fayer. 

2002. Alternative Cover Assessment Project 

Phase I Report, Publication No. 41183. Desert 

Research Institute, NV. 203 pp.

Albright, W., C. Benson, G. Gee, A. Roesler, 

T. Abichou, P. Apiwantragoon, B. Lyles, and S. 

Rock, 2004, “Field Water Balance of Landfill Final 

Covers.” J. of Environmental Quality, 33;2317-

2332.

Albright, W. and C. Benson. 2005. Alternative 

Cover Assessment Program: Report to Office of 

Research and Development National Risk Management Research Lab Land Remediation and 

Pollution Control Division. Desert Research Institute and University of Wisconsin, 54 pp. 

Albright, W., W. Waugh, and C. Benson. 2007. 

Enhancements to Natural Attenuation: Selected 

Case Studies, Washington Savannah River Company, WSRC-STI-2007-00250, p 9-30. 
12

Hadj-Hamou, T. and E. Kavazanjian, Jr. 2003. 

“Monitoring and Evaluation of Evapotranspirative 

Cover Performance.” Proceedings of the 9th 

International Waste Management and Landfill 

Symposium, Sardinia, Italy, 6-10 October. 

Hakonson, T.E. 1997. “Capping as an Alternative 

for Landfill Closures-Perspectives and Approaches.” Environmental Science and Research 

Foundation. Proceedings, Landfill Capping in the 

Semi-Arid West: Problems, Perspectives, and 

Solutions. Grand Teton National Park, Wyoming. 

May 21-22. ESRF-019. p 1-18.

Hakonson, T., et al. 1994. Hydrologic Evaluation 

of Four Landfill Cover Designs at Hill Air Force 

Base, Utah. Los Alamos National Laboratory, Los 

Alamos, New Mexico. LAUR-93- 4469.

Hauser, V.L., and B.L. Weand. 1998. “Natural 

Landfill Covers.” Proceedings, Third Tri-Service 

Environmental Technology Workshop. San 

Diego, California. August 18-20.

Hauser, V.L., B.L. Weand, and M.D. Gill. 2001a. 

“Natural Covers for Landfills and Buried Waste.” 

Journal of Environmental Engineering. Sept. p 

768-775.

Hauser, V., B. Weand, and M. Gill. 2001b. Alternative Landfill Covers. Air Force Center for Environmental Excellence. 38 pp.

Hauser, Victor L. 2009. Evapotranspiration Covers for Landfills and Waste Sites. CRC Press, 

Boca Raton, FL. ISBN: 13: 978-1-4200-8651-5, 

203 pp. 

ITRC. 2003a. Technology Overview Using Case 

Studies of Alternative Landfill Technologies and 

Associated Regulatory Topics. 107 pp.

ITRC. 2003b. Technical and Regulatory Guidance for Design, Installation, and Monitoring of 

Alternative Final Landfill Covers. 198 pp.

Kelln, C.J., S.L. Barbour, A. Elshorbagy, and C. 

Qualizza. 2006. “Long-Term Performance of a 

Reclamation Cover: The Evolution of Hydraulic 

Properties and Hydrologic Response.” Unsaturated Soils 2006: Proceedings of the 4th International Conference on Unsaturated Soils, 2-6 

April 2006, Carefree, Arizona. ASCE, Reston, VA. 

Geotechnical Special Publication No. 147, ISBN: 

0784408025.

Albright, William H., Craig H. Benson, and W. 

Joseph Waugh, 2010. Water Balance Covers 

for Waste Containment Principles and Practice, 

ASCE Press, 158 pp.

Benson, C.H. 2001. “Alternative Earthen Final 

Covers (AEFCs) or ‘ET’ Caps.” GEO Institute. 

Proceedings, Liners and Covers for Waste Containment Facilities. Atlanta, Georgia. November 

14-16.

Benson, C.H. et al. 2001. “Field Evaluation of 

Alternative Earthen Final Covers.” International 

Journal of Phytoremediation. Volume 3, Number 

1, p 105-127.

Benson, C.H. et al. 2002. “Evaluation of Final 

Cover Performance: Field Data from the Alternative Landfill Cover Assessment Program (ACAP).” 

Proceedings, WM 2002 Conference. Tucson, Arizona. February 24-28.

Benson, C.H., A. Sawangsuriya, B. Trzebiatowski, and 

W.H. Albright 2007. “Postconstruction Changes in 

the Hydraulic Properties of Water Balance Cover 

Soils.” Journal of Geotechnical and Geoenvironmental Engineering 133(4):349-359.

Bolen, M.M. et al. 2001. Alternative Cover Assessment Program: Phase II Report. University of 

Wisconsin-Madison. Madison, Wisconsin. September. Geo Engineering Report 01-10.

Chadwick, Jr., D. et al. 1999. “Field Test of Potential RCRA-Equivalent Covers at the Rocky Mountain Arsenal, Colorado.” Solid Waste Association 

Proceedings, North America’s 4th Annual Landfill Symposium. Denver, Colorado. June 28-30. 

GR-LM 0004, p 21-33.

City of Los Angeles. 2003. Personal communication regarding Lopez Canyon Landfill from 

Doug Walters, Sanitary Engineer, Department of 

Public Works, to Kelly Madalinski, EPA. September 25.

Dwyer, S. 2003. Water Balance Measurements 

and Computer Simulations of Landfill Covers. 

University of New Mexico, Civil Engineering Department. May.

Dwyer, S.F., J.C. Stormont, and C.E. Anderson. 

