AGENDA #2a
BUDGET WORKING PAPER
TO: W. Calvin Horton, Town Manger
FROM: George Small, P.E., Director of Engineering
SUBJECT: Discussion on Vac-truck and Operator for the Stormwater Management Program
DATE: April 27, 2005
The Town Stormwater Management Program is recommending in its FY2005-06 budget the purchase of a vac-truck and hiring of an operator for the truck. This recommendation was developed following consultation with Engineering Department and Public Works Department staff regarding equipment necessary to support a comprehensive drainage system maintenance program. The vac-truck and driver were included in the development and implementation recommendations presented to the Council when the Stormwater Management Utility was established last year.
The Town is responsible for inspecting and maintaining public drainage infrastructure including curb and yard inlets, culverts and drain pipes, catch basins, curb and gutter, ditches, and other stormwater management facilities.
Maintenance of the community drainage infrastructure is performed by Public Works Department staff. The Town does not have efficient and effective equipment to clean debris and sediment from pipes, catch basins, junction boxes and/or similar facilities. In the past, we have used a pressure washer or fire hose to flush out blockages from pipes and catch basins. Typically, this method is only partially successful in removing sediment and debris blockages. Also, it is no longer acceptable practice to flush silt and other pollutants out of pipes and into streams, ditches, or ponds. Much of the silt and debris in storm drain pipes and catch basins is highly polluted from roadway runoff that carries oils, metals, hydrocarbon materials and other pollutants.
The Town is obligated to maintain the functional capability of its storm drainage systems, and is further obligated as a part of its NPDES Phase II permit requirements to reduce pollution resulting from stormwater runoff. The N.C. Division of Water Quality has noted that most of the Town’s streams are impacted and/or impaired to some degree, primarily due to sediment loading. A portion of the sediment in the Town’s streams is flushed out of storm drain pipes during heavy rain events when flow velocities in the system increase such that previously deposited sediment is scoured out of pipes and catch basins. One objective of routine maintenance of the storm drain system is to keep drainage facilities free of deposited sediment so that it does not wash out into streams and ponds during storm events.
Another stormwater management objective is to minimize flooding and flood-related damage. Many flooding events in Chapel Hill are localized and result from clogged or partially clogged drainage facilities. A comprehensive preventive maintenance program including removal of sediment and other accumulated materials in drainage facilities and pipes would maximize the capability of existing facilities to convey stormwater runoff and would minimize flooding potential.
A vac-truck combines a water flushing system (to loosen and transport sediment and debris) with a vacuum system (to collect the sediment and debris loosened by the flusher). Use of a vac-truck is the only effective way to clean stormdrain infrastructure without transferring polluted materials downstream. We believe that the Town must acquire a vac-truck in order to implement a comprehensive routine and preventive maintenance program for the community storm drain system. Once the drainage infrastructure is cleaned and kept clean, we would expect to see a reduction in sediment/pollution loading in many of our smaller streams.
A vac-truck typically requires a 2-man crew for efficient operation. We propose hiring one new employee and training one existing Public Works staff member to crew the vac-truck. Without hiring at least one new employee, existing Public Works staff would be unable to fully utilize the vac-truck as necessary to implement the comprehensive drainage system maintenance program that we are proposing.
We estimate that the annual cost to purchase and operate a vac-truck is $80,000 including disposal fees for polluted materials that we would expect to encounter in some instances. Funding for a vac-truck and crew are included in the proposed Stormwater Management Program budget for FY 2005-06. The vac-truck and would be included in the Town’s fleet purchase program schedule which generally provides for equipment order and delivery turnaround in a nine-month period. The vac-truck and new staff member would likely enter Town service sometime in the spring of 2006.