AgdaPkt 2018-03-26 Joint SA PFA - Laserfiche WebLink

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to achieve the required compaction. While soils similar to this are found within Redwood City, most are able to provide compaction values at or near the required 95%, and the unsuitability of this particular soil was unforeseen. After the compaction testing took place, there were several rainy days. These rains added moisture to the soil and adversely affected the contractor’s ability to achieve the required compaction. Several options were considered to mitigate the unsuitability of the soil. Most of the options included the removal of the soil to various depths (4”, 12” and 24”) and replacement with either clean, granular fill or aggregate base rock, in combination with geotextile fabric. One alternative that left the soil in place was a lime treatment of the existing soil, which works to dry the soil through a chemical reaction, and also changes the structure of the clay into a more granular, workable material with much lower plasticity (the tendency for soils to shrink and swell depending on the moisture content). Due to the type of soil, the cost to excavate, off-haul, and dispose it are higher than average, coming in at approximately $45,000 for each 12” of soil removed, without considering the additional cost of bringing in the new fill material and geotextile fabric. The cost for in-place lime treatment came in at just under $39,000. With that in mind, the option that was most cost effective and would provide the best long-term solution for the project was the lime treatment, and a change order to the project was prepared allowing for this solution. The change order, for $38,911.82, was approximately 9.7% above the contract amount, and within the range for authorization by the City Manager, but very close to the maximum 10% allowed. Staff is now requesting that the City Manager be authorized to increase project funding by 10% of the original contract price, $40,137.90. This would increase the total funding allowed for the project from $441,516.90 to $481,654.80. This additional funding would allow for any other, minor changes that are typical within pavement projects (i.e. more asphalt was placed than was calculated during design). ALTERNATIVES Council may choose to not approve the additional funding for the National Guard Armory Building Parking Lot Improvements Project, and direct staff to complete construction within the allocated funding. This would limit staff’s ability to pay for any final quantity adjustments that are typical of this type of project. FISCAL IMPACT The Capital Outlay Fund - National Guard Armory-Improvements Per Lease has an available balance of $97,017.14 as of January 31, 2018, which is more than the 20% total increase requested. ENVIRONMENTAL REVIEW As the lead agency, the City of Redwood City determined that as proposed, the project is categorically exempt from the requirements of the California Environmental Quality Act (CEQA) Guidelines per Section 15302 “Replacement or Reconstruction” for removal and replacement of existing asphalt paving; and Section 15332 “In-Fill Development 6.1.C. - Page 2