1999. Mixed Waste Landfill Design Report. Sandia 

National Laboratories. SAND99-2514. October.
13

Kelsey, J.A., J.T. Kay, M. Ankeny, and M. Plummer. 

2006. “Darcian Flux Estimations in Evapotranspiration Landfill Covers.” Unsaturated Soils 2006: 

Proceedings of the 4th International Conference 

on Unsaturated Soils, 2-6 April 2006, Carefree, 

Arizona. ASCE, Reston, VA. Geotechnical Special Publication No. 147, ISBN: 0784408025.

Khire, M.V., C.H. Benson, and P.J. Bosscher. 

1997. “Water Balance Modeling of Earthen Final 

Covers.” Journal of Geotechnical and Geoenvironmental Engineering. August, p 744- 754.

McGuire, P.E., J.A. England, and B.J. Andraski. 

2001. “An Evapotranspiration Cover for Containment at a Semiarid Landfill Site.” Florida State 

University. Proceedings, 2001 International 

Containment & Remediation Technology Conference. Orlando, Florida. June 10 - 13.

Mitchell, M. 2009. Mixed Waste Landfill Quarterly 

Progress Report Evapotranspirative Cover Construction Project, August - October 2009. Sandia 

National Laboratories, 38 pp.

Roesler, A.C., C.H. Benson, and W.H. Albright. 

2002. Field Hydrology and Model Predictions for 

Final Covers in the Alternative Cover Assessment 

Program-2002. University of Wisconsin-Madison. 

Geo Engineering Report No. 02-08. September 

20, 279 pp. 

Scanlon, B.R., et al. 2002. “Intercode Comparisons for Simulating Water Balance of Surficial 

Sediments in Semiarid Regions.” Water Resources 

Research. Volume 38, Number 12 

Scanlon, B., R. Reedy, K. Keese, and S. Dwyer. 

2005. “Evaluation of Evapotranspirative Covers for Waste Containment in Arid and Semiarid 

Regions in the Southwestern US.” Vadose Zone 

Journal, 4, p. 55-71. 

Stormont, John C. 1997. “Incorporating Capillary 

Barriers in Surface Cover Systems.” Environmental 

Science and Research Foundation. Proceedings, 

Landfill Capping in the Semi-Arid West: Problems, Perspectives, and Solutions. Grand Teton 

National Park, Wyoming. May 21 through 22. 

ESRF-019, p 39-51. 

EPA. 1989. Technical Guidance Document: Final 

Covers on Hazardous Waste Landfills and Surface Impoundments. EPA/530-SW-89-047. July.

EPA. 1991. Seminar Publication, Design and 

Construction of RCRA/CERCLA Final Covers. 

EPA/625/4-91/025. May.

EPA 1992a. Seminars: Design, Operation, and 

Closure of Municipal Solid Waste Landfills. 

EPA/600/K-92/002

EPA. 1992b. Subtitle D Clarification. 40 CFR 257 

& 258. Federal Register pages 28626 through 

28632. June.

EPA. 2000. Introduction to Phytoremediation. 

Office of Research and Development. Washington, 

DC. EPA/600/R-99/107. February.

EPA. 2004. Survey of Technologies for Monitoring Containment Liners and Covers, EPA 542-R04-013, 64 pp.

Weand, B.L. et al. 1999. “Landfill Covers for Use 

at Air Force Installations.” AFCEE. Brooks Air 

Force Base, Texas. February.

NOTICE

Preparation of this fact sheet has been 

funded wholly by the U.S. Environmental 

Protection Agency under Contract Number EP-W-07-037. For more information 

regarding this fact sheet, please contact Steve Rock at (513) 569-7149 or 

rock.steven@epa.gov or Linda Fiedler at 

(703) 603-7194 or fiedler.linda@epa.gov.

This fact sheet is available for viewing or 

downloading from EPA’s Hazardous Waste 

Cleanup Information (CLU-IN) web site at 

http://cluin.org. 
14

GLOSSARY

Arid and semi arid climates. In 1953, Peveril 

Meigs divided desert regions on Earth into three 

categories according to the amount of precipitation they received. In this now widely accepted 

system, extremely arid lands have at least 12 consecutive months without rainfall, arid lands have 

less than 250 millimeters of annual rainfall, and 

semiarid lands have a mean annual precipitation 

of between 250 and 500 millimeters. Arid and 

extremely arid land are deserts, and semiarid 

grasslands generally are referred to as steppes. 

(USGS webpage http://pubs.usgs.gov/gip/deserts/

what/)

Caliche. A subsurface carbonate horizon formed 

in a soil in an arid to semiarid region under conditions of low rainfall. The leaching of carbonates 

from the upper soil by precipitation combined with 

its limited downward percolation results in an 

accumulation of carbonates that form an often 

hard carbonate horizon and designate the deepest penetration of the precipitation.

Composite cover. A landfill cover that includes a 

synthetic layer such as a geomembrane.

Dump. An area where illegal waste disposal has 

occurred.

Evapotranspiration. The combination of water 

lost from the soil through direct evaporation and 

water lost to the atmosphere through plant transpiration.

Geosynthetic clay liner. A woven fabric that 

encases a clay material, generally a smectite 

clay, to provide a low permeability layer.

Hydraulic conductivity. In hydrology, a numeric 

coefficient describing the rate that water can 

move through a porous media. Usually expressed 

in cm/sec.

Infiltration. The movement of water from the soil 

surface into the soil.

