Memorandum

City of Lawrence

Utilities Department

TO:	David L. Corliss – City Manager Cynthia Wagner - Assistant City Manager Diane Stoddard - Assistant City Manager
FROM:	John Shutak – Utilities Engineer
CC:	Dave Wagner – Director of Utilities Philip Ciesielski – Asst. Director of Utilities Mike Lawless – Asst. Director of Utilities Beth Krishtalka – Assistant to Director Mark Hegeman – Utilities Operations Superintendent Dave King – Utilities Maintenance Superintendent
Date:	January 9, 2013
RE:	January 15, 2013 Agenda Item – Approve Change Order No. 2 for priority group I of Project UT0919CS General Wastewater Pumping Station Improvements.

Please include the following item on the City Commission Agenda for consideration at the January 15, 2013 meeting:

Authorize the City Manager to execute Change Order No. 2 to the construction contract with EmCon Inc. for priority group I of Project UT0919CS General Wastewater Pumping Station Improvements increasing the contract amount by $41,094.75 and contract time by 63 calendar days.

Project Description:

The Department of Utilities budgets a yearly fund for the ongoing maintenance, repair, and, when necessary, replacement of existing wastewater pumping stations within the collection system.

Project Details:

The Department of Utilities operates a number of small (80 to 300 gpm) vac-prime wastewater lift stations to convey sewage to its wastewater treatment plant. These lift stations were installed by the development community to provide service to localized areas of development. The lift stations are typically located in utility easements adjacent to or surrounded by residential property. The existing stations are 15 to 40 years old, many have exceeded their useful lives, are unsafe to maintain as several of the lift stations are classified as confined space entry, many are no longer supported by the original manufacturer and require replacement to bring them up to current KDHE minimum design standards.

The general intent of the project is to replace a number of the existing vac-prime lift stations with rail-mounted submersible pumps, valve vault, overflow prevention, backup power connection and flow metering in order to meet current KDHE minimum design standards. Some modifications to the existing gravity lines upstream of each station may be required. The Department of Utilities will provide wet well level instrumentation, programmable logic controllers and programming. The vac-prime lift stations included in Priority Group I of the General Wastewater Pumping Station Improvements are identified on the attached map.

Project Status:

To date the contractor, EmCon Inc., has completed construction of the improvements per the project plans and specifications for pump stations 35 and 37. Remaining work includes only the decommissioning of the existing pump station 37 and the adjustment of an existing manhole on the south side of Pikes Peek Place.

The improvements related to pump station 35 included the installation of an additional 320 lineal feet of gravity sanitary sewer line between the residences located at 506 and 502 Sandpiper Court, from new MH 35-1 to existing manhole SW241219-041 on the south side of Pikes Peek Place, as shown on the attached exhibit. The construction documents identified this line to be installed by Horizontal Directional Drilling (HDD) to avoid removal of trees and landscaping and to minimize the extent of surface disruption to resident’s property.

On April 18, 2012 M&D Excavating, a subcontractor to EmCon Inc., began the HDD work to install the gravity sanitary sewer from proposed MH 35-1 to the existing manhole SW241219-041 on Pikes Peek Place. The initial installation of the sewer line was completed and the City completed pre-acceptance video inspection of the line on April 30, 2012. The inspection showed the line to contain unacceptable low spots or “sags” at various locations between plan station 10+75 and 11+75.

Subcontractor M&D Excavating made repeated attempts to correct the installation issues throughout the months of May and June of 2012. Corrective efforts included repeated back-reaming of the original drill path, re-installation of the PVC gravity sewer piping, and video inspection to assess the effectiveness of the corrective effort. M&D Excavating also obtained new sonde and locating equipment as part of this process to establish a greater level of precision during the back-reaming operation. These efforts failed to adequately correct the sags noted between plan stations 10+75 and 11+75 during the original pre-acceptance video inspection. As a final attempt to correct the installation issues, a 16” casing pipe was pushed through the original bore path with the intent of “straightening” the bored hole. This corrective action also failed to correct the sags noted between plan stations 10+75 and 11+75 during the original pre-acceptance video inspection.

During discussions between City staff, the design engineer, and the general contractor it was generally agreed that repetitive failures of the corrective actions taken by M&D were most likely to have been caused by either a change in the subsurface geology or the presence of debris as either of these would deflect the drilling and reaming equipment. Boring logs had been taken throughout the project area prior to construction to establish soil types and the presence of rock and/or groundwater. Boring logs indicated only the presence of topsoil and clay materials within the elevation range of the gravity sanitary sewer to be installed, thus effectively eliminating a change in subsurface geology as a cause of the failure. To ascertain if debris might be located within this area, City staff contacted the Kansas Department of Health and Environment (KDHE) to determine if any of the property in the area had been previously designated as a landfill. KDHE confirmed that the development known as Pike’s Peek Place Addition had been formerly classified as a construction/demolition landfill, owned and operated by W.A. Dunbar and Son under Bureau of Waste Management permit No. 0536. Presence of the construction/demolition landfill was not indicated on documents obtained and reviewed during the design phase of the project.

Based on the likely presence of debris from the former landfill site impacting the alignment of the directional bore, City staff authorized a change in construction method from HDD to open trench. The general contractor was directed to negotiate with, and secure property access rights from, property owners adjacent to the proposed sanitary sewer line. Once access agreements had been finalized, the contractor installed the gravity sanitary sewer line utilizing open trench methods. Installation and restorative efforts were completed within 9 calendar days from the start date of the installation.

Change Order No. 2 includes additional contractor costs for property access rights, open cut installation, and surface restoration associated with the installation of the gravity sanitary sewer line from manhole MH 35-1 to existing manhole MH241219-041 in the amount of $39,114.74 and an additional 63 calendar days for the delay caused by the unforeseen condition. Change Order No. 2 also includes additional costs in the amount $1,980.01 associated with the replacement of the top section of an existing manhole on the south side of Pikes Peek Place. Adjustment of this manhole is necessary to match the existing grade as shown on the attached photos.

Construction Contract Costs:

	Cost	Days
Original Contract	$1,105,954.60	150
Change Order 1	$54,474.80	0
Change Order 2	41,094.75	63
Current Contract Total	$1,201,524.15	213

To date change order adjustments represent 8.6% of the original contract amount.

Project Funding:

These projects are funded out of the 2009 Department of Utilities bonded construction fund per resolution No. 6835. A total allocation of $2,846,000.00 has been identified for completion of the design and construction of the General Wastewater Pumping Station Improvements, Project UT0919CS, through the bond resolution. Expenditures in excess of the available 2009 bond funding are funded from the Department of Utilities non-bonded construction fund.

Action Request:

Thank you for your assistance. Please advise if you have any questions.