Title
CHANGE ORDER NO. TWO TO CONTRACT NO. K-1314-114: BY AND BETWEEN THE NORMAN TAX INCREMENT FINANCE AUTHORITY AND SILVER STAR CONSTRUCTION COMPANY, INC., INCREASING THE CONTRACT AMOUNT BY $131,094.25 FOR A REVISED AMOUNT OF $4,031,153.10 FOR THE INTERSTATE DRIVE EAST EXTENSION PROJECT AND BUDGET APPROPRIATION FROM THE NORTHPARK TIF FUND BALANCE.
Body
BACKGROUND: On August 22, 2006, City Council approved Contract No. K-0607-45 by and between the City of Norman and the University Town Center L.L.C., regarding Development Agreement No. 1 for the initial project activities associated with the traffic improvements needed to mitigate the additional traffic generated by the University North Park (UNP) development.
In 2008, the City constructed 0.62 miles of the 1.7 miles of the I-35 frontage road (Interstate Drive East) from Robinson Street to Conference Center Drive. During the design of the Rock Creek Road Overpass, the bridge was designed to span the future frontage road. On May 7, 2012, City Council approved Development Agreement No. 5 for the UNP Tax Increment Finance (TIF) District which included funding to complete the frontage (Interstate Drive East) road from Conference Center Drive to 24th Avenue NW. During the summer of 2012, the I-35/Robinson Street Interchange NE Quadrant project tied the I-35/Robinson Street Interchange ramps with the frontage road.
The construction contract with Silver Star Construction Company, Inc. of Moore Oklahoma for the Interstate Drive East Extension was approved by Council on April 22, 2014. The Interstate Drive East Extension Project (the “Project”), includes the following components:
• Construction of approximately one mile of frontage road
• Construction of a modern roundabout
• Construction of the intersection of 24th Avenue NW with Interstate Drive East/Corporate Center Drive including decorative pavement and signalization
• Installation of approximately one mile of 12-inch public waterline and appurtenances
• Construction of storm drainage facilities
The total contract amount for these components was $3,900,058.85. The Norman Economic Development Coalition and University North Park agreed to reimburse NTIFA for certain costs associated with the intersection of Interstate Drive with 24th Avenue and certain storm sewer upgrades. Additionally, the Norman Utilities Authority (NUA) created a Payback Project for the 12 inch public waterline which provides for pro-rata reimbursement to the Norman Utilities Authority as each private development parcel connects to the waterline.
DISCUSSION: The design of the asphalt roadway section for the Interstate Drive East Extension includes a compacted sub-base, an 8-inch stabilized subgrade, and 8-inches of asphalt pavement. Attachment A is the typical section for the asphalt roadway. The stabilized subgrade consists of the compacted soil blended with a chemical additive which hardens the soil and increases the subgrade’s ability to handle traffic loads and is necessary to properly support the roadway to minimize long term maintenance costs. Typical chemicals added to the soil for stabilization are fly ash or cement kiln dust (CKD). To insure that the proper stabilization materials are selected, testing of the soil is required.
The design engineer on the project, SMC Engineering, contracted with EST for the geotechnical investigation and for the pavement design. Due to their past experience in the UNP TIF area, EST expected low sulfate levels in the soil, but recommended verifying the sulfate level prior to subgrade modification. For the most part, the soils in the UNP area have contained low sulfate levels. High sulfates have not been a problem on other City projects or SMC Engineering designs for the development in the UNP area.
Recent soil testing for the Frontage Road Project indicated the sulfate levels were high enough that when blended with a soil additive the formation of sulfate crystals could cause the subgrade to swell. If the subgrade swells, the asphalt pavement will be damaged and may require extensive, costly City street maintenance.
Several options were considered by the project team for correcting the sulfate issues in the soil. The preferred option to counteract the high sulfates is to “mellow” the subgrade material by blending a small amount of quick lime, another chemical additive commonly used in roadway construction, with the existing soils. After allowing the quick lime sufficient time to react with the sulfates, the contractor will stabilize the soil using CKD as determined from soil testing. While quick lime mixing is not the only way to solve this problem, it is the lowest cost solution for this project.
Other options, as shown in Attachment B were considered but were found to be considerably more costly. Option #1 is the addition of the quick lime with the soils. Options #2 and #3 involved removal of the high sulfate soils and replacing them with aggregate base or different soils. The process of removal and hauling in new material increases the cost significantly. Attachment B is a cost estimate of all possible solutions.
Deposits of high sulfate soils in central Oklahoma are not common but do occur. The North Porter Avenue Gap Paving Project from Rock Creek Road to north of Tecumseh Road, which was completed in 2013, had a similar situation. Testing samples taken between Rock Creek Road and Tecumseh Road prior to stabilization contained low levels of sulfates. However, the soil under the roadway north of Tecumseh Road had sulfate levels three or four times the levels in the soil south of Tecumseh Road.
The solution on the North Porter Avenue Gap Paving Project was to remove the high sulfate soils and replace them with 8 inches of aggregate base. This type of repair is the same as Option #2 as described above. The additional cost to the North Porter Avenue Gap Paving Project for this repair was approximately $90,000 of which the City of Norman was responsible for $18,000 or 20% of the cost because the remainder of the project was eligible for federal funding. The cost to install the 8 inch aggregate base along 700 feet of Porter Avenue figures to be $130 per foot of road while the cost to mellow 6,150 feet of Interstate Drive is only $22 per foot of road.
The total proposed increase to the contract is $131,094.25 or a 3.4% increase over the current contract amount of $3,900,059. If approved, funds are currently available in the University North Park TIF General Fund Revenue Account (Account No. 057-0000-253.20-00).
If approved, Change Order No. 2 will also add 20 calendar days to the project schedule. This will extend the completion date on the project to December 5, 2014.
RECOMMENDATION No. 1: Staff recommends approval of Change Order No. 2 increasing Contract No. K-1314-114 by $131,094.25.
RECOMMENDATION No. 2: Staff further recommends appropriating $131,094.25 from the University North Park TIF Fund Balance (Account No. 057-0000-253.20-00) to the Interstate Drive East Extension Construction (Account No. 057-9545-431.61-01 Project No. UT0009).