Natural analog. A subsurface feature that occurs 

naturally that can be used to evaluate a similar 

engineered feature. In ET design the presence of 

a near surface caliche layer or chloride ion accumulation gives an indication of how deep precipitation is percolating in the subsurface.

Percolation. The movement of water through soil.

Permeability. The capacity of a porous media to 

transmit a fluid.

Richards equation. A numerical representation of 

unsaturated flow of a fluid through porous media.

Water balance. In the context of a landfill cover, 

the evaluation of the end fate of precipitation; that 

is, percent run-off, infiltration, evaporation, transpiration, and percolation. 

Store and release. In the context of an ET cover, 

the cover soil will store precipitation (i.e., prevent 

its drainage into the underlying waste), until the 

water either evaporates or is transpired by the 

vegetative cover.
15

APPENDIX A

PROPOSED, APPROVED, AND INSTALLED SITES HAVING 

EVAPOTRANSPIRATION COVERS
16

This table is a list by region and state of sites that have proposed, approved, or installed ET covers. It 

also contains sites that had demonstration scale pilots, which may or may not have gone on to full scale. 

Proposed covers include sites where an ET cover has been proposed by the facility and approved by the 

governing agency (e.g., California) or has been proposed by the facility but approval is pending (e.g., 

Texas). In Texas the proposal is generally to amend an existing permit to add ET covers as an option. The 

state of Oklahoma provided a list of landfills that had approved and installed ET covers as did the states of 

Colorado and Montana. The state of Arizona provided electronic copies of the permits of facilities that had 

approved or installed ET covers. The California Regional Water Control Boards maintain electronic copies 

of their permits on their webpages as does the state of Utah. Sites were excluded from the list if the permit 

specifically called for a water infiltration barrier layer even though the permit referred to the cover as an ET 

cover. A legend and list of definitions is found at the end of the table.

