Learn how to minimize leachate and contact water management costs at coal combustion residual (CCR) landfills using good design, physical controls, and operational practices. Through the SCS use of case studies, you will learn how to assess leachate and contact water management issues and implement cost-saving techniques at your landfill.
Leachate management and contact water management at CCR landfills can be expensive, cause operational headaches, and divert valuable resources from other critical plant needs. The SCS presentation at USWAG will provide you with useful tools to ensure your landfill is designed and operated to cost-effectively reduce leachate and contact water and alleviate operator stress. We will present case studies that highlight how design features, physical controls, and operational practices have effectively decreased leachate and contact water management at CCR landfills.
SCS Engineers – Serving Utilities Nationwide
Unofficial English Translation
For Information Only
According to the letter on the Institute of Scrap Recycling Industries, Inc. (ISRI) website, all ports are required to strictly follow newly imposed national environmental protection standards, and inspection and quarantine procedures imposed from May 4, 2018 through June 4, 2018. During this period pre-shipment inspections on importation of wastes as raw materials (PSI) will be temporarily shut down.
For those shipments that have been inspected and obtained the certificates for wastes as
raw materials by CCIC’s Northern America Limited Company before and on May 3, 2018, they could continue to proceed with import custom applications, based on original rules.
Read the letter as posted: http://www.isri.org/docs/default-source/default-document-library/2018-05-03-gac-announces-ccic-na-one-month-suspension-(en).pdf
SCS Engineers along with our industry associations SWANA and NWRA will follow the news closely.
Deep injection wells (DIW) mean different things in different parts of the country. In the midwest DIWs have been used for decades to dispose of industrial wastewaters, mining effluent, and produced water from oil and gas production activities and are from 3,500 feet to more than 10,000 feet deep. In Florida, deep injection wells have been used since the 1960s; however, they are used to dispose of treated municipal wastewater, unrecyclable farm effluent, and in some cases landfill leachate. DIWs in Florida range from 1,000 feet to around 4,500 feet deep.
This is a two-part blog, the first part discussing what constitutes a DIW, their general features, their cost relative to other wastewater management alternatives, and the range of industrial wastewaters suitable and safe for disposal. The second part, covered in the next SCS Environment issue, will be on the challenges for deep well developers created by public and environmental organizations, and strategies to counter misinformation and means to obtain consensus from stakeholders.
A DIW construction is a series of casings set in the ground where the initial casing starts out large and subsequent casings become smaller in diameter, progressively telescoping downward. Casing materials are typically steel alloys or fiberglass for better chemical resistance. As a casing is set and rock is drilled out, the next casing is set and cemented with a chemically resistant grout. The process continues with each progressively deeper casing. These redundant “seals” are what keep the injected liquid from escaping into the protected aquifers.
A DIW typically has three upper casings to protect the aquifers and isolate the wastewater to the desired disposal zone. The inner casing, called the injection tube, extends to the injection zone. Mechanical packers seal the space between the injection tube and the last casing with the annular. The resulting annular space is filled with a non-corrosive fluid. This fluid is put under pressure to demonstrate the continuous mechanical integrity of the well. The annulus is monitored for potential leaks, which would register as a loss in pressure and promptly stop the injection. Figure 1 is a simplified view of a DIW casing system used in south Florida.
Vertical turbine pumps working in conjunction with a holding tank, which is a used to smooth out the fluctuating flow of the wastewater feed pumps, propel the liquid down the well. As part of the permitting efforts, a chemical compatibility study is conducted to determine the level of pre-treatment if any to protect the well components and minimize downhole plugging. Municipal wastewater effluent is regulated differently and must receive at least secondary treatment before injection.
In the Midwest, DIWs are constructed to the same EPA criteria with a wide range of operating conditions. Some wells take fluid under gravity with no pumping, while others require higher pressure pumps that exceed 2,500 psi for injection. This blog focuses on wells used in Florida and typical fluid types and operational parameters.
In central and south Florida the injection zone lies below the underground sources of drinking water (USDW) which is the depth at which water with a total dissolved solids (TDS) concentration exceeds 10,000 parts per million (ppm); or the “10,000 ppm line”. This water is considered to be unusable in the future as a drinking water source. In parts of Florida, the injection zone is dolomite overlain by a series of confining units up to 1,000 feet thick made up principally of limestone with permeability several orders of magnitude less than the injection zone. (1)
In central and south Florida the target injection interval is the “Boulder Zone,” reportedly named because drilling into the formation often broke off pieces of the formation and made drilling difficult. The Boulder Zone is also known as the lower portion of the Floridan Aquifer. Later down-hole imaging technologies revealed this zone to be characterized by highly fractured bedrock and large karstic caverns, and the ability to inject relatively high flow rates with relatively little backpressure. It is not uncommon for Florida DIWs to have well flow rates exceeding 15 million gallons per day (MGD) and backpressures ranging from 30 up to 100 pounds per square inch (psi).
