VIEWS: 12 PAGES: 8 POSTED ON: 11/12/2011
SPRAY & DRIP IRRIGATION Spring 1999 Pipeline Vol. 10, No. 2 Small Community Wastewater Issues Explained to the Public INFILTRATION AND INFLOW CAN BE COSTLY FOR COMMUNITIES any small towns in the U.S. upkeep of their wastewater collection sys- M have aging wastewater collection systems (sewerage systems) that are deteriorating or in desperate need of repair. Some older tems, the problemsthat result can threaten public health and the environment and tend to be far more expensive to correct than they are to prevent. Infiltration and inflow are Communities should be concerned about I/I because… towns still use brick sewers built more two such problems affecting large and small • I/I decreases the efficiency and capacity collection systems around the country. of wastewater collection systems and than a century ago, while many more treatment systems, which can impact communities rely on outdated combined What is infiltration? a community’s potential for growth, systems to collect both wastewater and stormwater flows. The term infiltration is used by waste- • I/I can hurry the need for the construction Collection systems need regular moni- water professionals to describe the excess of relief sewer facilities, toring and maintenance just like other parts water that sometimes seeps, trickles, or of the wastewater system. But because flows into old or damaged collection sys- • I/I contributes to the hydraulic overload- they are located underground, problems tems from the surrounding soil. For exam- ing of treatment processes, which can affect public health and the community’s often go unnoticed until major complications ple, high groundwater or water remaining compliance with state and federal water surface in the community, such as sewer in the soil after rain or snow often can quality standards, backups, flooding, collapsed streets, or con- infiltrate mainline pipes, joints, service lat- tamination of nearby water resources. erals, connections, and other parts of a col- • I/I can cause backflooding of sewers When communities fail lection system that have deteriorated, into streets and private properties, and to adequately cracked, sagged, or collapsed. invest in the • I/I can increase collection system and What is inflow? treatment facility operating costs—for example, adding to the necessary run Additional unwanted time for pumps and pump stations and water also can enter costs for energy, maintenance, and repairs. collection systems from above-ground sources. During storms or snow thaws, for example, large What is I/I? volumes of water may flow When collection systems are old and in into systems through leaky disrepair, it often is very difficult to deter- manhole covers or combined mine exactly how much of the extra waste- stormwater/wastewater water in the system is the result of inflow connections. versus infiltration. When uncertainty exists, In addition, private residences wastewater professionals usually refer to may have roof, cellar, yard, area, the overall problem as I/I. or foundation drains inappropriately connected to sanitary sewers. Any What are the costs of I/I? extra water flowing into I/I problems place an additional burden wastewater collection on community collection systems and systems from above- wastewater treatment facilities. Collection ground sources, either systems can be damaged when they are intentionally or uninten- forced to transport larger volumes of flow tionally, is referred to than they have been designed to handle. as inflow. continued on page 2 INFILTRATION AND INFLOW INFILTRATION AND INFLOW CAN BE COSTLY FOR COMMUNITIES continued from page 1 In extreme cases, pipes can collapse meet National Pollutant Discharge or burst causing pavement to buckle. Elimination System (NPDES) permit Damage to pipes from I/I also can allow requirements and eventually be corrected. wastewater to contaminate vital ground - Monitoring and correcting SSOs and CSOs water and drinking water sources. is costly for communities. Causes of Infiltration: I/I also increases operation and treatment This Pipeline issue provides an overview costs for the facilities that receive the addi- of common methods for evaluating and • poor soil conditions in which sewer tional wastewater flow. After rain and snow correcting I/I problems in small communities. lines are laid, events, in particular, excess flows from I/I I/I prevention and collection system main- • poor materials or shoddy construc- can overburden treatment plants to the extent tenance also are discussed. tion and workmanship, that untreated wastewater must be discharged Readers are encouraged to reprint to the environment. Pipeline articles in local newspapers or include • excessive groundwater levels, Sanitary and combined sewer overflows them in