SEWER TESTING

The Municipal Smoke Testing Technique is an uncomplicated and positive means of locating sources of storm/surface water inflow, one of the principal causes of overloaded treatment collection systems following rainfall. The cost is pennies per foot. The technique consists of blowing a large volume of air combined with smoke into the system, where under pressure it follows the path of the intruding waters in reverse to the surface, disclosing the source within seconds. Smoke tests reveal the following: Leaks permitting storm/surface water inflow Connected roof and cellar drains Connected sanitary and storm sewers All connected lines, including abandoned and supposedly unconnected lines Line stoppages Leaky manholes Uncapped lines Lost manholes Unmetered connections (where meters are required) Rodent passages leading into lines Communication between sanitary and storm sewers due to structural and/or flooding damage Personnel and Cost A crew usually consists of a supervisor or foreman with 2 laborers. The smoke testing technique is uncomplicated and can be performed by regular maintenance laborers who quickly master the fundamentals. A crew can easily test a minimum of 10,000 linear feet of sewer line in an eight-hour period. The cost is only a few cents per foot, including labor, blower, smoke bombs, and truck. This is only a fraction of the cost of other inspection methods. Professional Services Public Law 92-500 specifies an infiltration/inflow analysis of the collection system. Professional direction is a must in complying with Federal regulations or in upgrading or constructing collection/treatment systems. Surface waters usually enter sewage systems through openings in mains, house service lines, roof leaders, foundation drains, manhole covers, cross connections from storm sewers, combined sewerage and catch basins. Rainfall is intermittent in nature and a major contributor to surface water inflow/infiltration. Inflow sources are quickly and easily identified by smoke under pressure traveling along lines and filling all openings, including paths in the soil invisible to the naked eye, made by surface water. Detailed field observations supported by videotapes are made for evaluation and eventual elimination of these sources. Sources of inflow are relatively easy to eliminate once they have been identified. Elimination of surface and storm water from collection systems is required by Federal law and can sometimes eliminate the necessity of expanding treatment facilities In addition to locating the leaks or faults within a sewer system, smoke is recommended for tracing sewer lines to verify existing maps. Any variation should be shown on updated maps Unidentified discharges in areas with a number of lines can be identified by blowing smoke into the line showing the discharge and checking manholes until smoke in the line identifies the origin of the discharge. Sources of surface water inflow/infiltration in sewerage systems are extremely difficult to observe unless water is actually entering the line at the time of the survey. Professional studies supported by visual observations, flow studies and smoke test data permit cost-effectiveness conscious operators to limit areas to be surveyed by more time consuming and costly methods. Recommended Equipment One three minute smoke bomb for each test (usually 300-500 feet of 8”-12” line or one manhole to manhole section.) A portable air blower with a minimum capacity of 1500 CFM. A blower of lesser capacity will not generate sufficient pressure to disclose all openings on a line. A hose configured for direct line hookup to each line will be provided with a specially designed sleeve which inflates and cause pressurization of the line being tested. Line plugs or Muni-balls Camcorder Advance notices to building residents Procedure Normally one section of line (300-500 ft. per test) is tested at a time. Blocking or plugging of lines is not necessary and can cause a surcharge condition that will not allow smoke to penetrate an entire manhole to manhole segment. The smoke under pressure quickly fills the sewer main plus all connecting lines, and following the line of least resistance, flows through all openings to the surface, revealing the location of the faults. Invariably, the fault will be found at the site of the smoke or within a few feet. Smoke tests are effective regardless of the surface, type of soil, or depth, providing an opening exists for the smoke to follow. For instance, it is not unusual to see smoke escaping from cracks in paved surfaces, showing points of surface water entry. Tests can be conducted any time of the year, even when the soil is frozen. Best results are obtained on dry days, when no water is leaking into the line. After placing hose in line, start blower and allow time to create draft. The smoke is introduced through the exhaust port of the blower, where a chamber is provided to house the burning smoke bombs. In less than a minute smoke will be issuing from the roof vents of connected buildings. The crew will fan out, checking buildings, grounds and streets for tell-tale signs of smoke. Smoke immediately backing up in the blower indicates a line blockage. Discontinue testing until the line has been cleaned. Smoke issuing from the ground, pavement, yards, roof drains, etc. shows sources of inflow. Each home should be observed for vent pipe indication and also should be walked around entirely to notice any possible leaks. A report is filled out for each and every line. Video is taken only of defects found for location and quantifying potential inflow volumes. House Connections The smoke emitted by the smoke bombs is non-toxic and will leave no residue to damage the interior of buildings. It is irritating to breathe, but any irritation quickly disappears once exposure has ceased. All buildings connected to the lines being tested should be checked for smoke. If a concentration of smoke is present, occupants should be evacuated and the building ventilated by opening doors and windows. The smoke will dissipate quickly. The point of entry for the smoke should be found. If unable to gain access to the building after smoke is discovered indoors, it is advisable to return later and determine the point of entry. If unvented, the smoke will settle out of the air without leaving residue. Any smoke entering a house should be reported so that the defect can be repaired, thus avoiding the possibility of potential sewer gas poisoning. Insurance Separate liability insurance coverage is usually unnecessary for smoke tests, as Municipal Pipe Tool Co., Inc. carries general liability insurance, and insurance companies do not exclude smoke testing. The smoke is non-toxic and non-staining, but there is always the remote possibility that someone may claim property or personal damage. Although the probability of proving smoke damage is nil. Therefore, before starting smoke tests, it is advisable to take precautions of making certain of proper insurance coverage Public Relations Good public relations are essential. Fire and police departments should be alerted in advance as to the date and location of tests. They should be familiar with the purpose of the tests, the harmless nature of the smoke, and be prepared to advise ventilating any building containing smoke. The tests frequently will arouse the curiosity of on-lookers. This provides an excellent opportunity to maintain good public relations by answering questions in a friendly and intelligent manner. Frequently, one person is delegated to answer questions. It is also advisable to have announcements made in local newspapers and the local radio stations. There are two schools of thought on distributing advance notices. One distributes notices 24 hours or more in advance of the tests to occupants of buildings connected to lines, to forestall alarm in the event that smoke does enter the building during the test. The other checks each building connected to the line immediately prior to the tests. This can slow the testing crew, but does not give unscrupulous persons time to block cellar and roof drains, etc. before the tests and remove the blocks later. The following is the form for advance notice used by Municipal Pipe Tool Co., Inc.: ATTENTION RESIDENT Please be informed that Municipal Pipe Tool Co., Inc. of Hudson, Iowa will be conducting a sewer line smoke test of the sewer lines in your area within the next few days. This test is being conducted in an effort to reduce rainwater access to the sanitary sewer. The smoke being used is not harmful or toxic in any way and should not appear in your premises unless you have a leak within your system. Any presence of smoke detected in your house should be reported to the workers performing the testing operations, by calling our office at 1-800-798-4205, or by calling your City Hall. These deficiencies can then be corrected for your safety so that sewer gas does not have an opportunity to enter your home. Also, it is advised that you pour water in all drains that are not used on a regular basis so that the traps are full of water and smoke will not pass through. Conclusion A high reading on treatment plant inflow gauges during or following rainfall is a positive indication of storm/surface water inflow. Smoke testing is a fast, economical, and positive means of locating sources of surface water intrusion in collection/treatment systems. Elimination of these sources as required by law in the United States will improve treatment plant operations and correct overloaded collection system problems, a major contributor to pollution of water resources.