About Chlorine In Drinking Water -}
The City of Olympia is currently testing two new wells at a site just south of the City's water supply facilities at McAllister Springs. The wells will add another level of safety to the City's water supply and represent a major re-commitment by the City to be a regional partner in protecting the large aquifer that supplies McAllister Springs and McAllister Creek.
The Need For The New Wells
Olympia developed its McAllister Springs water supply facilities in the late 1940's. Water is pumped into the City's drinking water system from the lagoon at McAllister Springs, which receives its supply directly from groundwater flow out of an underground aquifer. The water is chlorinated at a very low level as it is pumped out of the Springs and into the supply system. This protects against micro-organisms that cause human disease.
This water system has worked well for years, and the water is safe and of high quality today, but the City decided to look for even more water safety insurance at McAllister for a couple of important reasons.
The first water quality safety enhancement has to do with summertime conditions at McAllister Springs. The aquifer discharges directly into the lagoon at the Springs, and the City's pumping facility is built over part of the lagoon so that the pump intakes extend into the lagoon directly above where the crystal clear water comes out of the bank and into the lagoon. Because summertime pumping rates are higher, water can sometimes be drawn into the covered (indoor) pumping area from the uncovered (outdoor) area of the lagoon. This increases the chance of contaminants from animals entering the water supply. Disinfecting the water is effective protection against this form of contamination, but health protection regulations are placing increased emphasis on eliminating the possibility of contamination altogether. By augmenting the water supply from the wells, the City can reduce the pumping at the Springs and thereby entirely avoid the possibility of pulling contaminants from the lagoon. The City has taken steps to assure the summertime water supply is safe while the wells are developed: the lagoon has been protected by installing fencing, and the effects of pumping at higher rates are closely monitored. The water will continue to be disinfected for the extra public health protection that process provides.
The second water quality safety enhancement involves the major rail line that traverses the McAllister aquifer just south of McAllister Springs. The groundwater flows in a northerly direction; it is moving directly towards McAllister Springs from the rail line. If a train accident were to occur with a hazardous chemical spill that seeps into the ground, the pollution would show up in McAllister Springs in less than a week. This would shut down the water intake at the Springs. McAllister Springs accounts for about 80 percent of the Olympia water supply, so this dramatic decrease in the quantity of water available would trigger emergency water restrictions because the City's other wells could not keep up with normal customer demand. Cleaning up the chemical spillage, if it were even possible, would likely take months, perhaps years. Even though the possibility of this catastrophe is very low, the consequences would be dire. The new wells will not be vulnerable because they are "up gradient" (the same as up stream for a river) of the rail line; the underground flow of water toward the north will carry any rail accident pollution away from the wells. The wells will be able to supply high quality water in the event of a major chemical spill along the rail corridor through the McAllister Springs area.
The new wells are being planned as a companion water supply facility to the McAllister Springs pumps for these specific reasons. Most of the time, the City expects the two sources to operate together to supply the same amounts of water that have exclusively come from the Springs in the past. The City intends to retain its facilities and land at McAllister Springs indefinitely as a back-up supply to the wells.
McAllister Aquifer - A Regional Treasure
The groundwater that will supply the City's new wells is from an underground aquifer that covers about 50 square miles south of McAllister Springs. Rain water naturally recharges the aquifer, and the underground flow of water is to the north towards McAllister Springs and McAllister Creek. So, if any problems occur in the aquifer because of pollution, all of the wells in the aquifer and the Springs and Creek could be affected. Clearly, protecting the aquifer is important for everyone in the region.
An aquifer is technically an underground layer of soil and gravel that has 'pores' between the stones and soil particles. These voids can hold water and will allow water to 'flow' through the mass of the aquifer - an 'underground stream' - with the help of gravity, of course. On a scale of 1 to 10, the McAllister aquifer is a true 10! It holds massive amounts of water and the water flows through it at an excellent rate.
Like all natural resources, the McAllister aquifer is complex, and we must work to understand it if we are to benefit from it and protect it for future generations. Some of the great advantages of the aquifer can also be vulnerabilities if they are not fully understood. For example, the permeability of the soils and gravel that carry the groundwater so well can also move pollution into the underground water very rapidly. For this very reason, local governments, the Nisqually Indian Tribe and private citizens have been working together for years in Thurston County to protect our groundwater by preventing pollution from happening. The City of Olympia is an active participant in these programs.
Protecting the quality of the groundwater that supplies McAllister Springs and the new wells is the centerpiece of the City's strategy for assuring a high quality drinking water supply today and in the future. The new wells, and the flexibility they will provide to the City in operating the water supply facility at the Springs, are a component of this larger strategy.