flyers, newsletters, or educational • precipitation and percolation (SSOs and CSOs) can occur when waste- presentations. of surface waters, water flow volumes exceed the design If you have any questions about reprinting • water retained in the surrounding capacity of the treatment plant. If the treat- articles or about any of the topics discussed soils, and ment plant cannot store the extra flow for in this newsletter, please contact the National • poor condition of pipes, joints, later treatment, the excess wastewater by- Small Flows Clearinghouse at (800) 624- and connecting sewer structures. passes the facility and is dumped untreated 8301 or (304) 293-4191. into receiving waters. SSOs and CSOs must Causes of Inflow: Trouble Signs of I/I In The System • deliberate or poorly planned connections of storm water or other drainage water into sewer systems, How do you know if I/I is a problem for water quality problems in the and your community’s collection system? The following conditions can indicate community that could be associated • draining of swamps, wetlands, with the raw wastewater discharge, or low-lying or flooded areas into the presence of I/I and the need to evaluate collection systems through connec- your system. surcharging of manholes resulting tions or leaky manhole covers. in a loss of pipe, greater than anticipated flows Source: U.S. Environmental Protection measured at wastewater treatment overburden through defective pipe Agency (EPA). Inflow/Infiltration: A facilities, joints, Guide for Decision Makers. hydraulic overloading of treatment complaints of odors, facilities indicated by “washout” For more information or to order this of treatment processes, EPA document from the NSFC, refer to pipe corrosion, the list of products on page 8. Please sewer system overflows or bypasses, request Item WWBLGN31. settlement, structural failure, basement floodings after rainfall or eventual collapse of pipes. events, Source: U.S. Environmental Protection lift station overflows, Agency (EPA). October 1991. Sewer System Infrastructure Analysis and Rehab- excessive power costs for pumping ilitation. EPA/625/6-91/030. NSFC Item stations, #WWBKDM67. overtaxing of lift station facilities, For more information or to order this perhaps resulting in frequent EPA document from the NSFC, refer to motor replacements, the list of products on page 8. Please request Item #WWBKDM67. excessive treatment costs 2 PIPELINE - Spring 1999; Vol.10, No. 2 National Small Flows Clearinghouse 1-800-624-8301 INFILTRATION AND INFLOW Gathering Information Is First Step In Fighting I/I The only way community officials can can provide guidance for dealing with reg- these maps at least accurate include and identify whether I/I or any other problems ulations regarding wastewater treatment, up-to-date information about the location exist for certain in the community’s waste- collection systems, and relevant jurisdic- and condition of the following: water collection system is by performing tional issues. a preliminary evaluation of the system, Homeowners should be interviewed as maps and/or as-built drawings followed by a thorough system-wide well. They often can provide important of all sanitary and combined inventory known as a sanitary system information about the construction or sewers, indicating their size, slope, and direction of flow; evaluation survey (SSES). condition of the service laterals leading to According to the U.S. Environmental the main sewer from their homes including the location of all treatment facilities, Protection Agency, small communities can any maintenance, additions, or repairs. pumping stations, and overflow and bypass points; successfully conduct their own SSESes and They also can report on any problems in correct many I/I problems without hiring their area with flooding of streets or base- the materials used to construct outside consultants or sewer service ments or frequent sewer backups. sewers; companies. However, if a preliminary the type of soil and bedding around investigation reveals evidence of serious Determine the Base Flow sewers; or widespread collection system problems, In addition, officials should interview local wastewater and water treatment plant the date of their construction; hiring a qualified professional who specializes in sewerage system evaluation and reha- operators, industry representatives, and the types of joints used; bilitation can be a very wise investment. homeowners to find out about local water all manholes, including those that (Refer to page 7 for information on hiring usage to calculate the base flow—the vol- may have become buried; a qualified consultant.) ume of wastewater that is supposed to be Regardless, community leaders can save collected and conveyed by the sewerage any new sewer extensions or