With that said, I also presented other investigative work on the greywater-groundwater nexus during the March meeting of the Graywater Advisory Committee because of the initial response to "what others are saying" about the topic. I was unable to locate a peer-reviewed journal article on a case study linking groundwater contamination to greywater reuse. This is not to say one does not exist; I could not locate a case study in the hydrogeologic or groundwater engineering literature that I frequently read. I also don't recall hearing of a case where greywater was an issue while conducting Potential Contaminant Source inventories for Drinking Water Source Protection Plans for many municipalities or private water systems across the western US that I completed since the early 1990s as part of my previous career as a consulting hydrologist. I contacted colleague Tom Pattee of the Drinking Water Section of the Oregon Department of Human Services to get his opinion on the matter.
Tom confirmed that greywater was not on the list of Potential Contaminant Sources (PCS) that practitioners use during the course of completing Source Water Assessments. While greywater was not on the "official" list of PCS, greywater would be considered under the broad categories of contaminants under microorganisms specifically within the Two-Year Time of Travel (TOT) delineated for a public water supply well or public water supply spring. This approach is not unique to Oregon, but rather indicates the general approach recommended by EPA guidelines. State programs vary regarding the TOT. Even if greywater was apparently discharged within this TOT, it is my understanding that the DHS would require the public water system (PWS) to analyze the source water for bacteria monthly for one year. Most PWS probably do this already. If there were no positive "hits", DHS would more than likely consider the "threat" to be minor and not require additional testing. Using their guidelines on Aquifer Susceptibility Analysis , it is likely that the "negative" results indicated that the aquifer was not susceptible to this type of contamination. Notice that there are many ways to determine if an aquifer is susceptible to contamination or not. Also note that the main target focuses on well construction. If the grout seal is judged inadequate, or if no well report is available, the aquifer is determined to be susceptible. This sounds a little like what Art Ludwig is saying.
Next some members of the Graywater Advisory Committee suggested that siting standards for greywater should follow the standards for Underground Injection Control (UIC) as outlined in OAR 340-044-0010 which lists "...requirements to limit and control injection of wastes into the subsurface to protect existing groundwater quality for current and future beneficial uses including use as a source for drinking water." The standards under 340-044-0018 Authorization of Underground Injection by Rule for all storm water injection systems include among other things:
- The injection system is not located within the 2 year time-of-travel zone as delineated by the Oregon Health Division or closer than 500 feet to a public water supply well, whichever is more protective.
- The injection system does not exceed a depth of 100 feet and does not discharge directly into groundwater or below the highest seasonal groundwater level.
- A confinement barrier or a natural or engineered filtration medium is present between the base of the injection system and the highest seasonal groundwater level and prevents contaminants from reaching groundwater, or the owner or operator implements best management practices that prevent or treat storm water contamination before injection (emphasis added).
Let's visit 340-071-0150 Site Evaluation Procedures for On Site Septic Systems. For the Site Evaluation Report, the standards include, among other things "...applicants must provide at least two test pits, with dimensions and configuration as directed by the agent, located approximately 75 feet apart and within the area of the proposed system, including the repair/replacement area", where "Soil profiles determined from test pits provided by applicant" and "Water table levels (as indicated by conditions associated with saturation or water table observations)". This doesn't sound unreasonable until one sees this requirement "Site evaluation reports for subdivisions or other land divisions must be based on an evaluation of each lot" (emphasis added).
paper that I was invited to prepare by the National Ground Water Association titled "Water Wars, War of the Well, and Guerilla Well-fare" that summarized the "dueling expert" problem described by Australian mediator John Wade and how it applies to the groundwater industry. This diagram is from my article which depicts the issues "dueled" over within the field of groundwater hydrology.
"Ludwig's Law" said it best "Experience with groundwater contamination from septics does not translate to greywater". I will add "from septics and UIC" to this maxim. Practical experience and a common sense approach from practitioners and greywater experts like Art Ludwig and Laura Allen may be all we need for Oregon's siting assessment standards rather than falling into the "Site Testing Trap" where the only winners are the usual conflict beneficiaries - attorneys and expert witnesses.
And the Greywater Gadget of the Week is a tribute to do-it-yourself eco-innovators. Check out the Recycled Water Saver for $1.25. A great video goes along with the article.