Hemet Water Filtration Plant Modifications for New Source Water


SCH Number
Lead Agency
Eastern Municipal Water District
Document Title
Hemet Water Filtration Plant Modifications for New Source Water
Document Type
NOE - Notice of Exemption

Document Description
Due to the current drought conditions throughout CA, Eastern Municipal Water District (Easter) is proposing to change the raw water supply for its Helmet Water Filtration Plant (HWFP) from State Water Project Water (SPW) to Colorado River Aqueduct Water (CRA). Modifications to the pretreatment for HWFP are necessary in order to obtain CA Department of Public Health approval for the District to connect to CRA as the feed source water to HWFP. Eastern has eleven years of experience in successfully treating CRA at its Perris Water Filtration Plant (PWFP) using processes to those at HWFP. However, HWFP currently lacks two pretreatment chemical feeds necessary to prevent membrane fouling and maintain fiber integrity when operating on CRA. To address concerns resulting from the hardness of water polyphosphate is used as a scale inhibitor. Additionally, free chlorine is used to prevent Quagga mussel colonies from establishing in the membrane basins. Other treatment goals for the CRA are addressed with the existing treatment process at HWFP. Based on review of the membrane system design criteria and water qualities, these pretreatment chemicals are critical for efficient and reliable operation of HWFP on CRA. With these additions, HWFP is expected to meet all filtration, disinfection, and disinfection byproduct goals for the plant. Additionally, sodium hypochlorite will be closed at the inlet to the Warren Road Pump Station on EM-14, approximately 3.4 miles from HWFP (Figure 1). A double walled polyethylene tank will be installed outdoors on a concrete pad with double contained solution piping from the tank pad to dosing point (Figure 2). Also, a polyphosphate storage and feed system, consisting of 275 gallon polyethylene totes and two metering pumps (one redundant) will be located in the strainer room at the HWFP (Figure 3).

Contact Information
Helen Stratton
Eastern Municipal Water District
2270 Trumble Road P.O. Box 8300
Perris, CA 92572-8300

Phone : 951-928-3777 x.4545



Notice of Exemption

Exempt Status
Categorical Exemption
Type, Section or Code
S:15301, Class 1
Reasons for Exemption
Modification to the HWFP necessary to accommodate a change in feed source water from SPW to CRA will not result in increased capacity to the facility. This project meets the criteria for the existing operations for Eastern Municipal Water District Waste Discharge and Sewer under the categorical exemption provided for within CEQA Guidelines §15301.

Disclaimer: The document was originally posted before CEQAnet had the capability to host attachments for the public. To obtain the original attachments for this document, please contact the lead agency at the contact information listed above. You may also contact the OPR via email at state.clearinghouse@opr.ca.gov or via phone at (916) 445-0613.

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