Allan Chartrand Joins Robinson Noble
Robinson Noble is pleased to welcome Allan Chartrand as an Associate Environmental Scientist in our Woodinville office. He has over 25 years of professional experience. Allan specializes in the design and implementation of cost-effective environmental investigations of contaminated sites, and innovative approaches to remediation and ecological restoration. As a former regulatory scientist for California’s Regional Water Quality Control Board, Allan also has broad regulatory compliance and permitting expertise in the areas of water quality and contaminated sediments.
Allan’s capabilities broaden the scope of environmental services that Robinson Noble provides. We believe that our clients will benefit from his extensive experience in CERCLA, MTCA, and NRDA projects, including: RI/FS; ecotoxicology and ecological risk assessment; natural resource injury and damage assessments; CWA water quality evaluations, including NPDES and TMDL projects; and NEPA/SEPA and ESA compliant planning projects.
Eliminating Known Unknowns
By Rick A. Bieber
One question we as hydrogeologists are commonly asked about problem wells is "Where has our water gone?" A very interesting question and one that is much harder to answer then you might think. Our newsletters over the years have discussed some of the ways in which the groundwater industry has changed, but one thing has remained constant-the need for good quality water level data. Robinson Noble has assisted several water purveyors with the development and implementation of well field monitoring plans designed to provide good quality data to foster proactive aquifer management. Generally, these monitoring plans have focused on the collection of long term aquifer water levels and production data. However, monitoring plans can also be tailored to a specific well or aquifer concern.
In the context of trying to answer the "Where has our water gone" question, the availability of good quality data plays a crucial role. Many well owners have little to no documentation of the well's historic production capabilities and, in some cases, no information regarding the well's final construction. Without an accurate understanding of the well or wellfield's historical trends, it is difficult to assess the likely cause of a well's decrease in pumping capabilities or its outright failure. The collection of timely and accurate water level data is essential to proper well diagnosis and forecasting trouble that may be brewing.
So what data should be collected in order to provide the proper tools for a well evaluation? In general, the following information and data should be collected and stored for each well: construction details and the geology encountered during drilling (typically from the Water Well Report filed by the driller or a consultant's report); post-construction well rating and water quality (consultant's report); static and pumping water levels and long term production quantities (manual data collection or SCADA systems). If data collection has not been made a priority, it may be hard to come by, leaving purveyors (large and small) scrambling to compile data that has been sporadically collected over the years since the well was drilled. A proactive collection of this data will allow for a faster, less expensive determination of potential well problems.
While there have been many advancements in the ways to collect, store, analyze, and ultimately work with data, the data required has not changed. Without accurate and consistent water level data collection, many of the new tools fail to produce a quality solution. A groundwater flow model, for example, is only as accurate as the data from which it is built. For the purposes of this article we will discuss the two most common methods of water level data collection, manual measurements by system personnel and electronic measurements through the deployment of a data logging pressure transducer. There are a number of pros and cons to each method. For example, manual measurements only require the purchase of well sounder and the time it takes personnel to visit the site; however, the number of datapoints collected is generally limited to the number of times staff visit the site, which may be at an insufficient frequency to diagnose a problem. Data loggers, on the other hand, can collect nearly constant data but may have a high up-front cost (depending on well construction and system specifications). Regardless of the methodology employed, the accuracy of the data is dependent on the level of care administered by the data collector.
When manually measuring water levels, a consistent method should be used. Soundings should be referenced to a consistent datum, like a particular location on the top of a sounding tube or casing, relative to ground surface. If the pump is running, note how long it has been pumping and at what rate; if the pump is off, note the time since pumping ceased. Understanding the state of the well during water level collection provides a reference point for the measurement to be interpreted and compared to other data points. Knowing whether the well has been pumping for two minutes or two hours greatly changes the interpretation of the collected "pumping" water level. Similarly, "non-pumping" water levels collected during a state of recovery may have drastically different depths relative to the time since pumping ceased.