sewer line changes; time and money by first gathering some system. Estimating the base flow is essential basic information about their sewerage for determining the amount of excess water groundwater elevations in the area system from the community. in the system due to I/I. and precipitation rates; and Water treatment plant managers maintain any storm sewers near, crossing, Interview Local Experts records of local home and industrial water or constructed in the same trenches as sanitary sewers. Community officials or wastewater con- use. These records, along with population information and a survey of industrial plant sultants conducting a collection system evaluation should begin the process by personnel, local businesses, and homeowners, Identify Likely Problem Areas will help officials develop an accurate Updating and verifying all the information questioning those in the community who picture of water use in the area and possible about a community’s wastewater collection may have firsthand knowledge of the sys- ways to reduce the burden to the system system is a huge undertaking. Therefore, tem’s condition and problems. Some of the through water conservation. (Refer to page6 the most practical course of action usually people who should be interviewed include for more information about the benefits is to first take inventory of all known and active and retired local wastewater and of water conservation.) likely problem areas so they can be taken water treatment plant managers and oper- care of as quickly as possible. ators, sewer maintenance personnel, local contractors, municipal engineers, and offi- Analyze and Update Records In addition to areas where sewer backups, All communities with collection systems flooding, or other problems have been cials who have dealt with the wastewater should maintain current and complete sewer reported, the following areas may warrant system on a regular basis. maps on file. But these records often must quick attention: For example, treatment plant operators, municipal engineers, and sewer maintenance be updated before they can be used to accu- personnel can provide information about rately assess system conditions. low-lying areas, the structure of the existing system, any However, analysis of existing sewer maps areas with poor unstable soils, inspections or maintenance that has been combined with an analysis of area records performed, and observed or reported prob- from prior collection system maintenance; areas with high groundwater, lems with the system. Retired personnel local topographical, climatological, and old sections of sewers, also should be interviewed in case they geological information; and the information collected by interviewing community officials, sewers located near or crossing know of any changes or additions to the storm sewers, and system that occurred in the past for which residents, and local professionals, usually sewers constructed near rivers, documentation may be scarce or nonexistent. will provide enough information to indicate streams, ponding areas, or swamps. Local contractors know about construction if a more in-depth SSES is warranted. practices typically followed for area homes Ideally, all of the information in the sewer and public buildings, and community officials maps should be verified. It is important that 3 PIPELINE - Spring 1999; Vol.10, No. 2 National Small Flows Clearinghouse 1-800-624-8301 INFILTRATION AND INFLOW Field Inspections Help Pinpoint I/I Once officials have analyzed all the Likewise, inspections for inflow should any jurisdictional issues, since workers preliminary data and identified likely I/I be timed to take place only during periods may need to inspect private building trouble spots in the community, the next of heavy rainfall when inflow is at its peak. connections. step is to proceed with field inspections of these sections of the sewer. This way, Flow Monitoring Dye Tests communities can combine the necessary In addition to a visual assessment of the Dye tests are useful for locating sources task of updating and verifying the sewer degree of inflow and infiltration in the sys- of inflow from storm sewers or private map information, while tackling the most tem, in some cases, it may be necessary properties. A dye test can be used to veri- urgent I/I problems first. to measure the amount of wastewater flow fy the results of a smoke test, or in place in the system over time and compare it with of a smoke test if the pipes have dips or Visual Inspections base flow estimates to determine the amount are flowing at full capacity. Internal and external visual inspections of extraneous water in the sewer system. The dyes that are used are usually fluo- should be performed first. Often major Flow monitoring may not be necessary rescent and easily