Billerica Water Works Overview

Billerica Water Works was established by an act of the Massachusetts Legislature in 1897. Construction of the original works began in 1898 and continued for several years. The water works was first activated in January of 1899. Water was at that time drawn from wells located in the area of the present Water Treatment Plant, where the original pumping station building remains.

Treatment Plant
The Water Treatment Plant (WTP) was built in 1955. As originally built it had a capacity of 3.5 million gallons per day (MGD) and was intended to be expanded to 7 MGD at a later time. In 1967 the plant was expanded to its intended maximum capacity. As growth in Town continued the plant's capacity was again increased in 1976, this time to 14 MGD.

Over the years some of the process have changed.

1) In the 1979 the Powdered Activated Carbon applied in the pretreatment was replaced by changing the filter media from anthracite coal to Granular Activated Carbon this lowered cost and reduced sludge volume.

2) In the 1987 sodium hydroxide was replaced with potassium hydroxide to reduce the sodium level in the water.

3) In December of 1992 fluoridation of the Water Supply began.

4) In May of 1997 an ozone generating and feed system was installed. This was done to remove the manganese which caused "brown water". This treatment also reduces taste and odors and very effectively inactivates virus and cysts.

5) In September of 1999 ammonia was added to change the secondary disinfectant to from free chlorine to chloramines. This was done to lower the trihalomethanes levels. This adjustment has been very successful.

Treatment Plant Operations
The Water Treatment Plant is designed as a continuous process, therefore it runs on a twenty four hours a day seven days a week basis. The Treatment Plant is normally shut down only for maintenance, severe storms, and power failures.

The Filter Operators monitor the process by checking chemical use every hour and bench testing water from various parts of the treatment process every other hour. The Filter Operators also receive bulk chemical deliveries. Daily chemical handling involves transferring of chemical from storage to day tanks. The operators also perform maintenance on the some of the control systems as needed. They adjust the treatment rate according to changes in the standpipe water level, which is a reflection of water consumption by our customers.

The laboratory staff performs the equipment calibrations and non-daily testing. Most critical of these are the bacterial samples collected and analyzed each week from ten DEP approved site in the distribution system. The laboratory staff also collects the many samples required to comply with the Safe Drinking Water Act. and writes the annual Consumer Confidence Report.

Distribution Works
The Distribution Works consist of the piping that carries the water to the customers, this piping ranges in size from 2" to 24" diameter. The original mains most of which are still in use are made of pit cast iron. Shortly after the original construction galvanized iron piping came into use, usually only for one and a half to two inch lines, some of these are still in service. In the mid-1950s cement asbestos was used for water mains. The current material used is ductile iron.

There are over 2000 fire hydrants connected to our system, of these over 1800 are public hydrants under the care of our staff. The hydrant inventory by age is given below:

No date, includes unknown date .......... 13.9%
1956 - 1959 ...................................... 1.46%
1960 - 1969 ...................................... 19.75%
1970 - 1979 ...................................... 20.48%
1980 - 1989 ...................................... 21.12%
1990 - 1999 ...................................... 23.26%

Note: Hydrant manufacturers did not begin casting the year in the hydrant barrels until the mid 1950s

Service lines are the connections from the main to the customers water meter or fire system. The older lines are galvanized iron tubes. Since the 1950s copper has been used for the smaller house lines. Fire lines are normally of the same materials being used for water mains.

The two tanks in the Center are called standpipes. They are connected to the Treatment Plant by a sixteen and a twenty-four inch diameter Forced Mains. These Forced Mains also diffuse water to the distribution works. The function of the standpipes are to even out the production demand on the treatment plant, maintain pressure, and to have on hand a ready supply of water for emergencies. Each standpipe has only one connection to the distribution system, they "float" on the system. When the treatment plant is producing more water than is being consumed the water level in the standpipes rises. When there is more demand than production the water level in the standpipes falls. The water level in the standpipes is normally kept within fifteen feet of the overflow. Water pressure at any particular point in town is controlled by the distance that particular point is below the water level in the standpipes.

Distribution Works Operations
Our system averages about forty main breaks per year. Most of these occur in the winter. Sometimes the pipe is found to have a rock under the pipe or be passing through an old sewer trench which has settled. The majority of breaks are unexplained. When a main fails we must isolate (shut-off) the area and call Dig Safe to locate underground utilities.

There are two basic types of main breaks. The first is beam breakage, which results in the pipe splitting around its circumference. We repair this with a "wrap-around" clamp. The second type of break is lengthwise. This is usually more difficult to repair and can require a larger excavation. A lengthwise break requires that a section of pipe be cut out and replaced, these cracks can run nine to ten feet along the pipe. After the break has been repaired and the excavation has been largely filled in the water will slowly be turned on to fill the main. Then the area mains will be flushed through the hydrants to rid the main of air and sediment.

The flushing of the hydrants are usually done twice a year. Although it appears to be a hydrant based activity its purpose is to flush sedimentation from the water mains, this is normally done by opening all the hydrants at the ends of the mains. This usually takes two to three weeks.

Our staff performs the maintenance and replacement of public hydrants. All of our hydrants have automatic drains, which drain the barrel after use to prevent freezing and the accumulation of stagnant water. Occasionally these do not work and require repair. Because we use a river source there is great seasonal fluctuations in the water temperature. This does occasionally cause hydrants to leak. The majority of hydrant replacements are done by our staff. The exceptions are those cases where hydrants are damaged by vehicle collisions. These are replaced by a contractor at the expense of the driver's insurance company. Most of our hydrants have stainless steel identification tags, which give the hydrant's inventory number. Our staff also paints the public hydrants as weather permits. Painting is an on going and continuous operation.

Our staff repairs or replaces the portion of the service lines between the main and the property line as needed. These are similar to water main repairs. Many of these are not emergencies but are scheduled. When an old galvanized iron service line corrodes the inside opening becomes smaller which restricts the flow, replacing these restores capacity. We usually will do this after the homeowner has changed the service line on his or her property to type K copper.

As other utilities mark out the location of their buried lines when we are digging we must locate our lines for them. We are not a member of the Dig Safe System, and must be contacted separately by those are planning to excavate. We also mark out our lines at the planning stage of projects such as the sewer collection system extensions.

Cross Connection Control Program
The function of this program is to see that connections between the drinking water system and any other liquid or gas do not pose a threat to the safety of the drinking water. There are two conditions under which cross connections are a problem. The first is when the pressure in the main drops and contaminates are siphoned back into the mains. This can happen when there is a main break or a large fire demand in the area. The second is when the pressure a building's plumbing system exceeds the pressure in the main. This can be caused by pressure type boilers or any process which is connected to the plumbing and heats liquids or gases. Billerica Water Works has regulations requiring that all commercial building have a reduced pressure zone (RPZ) valve after the water meter. While our efforts are directed to the commercial properties the homeowner should be aware that he or she may have cross connections in their plumbing. The most common is probably at garden hose with a sprayer attached or a hose being placed in swimming pools.

Cross Connection Control Program Operations
The Head Tester is responsible for surveying all commercial building for cross connections. When these are found and cannot be physically separated a special check valves must be installed. Normally a RPZ valve will be used. The exceptions are the valve on the fire lines which are double checks. The Head Tester tests the RPZ valve twice a year and the double checks once a year. The Head Tester also inspects and seal primary meters in new buildings.