Memorandum

City of Lawrence

Utilities Department

TO:	David L. Corliss – City Manager Cynthia Wagner – Assistant City Manager Diane Stoddard – Assistant City Manager
FROM:	Leah Morris – Project Engineer
CC:	Dave Wagner – Director of Utilities Mike Lawless – Deputy Director of Utilities Philip Ciesielski – Assistant Director of Utilities Beth Krishtalka – Assistant to the Director Bob Brower – Utilities Operations Superintendent
DATE:	May 13, 2014
RE:	Agenda Item – Project UT1205, Contract 1 - South Lawrence Trafficway 24” Sanitary Sewer Relocation, Approve Request For Change #014

Background

The South Lawrence Trafficway is currently under construction by Emery Sapp & Sons the general contractor for the Kansas Department of Transportation.

Required watermain and sanitary sewer relocations in the area of 31^st and Haskell were designed and bid as part of the KDOT SLT project due to the required construction sequencing in this area. The construction of these relocations will be paid for by the City of Lawrence.

The sanitary sewer and watermain relocations in the area of 31^st and Louisiana have been included into the KDOT Project No. K-8392-04 South Lawrence Trafficway plans by the execution of the City – State Supplemental Agreement No. 1. City Commission approved the execution of the City – State Supplemental Agreement No. 1 with KDOT during the March 25^th, 2014 City Commission meeting. The construction of these relocations will be paid for by the City.

Project Status

In the process of construction of the relocated 24” gravity sanitary sewer located southwest of 31^st and Louisiana (see attached map), an unforeseen geotechnical condition was encountered. During the excavation for the sewer, a perched water table was encountered near the flow line of the proposed sewer. This perched water table changed the soil conditions enough that the typical means and methods of sewer installation weren’t possible. The method of installation that is acceptable to stabilize the pipe in these conditions includes removing 5-7 feet of unsuitable material and replacing it with a bed of graded shot rock then followed by the City’s standard pipe embedment material. The bed of graded shot rock is averaging 6 feet deep and 6 feet wide and consists of rocks as large as 24” in diameter being placed at the bottom. This process is described in the attached letter from ESS. The installed sewer is being monitored daily by Utilities inspection staff as well as weekly by Utilities Department staff by CCTV and survey to ensure that the installed pipe has no deflections. Utilities staff have observed the construction methods and feels that this process is the best installation alternative for the sewer.

Emery Sapp is requesting additional costs to perform this work. As outlined in the attached letter, they have provided a unit cost of $72.58 per cubic yard of the additional shot rock placed, which includes the additional labor and material. It is estimated that this method of stabilization will be necessary for 2,500 of the 3,203 linear feet of sanitary sewer being constructed. Based on Note 6 within the Contract 1 plan set, which states “The Contractor shall provide a stable foundation at the base of the sanitary sewer excavation. Over excavation and placement of additional crushed stone and/or over excavation and placement of lean concrete seal is anticipated, this work is at the contractor’s expense”, Emery Sapp will be responsible for the first 1.5’ of depth stabilization within the trench and it is requested that the City be responsible for the remaining depth. Measurements are being recorded daily to track the actual volume of rock placed. At the estimate of 6 feet deep and 6 feet wide, the total cost for 2,500 linear feet of pipe will amount to a cost of $181,450.00. If there is additional material required beyond the proposed limit of sanitary sewer, then another request would be made at a later time.

Construction Contract Costs:

Original Contract 1 - 24” Sanitary Sewer Relocation	$710,069.63
Original Contract 2 – Inverted Sanitary Siphon and Waterline	$1,212,298.10
RFC #14	$181,450.00
Current Contract Total	$2,103,817.73

To date cost adjustments are 9.4% of the original contract amount.

Action

Authorize the City Manager to execute RFC #014 to the construction contract with Emery Sapp & Sons for project UT1205 – Contract 1, South Lawrence Trafficway Sanitary Sewer Relocations increasing the contract amount by $181,450.00.