We all produce trash that must be managed and disposed of in a manner to protect human health and the environment. I am Steve Harbin, a professional engineer with 29 years of engineering experience, 28 of which have included a primary focus in the planning and implementation of more than 300 solid waste projects, including design of more than 40 municipal solid waste landfills.
MSW landfill design over the past 35 years has advanced from simple unlined, excavated holes in the ground to multimillion-dollar facilities with liners and leachate collection and treatment systems requiring design by multiple professional engineers with various specialties.
The process for designing a modern municipal solid waste landfill begins with an extensive evaluation of the site including, but not limited to, an evaluation of onsite soils, depth to groundwater, distance to wells and surface water intakes, distance to houses, transportation routes, distance to significant groundwater recharge areas, locations of streams, creeks and wetlands, locations of National Historic Sites, airports, flood plains, fault areas, seismic impact zones and unstable areas, as well as distance to adjoining county lines and cities. The content and presentation of this site evaluation is governed by Georgia laws and regulations.
The end result of the site evaluation is a letter from the Georgia Environmental Protection Division (EPD) indicating the suitability of the site for development as a MSW landfill. Prior to the issuance of this decision, the site must be properly zoned and be in compliance with the county’s Comprehensive Solid Waste Management Plan, and the applicant must have completed the Development of Regional Impact (DRI) review process with the Georgia Department of Community Affairs.
The local board of commissioners must also hold a meeting to make a decision regarding the siting of the facility. Then and only then can design of the facility proceed.
Design of MSW landfills is governed by the U.S. Environmental Protection Agency’s 40 CFR Part 258, Subtitle D regulations, the Georgia Comprehensive Solid Waste Management Act of 1990, OCGA Volume 10, Title 12, as amended, and the Rules of the Department of Natural Resources Environmental Protection Division, Chapter 391-3-4 Solid Waste Management.
When the design is completed, it is submitted to Georgia EPD for review by its engineers and geologists for completeness and compliance with all federal and state laws.
In addition to the solid waste handling permit, a MSW landfill must have a National Pollutant Discharge Elimination System (NPDES) stormwater permit for industrial activity, Title V air permit, wetlands permit (if wetlands are to be impacted) and a local land disturbing permit.
In addition to complying with the laws and regulations, I listen carefully to community concerns as part of the design process. As a professional engineer, I am responsible to hold paramount the safety, health and welfare of the public in the performance of my professional duties.
Therefore, I have listed below some typical concerns from previous communities in which I have worked, with a brief response on each one:
• Liners that leak. It is true that all liners leak – but the real question is how much does the amount of leakage impact the environment?
Engineers are problem solvers, and as an engineer, I use my training, design experience and available technology to design a facility that will minimize leakage and have systems in place to detect leakage.
With advances in technology, various remediation tools are available to capture, control and treat any impacting leakage before it leaves the landfill site. Remember, up until the mid-1980s, almost all landfills had no liners or other barriers to impede leakage. Most of the problems related to contaminated groundwater are in reference to those unlined sites.
• Noise. Most all of human and planetary activity results in some form of noise or sound. Most landfills are placed in rural environments where farm machinery, heavy tools and other equipment are typically in use.
The noise or sounds of a modern operating landfill are similar to those related to various agricultural or horticultural activities. Landfills in Georgia are required to have a minimum 200-foot-wide undisturbed vegetated buffer. This buffer helps greatly to dissipate noise and sounds from landfill operations.
• Dust. Dust is controlled at landfills utilizing paved entrance roads as well as water trucks and absorption in the buffer areas. Each site is required as part of their Clean Air Act, Title V Permit to have a dust suppression plan.
• Out-gassing and odors. As part of the required design and operational plan, safe venting of landfill gas is required. The Clean Air Act, Title V Air Permit required for MSW landfills requires strict control of gas emissions. Also, as a particular area of the landfill reaches final design grades, a clay and plastic cap are required for the landfill that controls release of the landfill gas through a designed collection system.
This landfill gas can then be flared and/or utilized to produce green energy or fuels. A current landfill site in the metro-Atlanta area is collecting this gas, cleaning it and powering a portion of their collection vehicles and public transportation vehicles.
• Groundwater contamination. Older landfills were constructed without liners or other controls to prevent leakage into the groundwater. Some sites constructed prior to regulatory oversight buried waste directly in contact with the groundwater.
Today’s landfills begin with a detailed site evaluation determining the depth to groundwater and requiring a dry soil buffer, usually 5-10 feet between the bottom of the liner system and the top of the seasonal high groundwater.
A composite liner composed of a high-density polyethylene (HDPE) liner underlain by a 2-foot thick clay liner serves as a barrier to the groundwater. A system of pipes, encased in stone on top of the liner, drains liquid (leachate) moving through the waste limiting the depth of accumulated leachate to a maximum of 12 inches.
Incoming waste is screened at the scale house and unloading area, as part of a required prohibited waste exclusion plan, to prevent the disposal of prohibited wastes that contain many of the chemicals and toxins harmful to the groundwater.
Employees are trained to recognize these prohibited wastes. Random loads are selected on a regular basis for detailed inspection and records of these inspections are required to be kept in the site’s operating record and reviewed by EPD during compliance inspections.
When a landfill area reaches final elevations, it is capped with a composite liner composed of a HDPE or similar liner underlain by 18 inches of a compacted soil liner to prevent rainwater from entering the waste. Prior to capping each area, operational techniques are utilized to carry surface drainage off the landfill before it contacts the waste to further reduce leachate production.
• Traffic. MSW landfills are most often accessed via federal and state highways or properly improved county-maintained roads so as to lessen the impact of existing traffic patterns. Most of these issues are not environmental and are regulated by the Georgia Department of Transportation (DOT).
• Vectors and spread of disease. This concern was one of the primary reasons for the development of laws and regulations to close open, burning dumps and create MSW landfills in which waste is properly received, inspected, compacted and covered daily with soil to prevent the spread of disease.
This is not an exhaustive list of potential concerns, and I look forward to discussing these listed concerns and others with the residents of Bryan County.
I am pleased to be a part of the design team working with Atlantic Waste Services to bring a state-of-the-art and environmentally sound MSW disposal facility to Bryan County that will be both a good neighbor and a benefit to all residents.
You can contact me and find more detailed information at the website set up for this project, www.atlantic-wastedisposal.com.
Harbin, professional engineer, is the president of Harbin Engineering PC of Forsyth.