Site Program Type of 

Site

Scale Status Type of 

Cover

Region 1

Region 2

New York

GE Main Plant, Schenectady, NY RCRA HWS F Installed M

State-Licensed Radioactive Waste Disposal Area, 

West Valley, NY

NRC Rad Demo Complete BE

Region 3

Maryland

Beltsville Agricultural Research Center (USDA), 

Beltsville, MD

NRC Rad Demo Complete BE

College Park Landfill, College Park, MD CERCLA MSW Demo Complete M

College Park Landfill, College Park, MD CERCLA MSW F Proposed M

Pennsylvania

Welsh Road Landfill, Honeybrook, PA CERCLA MSW F Installed M

Region 4

Georgia

Marine Logistics Base Albany Georgia ACAP MSW Demo Complete M

Marine Logistics Base Albany Georgia CERCLA MSW F Installed M

Region 5

Illinois

Sheffield City Landfill, Sheffield, IL NRC Rad Demo Complete CB

Michigan

Casting Sand Landfill, Detroit, MI RCRA IW Demo Complete M

Wisconsin

Omega Hills, Milwaukee, WI RCRA MSW Demo Complete CB

Region 6

New Mexico

Cerro Colorado Landfill, Albuquerque, NM RCRA MSW F Proposed M

Chemical Waste Landfill at Sandia National 

Laboratories, Albuquerque, NM

RCRA HWS F Installed M

Crouch Mesa Landfill, Farmington, NM RCRA MSW F Proposed M

Kirtland Air Force Base, Albuquerque, NM RCRA HW F Installed M

Evapotranspiration Covers
17

Site Program Type of 

Site

Scale Status Type of 

Cover

Los Alamos National Laboratory, Los Alamos, NM DOE Research Rad Demo Complete CB

Mixed Waste Landfill at Sandia National Laboratories, 

Albuquerque, NM

RCRA MW F Installed M

Molycorp Tailings Facility, Questa, NM CERCLA HWS F Proposed M

Red Rocks Regional Landfill, Thoreau, NM RCRA MSW F Proposed M

Rio Rancho Landfill, Rio Rancho, NM RCRA MSW F Approved M

Sandoval County Landfill, Bernalillo, NM RCRA MSW F Proposed M

Sandia National Laboratories, Albuquerque, NM RCRA NHWS Demo Complete M and 

CB

San Juan County Landfill, Aztec, NM RCRA MSW F Approved M

Valencia Landfill, Los Lunas, NM RCRA MSW F Approved M

Oklahoma

Alderson Landfill, McAlester, OK RCRA MSW F Installed M

American Environmental, Sand Springs, OK RCRA MSW F Installed M

Broken Arrow Landfill, Broken Arrow, OK RCRA MSW F Installed M

Canadian Valley Landfill, Shawnee, OK RCRA MSW F Installed M

Center Point Landfill, Prague, OK RCRA MSW F Approved M

City of Sallisaw, Sallisaw, OK RCRA MSW F Approved M

East Oak Landfill, Oklahoma City, OK RCRA MSW F Approved M

Muskogee Community Landfill, Muskogee, OK RCRA MSW F Approved M

Newcastle Landfill, Newcastle, OK RCRA MSW F Installed M

Oklahoma Landfill, Oklahoma City, OK RCRA MSW F Installed M

Osage Landfill, Bartlesville, OK RCRA MSW F Design M

Porter Landfill, Porter, OK RCRA MSW F Installed M

Quarry Landfill, Tulsa, OK RCRA MSW F Installed M

Red Carpet, Meno, OK RCRA MSW F Approved M

Southeast OKC Landfill, Oklahoma City, OK RCRA MSW F Installed M

Southern Plains, Ninnekah, OK RCRA MSW F Approved M

Stillwater Landfill, Stillwater, OK RCRA MSW F Approved M

Texas

Caliche Canyon Landfill, Lubbock, TX RCRA MSW F Proposed M

City of Corsicana Landfill, Corsicana, TX RCRA MSW F Proposed/

Pending

M

City of Fredericksburg Landfill, Fredericksburg, TX RCRA MSW F Proposed/

Pending

M

City of Kerrville, Kerrville, TX RCRA MSW F Proposed/

Pending

M

City of Lubbock Landfill, Lubbock, TX RCRA MSW F Installed M

City of Snyder Landfill, Snyder, TX RCRA MSW F Proposed M

City of Victoria Landfill, Victoria, TX RCRA MSW F Proposed/

Pending

M

DFW Recycling Disposal Facility, Lewisville, TX RCRA MSW F Proposed/

Pending

M
18

Site Program Type of 

Site

Scale Status Type of 

Cover

El Centro Landfill, Robstown, TX RCRA MSW F Proposed/

Pending

M

Golden Triangle Landfill, Beaumont, TX RCRA MSW F Proposed/

Pending

M

Itasca Landfill, Itasca, TX RCRA MSW F Proposed/

Pending

M

Mexia Landfill Mexia, TX RCRA MSW F Proposed//

Pending

M

Pantex Plant (USDOE), Amarillo, TX RCRA CD F Installed M

Pleasant Oaks Landfill, Mt. Pleasant, TX RCRA MSW F Proposed/

Pending

M

Rio Grande Valley Landfill, Donna, TX RCRA MSW F Proposed/

Pending

M

Sierra Blanca, Sierra Blanca, TX Texas Low 

Level Rad

Rad Demo Complete CB

Turkey Creek Landfill, Alvarado, TX RCRA MSW F Proposed/

Pending

M

Westside Landfill, Sledo, TX RCRA MSW F Installed M

Region 7

Iowa

Bluestem Landfill Site No. 1, Cedar Rapids, IA ACAP MSW Demo Complete M

Bluestem Landfill Site No. 2, Cedar Rapids, IA ACAP MSW Demo Complete M

Grundy County Landfill, Grundy Center, IA RCRA 

Cleanup

MSW Demo Complete M

Kansas

Barton County Landfill, Great Bend, KS RCRA MSW F Installed M

Chanute Landfill, Chanute, KS RCRA MSW F Installed M

Coffey County Landfill, Burlington, KS RCRA MSW F Installed M

Holcomb Combustion Waste Landfill, Holcomb, KS RCRA IW Ash F Proposed M

Johnson County Landfill, Shawnee, KS RCRA MSW F Installed M

McPherson County Landfill, McPherson, KS RCRA MSW F Installed M

Seward County Landfill, Liberal, KS RCRA MSW F Proposed M

Missouri

Electrical Power Plant, St. Louis, MO RCRA IW Ash Demo Complete M

RCRA Solid Waste Unit at Former Wood Treating 

Plant, Kansas City, MO 

RCRA HWS F Installed M

Nebraska

Douglas County Recycling and Disposal Facility, 

Bennington, NE 

ACAP MSW Demo Complete CB

Hastings Groundwater Contamination, Hastings, NE CERCLA MSW F Installed M

Region 8

Colorado

Buffalo Ridge Landfill, Keenesburg, CO RCRA MSW F Approved M

Clear Springs Ranch Ash Monofill, Fountain, CO RCRA IW F Approved M

Colorado Springs Landfill, Colorado Springs, CO RCRA MSW F Installed M
19

Site Program Type of 

Site

Scale Status Type of 

Cover

Conservation Services, Inc. Adams County, CO RCRA MSW F Installed M

Custer County Landfill, Westcliffe, CO RCRA MSW F Installed M

Denver Arapahoe Disposal Site, Arapahoe, CO RCRA MSW F Installed on 

closed cells

M

Fort Carson, Colorado Springs, CO RCRA MSW F Installed M

Kit Carson County Landfill, Burlington, CO RCRA MSW F Proposed M

Mesa County Landfill, Grand Junction, CO RCRA MSW F Installed M

Midway Landfill, Fountain, CO RCRA MSW F Installed M

North Weld Landfill, Ault, CO RCRA MSW F Installed M

Rocky Mountain Arsenal (US Army), Denver, CO DoD HWS Demo Complete M

Rocky Mountain Arsenal (US Army), Denver, CO CERCLA HWS F Installed CB

Southside Landfill, Pueblo, CO RCRA MSW F Approved M

West Garfield County Landfill, Rifle, CO RCRA MSW F Installed M

Montana

Allied Waste of Montana, Missoula, MT RCRA MSW F Installed M

City of Billings, Billings, MT RCRA MSW F Installed M

City of Bozeman, Bozeman, MT RCRA MSW F Installed M

City of Butte Landfill, Butte, MT RCRA MSW 

(old fill)

F Installed M

City of Butte Landfill, Butte, MT RCRA MSW 

(new fill)