detectable. They also sources of inflow can be easily identified if the sources of I/I are obvious and relatively are biodegradable and safe for the envi- simply by walking around a section easy to correct. Although it is advisable to ronment and the sewer lines. of the sewer. correct all instances of I/I to protect the From the surface, inspectors should note system, public health, and the environment, Closed-Circuit Television obvious defects to manhole covers and some communities may find flow moni- By far the most effective and high-tech frames and whether the covers fit or are toring helpful for prioritizing repairs when method of pinpointing and evaluating properly situated. They also should note funding is limited. sources of I/I is subsurface inspection conditions at stream crossings and drainage with closed-circuit television cameras. patterns in the area, the number and direc- Smoke Tests Small communities often can rent equip- tion of incoming and outgoing lines, and Smoke testing is a common, simple, and ment or hire professional collection sys- the condition of the manhole stairs and walls. inexpensive method for detecting improper tem inspectors who have this equipment. To perform an internal (subsurface) visual sewer connections and other possible sources The contractor will provide a video copy inspection, it is necessary to enter the man- of inflow. and log describing his or her observations. hole with special equipment, such as port- Smoke from a smoke bomb is released In very large sewers, the inspector may able lamps or mirrors to determine the into a section of the sewer pipe that is iso- be able to perform a manual TV inspec- condition of the sewer between two adjacent lated with pipe plugs or heavy canvas cur- tion, meaning he or she walks through the manholes. (Refer to the section about tains with weights, and then it is blown lighted section of pipe pointing the cam- safety precautions on page 6.) through the section of the line by means of era up and down the pipe walls stopping Through lamping, workers often can a motorized blower positioned over the and commenting at points of concern or assess the structural condition of the sewer manhole. Smoke testing is not appropriate interest. Otherwise, the television is line, the condition of the joints, whether if the sewer lines have sags, water traps, or pulled through the sewer line using either roots and debris are present, and the location are flowing full, because the smoke will not electric or manually operated winches. and estimated rate of infiltration. be able to properly travel through the Closed circuit television can even be lines, which may lead to false results. The used to inspect small-diameter service Timing test also will not reveal underground struc- connections from individual buildings. For the most accurate results, inspecting tural damage or leaking joints if the Sometimes light hydraulic cleaning of the sites for infiltration should be planned to ground is covered, paved, frozen, lines is required prior to inspection. correspond with periods of high ground- or saturated. Although visual inspections and smoke water, since this is when infiltration is at In addition to revealing damage to pipes and dye tests are very low-cost, closed- its peak. To identify major sources of just below the surface, smoke tests are circuit television inspection also can be a infiltration without influence of rainfall effective at indicating sources of inflow very economical choice for small commu- or added domestic or industrial flows, from inappropriate storm water connec- nities because of its accuracy in pinpoint- inspections should be performed for three tions—often on private property. ing I/I sources. consecutive days in the early morning hours Local residents, police, and fire officials For more detailed information about I/I before 6 a.m. on days when it hasn’t rained should be notified prior to smoke testing field inspection, testing procedures, SSES for the past 24 hours. Groundwater gauges and be reassured that the smoke is harm- criteria, refer to the documents listed on can be used to verify that the level of ground- less. Also, wastewater and sewer codes page 8. water is about the level of the sewers. should be reviewed in advance to settle 4 PIPELINE - Spring 1999; Vol.10, No. 2 National Small Flows Clearinghouse 1-800-624-8301 INFILTRATION AND INFLOW Communities Have Many Options For Rehabilitating Systems In some cases, identifying I/I in the sys- Types of chemical grouts used for sewer CIPP is formed by inserting a polyester tem is easier than deciding on the best way pipe repairs include acrylic-based gels, ure- or epoxy resin-filled felt tube into a pipe, to solve the problem. The solutions to such thane gel, and polyurethane foam. The which is inverted