Pescadero CSA11 Water System February 19, 2009

Draft report on increasing water flow from the Pescadero commercial district hydrants to meet the state requirements of 1500 gallons per minute for two hours.

Draft Fire Flow Study January 2009 PDF

The existing Pescadero water system that serves CSA11 supplies household water and fire protection to the town of Pescadero and the CSA11.

Pescadero, CA CSA11 Water System Google Earth Map Overlay CSA11.kmz

Fire protection for Pescadero is provided by the CDF station in Pescadero. After the water system was installed the state fire codes were changed to require an increased fire flow rate and storage capacity. County code requires a flow rate of 1500 gallons per minute for two hours in the commercial distinct with a reserve left over. 

The increased flow and storage requirements are for the commercial district. The residential areas meet current fire codes. 

The community of Pescadero asked the San Mateo county public works department to evaluate the cost of upgrading the system to support increased flows in the commercial district. The response was that the water system would need to be replaced from the tank to the town center of Pescadero at a cost of several million dollars. 

This cost is not supportable by the CSA11.

Members of PMAC asked San Mateo county public works to evaluate the feasibility of a booster pump located at the water tank. The concept is for the booster pump to turn on during high flows and increase the water pressure in the system to ensure the 1500-gallon-per-minute supply to the commercial district.

Through the efforts of Supervisors Gordon's office funds have been found to pay for the engineering analysis of upgraded fire flow in Pescadero. 

Water System Concepts Questions

The members of the Pescadero community have asked if the following questions:

How much storage capacity is required to meet the fire flow requirements and provide a reserve for CSA11. The existing CSA1 water tank is 140,000 gallons.

Add a fire pump to the water system at the water tank location.

1) Can a booster pump be added to the system to meet the fire code flow requirements?

Members of the community have done rough calculations that indicate a pump may be feasible. It is estimated at a 50 to 120 horsepower booster pump may be sufficient to support the fire flows.. The pump size estimate is based on the fire hydrant flow tests conducted in 2005. The pump would be activated when very high flows are required. The pump would activate based on flow rate through the system and not require the fire department to activate the pump.

2) What are the estimated costs for a pump and storage tank upgrade?

3) The CSA11 water well is located at an elevation that will provide increased pressure to the system if the storage tank is relocated. Is a tank relocation feasible?

Add a pond in Pescadero with a fire pump.

1) Can a local fire pump supplied from a pond be used to meet the fire flow requirements in the commercial district?

This would be a separate system to support fire flow requirements in the commercial district. New pipe and hydrants would be required.

Fire Hydrant Testing.

The last hydrant tests in Pescadero were performed in June 2005

Should new testing be done as part of the analysis being preformed by the county on the fire flows?

Pescadero , CA CSA11 Fire Hydrant Testing
June 2005

Static Pressure
No flow

Flow and Residual Pressure

P-1 719 North Street

80 PSI

790 GMP at 38 PSI

P-2 Pescadero Creek Road & Stage Road

80 PSI

870 GPM at 50 PSI

P-3 7036 Pescadero Creek Road

80 PSI

960 GPM at 54 PSI

When the fire hydrants are next tested on Stage Road in Pescadero can the fire trucks be used to pull higher flow through the system. This test may be a low cost way to gather data to support the fire pump concept.

Answer from CDF

I is not advisable to pull down the pressure in the system. It pulls out all of the crud in the pipes and may damage the system.