Water Quality

INFORMATION REGARDING DISINFECTION BYPRODUCTS AND YOUR DRINKING WATER

DECEMBER 2020

The Newport Water Division is a Public Water System and routinely tests at various sites within the distribution system for Disinfection Byproducts (DBPs).  EPA sets standards for controlling the levels of disinfectants and DBPs in drinking water, including total trihalomethanes (TTHMs).  The Environmental Protection Agency (EPA) standard for TTHMs as part of the Stage 1 Disinfectants and Disinfection Byproducts Rule (DBPR) effective January 1, 2002 was 80 parts per billion (ppb) for an annual running average. Compliance for TTHM was based on a running arithmetic average, computed quarterly, of all quarterly averages of the eight (8) samples that Newport Water analyzed.  Newport Water Division was required to collect samples for the TTHM analysis during the first two weeks of each quarter.

Many water systems treat water with a chemical disinfectant, such as chlorine, in order to inactivate pathogens that case disease.  While disinfectants are effective in controlling many harmful microorganisms, they react with organic and inorganic matter in the water to form DBPs, some of which pose health risks at certain levels.

Some people who drink water-containing trihalomethanes in excess of the MCL over many years may experience problems with their liver, kidneys, or central nervous system, and may have an increased risk of getting cancer.  The public health benefits of chlorine disinfection practices are significant and well recognized.  Consequently, one of the most complex questions facing water supply professionals is how to reduce risks from disinfectants and DBPs while providing increased protection against microbial contaminants.

The Stage 2 Disinfectants and Disinfection Byproducts Rule builds upon Stage 1 DBPR to address higher risk public water systems for protection measures beyond those required as part of the Stage 1 DBPR.  As part of the Stage 2 DBPR the RIDOH reviewed and approved the monitoring sites for TTHM compliance.  The Newport Water Division under the Stage 2 DBPR collects samples from the four (4) approved monitoring sites within the distribution system on a quarterly basis.  Compliance for TTHM per the Stage 2 DBPR is based on a locational annual running average not exceeding 80 ppb.  That is at each monitoring site the four quarter running average must not exceed 80 ppb which differs from the Stage 1 DBPR which determined compliance as running annual average of all the samples taken in the quarter.  The compliance monitoring for the Stage 2 DBPR became effective October 1, 2013.  The schedule for the collection of the quarterly samples for Stage 2 DBPR has also changed; samples will be collected during the first week of the second month of each quarter ( February, May, August, and November) starting in the fourth quarter of 2013.

The Safe Drinking Water Act contains provisions to allow for compliance deadline extensions for Water Systems that need additional time for required capital improvements to be completed.  The Newport Water Division requested a compliance extension from the RIDOH.  After review of the required documentation, the RIDOH granted a 15 month extension to the Stage 2 DBPR compliance monitoring beginning January 1, 2015.  The compliance extension was supported by the current construction underway of the new Lawton Valley Water Treatment Facility and the improvements to the Station 1 Water Treatment Facility.  Starting in the fourth quarter of 2013 Newport Water began using the four (4) approved Stage 2 monitoring sites to calculate quarterly TTHM averages.  TTHM compliance through the end of 2014 will continue to use a running annual (four quarter) average similar to the method used in the Stage 1 DBPR.  The Stage 2 DBPR locational running annual average calculation for TTHM compliance began with the first quarter of 2015.  However, the first true "four quarter running average" begins with fourth quarter of 2015.

In January 2012 the City of Newport awarded a design build contract to the joint venture of AECOM - C.H. Nickerson for the Station No. 1 Water Treatment Plant Upgrade and the New Lawton Valley Water Treatment Plant.  The value of the contract is $67,000,000.00.  Prior to the award of the contract, Newport Water conducted detailed pilot testing to determine the optimal treatment method to reduce TTHMs.  Based on the results of the studies, Newport Water required advanced water treatment processes to be included in the improvements to the treatment plants in order to assure the sufficient level of organics removal in order to control TTHMs.  Construction activities at both facilities began in September 2012.  The Phase 1 treatment improvements at the Station 1 facility went into service on May 30, 2013.  The Phase 2 treatment improvements at Station 1 went into service on July 25, 2014. The new Lawton Valley facility went into service September 17, 2014.