INTRODUCTION

In communities that are spread over a number of hills there are often pockets of homes in low places where water main pressures would be excessive. Where the number of customers are insufficient to warrant a separate reservoir and distribution system, large regulator sets can be placed on the distribution mains to control water pressure at the lowest end of the system and maintain pressures at an acceptable levels. Five small pressure zones in Orinda are supplied through regulator sets. Four of these sets were in the original Orinda Fire District. One set, the Whiteoak Regulator zone which serves only two hydrants in Orinda is located in east Orinda territory recently annexed into the district. Orinda's regulator sets were installed in the 1930s and 1940s when design criteria did not consider modern fire flow requirements. Consequently, as the community and its needs grew these regulator sets became "choke points" for emergency high-volume water delivery into the water mains which they supplied. Additionally they were primitive in operation and when downstream appliances such as fire hydrants were closed too quickly, they the old regulators tended to slam shut and cause significant upstream water hammer. While the concept may seem simple, modern regulator sets are a complex assembly of several large and expensive regulator devices, each set to open at a slightly different pressure so that the impact of sudden decrease in demand on the water system can be cushioned, minimizing water hammer and other potential problems. These devices are located in underground vaults and a modern assembly can cost upwards to a quarter million dollars.   NEW REGULATOR SETS AND VAULTS INSTALLED The regulators are set in pits which have a regular "vault" covering. Nearby or at either side of the regulator are two fire hydrants. One hydrant is connected to the high pressure side of the regulator. The other hydrant is connected to the regulated side. Both hydrants can be used for firefighting. Since the regulated hydrant is taking supply from the same original feed as the high pressure hydrant (albeit through the regulator set), the additional volume available from the second hydrant may be limited. Of greater consequence is the ability to bypass the regulator set with hoses connected between the hydrants in the event that the regulator fails to operate properly or if needed fire flows exceeded the throughput capacity of the regulator set. Such action, however, would only be taken in extenuating circumstances as directed by an on-scene EBMUD Field Supervisor and would have to be closely monitored. Fire District Procedure: If ordered or authorized to do so by an EBMUD Field Supervisor, the engine company assigned to bypass the regulator shall take suction from the higher pressure (green cap) hydrant and prepare to discharge into the lower pressure (orange cap) hydrant. The Engineer shall determine the static pressure on the lower pressure (regulated) hydrant prior to bypassing by either noting the static pressure which is stenciled on the hydrant or taking a gauge reading prior to bypassing water. The Engineer shall maintain a bypass pressure of not more than 10 p.s.i. above the static pressure on the regulated zone. A gauge may be attached to the discharge hydrant which can be monitored and the flow rate controlled by adjusting the hydrant valve. The bypass can be made through the engine using the engine valves and gauges to maintain appropriate flow rates. For sustained operations a pressure controlled dump valve (provided by EBMUD) should be attached to the low pressure hydrant in order to relieve excess pressure. EBMUD shall be notified immediately upon termination of the pump-around operation so that appropriate testing of the water system for sanitary purposes can be expedited. Return to Water Supply Index Back to Information Section