Injection well

Surface completion of a deepwell. The proposed deepwell at the Newton County Landfill will not appear much different than this on the surface.

NEWTON COUNTY — Waste is a by-product of manufacturing processes that create thousands of the products we use in the course of everyday living. We also unavoidably generate massive volumes of municipal waste daily. While we continue to research and implement ways to reduce waste by recycling and improving manufacturing processes, generated wastes still require disposal.

There are many acceptable and environmentally safe ways to dispose of wastes including waste incineration, biological or chemical treatment, and landfills. Wastewaters or liquid waste represent a large portion of our waste. While some areas have rivers or other water bodies at the surface that can receive this treated water stream, others are very sensitive waters that make disposal of this wastewater unsafe and impractical.

One of the most safe and environmentally acceptable ways is disposal through injection wells. Injection wells penetrate thousands of feet below the earth’s surface into rock formations where the waste is isolated from Underground Sources of Drinking Water (USDWs).

To dispose of fluids safely, the wells need to be in ideal geologic settings, properly constructed, operated, maintained, and monitored. However, dug wells, certain septic systems, and other shallow fluid distribution systems are very simple and do not have the same standards.

In the late 1960’s, the realization that subsurface injection could contaminate groundwater if wells were not properly located and operated prompted many states to develop programs to protect underground sources of usable water. Additionally, to increase groundwater protection, a federal Underground Injection Control (UIC) program was created and established under the federal Safe Drinking Water Act (SDWA) of 1974. The goal of the program is the effective isolation of fluids from USDWs.

The US EPA oversees approximately 700,000 injection wells of various types in the U.S. The injection well program consists of six classes of injection wells and each well class is based on the type and depth of the injection activity. Each type of well must be located, designed, constructed, operated and monitored to protect drinking water supplies.

Class I wells, the most sophisticated and stringently regulated, are used to inject hazardous and non-hazardous wastes into deep, isolated rock formations which keep the fluids away from USDWs. The two deepwells currently being considered in Newton County are non-hazardous Class I wells and will not accept waste other than from the company’s landfills.

The UIC Program requirements were designed to prevent contamination of USDWs resulting from the operation of injection wells. A USDW is defined as an aquifer that contains less than 10,000 milligrams per liter of total dissolved solids. Since the passage of the SDWA, state and federal regulatory agencies have modified existing programs or developed new strategies to even more effectively protect drinking water sources.

Class I wells typically inject thousands of feet beneath the earth’s surface. Most drinking water sources are much shallower, often less than 1,000 feet. In Newton County, the base of the deepest USDW is approximately 790 feet below ground. The proposed Newton County Landfill wells will be injecting between 3,000 and 5,000 feet below the surface – over three times the depth of the USDW.

In order to be permitted, confining or impermeable zones must be present above and below the injection zone, providing long-term confinement, making it an environmentally sound waste disposal method. Because these wells inject waste below the deepest USDW, there is little chance of any negative effects on potentially usable groundwater.

In Newton County, the Mt. Simon Formation would serve as the injection zone. This deep geologic formation is approximately 3,000 feet below land surface and isn’t a stranger to injection. There are approximately 50 deep injection wells in operation that are completed in the Mt. Simon throughout Indiana, Michigan, Ohio, and Illinois.

In Newton County, the proposed injection zone is capped by approximately 660 feet of the Eau Claire Formation, a geologic confinement that has low permeability and prevents the upward movement of fluids into the shallow drinking water sources, effectively isolating the injected waste.

The primary objective in the construction of a Class I injection well is the protection of groundwater by assuring containment of the injected wastes through a multilayer protection system, beginning with well construction. Several layers of steel and cement provides multiple barriers that protects the groundwater. Electronic logs are run throughout the well construction process to validate the well was properly installed.

An injection packer, which is like a drain plug with a hole in the middle, is located inside the multiple well casings above the injection zone. A smaller protective pipe, known as injection tubing, is placed inside the multiple strings of casing and through the packer. The space between the casing and tubing, called the annulus, is then filled with a corrosion inhibiting fluid. The pressure in the annular space is constantly monitored so that any change, indicating a potential failure of safety systems, would cause the well to be shut down immediately.

Before waste can be injected, the mechanical integrity of the well is tested and only if it passes can injection begin. Mechanical integrity testing is conducted at a frequency determined by the US EPA.

Thousands of data points including the pumping pressure for fluid disposal, annulus pressure, and fluid data are continuously monitored and recorded. If unusual pressures are sensed by the monitoring equipment, the well automatically shuts off. Disposal in the well does not resume until the cause of the unusual event is investigated.

The wells are also tested regularly, recording data about the well, the surrounding rock formations, and wellbore conditions. Regulators review all the data and regularly inspect the well site to make sure everything is operating according to the requirements put in place to protect drinking water sources.

While there are risks associated with any method of waste disposal, it is important to recognize that the alternatives to underground injection carry much greater inherent risk because of their proximity to the near surface environment. In the final analysis, it could be said that if the success of a regulatory program is measured by the prevention of environmental harm, the UIC program is a candidate for the most successful environmental protection program in history. It’s a “mature” regulatory program that suggests the major processes are working smoothly, the principal issues are well understood, and significant problems encountered have been solved.

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