WATER LEAK DETECTION SURVEYS
DESCRIPTION OF EQUIPMENT: The leak locator we use is an electronic instrument, Model HL90, manufactured by Metrotech Inc., of Sunnydale, California. This device is a self-contained instrument equipped with headphones, sensitivity and gain controls and a ground pick-up. This device is very sensitive to sound and is capable of detecting water leakage of approximately 1/2 gallon per minute. Our company has used this particular leak locator in all our previous leakage surveys and consider this device to be excellent in the field.
We are also equipped with a leak correlator, the PAL 300, manufactured by Gutermann Messtechnik in Switzerland. Sensors are placed on the pipe on both sides of the leak (e.g. on a valve). The sensors will pick up the leak noise which is then processed on the PAL. Within seconds the exact position of the leak is displayed on the PAL screen.
We recently purchased a WaterPoint PLD mobile leak detector. It includes an advanced sensor and a high resolution signal processor that removes unwanted noise, zeroing in on a leak sound. The ground mike works wirelessly through an Apple iPod Touch. This unit is manufactured by 64seconds in Framingham, MA.
We also are equipped with the necessary tools for conducting the survey such as electronic gate box finders, underground pipe locators, gate and service keys, etc.
LEAK DETECTION SCOPE OF WORK
First we must be provided with a water system map with a up-to-date location of each hydrant and gate valve in the system. Each hydrant and all accessable gate valves are listened to with our leak locator and readings are recorded on the map. Once all the hydrants and gate valves in the system have been recorded, we return to those hydrant and gate valves that had leak sounds. A thorough search in the particular section of the recorded leak is conducted, including listening on service valves, gate valves, and walking directly over the pipeline to pinpoint the leak. The leak correlator will be used if the leak cannot be located by sonic listening equipment. The survey can be conducted during the daylight hours, so that assistance from the Water Department is available when needed. A final written report in detail will be submitted upon completion of the survey.
COST FOR LEAKAGE SURVEY
The cost to conduct an entire survey for a particular city or town is based on our manpower and the estimated days and hours needed to complete the survey. Once all the leaks have been located and the necessary repairs made, the result could be a savings of millions of gallons of water costing thousands of dollars annually, thus increasing revenue in the Water Department's budget.
FIRE FLOW TESTING SERVICE
Flow tests are important for determining the effciency and adequacy of the distribution system for transmitting water, particularly during peak demand, and to determine the amount of water available from hydrants for fire fighting. To perform such tests it is necessary to induce a flow from one or more hydrants within the area of the testing, and gauge another non-flowing hydrant to determine static and residual pressure with the upstream or downstream hydrant flowing fully open at the 2-1/2" nozzle. To determine flows, or gallons per minute, from a hydrant, a hydrant pitot gauge must be used. This is an instrument with a tube which has a small hole in one end which is centered in the stream flowing from the 2-1/2" nozzle. The velocity of flow is transmitted as pressure to a pressure gauge attached to the tube. The National Board of Fire Underwriters (NBFU) generally prescribes that there should be a certain flow, such as at least 500 GPM at a test location with a residual pressure of no less than 20 psi. Some cities and town's Fire Chiefs require between 800 to 1000 GPM with a 20 psi residual. This can only be achieved if the normal static pressure within the system is at least 80 psi.