Submerged appurtenances and pipelines: An assessment of water levels and contaminant occurrence

Abstract

Submerged air vacuum valves and pipe leaks are potential entry points of contaminated water into drinking water distribution systems under low‐pressure conditions. Water levels in 20 valve vaults and 17 groundwater wells were monitored weekly for 8 months. The assembled data set indicated that water mains and air vacuum valves were commonly submerged in the investigated system. Urban runoff was found to be the dominant source of flooding in 11 of the 16 vaults containing water. A subset of 14 vaults and 10 piezometers were sampled for microbial and chemical parameters. Concentrations of chemical contaminants generally did not exceed drinking water standards. However, high counts of microbial fecal indicators were detected in numerous vaults. Runoff volumes of up to 255 L/mm of rainfall were found to enter a tested vault, and runoff water was identified as the main source of pesticides, personal care products, microbial fecal indicators, and hydrocarbons in vaults.