Grass Valley Waterwater Treatment Plant*

Collection of Grass Valley's wastewater is done partially by gravity and also by eight pumping installations throughout the city. Storm water is collected separately and discharged to Wolf Creek.

The wastewater treatment plant has a present capacity of 1.7-million gallons of wastewater per day in the summer and 4.8-million gallons per day in the winter. The difference is mostly infiltration of surface water to old and broken collection piping. Replacement of a main collector line beside the bed of Wolf Creek earlier this year should substantially reduce infiltration. The city is actively pursuing a program of finding and replacing broken pipes to lower the amount of surface water infiltration.

The plant is currently undergoing an expansion to 7-million gallons per day and will attain that capacity in mid-2001. This capacity is expected to be adequate to take care of the contemplated growth of the city until the year 2015.

The expansion cost will be $9.2 million, most of which is on hand from user and connection fees. The much larger processing equipment that is being installed is of the latest design and the new state-of-the-art computer system should permit control of most plant functions from the operator's control room

Emergency power is provided by diesel-powered generators that are tested under load at proper intervals.

Most odors at the plant have their source at the head works of the plant where the incoming wastewater is screened to remove cloth, plastics, wood fibers, etc. which can plug up plant pumps and piping. Some cloth that passed the screen in May, 2000 resulted in a pump plug and a spill of several thousand gallons of sludge to Wolf Creek.

An activated carbon odor control system at the head works is being expanded and upgraded to minimize odors emanating from the plant. The remainder of the plant processes are relatively odor free, although occasionally certain uncontrollable combinations of water temperature, contained chemical compounds and atmospheric conditions will cause some odors to be emitted.

The final products from the plant are water and a digested sludge. The water discharged to Wolf Creek meets California standards. The sludge is collected in a lagoon before RESPONSES .... CITY COUNCIL LINDA STEVENS, MAYOR PATTI INGRAM, VICE MAYOR DE VERE "DEE" MAUTINO STEVE ENOS GERARD TASSONE Valley GENE HAROLDSEN A CENTENNIAL CITY CITY ADMINISTRATOR February 14, 2001 125 EAST MAIN STREET GRASS VALLEY, CA 95945 (530) 274-4310 FAX: 274-4399 Honorable Carl Bryan II Presiding Judge of the Nevada County Courts 201 Church Street Nevada City, CA 95959 Re: Grass Valley Waterwater Treatment Plant Your Honor, We received the Nevada County Grand Jury's January 16, 2001 report regarding the City's Waterwater Treatment Plant. The City is delighted that the Grand Jury's conclusion is that "The expansion of the Grass Valley waterwater treatment plant is one of the largest public works projects ever done in Nevada County and is the result of commendable forward planning by the city." We appreciate that no response by the City is required. However, it is important that the City clarify Finding #3 which states that "The plant is currently undergoing expansion to 7-million gallons per day and will obtain that capacity by mid-2001." 7-million gallons per day will be the expanded plant's wet weather (winter) flow. Actually dry weather (summer) flow is being expanded to 2.78 million gallons per day. If you have any questions, please contact Rudi Golnik, Director of Public Works / City Engineer at 274-4350. Thank you for your consideration of this clarification. Sincerely ∟ında Stevens Mayor City Council cc: Claude Biddle, City Attorney Rudi Golnik, Director of Public Works / City Engineer David Janison, Nevada County Grand Jury Foreman E-mail: council&[email protected] www.cityof.grass-valley.ca.us being filtered and trucked once a year to a company that sells it to apply to certain agricultural crops or sends it to a certified land-fill.

Management states the expansion project is on budget although the finding of some mercury from an old gold amalgamation plant on the property will cause some extra ÷. expense that should be covered by a contingency fund. CONCLUSIONS The expansion of the Grass Valley wastewater treatment plant is one of the largest public works projects ever done in Nevada County and is the result of commendable forward planning by the city