Cavendish Municipal Water System Update - February 2010

The water filtration project is complete and levels of iron and manganese in the water supplied to customers are significantly reduced. We continue to fine tune processing in the filtration plant to ensure that we get the maximum effectiveness and efficiency from the new equipment and have streamlined operations. Since September, levels of manganese in the water going out into the distribution system have been less than 0.02 mg per liter (mg/l) and the level of iron has been consistently less than 0.1 mg/l since last June. These levels mean that the equipment is working well and that we are operating at our target removal levels. Water leaving the plant has levels of iron and manganese comfortably below state and federal recommended maximums. Customers have reported that they are very glad to not have iron staining to contend with anymore and, for any number of reasons, we’re glad to have both minerals reduced to insignificant levels. This past fall, the system water mains were flushed and both storage tanks were professionally cleaned.

One remaining issue with regard to other water characteristics relates to the fact that the new filtration process injects air into the water as it enters the filters to facilitate the biological removal process. Because the water stays under pressure as it leaves the vessels, there is a significant amount of dissolved air in the water. This air stays in the water so long as it remains under pressure and, if the water goes directly from the pump to your faucet without depressurization, you may sometimes
get water that has a whitish cast as it first comes out of the tap and, especially after a period of limited use, faucets may sputter and spit a bit. The whitish appearance is caused by minute air bubbles. These bubbles are just air, are harmless, and usually dissipate in a matter of seconds. The system operator, the engineers and the town manager are presently working on a remedy to the excess air in the finish water and it is hoped that, by the end of spring, that too will be gone. The fix
being worked on involves a temporary depressurization of the water in a clear tank within the plant which will allow the air to come out of solution prior to its being re-pumped into the distribution network.

We would like to point out that, although the water being pumped into the system now consistently has very low levels of iron and manganese, the reduced mineral content is still a relatively new phenomenon. When brim-full, the system holds almost 600,000 gallons of water. The filtered water enters the distribution system at a fixed point in a complex distribution piping network and flows out of user spigots and fixtures at varying rates and at various distances from the source. The 300,000 gallon tank in Proctorsville and the 250, 000 gallon tank in Cavendish make for a constant pressure and consistently provide enough storage to allow us sufficient reserve capacity to meet heavy demand periods and allow adequate reserve for fire protection purposes. The net result of these complicated flow dynamics is that the complete changeover of the water in the system does not, and cannot, happen quickly. Rather, it is a long process that changes over the water by a continuous dilution process. As a result, while the water being supplied for distribution has been consistently very low in the iron and manganese content, the water flowing out of your tap did not all of a sudden start coming out at that same reduced level of mineral content. That being said, the water coming out of consumer taps now is certainly very much improved from what it had been, but, it may take some time for it to totally match the quality of the water leaving the plant.

In addition to the dilution process, another consideration is that, since there were many years of iron and manganese rich water which flowed through the system water mains and end-users’ plumbing, there is a likely build-up of residual mineral coating on the inside of the water mains, service entrance pipes and household plumbing. Now that the water with lowered levels of these minerals is flowing through these pipes, it is likely that there will be a gradual erosion of the mineral coating which may temporarily cause a slight increase in the level of the minerals in the water coming out of domestic water taps.

A recent check of iron and manganese levels at several consumer points on the distribution system has shown that the levels of iron removal are consistently very good with all samples taken below the advisory level. The manganese levels at various end user taps recently sampled has been detected at levels anywhere from less than 0.02 mg/l to 0.21 mg/l. which means anywhere from 99+% to 90% removal. The Vermont Health Department advisory level for manganese is 0.3 mg/l.
Water samples taken at our system sampling tap (which is located at a point about 20 minutes after leaving the water plant) is reading the same as the water sample just before it leaves the plant. This is indicative of the water mains becoming cleared of old iron and manganese residue. Lines with large volumes of water running through them get cleared faster than the lines with only small flows. This further demonstrates the value of line flushing which helps to clear those lines of old mineral residue and thus deliver water which has the desired full reduction in the iron and manganese.