F Approved M

Harve Class II Landfill, Havre, MT RCRA MSW F Proposed M

High Plains, Great Falls, MT RCRA MSW F Installed M

Lake County Landfill, Polson, MT ACAP MSW Demo Complete CB

Lake County Landfill Full Scale, Polson, MT RCRA MSW F Approved CB

Lewis & Clark County Landfill, Helena, MT ACAP MSW Demo Complete CB

Mr. "M" Landfill, Lewiston, MT RCRA MSW F Installed M

Sanitation, Inc., Lewistown, MT RCRA MSW F Installed M

Unified Disposal District, Havre, MT RCRA MSW F Proposed M

Valley County Landfill, Glasgow, MT RCRA MSW F Proposed M

Valley View, East Helena, MT RCRA MSW F Installed M

North Dakota

Grand Forks Municipal Solid Waste Landfill, Grand 

Forks, ND

RCRA MSW F Approved BE

Great River Energy - Coal Creek Station, Underwood, 

ND 

RCRA IW Ash Demo Installed M

South Dakota

Mitchell Landfill, Mitchell, SD RCRA MSW F Approved M

Municipal Sanitary Landfill (Sioux Falls Regional 

Municipal Landfill), Hartford, SD 

RCRA MSW F Approved M

Pierre Landfill, Pierre, SD RCRA MSW F Installed M

Utah
20

Site Program Type of 

Site

Scale Status Type of 

Cover

Bayview Landfill, 6 miles N. of Elberta, UT RCRA MSW F Installed M

Chester Class II Landfill, 5 miles north of Ephraim, UT RCRA MSW F Installed M

Emery County Class I Landfill, Castle Dale, UT RCRA MSW F Installation 

ongoing

M

Hill Air Force Base, Ogden, UT DoD Research Demo Complete CB

Monticello Mill Tailings (USDOE), Monticello, UT CERCLA Rad Demo Complete CB

Monticello Mill Tailings Repository, Monticello, UT CERCLA Rad F Installed CB

Mountain View Landfill, Salt Lake City, UT RCRA CD 

Asbestos

F Approved M

Sanpete Sanitary Landfill Cooperative White Hills 

Class I Landfill, Sanpete County, UT

RCRA MSW F Approved M

Region 9

Arizona

Blue Hills Regional Landfill, St. Johns, AZ RCRA MSW F Proposed M

Butterfield Station Facility, Mobile, AZ RCRA MSW F Approved M

Cactus Landfill, Florence, AZ RCRA MSW F Approved M

Calmat Avondale Reclamation Landfill, Avondale, AZ RCRA CD F Approved M

City of Eloy, Eloy, AZ RCRA MSW F Approved M

City of Glendale Municipal Landfill, Glendale, AZ RCRA MSW F Approved M

Cochise County Western Regional Landfill Facility, 

Huachuca, AZ

RCRA MSW F Approved M

Copper Mountain Landfill, Wellton, AZ RCRA MSW F Approved M

Gray Wolf Regional Landfill, Dewey, AZ RCRA MSW F Approved M

Ironwood Non Municipal Landfill, Florence RCRA CD F Approved M

Irvington Municipal Landfill, Tucson, AZ RCRA MSW/ 

CD

F Installed M

La Paz County Regional Landfill, Parker, AZ RCRA MSW F Approved M

Lone Cactus Landfill, Phoenix, AZ RCRA CD F Approved M

Los Reales Landfill, Tucson, AZ RCRA MSW F Approved M

Northwest Regional Landfill, Surprise, AZ RCRA MSW F Approved M

Painted Desert Landfill, Joseph City, AZ RCRA MSW F Approved M

Silver Bar Mine Regional Landfill, Florence, AZ RCRA MSW F Approved M

Southwest Regional Solid Waste Landfill, Buckeye, AZ RCRA MSW F Approved M

Speedway Construction Debris Landfill, Tucson, AZ RCRA CD F Approved M

California

Allied Imperial Landfill, Imperial, CA RCRA MSW F Installed M

Altamont Landfill & Resource Recovery Facility, 

Livermore, CA

ACAP MSW Demo Complete M

Altamont Landfill Closure, Livermore CA RCRA MSW F Conditionally ApprovedM

Anza Sanitary Landfill, Anza, CA RCRA MSW F Installed M

Apple Valley Landfill, Apple Valley, CA ACAP MSW Demo Complete Varies

Apple Valley Landfill, Apple Valley, CA RCRA MSW F Installed M

Azusa Landfill, Azusa, CA RCRA MSW F Proposed M

Bakersfield Sanitary Landfill, Bakersfield, CA RCRA MSW F Installed M
21

Site Program Type of 

Site

Scale Status Type of 

Cover

Benton Class III Landfill, Benton, CA RCRA MSW F Installed M

Bishops Canyon Landfill, Los Angeles, CA RCRA MSW/ 

CD

F Installed M

Bradley Landfill, Los Angeles, CA RCRA MSW F Installed M

Burbank Landfill No. 3, Burbank, CA RCRA MSW F Design M

Buttonwillow Landfill, Kern County RCRA MSW F Approved M

California Valley Landfill, California Valley, CA RCRA MSW F Installed M

Camp Pendleton Marine Corps Base, San Diego 

County, CA

RCRA MSW/ 

CAMU

F Installed M

Cedarville (East) Landfill, Cedarville, CA RCRA MSW F Installed M

Chalfant Class III Landfill, Mono County, CA RCRA MSW F Installed M

China Grade Sanitary Landfill, Bakersfield, CA RCRA MSW F Installed M

Coachella Sanitary Landfill, Coachella, CA RCRA MSW F Installed M

Eagleville Landfill, Modoc County, CA RCRA MSW F Installed M

Edom Hill Sanitary Landfill, Riverside County, CA RCRA MSW F Installed M

Edwards Air Force Base Operable Unit 7 Chemical 

Warfare Materiel, Lancaster, CA

CERCLA HW/

MSW

F Installed M

El Toro Marine Corps Air Station, El Toro, CA CERCLA HW/

MSW

F Installed M

Forward Landfill, Manteca, CA RCRA MSW F Installed M

Foxen Canyon Closed Class III Landfill, San Luis 

Obispo, CA

