MBSE Conditions of Approval

Attachment 4

 

Water Accounting Protocol for SNG Property (APN 011-501-014)

Prepared by Darby Fuerst, August 10, 2010

 

1.         At least weekly during the November through April period, Cal-Am will pump water from the Hilby Tanks[1] into its main distribution system.  Based on current practice, this pumping occurs once a week for approximately four hours at a rate of 1,400 gallons per minute (gpm). As a result, approximately 1.03 acre-feet of water are pumped from the Hilby Tanks into the main distribution system each week, or approximately 4.12 acre-feet each month.  This pumping is conducted to maintain water quality in the tanks.

 

As the SNG property is developed and water demand increases, Cal-Am may increase the duration or frequency that water is pumped from the Hilby Tanks into the main distribution system to ensure that sufficient storage capacity is available in the Hilby Tanks for “front loading” of “prior to delivery” production of water from the Seaside Basin.

 

2.         During the November through April period when flow in the Carmel River at the Highway 1 Bridge gage exceeds 40 cubic feet per second and Cal-Am is required to minimize its pumping from the Seaside Groundwater Basin[2], Cal-Am will pump sufficient water from its wells in the Coastal Subareas of the Seaside Groundwater Basin each week to equal or exceed the amount of water necessary to refill the Hilby Tanks[3] and serve the estimated water demand for the SNG property.

 

            It is expected that Cal-Am will utilize either its Plumas Well, Playa #3 Well, or both of these wells during the November through April period to serve the SNG property.  Presently, the Plumas Well can pump approximately 250 gpm and the Playa #3 Well can pump approximately 350 gpm.  If these wells are used to serve the SNG property, they would be pumped in advance of the weekly pumping from the Hilby Tanks.  To equal the 1.03 acre-feet of water pumped from the Hilby Tanks, the Plumas and Playa #3 Wells would need to operate approximately nine hours for one day.

 

            If one of these wells fails, the other can serve as a backup and operate for a longer period.  Similarly, if both wells fail, Cal-Am can operate one of its larger wells, e.g., Ord Grove or Paralta Well, for a shorter period to ensure that water is pumped from the Seaside Basin during this period to serve the SNG property.

 

3.         For purposes of estimating monthly and daily water demands for the SNG property, an annual production requirement of 90 acre-feet is assumed.  Monthly water demands will be estimated based on the long-term average monthly water distribution in Cal-Am’s main system.  For example, in January, 6.39 percent or 5.75 acre-feet of the annual production requirement is expected to occur.  Similarly, in July, 10.80 percent or 9.72 acre-feet of the annual production requirement is expected to occur.  Daily water demands for the property are estimated by dividing the average monthly quantities by the number of days in the respective month.  For example, the average daily demand expected in January would be 0.19 acre-feet and the average daily demand expected in July would be 0.31 acre-feet.

 

            The estimated demands will be adjusted by the reported demands to account for the construction and early operational phases before the project if fully implemented.          

 

4.         During the November through April period specified above, Cal-Am will maintain a buffer of at least 2.0 acre-feet of production from its Seaside Basin wells to ensure that sufficient water is available in advance to serve the SNG property, in the event of an unexpected increase in water demand for the property.

 

 

 

 

 

 

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[1] Each Hilby Tank originally stored 1 million gallons or 3.07 acre-feet.  These capacities have been reduced due to seismic retrofits.  Presently, Hilby Tank #1 stores 730,000 gallons or 2.24 acre-feet and Hilby Tank #2 stores 823,000 gallons or 2.53 acre-feet.  Total usable storage capacity in the Hilby Tanks is 1.553 million gallons or 4.77 acre-feet.

[2] SWRCB Order WR 98-04, Condition 4, adopted February 19, 1998.

[3] Consistent with the May 11, 2009 Court Order regarding the “commingling of water and storage from different sources”,  the physical water stored in the Hilby Tanks during the November through April period will be primarily derived from the Carmel River.  An equivalent amount of physical water will be pumped from Cal-Am wells in the Coastal Subareas of the Seaside Groundwater Basin during this period and provided directly to Cal-Am’s main distribution system.