The versatility of the DIW in Florida to accommodate numerous different types of wastewater is an advantage. DIWs are being used on a large variety of waste streams that continues to expand, including:
Any wastewater considered for disposal must be compatible with the target formation and the final casing material. Therefore, depending on the wastewater, it may be straightforward to use existing industry references to confirm compatibility. In some cases, laboratory bench tests may be necessary to confirm compatibility.
Compatibility also includes the potential for creating unwanted microbial growth and scale formation within the injection interval. Growth and scale can happen with effluent containing sulfur or ammonia, two food sources for microorganisms or wastewaters supersaturated with minerals. Unless planned for and evaluated properly, both of these items have the potential to grow and clog the formation around the well, significantly reducing flow and increasing back pressure. This can result in higher energy costs, regulatory action and significant, unplanned costs to rehabilitate the well.
Another significant aspect of municipal wastewater is that they are primarily composed of freshwater and thus when injected into the highly saline Boulder Zone or similar saline zones, will tend to have a vertical migration component because of the density difference and greater buoyancy than the target zone. A few wells have been taken out of service because the seals designed to prevent this migration failed and allowed wastewater to seep upwards into the USDW.
The US EPA Underground Injection Control (UIC) program is designed with one goal: protect the nation’s aquifers and the USDW. There are several protective measures in a DIW that are intended to meet this objective;
The U.S. EPA conducted a study in 1989-1991 of health risks comparing other common and proven disposal technologies to deep wells injecting hazardous waste. The U.S. EPA concluded that the current practice of deep well injection is both safe and effective, and poses an acceptably low risk to the environment. In 2000 and 2001 other studies by the University of Miami and U.S. EPA, respectively, suggested that injection wells had the least potential for impact on human health when compared to ocean outfalls and surface discharges(3). William R. Rish examined seven potential well failure scenarios to calculate the probabilistic risk of such events.These scenarios included four types of mechanical failures, two breaches of the confining units, and the accidental withdrawal of wastes. The overall risk was quantified by Rish as from 1 in 1 million (10-6) to 1 in 100 million (10-8) (4), which is no greater than the current EPA risk criteria for determining carcinogen risk. As a comparison, 10-6 is the same risk level used by EPA for contaminants in soil or groundwater that are a known carcinogen.
There are several studies in Florida conducted by researchers and practitioners in the deep injection well field to assess the actual potential for municipal wells to contaminate the USDW. The maximum identified risk associated with injection well disposal of wastewater in south Florida is the potential migration of wastewater to aquifer storage and recovery (ASR) wells in the vicinity of injection wells (Bloetscher and Englehardt 2003; Bloetscher et al. 2005).
In a 2007 study, 17 deep wells in south Florida, used for municipal waste disposal, that had known upward migration into the USDW, were evaluated to develop a computer model to simulate these phenomena and extrapolate vertical migration over longer time periods. The results indicated that the measured vertical hydraulic conductivities of the rock matrix would allow for only minimal vertical migration. Even where vertical migration was rapid, the documented transit times are likely long enough for the inactivation of pathogenic microorganisms (5).
In a 2005 study of 90 South Florida deep injection wells, the authors took actual field data and constructed a computer model calibrated to actual operating conditions. The intent was to model performance of two injection wells in the City of Hollywood, Florida that the authors were familiar with and to determine the likelihood of migration, and what might stop that migration. Density differential and diffusion were likely causes of any migration. No migration was noted in Hollywood’s wells. The preliminary results indicate that Class I wells can be modeled and that migration of injectate upward would be noticed relatively quickly (3).
A deep injection well lifecycle cost compares favorably with other traditional waste treatment and disposal techniques. A life-cycle cost includes the capital cost and operating and maintenance costs for the useful life of the system. On a recent project, the wastewater for disposal was groundwater contaminated with ammonia nitrogen from a former landfill. The estimated groundwater recovery rate and the deep injection well disposal rate was calculated to be 1.2 million gallons per day (MGD). The proposed deep well was designed to have a final casing of 12-inch diameter, an 8-inch diameter injection tubing to a depth of 2,950 feet, and below that approximately 550 feet of open bore hole. The lifecycle cost estimate comparison to other viable technologies is shown in the Table below.
