The Effects of Utility Pole Placement and Characteristics on Pentachlorophenol Concentrations Entering Underground Injection Control (UIC) Devices: City of Gresham, Oregon

摘要

Urbanization is causing increased amounts of stormwater runoff, while simultaneously decreasing the amount of pervious surface area for infiltration. Multiple priority pollutants have been identified in urban stormwater, including pentachlorophenol (PCP). PCP is often found in stormwater samples exceeding the Safe Drinking Water Act limit of 1μg/L and can cause human health issues with exposure over time. Treated wood utility poles are the major source of PCP in urban stormwater. With the use of underground injection control (UIC) devices as an alternative method to treat and dispose of stormwater, the potential exists for groundwater contamination of PCP. The City of Gresham currently owns and operates approximately 1,100 UIC devices.In this study 60 UIC device contributing areas were surveyed for the presence and characteristics of utility poles. A positive correlation was found between utility pole surface area in a UIC contributing area and PCP concentration in stormwater. A stronger correlation exists for surface area of utility poles surrounded by concrete and PCP concentration in stormwater. The year of the last inspection by the electrical company could also be an indicator of PCP concentration in stormwater, as additional treatment compound is often injected into utility poles during these inspections. The intensity of the rainfall event during stormwater sample collection, in combination with these other attributes, may impact how much treatment compound is able to leach from the pole. Recommendations for future work include adding to the sample set of PCP concentrations for multiple UIC sites and using GoogleEarth to identify utility poles surrounded by concrete in other UIC contributing areas.