The collection of data using electronic data loggers allows for nearly constant water level data collection. As with manual measurements, the data logger should be referenced to a consistent datum. That datum should be used when collecting any supporting manual measurements at the well. For long-term data collection, data loggers can be deployed to collect a water level measurement at a frequency of 15 minutes. At this sampling frequency, it is less critical to know the exact moment the well began or ceased pumping as it can be estimated to a single 15-minute period. In addition, some data logging equipment can be specifically designed to work with SCADA systems already in place. If a data logger is to be used, sounding tubes should be installed in the well by a licensed drilling contractor to ensure the equipment does not hang up on the power cable or pump column. Typically, sounding tubes with a clear inside diameter of one inch are suitable for this purpose. If room is available in the well casing, purveyors may benefit from installing more than one sounding tube, allowing one to be dedicated to the data logger and leaving the second one free as a backup and for the collection of manual water level measurements.
There is one additional data point which should be collected: a "static" water level. There is often confusion regarding what this term means. A static water level is not simply a non-pumping water level. While it is true that a static water level is collected when the pump is off, it is also necessary for the water level to have fully recovered from any recent production. This can be difficult to achieve in an active well or well field, but is necessary to have an accurate understanding of the aquifer's long term health and sustainability. If data are being collected manually and a true static water level cannot be measured during routine inspections, a special effort should be made at least quarterly to collect a representative static water level. Depending on the operational design of the water system, it may be necessary to temporarily disable any on-demand pumping systems in order to collect a true static water level. Systems may be able to top off and extend storage quantities, allowing for an extended period of non-pumping and the collection of static water level.
The cost of collecting and archiving historic water level data will differ substantially for a residential well a and large purveyor that may have multiple wells or well fields. However, owners of even a single well can benefit from the collection of water level data and an understanding of how water levels change over time. However the necessity of having this data is often not evident until a well undergoes a catastrophic failure.
Red is Good, Green is Bad
Noble's Notes: “A quarterly recollection from 40 years of service to the groundwater community.”
By John Noble
[Ed. Note: The following article originally appeared in our first newsletter edition, published in October 1999.]
Some things that are so obvious turn out to be not true at all. One of these is predicting the presence of iron in ground water – perhaps the most common and pervasive water quality problem with wells in much of the country. Ground water with dissolved iron commonly looks as pure and pristine as a mountain stream. However, it tastes like rusty pipes. The taste is bad enough, but let the water stand in air overnight and the iron will precipitate out into a red floc which is truly ugly. When I used to canvass domestic wells in Western Washington, under negative comments of quality, the commonest was “red water” or “too much iron”. Many drillers I have known have bypassed zones of red sands and gravels that are obviously rich in iron. They wanted a satisfied customer for their finished well. Unhappily, they were often dead wrong. The obvious problem was not really there at all.
The apparent contradiction is that troublesome iron in water must first be in a reduced (unoxidized) state. In that state, all iron is dissolved. It may taste bad, but does not look bad. When the drill goes through reddish formations, and the bailings are all rusty, it is likely that the iron has already precipitated and the water contains no dissolved iron. If a well is completed in these “rusty” zones, and developed or pumped enough to clear the water of turbidity, the tested water quality is generally low in iron and does not have the characteristic metallic taste. The driller’s concern about quality may have been in serious error.
I learned these facts from my first boss in the water well industry. John Robinson had a long suit in pragmatic observations and enough chemistry to see the ironic truth. Between us, we tried to pass on the truth but were not fully successful. Even today, drillers are passing up good red water.
The converse of being incorrectly wary of rusty drill water is not being wary of exceptionally “clean or bright” sands, especially those that have a blue or green color. These formations commonly contain water that is in a “reduced” state, or hungry for oxygen. Drilling samples laid out for future inspection or reference that have the bluish or greenish color commonly are rusty in the morning. Another sign of possible trouble from this reduced water is the appearance of drilling tools pulled from the well on the following morning. The drill stem, which was polished all silvery during the prior day’s work, is not rusty but is instead a bright green. When this is observed, bet that the dissolved iron content will be high enough to fail the water quality tests.
In simple summary, iron that has already precipitated out in the formation will cause you no problems. Iron that is dissolved, but waiting to precipitate out in your glass, will be a problem. Brown is good and blue or green is bad.