Groundwater contamination: the point souce dilemma

Friday, November 23, 1990

R.V. Nicholson

Shortly after joining an environmental consulting firm in the summer of 1984, I naively bid, on and won, a contract from Environment Canada to provide an "Assessment of Ground Water Contamination in Canada". This seemed to be a good opportunity at the time to learn about the character of contamination and summarize the "major" problems found to date in Canada. This overambitious project with an underachieving budget, needless to say, was not a complete success, but it was a classic learning experience.

Initially, my faulty intuition suggested that the project team would be able to collect sufficient information on the topic from provincial environment ministry offices because "certainly the major problems would have been well documented and organized". Files were available but unfortunately these were not arranged in a way that we could readily extract the important information. First, there was no central registry for the multitude of reported cases of groundwater contamination. The files were held in regional or district offices in each province where, operationally, they were of the most use, but where they seemed to be of little value for assessment, planning and administration. To some extent this is due to the nature of the beast with independent localized problems and the mode of groundwater exploitation with the largest number of individual wells for household use or small communities in Canada. Secondly, there was no level of importance or impact in files in general and the "major" events were those that were politically hot.

The investigation revealed a number of important findings, some technical and others not. The documented cases of groundwater contamination covered a broad spectrum of problems that range from rather mundane effects of road salt application to those of synthetic organic substances that are highly toxic at very low concentrations. The cases reflected to some extent, the diversity of actual problems, but more so are indicative of recognized contaminant sources. Most cases were related to waste disposal sites that, as a group, have been in existence for many years. The findings showed that, generally, groundwater studies were initiated after complaints were made by individual users of well water, or where obvious surface manifestations of groundwater contamination occurred. Some studies, particularly those related to waste disposal sites, were initiated because potential problems were recognized for past experiences at similar sites. A good reason for keeping records and evaluating and classifying existing problems.

Even with the large amount of data collected for the review, it was difficult to evaluate fully the importance of the impact that groundwater contamination has on Canadian society. As an example, it is known that many gasoline spills are detected every year in large cities, yet these were not highlighted in Ministry files on groundwater. This problem was usually in the realm of a different ministry and budget did not allow a review of the data. These occurrences also may not have been viewed as groundwater problems because individual drinking water supplies are not usually present to be affected in highly populated areas.

Even though a variety of waste products, including toxic organic substances, have been in existence for some time, there was only beginning to be a recognition in the mid-1980’s that potentially more serious contamination than nitrogen compounds or some metals, have affected groundwater zones. Coal tar wastes and chlorinated solvents are examples of such classes of compounds and DMNA is a specific example related to recent discoveries.

It was evident during the review that much of the effort expended on groundwater contamination studies at the provincial level is conducted in response to complaints by individual well users. Review of typical cases showed that the great majority of these complaints originated from problems of well maintenance or constructional deficiencies that are the responsibility of the well owner. Nonetheless, this activity requires time and resources to review the problem, and to be relatively certain that significant contamination or groundwater is not involved. The effort involved in a preliminary review for each case is related to the technical level required and professional skills of personnel available to interpret the results of groundwater investigations. Often, the straightforward problems with bacteria were afforded only a cursory review based on hydrogeologic intuition which other reported cases required more extensive study.

The more significant documented cases presented for each province were somewhat unique. British Columbia has identified a number of problems involving spills or wood preservative in addition to contamination from waste disposal and acidic drainage from some mining operations. The Prairie region had identified a large proportion of hydrocarbon leaks (Alberta), but a major PCB spill was also noted. Information from Ontario represents a large number of contamination studies at waste disposal sites with a notable number having liquid industrial waste. Information was available on pesticide contamination and widespread effects of agricultural nitrate. Deep well disposal of liquid wastes has resulted in contamination of some zones in the local fresh water aquifer in southwestern Ontario, but the extent of the effect was not then known. Quebec exhibited a high proportion of industrial waste sites. Limited information was available, however, on the effects to groundwater. One major case of contamination by industrial liquids was noted to have a large impact and require extensive restorative measures. The Atlantic region was characterized by a large number of hydrocarbon leaks with notable events of contamination by industrial organic solvents. Cases of agricultural pesticide and nitrate contamination were also noted. Road salt effects are widespread, and salt water intrusion is notable in some coastal areas. Very little information is available on groundwater contamination in the north.

In general, potential sources of contamination have been recognized through experience with developing problems and not by predictions based on expected behaviour. Although many sources are known, past experience also indicates that new sources will be recognized in time. In 1986, when the report was completed, it appeared that sources of greatest concern for future impacts include gasoline leaks from underground tanks, spills of organic liquids particularly dense non-aqueous phase substances, pesticide application to agricultural land and possibly septic systems.

The lessons learned from that limited review include the following:

  1. Most groundwater contamination events are related to point source problems. These are difficult to map in any organization way and are therefore not readily treated on an aquifer by aquifer basis;
  2. Contamination problems are related to certain practices (eg. Landfills) and when these practices are identified it is at least possible to establish controls that may lessen future problems – this is certainly the approach being used for waste disposal sites;
  3. The extent of contamination is related to the geologic environments encountered and major problems usually involve some specific geologic controls; and
  4. No adequate inventory of contamination sources exists to allow planning of environmental controls for groundwater protection in Canada.

If we take no measures to prevent contamination of the subsurface, we will likely stumble on in the haphazard manner of the past, identifying "type" problems that rear their ugly heads and require "immediate" attention and places a strain on our already limited technical and regulatory resources. It appears that the only solution to our ongoing woes is to develop environmental planning to prevent further "jack-in-the-box" contamination scenarios. Such planning is already a part of the European scene and attempts are being made in that direction in the USA. It is no trivial problem, to say the least, but attempts must be made to identify the worst known and currently unrecognized but probable actors in groundwater contamination and this information together with geologic susceptibility to contamination should be blended with land-use planning. This is vital in areas such as Kitchener-Waterloo where a population of over 350,000 inhabitants is served solely by groundwater to meet water needs.

That preliminary review ended in the summer of 1986 and in my own view created a feeling of uncertainty about the extent of groundwater problems and their potential solutions. Environment Canada has continued the quest for a more thorough evaluation of groundwater use, occurrence, and contamination in Canada. Dr. Christian Pupp has been assembling information with the help of provincial ministry officials and by various means has been able to "persuade" individuals to help in this quest. I understand the journey is long and arduous, not to mention the phenomenal phone bills to each of the provinces. Hopefully, when his study is complete, there will be a clearer picture of the problems that exist. What is done with that information greatly depends on the perceived importance of the resource both by politicians and the public. As groundwater professionals, we are responsible at least for interpreting the available data and making it available to those who can act on them.