INFILTRATION AND INFLOW CAN BE COSTLY FOR COMMUNITIES

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					                                                 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communities rely on outdated combined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

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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




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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
  nsfc_orders@estd.wvu.edu, 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

				
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