against the inner wall of problems as illegal connections from roof sewer lines must be cleaned thoroughly just the existing pipe and then allowed to cure. drains and area drains are fairly direct. prior to application of grout. A remote cutting device is used with a However, fixing old deteriorating collection closed-circuit camera to reopen service systems with a variety of I/I sources can Linings and Insertions connections. This method is practical be complicated. And sometimes, the systems Sections of pipeline often can be reha- because the resin can bridge gaps, fill cracks, with the worst problems are located in bilitated internally by sliding a slightly and maneuver around pipe defects. small communities with limited resources. smaller flexible liner pipe inside an existing Fortunately, new technologies have made pipe and then reconnecting the service line Coatings sewer line rehabilitation more affordable to the new liner. The space between the Coatings are sometimes used to extend than in the past. And when weighed against existing pipe and liner pipe may be grouted the life of an existing sewer by increasing the potential costs of I/I to the environment to provide added strength to the line. its strength and protecting it from corrosion. and to the community’s potential for growth Sliplinings for sewers can be constructed However, coatings and spray-on linings can and quality of life, I/I reduction always of polyethylene, fiberglass reinforced poly- be difficult to apply if infiltration is present. is a good investment. ester, polyrinyl chloride (PVC), or other materials resistant to thecorrosive atmos- Line Cleaning and Root Control Excavation and Replacement phere in the collection system. They may be Debris, grease, and root intrusion in sewer Digging up and replacing old deteriorat- inserted as a single flexible continuous lines can obstruct visual or video inspection ing sections of sewer line used to be one pipe or in short sections that can be jointed and reduce the effectiveness of rehabilita- of the only solutions available for stopping to form a continuous lining. tion methods. I/I. Today, this method is reserved only In another method, called fold and formed Small communities can rent or contract for cases in which the structural integrity or “deformed” pipe lining, folded or de- professional line cleaning services using of the pipe is severely degraded, the pipe formed pipe is pulled through the line high-velocity water machines and other is seriously misaligned, or when other between two access points, then the pipe hydraulically propelled devices. rehabilitation methods would be too expen- is heated, pressurized, and expanded or Roots also can be removed using an sive to be worth the effort. rerounded in the sewer to form a tight fit. EPA-approved chemical foam that is safe The cost-effectiveness of new trenchless Two other methods that involve the for the environment and won’t harm the or in-place rehabilitation technologies insertion of liners or pipes internally into rest of the plant above. have eliminated the need to excavate and existing sewers include spiral-wound replace sewer lines in many cases. The installation and cured-in-place pipe. With new technologies also are less disruptive spiral-wound installation, the wall pipe is to traffic patterns and utility services. fabricated at the bottom of a manhole or access shaft and is pulled through a winding Chemical or Cement Grouting machine with rollers to form a circular pipe. One less disruptive rehabilitation method The pipe may be expanded outward for a is cement or chemical grouting, which better fit or it can remain a fixed diameter. sometimes can be used to rehabilitate Cured-in-place pipe (CIPP), also some- sewer lines externally by excavating adjacent times referred to as inversion lining, is a to the pipe. Internal chemical grouting is popular and practical method for correcting a common technique communities use to I/I and rehabilitating rehabilitate leaking joints, manhole walls, pipes that need and minor cracks in nonpressurized pipelines. minor structural Chemical grouting is not a good option reinforcement. It is if the cracks in the pipe are large or affect also safer than some the structural integrity of the pipe—longi- other rehabilitation tudinal cracks, for example. Grouting does methods and not improve or reinforce the structural quicker to install. integrity of the pipes, and large joints and cracks and misaligned pipe may be impos- sible to seal or may require excessive amounts of grout. 