AWWA WQTC62461

In 2000 master planning studies conducted by the Hoopa Valley Public Utilities District's engineering consultantSpencer Engineering & Construction Management, Inc. (Spencer) of McKinleyville,California, determined that an additional water source of at least 0.5 million gallonsper day (mgd) was needed to serve present and future customers through the year2021. The water sources at that time consisted of two pressure filtration treatmentplants located on mountain streams capable of producing approximately 0.58 mgd.Traditionally, the Hoopa Tribal Council policy was to only utilize streams or creeksfor drinking water and not to use the Trinity River. However, due to unreliability ofthese creeks and streams to sustain the required demands without endangering theaquatic life during low flows and the difficulty in adequately treating these watersduring heavy rainfall events that result in high turbidities and clogging of intakefacilities, the Council agreed to utilize the water in the Trinity River. Due to the proposed plant size, location, and hydraulic conditions, two treatmentprocesses were studied and evaluated by the District's engineering consultant for thisproject, Boyle Engineering Corporation (Boyle). These two processes were acontinuous microfiltration (CMF) process and a contact clarification/filtrationprocess. Each of these processes are considered as alternative filtration technologiesand are approved as such by the California Department of Health Services (DHS).The advantages of these processes over the conventional treatment process in this sizerange are their compact size, low costs, and easier expansion capabilities. Althoughthe District is not regulated by state or federal agencies, the District has adopted thoserelevant standards of DHS and the U.S. Environmental Protection Agency (USEPA).The USEPA, through the Surface Water Treatment Rule (SWTR), dictates themaximum contaminant levels applicable to systems that use treated surface water.The SWTR requires the water supplier to achieve a 3-log (99.9%) removal/deactivation of Giardia cysts and a 4-log (99.99%) removal/deactivation of viruses. Includes tables, figure.

Product Details

Edition:

Vol. - No.

Published:

11/01/2005

Number of Pages:

10

File Size:

1 file , 900 KB