Partially treated sewage gets dumped in a deep hole.
Large sewage injection wells are permitted, and Gang Cesspools are not
R.H. Bennett, Ph.D.
Applied Life Sciences LLC and Kona Waterkeepers
Most people will likely react to this title with another question. What is an injection well? In Hawaii, an injection well is a hole deeper than it is wide and allows the flow of liquids into the ground. In the state, they are used to dispose of partially treated sewage or stormwater. It may or may not be lined or pipe fitted.
A gang cesspool is defined as follows. “Residential multiple-dwelling, community, or regional systems (e.g., townhouse complexes or apartment buildings) that dispose of sanitary waste or Non-residential cesspools that have the capacity to serve 20 or more persons per day per the EPA (5)”.
Sewer injection wells are fundamentally not different from gang cesspools. So why is one permitted and the other banned? Both systems have the potential to contaminate drinking water. Injection wells are regulated under federal statute, implemented by the state (4).
In Hawaii, all injection wells are used solely to dispose of rainwater, stormwater runoff, and sewage. That is right, partially treated wastewater can be put down a well and allowed to percolate to the groundwater below. In the mainland, injection wells can go very deep and below drinking water aquifers. On an island, the brackish groundwater circulates to and from the sea by tidal action. Some brackish groundwater flows in Kona are millions of gallons per day. The cold spots we swim into are due to this flow.
Our island is not at all like Kansas. Brackish groundwater penetrates the inland. Inland percolated rainwater floats on the saline groundwater. This floating water is our drinking water.
Underground injection wells are limited to the near-coastal zone as depicted by a UIC (Underground Injection Control) line around each island. The line sites injection wells close to the coast. Drinking water is protected by locating these wells nearshore and away from the upslope drinking water wells. No one would argue with that logic. However, below the line, near the ocean side of the UIC line, wastewater, stormwater, and sewage can be injected. Yet, where does this hazardous liquid go? It joins the brackish groundwater flowing toward the sea. It has nowhere else it can go. The fate of these pollutants is entirely unregulated.
Per the State of Hawai‘i, the marine waters off the Kona Coast are Class AA Pristine and to be kept in their “wilderness” state (HAR 11-54). How can the pristine state be possible when the polluted wastewater is flowing into the sea in seeps and lava tubes?
It is unlawful to run a wastewater pipeline into the sea without demonstrating via the permit process that the wastewater will not degrade the receiving waters. On Hawaii Island, there are at least two such pipeline permitted discharges operated by Hawaii County. In great contrast, Honolulu still pipes untreated sewage directly offshore. This still occurs in spite of a 2010 Consent Decree, where the city agreed to abate the polluting discharges.
In an injection well, the pipeline or well casing does not enter the sea. As Supreme Court Justice Kagan suggested during oral testimony on the Maui Case, if the underground pipeline stopped five feet from the sea, are we to presume that would be a permissible discharge? In the Maui injection well case, the Ninth Federal Circuit court said no. They said underground geologic conduits are fundamentally no different than a pipeline draining into the sea. Therefore, a discharge permit is required.
According to the Department of Health, Clean Water Branch, Underground Injection Control Program, or UIC, Hawaii island has 613 sewage injection wells. However, a limited review suggests many of these wells are closed where sewer service is available. Sewage in the context of the UIC program is all wastewater from domestic and commercial plumbing. Sewage treatment is to the Secondary Level, to include the removal of suspended and dissolved solids. There is no requirement for disinfection or nutrient removal.
An individual injection well is rather primitive as most are gravity fed. An example is shown below.
Professor Frank L Peterson of the University of Hawaii was the first to raise concerns about injection well performance and potential contamination of the nearshore waters in 1985.
"The extent of shallow coastal-water contamination is more problematic. Wastewater injected into coastal aquifers only a few tens or hundreds of meters from the shore must discharge, virtually undiluted, directly into the coastal waters” (3).
He went on to suggest that the functional life span of an injection well may only be a matter of a few years due to clogging and fouling. The performance of injection wells today is mostly unknown to the state for the lack of the required inspections.
On Hawaii Island, major injection wells operate as part of the Honoka'a wastewater treatment plant and found at some of the resorts on the Kona Coast. One such well is located very near the shoreline, as required, and can dispose of 400000 gallons of secondary sewage per day. The nutrients in this wastewater are detrimental to the nearshore ecosystem and especially the corals (2,6). In contrast, many Kona resorts the wastewater is reused to irrigate the golf course and grounds. Turf does a reasonable job of removing the fertilizing nutrients. This reuse conserves freshwater in the upslope and nearby aquifers.
The addition of wastewater nutrients to the sea is well documented to be deadly to coral, especially during warm water stress.
1. Hawaii Department of Health GUIDELINES FOR THE TREATMENT AND USE OF RECYCLED WATER (2013) https://health.hawaii.gov/wastewater/files/2016/03/03_V1_RWFacilities.pdf
2. Lapointe, Brian E., Peter J. Barile, Mark M. Littler, and Diane S. Littler. "Macroalgal blooms on southeast Florida coral reefs: II. Cross-shelf discrimination of nitrogen sources indicates widespread assimilation of sewage nitrogen." Harmful Algae 4, no. 6 (2005): 1106-1122.
3. Peterson, FRANK L., and June Ann Oberdorfer. "Uses and abuses of wastewater injection wells in Hawaii." Pacific Science 39, no. 2 (1985): 230.
4. US EPA Safe Drinking Water Act, Underground Injection Control. https://www.epa.gov/uic/underground-injection-control-regulations-and-safe-drinking-water-act-provisions
5. US EPA What is a large capacity cesspool https://www.epa.gov/uic/cesspools-hawaii#whatis
6. USGS 2018 Polluted Groundwater Threatens Coral Reefs https://www.usgs.gov/center-news/polluted-groundwater-threatens-hawaiian-coral-reefs?qt-news_science_products=4#qt-news_science_products