RCRA MSW F Approved M

Frank R. Bowerman Landfill, Irvine, CA RCRA MSW F Approved M

Gaffey Street Sanitary Landfill, Wilmington, CA RCRA MSW F Installed M

Hesperia Landfill, Hesperia, CA RCRA MSW F Installed M

Hirschdale Landfill, Hirschdale, CA RCRA MSW F Installed M

Holtville Sanitary Landfill, Holtville, CA RCRA MSW F Proposed M

Jolon Road Closed Class III Landfill, King City, CA RCRA MSW F Installed M

Kettleman Hills Facility, Kettleman City, CA RCRA HW/

MSW

F Proposed M

Kiefer Landfill, Sloughhouse, CA ACAP MSW Demo Complete M

Kiefer Class III Municipal Landfill, Sloughhouse, CA RCRA MSW F Approved M

Lake City Landfill, Lake City, CA RCRA MSW F Installed M

Lamb Canyon Sanitary Landfill, Beaumont, CA RCRA MSW F Proposed M

Lenwood-Hinkley Landfill, Lenwood, CA RCRA MSW F Installed M

Lopez Canyon Sanitary Landfill, Los Angeles, CA RCRA MSW F Installed M

Marine Corps Base Barstow, CA CERCLA HW/

MSW

F Installed M

Mead Valley Sanitary Landfill, Perris, CA RCRA MSW F Installed M

Midway Solid Waste Disposal Site, San Luis Obispo 

County, CA

RCRA IW F Installed M

Milliken Landfill, Ontario, CA RCRA MSW Demo Complete M 

Milliken Landfill, Ontario, CA RCRA MSW F Installed M 

Monterey Peninsula Landfill, Marina, CA ACAP MSW Demo Complete M
22

Site Program Type of 

Site

Scale Status Type of 

Cover

Needles Sanitary Landfill, Needles, CA RCRA MSW F Installed M

Newberry Springs Sanitary Landfill, Newberry Springs, 

CA

RCRA MSW F Installed M

Norton Air Force Base (Landfill #2), San Bernardino, 

CA

CERCLA MSW F Installed M

Ocotillo Class III Municipal Solid Waste Management 

Facility, Ocotillo, CA

RCRA MSW F Installed M

Operating Industries Inc. Landfill, Monterey Park, CA RCRA HW/

MSW

F Installed M

Phelan Landfill, Phelan, CA ACAP MSW Demo Complete M

Phelan Landfill Full Scale, Phelan, CA RCRA MSW F Approved M

San Marcos Landfill, San Marcos, CA RCRA MSW F Installed M

Spadra Landfill, Pomona, CA RCRA MSW F Installed M

Twentynine Palms Sanitary Landfill RCRA MSW F Installed M

U.S. Marine Corps Air and Ground Combat Center 

(MCAGCC) at Twentynine Palms, Twentynine Palms, CA

DoD MSW Demo Complete M

Yucaipa Landfill, Yucaipa, CA RCRA MSW F Installed M

Hawaii

Kaneohe Bay Marine Corps Base, Oahu, HI DoD MSW Demo Complete BE

Nevada

Nevada Test Site, NV (landfill U-3 ax/bl) DOE 

Research

Rad Demo Complete M

New Austin Landfill, Austin, NV RCRA MSW F Proposed M

U.S. Ecology Nevada Site, Beatty, NV RCRA HW F Approved M

Region 10

Alaska

Anchorage Pilot Study Site, Anchorage. AK RCRA MSW Demo Complete M

City of Elim Landfill, Elim, AK RCRA MSW F Proposed M

Elmendorf Air Force Base, Anchorage, AK RCRA MSW F Installed M

Minchumina Landfill, Lake Minchumina, AK RCRA MSW F Proposed M

Idaho

Idaho National Engineering Laboratory, Idaho Falls, ID CERCLA HWS F Installed CB

Oregon

Finley Buttes Regional Landfill, Boardman, OR ACAP MSW Demo Complete M

Washington

Duvall Custodial Landfill RCRA MSW F Installed M

Hanford 200-Area (USDOE), Richland, WA Prototype 

Barrier (BP-1) 

CERCLA Rad Demo Installed CB

Nonradioactive Dangerous Waste Solid Waste Landfill 

(DOE Hanford)

CERCLA HWS F Proposed M
23

Definitions

Approved A proposal to build an ET has been approved by the appropriate regulatory agency.

Complete Associated with demonstrations and indicates the demonstration is complete.

Proposed An ET design or proposal to construct an ET has been submitted to the appropriate regulatory agency

Installed Construction complete.

Legend

ACAP Alternative Cover Assessment Program

BE Bioengineered

CAMU Corrective Action Management Unit

CB Capillary Break

CD Construction Debris Landfill

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act

Demo Demonstration Project

F Full Scale

HW RCRA Subtitle C Hazardous Waste Facility

HWS Hazardous Waste Site—Generally concerned with cleanup activities

IW Industrial Waste Such as Coal Ash

M Monolithic

MSW Municipal Solid Waste Site

MSW/CAMU MSW being used in a RCRA cleanup to consolidate potentially hazardous wastes

NHWS Non-Hazardous Waste Site

NRC Nuclear Regulatory Commission

Rad Radioactive Waste

RCRA Resource Conservation and Recovery Act
24

APPENDIX B

DATA FROM TWO COMPARISON

DEMONSTRATION PROJECTS
25

ALTERNATIVE LANDFILL COVER DEMONSTRATION (ALCD)

DOE sponsored the ALCD, a large-scale field test of two conventional designs (RCRA Subtitle C and Subtitle D) and four alternative landfill covers (monolithic ET cover, capillary barrier ET cover, geosynthetic clay 

liner cover, and anisotropic [layered capillary barrier] ET cover). The test was conducted at Sandia National 

Laboratories, located on Kirtland Air Force Base in Albuquerque, New Mexico. Cover design information is 

available at http://www.sandia.gov/Subsurface/factshts/ert/alcd.pdf. 

