Golden State Water Company Del Monte Well 4 Arsenic Reduction

Claremont, CA


PACE was hired by Golden State Water Company (GSWC) to assist with the Del Monte Well 4 arsenic reduction project. The Claremont water system is owned and operated by GSWC and includes Del Monte Supply Wells 1, 2, and 4 located on College Avenue. The raw water from Well 4 contains arsenic levels generally exceeding the state maximum contaminant level (MCL) of 10 micrograms per liter (µg/L), with typical concentrations ranging from 20 to 40 µg/L.


Treatment and blending were required to reduce the average arsenic concentration to less than 8 µg/L. PACE proposed a plan with six operating scenarios and testing schedules for Well 4 based on the key findings from the site visit at the Del Monte storage tank and booster station plant. The plan also included installation concepts for the tank mixing system and analysis of the tank inlet/outlet. Water quality testing protocols were developed to properly monitor system performance using parameters including dissolved oxygen, oxidation-reduction potential, total dissolved solids (TDS), pH, color, alkalinity, total arsenic, dissolved arsenic, total iron, dissolved iron, total manganese, dissolved manganese, total chlorine, free chlorine, total volatile compounds, total organic carbon, ammonia, and sulfide.


Key Features:

  • Laboratory water quality analysis and piloting
  • Operations augmentation strategies
  • Wellhead treatment system

Golden State Water Company

Advanced Water Quality / Piloting