In this case, there were no projected revenues, so the alternative with the lowest net present value (NPV) would technically be the preferred alternative. Even though the aerated lagoon had the lowest NPV, it was ultimately judged too risky with a long break-in treatment period and significantly more space for treatment ponds needed.
The increasingly stringent surface water discharge standards are an ongoing challenge for industries generating a wastewater stream. DIW’s should be considered as a potentially viable option for long-term, cost-effective wastewater disposal, where a viable receiving geologic strata exists and when wastewater management alternatives are evaluated. In Florida, they currently provide an environmentally sound disposal option for many regions.
Within the SCS Engineers’ website, you will find the environmental services we offer and the business sectors where we offer our services. Each web page offers information to help you qualify SCS Engineers and SCS’s professionals by scientific and engineering discipline.
We provide direct access to our professional staff with whom you may confidentially discuss a particular environmental challenge or goal. Our professional staff work in partnership with our clients as teams. We are located according to our knowledge of regional and local geography, regulatory policies and industrial or scientific specialty.
Sometimes geosynthetic material specifications for a specific project, i.e., lining system or final cover system, is a performance-based specification which does not specify the type of product for use in construction. What does the engineer need to do when the selected contractor submits a product for approval in accordance with a performance-based specification? What should the engineer do when the owner purchases the material and identifies a product for use based on the performance-based specification?
Specifications that SCS has prepared are performance-based and include a qualifying procedure whether the product is introduced by a contractor or owner. This qualifying procedure is specifically left to the engineer to carry out by laboratory testing of typical samples of the specific product for use in construction. Typical reported values by the manufacturer or test results submitted by the contractor or owner are not acceptable under these procedures. Since the engineer is taking the liability of accepting a specific type of product for his or her project, the engineer should have the right to perform laboratory testing before the product is approved for use in the project, that only makes sense in the world of taking liabilities!
The testing performed by the engineer for qualifying a product do not count toward conformance testing of materials delivered to the site. The qualifying procedures are solely for accepting a certain type of product to be used in the project, but the specific rolls of pre-qualified product manufactured for use in engineer’s project must go through the required conformance testing specified in the specifications before use in the project.
The process of qualifying a product, ordering the qualified product, and performing conformance testing on the pre-qualified materials takes time. Engineers need to consider the amount of time necessary for the involved stages of approval into the construction schedule. If using material purchased by the owner, the owner needs to keep the timeline in mind to allow the engineer to carry out all necessary testing for the approvals to be in place before construction begins.
Repeating the qualifying procedure for a product from one project to the next depends on how the performance-based specification is written. Sometimes, the engineer accepts a product that was qualified for use in a prior project as long as the product has not changed since last used in accordance with statements by the manufacturer. If the performance-based specification includes such options, SCS highly recommends identifying the period between a prior project and the next project in the specification. In some cases, this means the product must go through a qualifying process even if it has not changed for many years but the previous set of qualifying data is older than a certain number of years. The period is based on the engineer’s judgment, but most professionals normally use five years in their specifications. During a five-year period, if the product changes or there are indications that the product might have changed due to recorded changes in certain reported values by the manufacturer, the qualifying process must be followed irrespective of the number of years passed since a recent past project to maintain quality and minimize risk.
Questions? Contact the author, Ali Khatami.
The industry standard SP001 is incorporated into many Spill Prevention, Control, and Countermeasure (SPCC) Plans is now updated. How does it affect your facility’s SPCC Plan?
The Steel Tank Institute (STI) recently released an updated version of SP001 – Standard for the Inspection of Aboveground Storage Tanks. This document is the industry standard used in most SPCC Plans for inspection guidelines and integrity testing for shop-fabricated aboveground storage tanks. In a typical SPCC Plan prepared by SCS Engineers, your monthly and annual inspection forms, and tank integrity testing frequency requirements are based on the criteria provided in SP001.
No. We recommend incorporating the updated inspection forms during your next SPCC Plan Amendment or 5-year renewal.
The inspection criteria have been simplified, and more flexibility is allowed with the revised inspection forms. This will help make your inspection process easier and of higher quality.
Need help sorting out the details of the revised standard, or have an SPCC Plan that needs amending or is due for a 5-year review? Contact , and we will help you stay on top of your SPCC needs with offices nationwide.
Coauthors: Denise Wessels and Amber Fidler.
SCS Engineers SPCC specialists in Pennsylvania.
Landfills are getting larger in height and greater in footprint area, but the location of leachate tanks, leachate ponds, or discharge points to an on-site or off-site leachate treatment plant usually don’t change.