The ALCD collected information on construction, cost, and performance that is needed to compare alternative cover designs with conventional covers. The RCRA covers were constructed in 1995, and the ET 

covers were constructed in 1996. All of the covers were 43 feet wide by 328 feet long and were seeded with 

native vegetation. The purpose of the project was to use the performance data to help demonstrate equivalency and refine numerical models to more accurately predict cover system performance (Dwyer 2003).

The ALCD collected data on percolation using a pan lysimeter and soil moisture to monitor cover performance. Total precipitation (precip.) and percolation (perc.) volumes based on 5 years of data are provided 

below. The ET covers generally have less percolation than the Subtitle D cover for each year shown below. 

More information on the ALCD cover performance can be found in Dwyer 2003.

1997 

(May 1-Dec 31)

1998 1999 2000 2001 2002

(Jan 1-Jun 25)

Precip.

(mm)

Perc.

(mm)

Precip.

(mm)

Perc.

(mm)

Precip.

(mm)

Perc.

(mm)

Precip.

(mm)

Perc.

(mm)

Precip.

(mm)

Perc.

(mm)

Precip.

(mm)

Perc.

(mm)

Monolithic 

ET

267.00 0.08 291.98 0.22 225.23 0.01 299.92 0.00 254.01 0.00 144.32 0.00

Capillary 

Barrier ET

267.00 0.54 291.98 0.41 225.23 0.00 299.92 0.00 254.01 0.00 144.32 0.00

Anisotropic 

(layered 

capillary 

barrier) ET

267.00 0.05 291.98 0.07 225.23 0.14 299.92 0.00 254.01 0.00 144.32 0.00

Geosynthetic 

Clay Liner

267.00 0.51 291.98 0.19 225.23 2.15 299.92 0.00 254.01 0.02 144.32 0.00

Subtitle C 267.00 0.04 291.98 0.15 225.23 0.02 299.92 0.00 254.01 0.00 144.32 0.00

Subtitle D 267.00 3.56 291.98 2.48 225.23 1.56 299.92 0.00 254.01 0.00 144.32 0.74
26

ALTERNATIVE COVER ASSESSMENT PROGRAM (ACAP)

EPA conducted the ACAP to evaluate the performance of alternative landfill covers. The ACAP began in 

1998, and cover performance was evaluated at 13 sites. The sites were located in eight states from California to Ohio and Georgia, and included a variety of landfill types, such as MSW, construction and demolition 

waste, and hazardous waste landfills. At eight sites, conventional and ET covers were tested side by side. 

At the remaining five sites, only ET covers were tested.

The alternative covers typically were constructed with local soils and native vegetation. At two facilities, 

however, hybrid poplar trees were used as vegetation. Percolation performance was evaluated by pan lysimeters. Soil moisture also was evaluated at all sites. Below are the field data for precipitation and percolation 

volumes at 11 of the sites. A summary of field cover performance for all 13 sites through 2004 is provided 

in Albright and Benson (2005). More information about ACAP is available on the Desert Research Institute 

website at http://www.dri.edu/acap-research.

ACAP Water Balance Results

Site Location Cover Design Data Year

(days)

Precipitation

(mm)

Drainage

mm As % of Precipitation

Altamont CA

ET

7/1/01 - 6/30/02 (365) 287 1.5 0.52%

7/1/02 - 6/30/03 (365) 425 2.5 0.59%

7/1/03 -6/30/04 (365) 291 64.5 22.16%

Annual Average 22.8 7.76%

Membrane 

Composite

7/1/01 - 6/30/02 (365) 287 0.0 0.00%

7/1/02 - 6/30/03 (365) 425 4.0 0.94%

7/1/03 -6/30/04 (365) 291 0.2 0.07%

Annual Average 1.4 0.34%

Apple Valley CA

ET

7/1/02 - 6/30/03 (365) 86 0.4 0.47%

7/1/03 -6/30/04 (365) 106 0.0 0.00%

Annual Average 0.2 0.24%

Membrane 

Composite

7/1/02 - 6/30/03 (365) 86 0.0 0.00%

7/1/03 -6/30/04 (365) 106 0.0 0.00%

Annual Average 0.0 0.00%

Compacted 

Clay

7/1/02 - 6/30/03 (365) 86 0.0 0.00%

7/1/03 -6/30/04 (365) 106 0.2 0.19%

Annual Average 0.1 0.1%

Cedar Rapids 

IA

ET

7/1/02 - 6/30/03 (365) 784 157.1 20.0%

7/1/03 -6/30/04 (365) 1742 365.7 20.99%

Annual Average 261.4 20.5%

Compacted 

Clay

7/1/02 - 6/30/03 (365) 784 94 11.98%

7/1/03 -6/30/04 (365) 1742 171 9.82%

Annual Average 132.5 10.9%

Membrane 

Composite

7/1/02 - 6/30/03 (365) 784 22.0 2.81%

7/1/03 -6/30/04 (365) 1742 62.2 3.57%

Annual Average 42.1 3.19%
27

ACAP Water Balance Results

Site Location Cover Design Data Year

(days)