5 PIPELINE - Spring 1999; Vol.10, No. 2 National Small Flows Clearinghouse 1-800-624-8301 INFILTRATION AND INFLOW Fixing Manholes Also Reduces I/I Sewer Workers Must Receive Safety Training Old, degraded, or leaky manhole struc- high density polyethylene, spiral-wound It is extremely tures often are a major source of I/I in liner, and cured-in-place structural manhole important that waste- communities. In areas with temperature liners. water system workers variations, movement of the surrounding In addition, unwanted inflow can enter receive comprehen- soil and the expansion and contraction of manholes through ill-fitting covers and sive training on safe- the surrounding pavement can cause struc- leaky frames. Surface water often can enter ty procedures for tural damage to the manhole frame seal, through holes in the cover or through the inspecting and rehabilitating collection chimney, or cone. space between the cover and the frame. systems. Some common hazards sewer Many of the options for reducing I/I Leaky manhole covers can be replaced with workers encounter include through manholes are similar to the options new watertight covers, or they can be fixed slips and falls on damp, available for rehabilitating sewer lines. For with rubber gaskets or by installing hole plugs icy, or slimy walls or falls example, chemical grouting or sealing is a or watertight inserts under the existing from corroded steps or cost-effective option that doesn’t add to the covers. structures that give way, structural integrity of the manhole. The Manhole frame-chimney joint area and injuries associated with confined spaces, In addition, cement coatings and chem- sometimes also can be sealed without excava- such as cave-ins, asphyxiation from gases ical patching compounds have been used to tion, or during excavation when the frame trapped in the system, or explosions from coat systems to reduce flow. They can be is being reconstructed or replaced. The seal methane, propane, gasoline, or other gases applied by machine or by hand. is achieved by installing a flexible material that find their way into the sewer. Like sewer pipes, manholes can be or manufactured seal to either the surface Safety precautions also must include structurally rehabilitated with the use of of the chimney or the frame. However, as training on proper sanitary practices to linings. Poured-in-place concrete linings, for is sometimes the case with sewer pipes, avoid contracting or spreading illness from example, have been used effectively. Other occasionally structural damage is so exten- pathogens present in wastewater or from choices include placed PVC rib-lock liners, sive that rehabilitation of manholes is not animals or insects in the sewers. Traffic prefabricated reinforced plastic mortar or a practical option and excavation and hazards, electrocution, and drowning are fiberglass reinforced plastic, prefabricated replacement is necessary. other risks that can be reduced through proper safety training. Residents Can Help By Conserving Water Sometimes an ounce of prevention can for the good of the community and to save be worth gallons and gallons of reduced on water bills can be well-worth the invest- wastewater flows. ment. One of the most effective ways commu- In addition, plumbing codes can be nities can reduce I/I and the costs associated changed to ensure that new homes and with it is by simply conserving water. buildings include water-efficient fixtures. Community leaders faced with costly col- Communities also may want to urge high- lection system repairs should consider volume industrial and commercial users identifying high volume water users in the in the community to implement a water community and adding a public education conservation program. component to their rehabilitation program For more detailed information on water focusing on water conservation. conservation and implementing a public education program, readers can contact Encourage the Use of Low-Flow Fixtures the NSFC to request a free copy of the In households without low-flow fix - Winter 1998 issue of the newsletter On tures, up to 75 percent of water is used to Tap, published by the National Drinking flush toilets and take showers. Apublic Water Clearinghouse. Please request Item education program encouraging residents ONTAP27. to replace old fixtures with low-flow models 6 PIPELINE - Spring 1999; Vol.10, No. 2 National Small Flows Clearinghouse 1-800-624-8301 INFILTRATION AND INFLOW Small Community Sewer Rehabilitation Project Reduces I/I in Alaska By Colleen Mackne High levels of I/I were causing hydraulic From the sewer system evaluation survey, overloading of the Cordova Wastewater the actual sources of I/I were identified Treatment Plant in Cordova, Alaska. This led to operational problems, resulting in National Pollutant Discharge Elimination using smoke testing, manhole inspection, and closed-circuit television inspection of pipelines. Smoke testing detected illegal CONTACTS System (NPDES) permit violations. storm drain connections suspected of being The