This would seem to be an opportune time to remind water users of the importance of flushing the domestic water lines in your home or business. Recent field testing has indicated that end user locations with domestic waterlines that have very low flows and residences and commercial locations which did not conduct a significant flushing exercise as we recommended last fall tend to show traces of iron and manganese a bit higher than those locations with higher flows and those that have indicated that they did a thorough internal flushing.

This is why we flush the system water mains at least twice each year (spring and fall). The hard flow flushing helps to clear out the build-up of mineral and sediment which may naturally occur. When we announced the fall hydrant flushing this past October, you may recall that we recommended that all users flush their domestic plumbing as soon as we were done with the water main flushing and the water was again running clear. A flushing of hot water heaters and hot water boiler tubes is an
important part of this process. Conversations with many Cavendish water users has indicated that a good percentage of users conducted the flushing of their lines, but some of those users did not sustain the high volume flow for a sufficient length of time and there appears to have been great variation in the thoroughness of the work. A number of consumers indicated that they did not flush their plumbing at all. Whether or not a customer flushes and the thoroughness of the flushing can significantly influence how quickly the fully reduced levels of mineral is realized at their taps. The enclosed sheet contains a procedural outline of suggested techniques to maximize the effectiveness of the flushing of household plumbing.

Household flushing activities are strictly at the option of individual homeowners and they are exclusively the homeowners responsibility. The Cavendish Municipal Water System offers the suggested procedures only as a convenience to the consumer but this offer specifically does not imply any responsibility on the part of the Water System for maintenance of consumers’ household plumbing or fixtures.

The Cavendish Municipal Water System will next conduct flushing of hydrants and water mains during April with specific dates to be announced.

Cavendish Municipal Water System - February 2010
Suggested Procedures for Flushing of Household Plumbing
1. Unscrew and remove any aerators, strainers and flow restriction devices that you may have on household faucets. While they are off, any strainer screens should be removed and cleaned by reverse flow and removal of any particles or debris that may
be trapped in them. An old, but clean, toothbrush may be helpful with this. These are often neglected items and, if upon inspection, any of the aerators appear to be defective or the strainer screens are torn or missing, you should consider buying new ones. They are generally quite inexpensive. Put the aerators aside for now.

2. Run as many of your COLD WATER faucets and spigots as you can simultaneously - at full force - in order to get the maximum volume and velocity of flow through the water service pipe that runs from the water main to your house. Run for five to ten minutes after discoloration of the water, if any, clears at the farthest point. Next close all of the faucets and spigot.

3. Starting at a point nearest the water service entrance and working outward, run all COLD WATER spigots and faucets, one at a time, wide open. Run each for five to ten minutes beyond the point when water runs clear. This activity includes all kitchen,
bathroom and laundry sinks and bathtubs and showers.

4. After all faucets and spigots have been run as described above, each toilet should be flushed several times.

5. Next take the steps necessary to flush your hot water heater or domestic hot water boiler tubing depending on which type of system you have. It is very important to thoroughly flush water heaters and hot water boiler tubes. If a user finds that they still get an occasional blast of rusty colored water, the hot water heating device is the likely culprit and it must be purged. Most domestic water heating systems have some sort of tap or drain port which can allow for flushing. This drain is usually in the form of a hose bib and the most convenient method is to attach a garden hose and run it outdoors, well away from the foundation. Flush the heater by running the drain at full force for five or ten minutes after the water runs clear. Note that sometimes the heater drain will run clear for a minute and then will cloud up and run rust colored, so don’t skip a thorough draining here just because the water comes out clear when you first open the drain.

6. Next run all of the HOT WATER faucets as you did in step #3.

7. Replace all aerators, strainers and flow reducers which were removed.

8. Replace any cartridges on any household water filters that you may have.

9. Clean the in-line strainers that you may have on clothes washer and dishwasher water inlets.

If you follow the procedures described above, you will likely improve the quality of your household water, will minimize the chance of mineral staining and you may even find you have improved flow at some of your sinks and washers. This activity is likely to help speed up the transition in your house to water with the desired full reduction of iron and manganese. The maintenance activities described above are routine and generally within the abilities of the average homeowner. If you find, however, that you are unable to perform these maintenance activities yourself, we would recommend that you seek the services of a maintenance person, handyman or plumber in order to accomplish the work.