Precipitation

(mm)

Drainage

mm As % of Precipitation

Omaha NB

Thin ET with 

Capillary Break

7/1/01 - 6/30/02 (365) 560 3.45 0.62%

7/1/02 - 6/30/03 (365) 475 50.9 10.72%

7/1/03 -6/30/04 (365) 511 68.5 13.41%

Annual Average 40.95 8.25%

Thick ET with 

Capillary Break

7/1/01 - 6/30/02 (365) 560 4.16 .74%

7/1/02 - 6/30/03 (365) 475 28.7 6.04%

7/1/03 -6/30/04 (365) 511 16.3 3.19%

Annual Average 16.4 3.32%

Membrane 

Composite

7/1/01 - 6/30/02 (365) 560 1.03 0.18%

7/1/02 - 6/30/03 (365) 475 9.15 1.93%

7/1/03 -6/30/04 (365) 511 10.9 2.13%

Annual Average 7.03 1.41%

Boardman OR

ET Thin

7/1/01 - 6/30/02 (365) 164 0.0 0.00%

7/1/02 - 6/30/03 (365) 185 0.0 0.00%

7/1/03 -6/30/04 (365) 177 0.0 0.00%

Annual Average 0.0 0.00%

ET Thick

7/1/01 - 6/30/02 (365) 164 0.0 0.00%

7/1/02 - 6/30/03 (365) 185 0.0 0.00%

7/1/03 -6/30/04 (365) 177 0.0 0.00%

Annual Average 0.0 0.00%

Membrane 

Composite

7/1/01 - 6/30/02 (365) 164 0.0 0.00%

7/1/02 - 6/30/03 (365) 185 0.0 0.00%

7/1/03 -6/30/04 (365) 177 0.0 0.00%

Annual Average 0.0 0.00%

Sacramento CA

ET Thin

7/1/00 - 6/30/01 (365) 379 1.4 0.37%

7/1/01 - 6/30/02 (365) 456 96.2 21.10%

7/1/02 - 6/30/03 (365) 426 3.9 0.92%

7/1/03 -6/30/04 (365) 159 108.4 68.18%

Annual Average 52.48 22.64%

ET Thick

7/1/00 - 6/30/01 (365) 379 0.0 0.00%

7/1/01 - 6/30/02 (365) 456 8.5 1.86%

7/1/02 - 6/30/03 (365) 426 0.0 0.00%

7/1/03 -6/30/04 (365) 159 0.6 0.38%

Annual Average 2.28 0.56%
28

ACAP Water Balance Results

Site Location Cover Design Data Year

(days)

Precipitation

(mm)

Drainage

mm As % of Precipitation

Polson MT

ET with

Capillary Break

7/1/00 - 6/30/01 (365) 358 0.18 0.05%

7/1/01 - 6/30/02 (365) 308 0.39 0.13%

7/1/02 - 6/30/03 (365) 326 0.19 0.06%

7/1/03 -6/30/04 (365) 254 0.20 0.08%

Annual Average 0.24 0.08%

Membrane 

Composite

7/1/00 - 6/30/01 (365) 358 1.16 0.32%

7/1/01 - 6/30/02 (365) 308 0.0 0.00%

7/1/02 - 6/30/03 (365) 326 0.0 0.00%

7/1/03 -6/30/04 (365) 254 0.5 0.20%

Annual Average 0.42 0.13%

Helena MT ET with

Capillary Break

7/1/00 - 6/30/01 (365) 252 0.0 0.00%

7/1/01 - 6/30/02 (365) 314 0.0 0.00%

7/1/02 - 6/30/03 (365) 288 0.0 0.00%

7/1/03 -6/30/04 (365) 103 0.0 0.00%

Annual Average 0.0 0.00%

Albany GA

ET (Trees)

7/1/00 - 6/30/01 (365) 1079* 134 12.42%

7/1/01 - 6/30/02 (365) 1039* 3.1 0.3%

7/1/02 - 6/30/03 (365) 1457* 218.2 14.98%

Annual Average 118.4 9.23%

Compacted 

Clay

7/1/00 - 6/30/01 (365) 909 291.9 32.11%

7/1/01 - 6/30/02 (365) 996 237.6 23.86%

Annual Average 264.8 27.98%

Marina CA ET with

Capillary Break

7/1/00 - 6/30/01 (365) 492 44.7 9.09%

7/1/01 - 6/30/02 (365) 401 64.2 16.01%

7/1/02 - 6/24/03 (359) 467 51.1 10.94%

Annual Average 53.3 12.01%

7/1/00 - 6/30/01 (365) 492 9.0 1.82%

7/1/01 - 6/30/02 (365) 401 25.0 6.23%

7/1/02 - 6/24/03 (359) 467 36.0 7.71%

Annual Average 23.3 5.25%

Monticello UT ET with

Capillary Break

8/12/00 - 6/30/01 (323) 393 0.0 0.00%

7/1/01 - 6/30/02 (365) 213 0.0 0.00%

7/1/02 - 6/30/03 (365) 342 0.0 0.00%

7/1/03 -6/30/04 (365) 315 0.1 0.03%

Annual Average 0.03 0.008%

*Precipitation values at Albany include irrigation of the ET cover test section.

Source: Albright and Benson 2005