A larger footprint means leachate force mains are getting longer and pumps have to work harder to push leachate through the system to a target point. Some operators carry on with the same pumps for decades and don’t monitor the performance of the pumps after expanding the landfill footprint.
SCS highly recommends that you evaluate the performance of the existing pumps again. Such an evaluation may require hydraulic analysis of the entire network of pipes along with pumps, or whatever segment of the network that is affected by the expansion. The effort is minimal in retrospect, but the operator makes sure that the system will function in an optimized zone with minimal wear on the pumps.
Sometimes the hydraulic evaluation may require up-sizing all or certain pumps in leachate sumps because not enough flow can go through the force main due to high friction loss in the expanded leachate force main. Up-sizing pumps may be achievable depending on the type of the leachate sump, i.e., riser system or vertical manholes. If the up-sized pump in a riser system is too long to fit inside a riser system or too long to the point of making routine maintenance too cumbersome, your engineer needs to come up with another idea.
Booster pumps along an expanded leachate force main can certainly be an option. Booster pumps can be the inline or offline type. Install the inline pumps on the actual force main, and position the offline type on the side so that liquids go through bends and elbows to reach the pump, and again through bends and elbows to get back in the force main. In either case, the booster pump adds hydraulic energy to the flow inside the force main to push the liquids at a higher pressure and velocity through the remainder of the force main and to the target point.
Operators need to be aware of the dynamic nature of the leachate piping network and the role of booster pumps in dynamic environments. After landfill expansion, with new cells coming online -increasing leachate generation, and when closing landfill slopes -decreasing leachate generation over time, the flow in the force main may change. Sometimes booster pumps have to be up-sized or down-sized depending on flow and pressure in the system.
Have a Leachate System question? Contact the author Ali Khatami.
It might feel like the July 1 deadline is far away, but it is time to start preparing to report your releases of toxic materials. The U.S. Environmental Protection Agency (USEPA) indicates that printing and related industries are subject to this report. It is an important part of your environmental compliance strategy if you have a facility with at least 10 full-time equivalent employees in a covered NAICS code that exceeded a reporting threshold in the previous calendar year. Reporting releases of toxic materials on an annual basis is one aspect of the Emergency Planning and Community Right-to-Know Act (EPCRA).
Read the article with steps to your report for printing and related industries.
Consolidated List of Chemicals Subject to the Emergency Planning and Community Right To Know Act (EPCRA), Comprehensive Environmental Response, Compensation and
Liability Act (CERCLA) and Section 112(r) of the Clean Air Act
Modeling for a Worst Case Release and the Alternative Release Scenario – not so mysterious after all. Lee Pyle explains it to you in her recent article in the RETA Breeze. Lee is SCS Engineers National Expert on Industrial Risk Management Plans and Process Safety Management.
All of us with over 10,000 pounds of ammonia in our plant system are well aware of the EPA Risk Management Program Hazard Assessment requirements (40 CFR Part 68.20). When the EPA inspector shows up, we hand them the manual and cross our fingers that they understand what they are reading and pray they do not ask a question.
Do not fret; chances are that the inspector at your plant is probably not much more fluent in dispersion modeling than you are. Much debate occurs over how long it would take to stop a release, but you do not want to get into a debate with an EPA inspector.
Read, share, or print Unmasking the Mystery of the Worst Case Release and the Alternative Release Scenario here. Happy Modeling!
Secondary containment is a basic engineering control to prevent a chemical or oil spill. There are misconceptions, though, regarding secondary containment requirements. In terms of oil-based storage, these misconceptions can lead to not enough containment capacity, significantly more containment capacity than necessary, or simply not providing the right level of containment when containers are grouped.
Chris Jimieson of SCS Engineers explains the five most common misperceptions and advises you how to keep your facility in compliance.
Read the article by clicking here.
This article discusses global air quality and how the collaboration between policy-makers and the scientific community can have a continued positive impact on air quality in the U.S. This collaboration has been the primary cause for the improvements observed in air quality over the past few decades.
U.S. Environmental Protection Agency (EPA) programs, such as the New Source Performance Standards (NSPS), New Source Review, and Maximum Achievable Control Technology standards, have all had a significant impact on improving air quality by lowering the ambient concentrations of NOX, VOC, CO, SOX, and PM.
Some areas, such as southern California, have committed to working toward electrifying the transportation network, implementing more stringent standards on diesel fuel sulfur content, and encouraging heavier utilization of public transportation.
Author: SCS Engineers’ Ryan Christman, M.S., is an air quality engineer and environmental management information systems specialist with experience in the oil and gas industry and the solid waste industry. He is just one of SCS’s outstanding Young Professionals.