National Small Flows Located in the southern maritime area major contributors to the city’s inflow Clearinghouse (NSFC) of Alaska, Cordova receives 168 inches problem. Manhole inspection indicated The NSFC offers technical assistance and free of rainfall each year. During heavy pre- that 73 percent of all manholes had structural and low-cost information about small community cipitation, the treatment plant often expe- problems. Seventy-one manholes had active wastewater technologies and issues, including rienced flows of more than 2.5 million infiltration, while 62 manholes were subject wastewater collection systems and I/I. Only a gallons per day (mgd). In addition, the to inflow. During closed-circuit television few of the NSFC's many resources and services underlying soils in Cordova are comprised inspection of the laterals, 44,172 feet of are listed in this issue. For a complete listing, mostly of bedrock, which tends to produce Cordova sewer mains were monitored, contact the NSFC at (800) 624-8301 or (304) high surface runoff. Portions of the city’s and a total of 182 defects were found. 293-4191 to request a free catalog, or visit the collection system are located in the tidal Seventy-one of them were located on pri- NSFC's Web site at www.nsfc.wvu.edu. flats of Orca Inlet and thus, are subject vate properties in the upper lateral sections. to seawater infiltration. Ultimately, the city implemented a program Local and State Health Agencies Originally built in 1948, Cordova’s col- to encourage homeowners to repair laterals. Community officials should contact their local and lection system includes 50,750 feet of gravity The cost of reducing I/I was compared state health agencies for assistance when plan- sewers and five pump stations. Seperate to the cost of constructing additional col- ning collectionsystem inspection and rehabilitation. sanitary and stormwater sewer systems lection and treatment facilities for peak I/I. State and local health agencies are listed in the exist but combine prior to arrival at the It was estimated that upgrading the collec- blue pages of local phone directories. wastewater treatment plant. I/I from parts tion system, pump station, and treatment of the storm drain systems are a major source plant would cost approximately $12.6 Rural Water Association (RWA) of flow to the wastewater treatment plant. million. However, the cost for rehabilitating Communities who wish to perform a smoke test A collection system rehabilitation proj- the collection system and reducing I/I was to determine if they have cracks or defective joints ect was initiated, which led to a 70 percent estimated at $4.2 million. Therefore, cor- in their sewer lines can contact their state Rural reduction in I/I. Starting with a sewer sys- recting the I/I problem in six of the eight Water Association (RWA) for advice on where to basins was the most feasible option. purchase or rent the equipment needed.State RWAs tem evaluation plan to analyze the problem, provide a variety of other services that can help the city’s collection system was divided During the rehabilitation project, 11,000 communities with collection systems. For the into eight sewer drainage basins.A monitor- feet of sewer main were sliplined, 3,000 number of your state R WA, contact the NSFC ing plan was designed to identify key mans feet were replaced, and 30,000 feet were or call their national office at (580) 252-0629. basins. In addition, several manholes were rehabilitated by chemical grouting and point visually inspected to identify possible repairs. In addition, the project included National Association of Sewer sources of I/I. rehabilitating 255 manholes, inspecting Service Companies (NASSCO) There was a significant amount of ground- 21,000 feet of sewer service lateral pipe, NASSCO is an association of the leading water infiltration in six of the eight basins, performing 111 repairs on lower laterals, providers of products and services to sewer col- ranging from 1.4 to 3.8 times the sanitary installing 370 feet of new storm sewers, lection system owners in North America. They flow rate. This indicated that there were and removing storm pipe connections. publish three importantreference works on col- many system defects below the ground- The total cost of the project came to lection systems that would be very helpful to any water table. $4.4 million. community planning to evaluate or rehabilitate To measure the effect of I/I on Cordova’s After rehabilitation was complete, the actual their system. The three works are NASSCO’s collection and treatment systems, a capacity percentage of I/I reduction was determined Specification Guidelines for Sewer Collection analysis was performed on the trunk sewers, by comparing I/I after rehabilitation to I/I System Maintenance & Rehabilitation, the Manual pump stations, and the treatment plant. This that was measured during the flow moni- of Practices for Wastewater Collection Systems, analysis evaluated the type and cost of toring stage. Wastewater flows and rainfall and The Inspector Handbook for Sewer Collection facility improvements necessary to transport, values were also used for comparison. A System Rehabilitation. Contact NASSCO head- treat, and dispose of peak wet-weather flows. 