Memorandum

City of Lawrence

Public Works

 

TO:

David P. Cronin, P.E., City Engineer

FROM:

Steven M. Lashley, P.E., Project Engineer – Infrastructure Management

CC:

Mark Thiel, Assistant Director of Public Works – Infrastructure Management

Charles F. Soules, P.E., Director of Public Works

Date:

August 15, 2013

RE:

Project No. PW1318 – 2013 Microsurfacing Program Update – City Manager’s Report

 

Please include the following item on the City Manager’s Report for the August 20, 2013 City Commission Meeting:

 

Project Description and Details.  The microsurfacing (surface sealing) project included a number of City residential and collector streets including streets generally bordered by Kasold Dr to Wakarusa Dr and W 6th St to Bob Billings Pkwy (see attached location map).  Streets that received microsurfacing were determined to be in generally good condition.  These streets were included with the microsurfacing planned process as a preventative maintenance work activity to preserve the streets while also addressing some structural deficiencies to prolong pavement life cycle and effectively sustain the infrastructure assets.  City streets that are deteriorated beyond the recommended condition for microsurfacing will be typically included in the maintenance plan for milling and overlay.

 

Project History and Funding.  The City’s annual pavement maintenance program was reviewed and approved by the City Commission on January 15, 2013. The pavement maintenance program is funded from several sources including the general fund, gas tax funds, sales tax and sales tax reserve, and capital improvement reserve accounts.  Funding for the program was approved in August, 2012 and adopted in the 2013 City Budget.  This project was included in the 2013 Pavement Maintenance Program for microsurfacing to be paid from the general fund.

 

Current Project Status and Additional Information.  All patching and microsurfacing operations have been completed, reviewed, and accepted by City Public Works staff.  Reestablishment of pavement markings was completed on August 14, 2013 which is also the final acceptance date starting the one year warranty period.

 

This project included preparation of the street asphalt pavements by performing partial depth and full depth patching of deteriorated areas followed by the microsurfacing of the entire pavement surface.  The microsurfacing material is a mixture composed of asphalt emulsion, cement, water, and crushed rock aggregates and applied as an approximate 3/8” thick slurry.  The material will tend to have a rougher appearance than that of a 2” mill and overlay finished surface.  Since the microsurfacing material is asphaltic and malleable, over time and with vehicular traffic, the surface seal material will tend to be kneaded including the smoothing out of surface imperfections.  For further information on other maintenance program information and microsurfacing, please see the attached “Guide to Street Maintenance in Lawrence” or visit the International Slurry Surfacing Association (ISSA) website for a more detailed look at “What is Microsurfacing?”

 

Prior to acceptance of the surface seal and during the review process, several unacceptable impacts to the surface were found which mainly included premature damage by vehicles.  For example, the higher frequency of damaged locations were typically as a result of drivers of vehicles performing aggressive u-turns at or near temporary road closures and not utilizing detour routes, bypassing designated road closure barricades, and/or turning around at driveway locations with hard power steering turning maneuvers while the material was still susceptible to greater damage.  Power steering marks in surface seal are not uncommon.

 

The City’s project inspector, a general contractor representative for Bettis Asphalt (asphalt patching), and a subcontractor representative for Vance Brothers (microsurfacing) performed a project walk through and review on August 6th/7th.  As part of this review process, all areas that were deemed unacceptable were designated for additional patch work.  The minor patch work was performed by hand application and by a crew that followed the project walk through representatives.  Areas of heavy impact, like Folks Rd just south of 6th St, the microsurfacing material was reapplied again by machine spread application.  The unacceptable issues, as designated by the walk through, were resolved as part of our review process.

 

Some pictures of damaged, patched, and completed locations are attached.