On-Site Hypochlorite Generation and Chlorate Occurrence – New AWWA Research Project

(RALEIGH, NC – August 22, 2011) – The American Water Works Association (AWWA) recently contracted Hazen and Sawyer to study the extent of chlorate, perchlorate, and bromate occurrence in on-site generated hypochlorite solutions through AWWA’s Water Industry Technical Action Fund (WITAF). This study is designed to support drinking water utilities, the AWWA, and the US EPA in obtaining the knowledge necessary to develop an informed regulatory framework for an eventual chlorate standard.

At a recent public meeting hosted by the US EPA on the status of regulatory determination for chemicals on the Third Contaminant Candidate List (CCL3 and RegDet3), data were presented regarding health effects and occurrence of 32 of the 112 CCL3 chemicals. Among those chemicals discussed was chlorate, a known byproduct of the decomposition of hypochlorite solutions used in drinking water treatment and a known product formed in the production of on-site generated (OSG) hypochlorite.

At the meeting, the EPA proposed a chlorate health reference level (HRL) of 210 ?g/L and, based on occurrence data presented, it would appear that the EPA may be planning a positive regulatory determination for chlorate in the future. However, data from a 2009 WaterRF and AWWA/WITAF funded project entitled “Hypochlorite – An Assessment of Factors That Influence the Formation of Perchlorate and Other Contaminants” indicate that chlorate formation in OSG hypochlorite is significant, yet not well understood.

Therefore, as the US EPA moves forward with developing a draft regulatory determination, there is a tremendous need to obtain a larger set of data regarding the extent of chlorate formation during on-site generation of hypochlorite around the country in order to build a better cost-consequence/analysis of any potential regulatory limits. Because the US EPA considers a combination of factors in any regulatory determination and standard, information regarding the potential costs of compliance will be an important component of the decision making process. Hazen and Sawyer was selected to design and lead this important study based on our subject matter demonstrated through publications, presentations, and past project work.

Since our founding in 1951, Hazen and Sawyer has focused on two things: providing safe drinking water and controlling water pollution. Our range of services encompasses the planning, design, and construction management of water and wastewater-related projects – from clean water treatment, storage, and distribution to wastewater and stormwater collection, treatment, and reuse.

Hear about new publications with our email newsletter

We will never share your details with anyone else.