70 percent reduction in I/I was achieved. quarters at (717) 264-5756 for information. 7 PIPELINE - Spring 1999; Vol.10, No. 2 National Small Flows Clearinghouse 1-800-624-8301 RESOURCES AVAILABLE FROM NSFC SPRAY & DRIP IRRIGATION To order products listed as available from Customized Bibliographic Database More Information Is Available the National Small Flows Clearinghouse Search The NSFC also offers a variety of products (NSFC), call (800) 624-8301 or (304) The NSFC’s Bibliographic Database is a on other subjects related to I/I, such as 293-4191, fax (304) 293-3161, e-mail collection of thousands of articles dealing combined sewer overflows (CSOs). For a firstname.lastname@example.org, or write with onsite and small community waste- complete listing, contact the NSFC to receive NSFC, West Virginia University, P.O. Box water collection, treatment, and disposal a free catalog. Request Item #WWCAT. 6064, Morgantown, WV 26506-6064. systems and related topics. Customers can Please request each item by number and request a search on infiltration or another PIPELINE title. A shipping and handling charge will topic and receive the latest literature on the apply. subject. Call the NSFC and ask to speak Inflow/Infiltration: A Guide for with a technical assistance specialist to Decision Makers request a customized search. The cost is 15 an equal opportunity/affirmative action institution This guide for local officials explains how to cents per page. Request Item #WWPCM12. Pipeline is published quarterly by the National Small Flows Clearinghouse at West Virginia University, evaluate inflow/infiltration (I/I) problems and P.O. Box 6064, Morgantown, WV 26506-6064 includes methods for identifying their source Manufacturers and Consultants Database Search Pipeline is sponsored by: and location. Safety procedures for collection U.S. Environmental Protection Agency system workers are included. This guide is The NSFC Manufacturers and Consultants Washington D.C. Steve Hogye—Project Officer particularly helpful for small com munities Database houses a list of industry contacts Municipal Support Division dealing with I/I problems. The price is $6.05. for wastewater products and consulting Office of Wastewater Management Request Item #WWBLGN31. services. This database serves as a reference National Small Flows Clearinghouse for engineers, private citizens, and com- West Virginia University Sewer System Infrastructure Analysis munity officials, and a referral database Morgantown,WV 26506-6064 Peter Casey—Program Coordinator and Rehabilitation for wastewater products and trade items. Jennifer Hause—Special Technical Advisor This 96-page handbook provides guidance Cathleen Falvey—Writer/Editor Customers can receive a list of people to Michelle Sanders—Graphic Designer to engineers and public decision makers on contact regarding sewer inspections and the evaluation and rehabilitation of existing Permission to quote from or reproduce articles in repairs, leak detection equipment, liners this publication is granted when due acknowledgement sewers. It presents information about typical and impermeable barriers, or other related is given. Please send a copy of the publication in problems, procedures, and methods for re- which information was used to the Pipeline editor at products and services. Call the NSFC and the address above. habilitation, as well as case studies and infor- ask to speak with a technical assistance mation on costs, the application and advantages specialist to request a customized search. ISSN 1060-0043 Pipeline is funded by the United States Environmental Protection and disadvantages of rehabilitation tech- The cost is 15 cents per page. Request Agency (EPA). The contents of this newsletter do not necessarily reflect the views and policies of the EPA, nor does the mention of trade names niques, and materials used in rehabilitation. Item #WWPCCM16. or commercial products constitute This free book could be useful to engineers, endorsement or recommendation for use. local officials, operators, contractors /developers, Printed on recycled paper and planners. Request Item #WWBKDM67. For wa s te wa ter information, call the NSFC at (800) 624-8301 or (304) 293-4191 8 PIPELINE - Winter 1999; Vol.10, No. 1 National Small Flows Clearinghouse 1-800-624-8301
"INFILTRATION AND INFLOW CAN BE COSTLY FOR COMMUNITIES"