El Dorado County Agency Warns of High Levels of Alkaline in Stormwater Near the El Dorado Trail

by Placerville Newswire / Feb 01, 2016 / comments

Placerville, CA – The El Dorado County Community Development Agency (CDA) has conducted pH tests of stormwater in the area of El Dorado Trail (near the end of Stage Court) that have indicated high alkaline levels of up to 12.8. Due to these test results, the County has placed a warning sign and temporary caution tape at the site. In addition, the County has placed a temporary fence at the site to further deter the public from coming into contact with the water. The public should not enter this area.

The water source in question is a seasonal drainage that flows northwest under the El Dorado Trail where it continues in a northward direction. The tests that have produced pH levels between 12 and 12.8 are located in an overflow area adjacent to the drainage where there is ponding. Field measurements conducted farther down the drainage (approximately 200 feet downstream) have produced pH levels of around 7, which are within the normal range for stormwater runoff (per the Central Valley Regional Water Quality Control Board (RWQCB) Basin Plan standards). The source of the higher levels of alkaline in the ponding area is currently being investigated. The County has been in contact with the State Department of Fish and Wildlife and is working jointly with the RWQCB.

pH measures the acidity or alkalinity of a liquid or substance in liquid. The pH scale ranges from 1 to 14 with 1 being highly acidic and 14 being highly basic. A pH of 7 is considered neutral (e.g. distilled water). A pH of 12.5 or greater is considered hazardous according to Title 22 of the California Code of Regulations. In order to determine the potential harmful effects of a high pH solution, the type and concentration of the substance or substances in the water causing the high pH must also be known. Lab results of the high pH water indicate a composition of predominately calcium hydroxide that is diluted. As this water evaporates the solid material remaining is predominantly composed of calcium carbonate (limestone).

The County will continue to monitor and conduct periodic testing through the wet weather season in conjunction with the RWQCB. The County is investigating the source of the high pH water and is evaluating potential mitigation measures.

For additional information regarding the County’s response to this issue please go to www.edcgov.us/emd. For questions about the current water tests in the El Dorado Trail area please contact the Environmental Management Division at (530) 621-5300.

See more here: http://www.edcgov.us/EMD/Stormwater_Drainage_Containing_Elevated_pH_Levels_Near_El_Dorado_Trail.aspx

Department:Community Development Agency
Contact:Creighton Avila
Date: January 29, 2016
(530) 621-5153