industrial wastewater

EPA’s PFAS Interim Strategy for Certain EPA-Issued Wastewater Permits

December 23, 2020

SCS Engiineers provides regulatory updates for industrial clients

On November 30, 2020, the Environmental Protection Agency announced it is aggressively addressing per- and polyfluoroalkyl substances (PFAS) in the environment. The agency announced two steps that it states would help ensure that federally enforceable wastewater monitoring for PFAS can begin as soon as validated analytical methods are finalized.

 

First, EPA issued a memorandum detailing an interim National Pollutant Discharge Elimination System (NPDES) permitting strategy for addressing PFAS in EPA-issued wastewater permits.

EPA’s interim NPDES permitting strategy for PFAS advises EPA permit writers to consider including PFAS monitoring at facilities where these chemicals are expected to be present in wastewater discharges, including from municipal separate storm sewer systems and industrial stormwater permits. The PFAS that could be considered for monitoring will have validated EPA analytical methods for wastewater testing. The agency anticipates being available on a phased-in schedule as multi-lab validated wastewater analytical methods are finalized. The agency’s interim strategy encourages the use of best management practices where appropriate to control or abate the discharge of PFAS and includes recommendations to facilitate information sharing to foster adoption of best practices across states and localities.

 

Second, EPA released information on progress in developing new analytical methods to test for PFAS compounds in wastewater and other environmental media.

In coordination with the interim NPDES permitting strategy, EPA is developing analytical methods in collaboration with the U.S. Department of Defense to test for PFAS in wastewater and other environmental media, such as soils. The agency is releasing a list of 40 PFAS chemicals that are the subject of analytical method development. This method would be in addition to Method 533 and Method 537.1 that are already approved and can measure 29 PFAS chemicals in drinking water. EPA anticipates that multi-lab validated testing for PFAS will be finalized in 2021. For more information on testing method validation, see https://www.epa.gov/cwa-methods.

 


 

EPA continues to expand its PFAS Action Plan to protect the environment and human health.  To date, it has assisted more than 30 states in helping address PFAS, and the agency is continuing to build on this support. Across the nation, the EPA has addressed PFAS using a variety of enforcement tools under SDWA, TSCA, RCRA, and CERCLA (where appropriate), and will continue to protect public health and the environment.

The agency is also validating analytical methods for surface water, groundwater, wastewater, soils, sediments, and biosolids; developing new methods to test for PFAS in air and emissions; and improving laboratory methods to discover unknown PFAS. EPA is developing exposure models to understand how PFAS moves through the environment to impact people and ecosystems.

Related Information

  • EPA published a validated method to test for and measure 29 chemicals in drinking water accurately.
  • EPA implemented the agency’s PFAS Action Plan by proposing to regulate PFOA and PFOS drinking water, asked for information and data on other PFAS substances, and sought comment on potential monitoring requirements and regulatory approaches. The EPA anticipates proposing nationwide drinking water monitoring for PFAS that uses new methods to detect PFAS at lower concentrations than previously possible.
  • EPA is working on the proposed rule to designate PFOA and PFOS as hazardous substances under CERCLA. In the absence of the rule, EPA has used its existing authorities to compel cleanups.
  • EPA issued a final regulation that added a list of 172 PFAS chemicals to Toxics Release Inventory reporting as required by the National Defense Authorization Act for Fiscal Year 2020.
  • EPA issued a final regulation that can stop products containing PFAS from entering or reentering the marketplace without EPA’s explicit permission.

 


 

Additional information about PFAS at www.epa.gov/pfas or on the SCS Industrial Wastewater Pre-treatment website.

 

This blog references information issued from the US EPA, Office of Public Engagement.

 

 

 

 

 

 

 

 

Posted by Diane Samuels at 6:00 am

Wastewater Deep Injection Wells For Wastewater Disposal – Industries Tap a Unique Resource

May 7, 2018

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.

Deep Well Features

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.

disposal of wastewater
Typical Casing System Used in South Florida for Deep Injection Wells

 

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.

Hydro-Geological Character of the Region

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).

wastewater disposal wells
Generalized Section of Florida Geology and Major Aquifers

 

Wastewater Compatibility

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:

  • Treated Municipal wastewater
  • Landfill leachate
  • Contaminated Groundwater (e., ammonia – impacted)
  • Reverse osmosis treatment concentrate
  • Fish farm wastewater
  • Various industrial wastewaters

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.

 

Protection of Drinking Water

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;

  • Proper design of the well casings and injection tubing for strength and chemical compatibility. These components are recertified every five years with a robust mechanical integrity testing program.
  • Demonstration that there is a confining zone of low permeability rocks to prevent upward migration of injectate. This demonstration includes documenting that any other nearby wells or borings drilled into the confining zone have been properly completed or plugged to prevent a short circuit contamination pathway.
  • Testing the injection interval to prove it can accept the fluids at the proposed rates and pressures.
  • Continuous monitoring of the well pressures and flows that include the well annulus monitoring.
  • Frequent sampling and reporting of the injected fluid.
  • Financial assurance via various means to plug and abandon the well if required.

 

Operational Considerations with Deep Injection Wells

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).

 

Treatment Cost Comparison

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.

waste water injection
Life Cycle Cost Estimate for Water Treatment Technologies

 

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.

 

Summary

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.

 

About the Authors:

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.

 

 

 

 

Posted by Diane Samuels at 6:03 am

Wastewater Pretreatment, Removing Fats, Oils, and Grease

June 5, 2017

ButterBuds® Food Ingredients supply their concentrated dairy flavors to consumers and food businesses all over the world. ButterBuds called in SCS Engineers to help them lower the concentrations of fats, oils, and grease (FOG) in their wastewater.

Fats, oils, and grease (FOG) causing wastewater issues for a food ingredients company.

Fats, oils, and grease (FOG) cause wastewater issues for food ingredients and food manufacturers. These companies must keep an eye on their compliance schedules to keep ongoing production from being disrupted.

For ButterBuds, SCS Engineers began by carrying out a multi-level review of the wastewater pretreatment issues. We conducted a process water balance, prepared a process flow diagram, measured process flows, collected/analyzed wastewater samples, evaluated chemical treatment testing and maintained communications with City staff.

The SCS team prepared engineering design drawings and specifications for the wastewater pretreatment system. We also helped ButterBuds staff with the selection of wastewater pretreatment equipment, bidding, construction, and start-up, as well as resolving operational issues.

The wastewater treatment equipment was housed in a separate building away from the food ingredient processes. This requirement meant the wastewater discharge piping had to be installed underneath the existing building using directional drilling to minimize any disturbance to production.

Outcomes and benefits

  • Regulatory compliance – Butter Buds operates in compliance with the permit standards.
  • Uninterrupted production – The SCS  solution enabled production to continue during the installation of the system.
  • Schedule compliance – The City’s compliance schedule was met despite tight requirements for system construction and the start-up deadline.
  • A happy and satisfied client.

 

Posted by Diane Samuels at 6:00 am