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Inflow Source Identification Program

The summer of 1999 marked the sixth successful year of the High School Inflow Source Identification Program established by Louisville and Jefferson County Metropolitan Sewer District (MSD). High school students were used to assist MSD in investigations of the sources of wet weather sewer problems. This program represents a public/private partnership between MSD, Waggener High School, the Louisville Education Employment Partnership (LEEP), Jefferson County Public Schools (JCPS) and several consultants including PDR Engineers, Inc.

This 1999 program consisted of downspout testing, smoke testing, sump pump testing, and CSO-area testing.

Downspout and Sump Pump Investigation
The 1999 investigation concentrated in several areas:

  1. Cardinal Hill PS
  2. East Rockford PS
  3. Falgate Court
  4. Garrs Lane PS
  5. Hazelwood PS
  6. Melody Lane PS
  7. Murray Heights PS
  8. Savage, Pioneer, and Fern Lea PS's
  9. Sonne PS

Each area is associated with a potential pump site or documented sanitary sewer overflow (SSO). In each separate sewer area, the collection system upstream of the MSD Facility was investigated.

In the course of the 1999 downspout program, crews canvassed approximately 3,400 homes during 4 weeks of the program. This can be translated into about 212 homes per crew day (canvassing 2 days per week). The identification of connected downspouts the last four years has remained significantly low when compared to the first two years of testing. The results can be found in Table E.1 and the areas tested are expressed graphically in Figure E.1.

Table E.1 Downspout and Sump Pump Canvassing 1999

Item Number Fraction
Originally canvassed 3384 ---
Total responses 585 17%
Crew inspection 84 42% of homes w/ sump pumps
Self inspection 83 14% of respondents
Positive tests 20 10% of homes w/ sump pumps
Sump pumps did not allow test and no self-test 32 16% of homes w/ sump pumps
Total sump pumps 199 34% of respondents
Connected downspouts 0 ---

Smoke Testing
Smoke testing using students and MSD's I&I field technicians was part of the program again this year, and the partnership proved to be very effective. The weather for the 1999 smoke testing investigation could not have been better - only one significant rain event occurred in late June. The lack of moisture created optimum ground conditions for allowing smoke to escape through leaks in the pipe.

Smoke testing crews focused on nine areas;

  • Falgate Court
  • Garrs Lane PS
  • Savage Lane PS (including Fern Lea PS and Pioneer PS)
  • East Rockford PS
  • Murray Heights PS
  • Hazelwood PS
  • Melody Lane PS
  • Cardinal Hill PS.

Crews were able to smoke test for approximately six weeks (nearly the entire duration of the program). Due to the lack of time, Sonne Lane PS was not tested. It is recommended that this be completed in the 2000 program. Two crews tested more than 33 miles (174,200 LF) of mainline pipe in streets and easements. The crews smoked a total of 22 days. Production rates can be translated into about 8000 LF of sewer main per crew day. There were 891 pipe sections with a total of 80 leaks in the 33 miles of mainline pipe.

This data was compiled electronically in an Access database. The Microsoft Access database structure that was created for this project will allow data migration to MSD's Infrastructure Management System (IMS). The results of smoke testing are shown in Table E.2.

Table E.2 Smoke Testing 1999

Item Number
Total pipe sections tested 891
Total pipe length tested 174,200 linear feet
Total number of defects identified 80

CSO Area
Several houses in a CSO area just southwest of Cherokee Park (east of downtown Louisville) were canvassed and downspouts and/or toilets were dye-water tested. This area has combined sanitary and storm lines as well as separate sanitary lines. Testing was initiated to determine downspout and toilet discharge locations. Results from dye tests indicate that downspouts and toilets were connected correctly in this area. Figure E.1shows the location of this area.

During the 1999 program, students identified sump pump inflow sources that could theoretically contribute a peak 800,000 GPD*. This figure does not include an estimate of smoke defect contributions, which would have a significant impact.

Continued identification of connected downspouts & sump pumps coupled with elimination of illicit connections with help from the Private Property Program will reduce treatment costs and help eliminate SSOs throughout the county. The success of the smoke testing and home sump pump verification can continue in similar areas to sustain this workforce concept in the future.

Potential Projects

  1. Private Source Disconnect Policy/Program Manual - Actual Field Experiences will provide insight into the ongoing Private Property Disconnection Study.
  2. Sump Pump Testing - The priority areas as identified in SSO Sections of the MS4 Report are likely areas for future sump pump testing.
  3. Downspout Testing - Continue program to close out entire county
  4. Smoke Testing - Priority areas as identified in SSO Sections of the MS4 Report
  5. Consider revisiting areas covered in the past for the purpose of Q/A and to determine the effectiveness of rehabilitation.
  6. CSO Testing - Should be initiated as needed and provide assistance with sewer separation projects (coordinate with CSO Engineer).

These areas could be canvassed in a manner similar to this year's student program. The program could be expanded to a year-round after-school student program to take advantage of homeowners' schedules by canvassing and testing in evening hours, and to expand on school-to-work educational concept.

* This figure is based on two assumptions; 1) 20 GPM per sump pump; 2) 1 in 4 sump pumps is running at any given time during the wet weather period.

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Last Updated: March 11, 2016

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