Memorandum

City of Lawrence

Utilities Department

TO:	David L. Corliss – City Manager Cynthia Boecker - Assistant City Manager Diane Stoddard - Assistant City Manager
FROM:	Philip Ciesielski – Assistant Director of Utilities
CC:	Dave Wagner – Director of Utilities Mike Lawless – Assistant Director of Utilities Beth Frailey Krishtalka – Management Analyst
Date:	October 29, 2009
RE:	November 3, 2009 Agenda Item – Status Update on Department of Utilities Watermain Condition Assessment and Prioritization

In December 2008 the Department of Utilities initiated an internal program focused on a comprehensive assessment of the completeness and quality of the GIS mapping and attribute data for the water distribution system. To date nearly 800 required changes and additions to the water distribution system information have been identified and 3,900 GPS shots have been taken in support of these identified changes. At this time approximately 40% of the 423 miles of existing watermain have been reviewed and corrected as necessary including accurate location via GPS. Initial efforts were focused on North and East Lawrence as these represent some of the oldest infrastructure and were known to have the highest percentage of inaccurate or null data.

Along with the water distribution mapping information staff have retrieved and mapped available watermain break records for 672 breaks occurring during the period 1998 – 2006. Additional data for 2007 to current is being processed and mapped along with available water quality and customer complaint data.

Data on the area soils and their corrosion potential has been obtained from the National Resources Conservation Service (NRCS) and mapped. Along with this data narrative information regarding the NRCS’s method for soil survey and corrosion analysis is being reviewed to determine the applicability of the data and the resulting corrosion index to the various watermain pipe materials.

Additional information to be mapped and utilized in the coordination and prioritization of watermain replacement and rehabilitation projects is Public Works proposed street and sidewalk repair and reconstruction schedules; other sanitary sewer or watermain projects adjacent to a given watermain; known County, KDOT and KTA projects and other City Department projects that have been proposed.

Observations from current mapping and data analysis (map attached):

60% of the existing water distribution system has been installed since 1980

61% of the recorded breaks have occurred on Cast Iron Pipe

25% of the existing system is constructed of Cast Iron Pipe

51% of the system is constructed of PVC pipe

16% of the system is constructed of Ductile Iron

20% of the 672 recorded breaks have had the related watermain replaced

43% of the recorded breaks are attributed to corrosion (soil condition)

37% of the recorded breaks are attributed to differential settlement (construction/bedding method)

As another part of the watermain condition assessment project Staff are currently preparing an RFP for services related to the in situ condition assessment of the 12.6 miles of large diameter concrete raw water and finished water transmission mains. This assessment is to be completed in early 2010. These mains were constructed during the 1950’s and late 1970’s. While they have traditionally been reliable structures, the critical nature of their use to convey raw water to the Clinton WTP as well as move large quantities of treated water from both the Clinton and Kaw WTPs makes the accurate assessment of their existing condition and expected remaining service life a high priority within the Department’s work plan.

The continued project work plan includes the completion of the distribution system data verification and correction; mapping of the additional watermain break, water quality and customer complaint data; evaluation of the mapped main break data for items such as break frequency per foot of watermain; time since last break; relationship of break timing, break type, watermain material, date of installation, and soil type. Staff anticipate completing the mapping and presenting an initial analysis in early 2010.