Next Steps To Develop The Wells
The new wells are being tested in early July by the City's groundwater consultants. By pumping the wells at a high rate for about three days, the test will measure the impact on the aquifer in the immediate area, at McAllister Springs and at representative neighboring wells within a radius of several miles. Based on prior survey work done on the aquifer and several past studies performed by the City, Thurston County and others, the City's consultant expects no impact from the pump test on neighboring wells. Similarly, nearby lakes will not be drawn down by the new wells. This includes Lake St. Clair, which is a 'perched' lake that does not rely on water supply from the much deeper McAllister aquifer.
Provided the pump test proves successful, the City will proceed with the installation of permanent pumps and controls. A connecting pipeline from the wells to the water disinfection facilities at McAllister Springs will also be constructed. The construction of additional wells will likely take two or three years; up to six are planned. In the short term, the City will be monitoring how effectively the first set of wells work in conjunction with the water supply pumping at McAllister Springs. The operation of the wells will also be carefully monitored to assure continued safety of the aquifer and no immediate impact on neighboring wells or McAllister Creek. The long-term impact of the wells on McAllister Springs and Creek will also be a part of a habitat evaluation project to be conducted by the Nisqually Tribe and the City. The City will expand to six wells at the new site if results show that further reducing the pumping rate at the Springs would be prudent, especially during summer months.
Land acquisition is the final important component of the actions to develop the new wells near McAllister Springs. The land acquired for the wells, plus development rights on another 100 acres, will assure that the wellhead area is protected from all but agricultural uses. The City also has a purchase option on 66 forested acres nearby that will increase the level of protection in the immediate wellhead area.
The City of Olympia highly values the McAllister aquifer as an important regional natural resource and as the key water supply resource for its drinking water utility. The City is dedicated to being a responsible steward of these resources and to work in cooperation with all who share in the aquifer's wealth to protect it for future generations.
For information on the City's education programs on groundwater protection, call Kristen Pilgrim at 753-8498. The project manager for construction of the wells is Vicky Epp, who may be reached at 753-2734. The author may be reached at 753-8463.
Bob Groncznack is the Water Resources Manager for the City of Olympia.
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Safeguarding Our Precious Groundwater - How Homeowners Can Help
Prevention of drinking water pollution costs far less than clean-up of contaminated wells. Homeowners who rely on wells or reside within a wellhead protection area can contribute to pollution OR prevention. If we all do our part to prevent pollution, the risk of groundwater contamination can be reduced.
Significant groundwater contamination sources in Thurston County include: failing septic systems; improper use, storage and disposal of household hazardous products; excessive pesticide and fertilizer use on lawns, gardens, and pastures; accidental spills of hazardous materials; and, leaking underground fuel storage tanks. Even old, abandoned wells can be a potential conduit for groundwater contamination.
A new community program is now recruiting volunteers to participate in the home assessment program - with the goal of protecting the quality of our ground- and drinking water. These teams will help homeowners living in sensitive groundwater areas work through a home assessment handbook. With help from the handbook and an easy-to-use checklist, homeowners identify activities at their homes that could pose a risk to groundwater. Most importantly, the handbook and volunteers will help homeowners with suggestions and solutions that lead to groundwater protection. Partners in this project include the Thurston Conservation District, Thurston County, City of Olympia, and the Volunteer Center/Retired Senior Volunteer Program (RSVP).
If you are interested in joining the home assessment team by volunteering to help homeowners reduce the risk of contamination to groundwater, call RSVP at 586-7787. Volunteer training activities begin in mid-July.
If you live in a groundwater sensitive area and would like to complete a home assessment checklist on your own - contact John Konovsky with the Thurston Conservation District at 754-3588, to receive a copy of the handbook.
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About Chlorine In Drinking Water
In 1908, chlorine was first used on a large scale in the U.S. to disinfect drinking water. Epidemic diseases, such as cholera, typhoid and dysentery have been essentially eliminated by disinfection of drinking water. They had been quite common. Because of the risk of disease transmission in drinking water, the City of Olympia treats its groundwater supplies with a small amount of chlorine (less than one part per million). This protects against the risk of contamination at the source of supply. It also protects against the risk of contamination entering the water distribution system through a small leak that may not be detected.
The City's drinking water is completely safe to drink as it flows from the tap. Customers who are sensitive to the chlorine taste or odor can remove the chlorine by simply allowing the water to stand in a container for a couple of hours; the chlorine will dissipate naturally. A good 'system' to accomplish this is to keep a container of water for drinking in the refrigerator. This is also a conservation measure because it won't be necessary to keep the tap flowing to get a cool drink.
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