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llLO� MN Report Number 14 -050 the city that works for you Agenda Section VI -3 Council Meeting Date March 11, 2014 REQUEST FOR COUNCIL CONSIDERATION ITEM DESCRIPTION: CONSIDERATION OF BIDS AND AWARD OF CONTRACT FOR CITY PROJECT 14 -5, OLD MILLER DUMP VERTICAL LANDFILL GAS VENTS. DEPARTMENT HEAD'S APPROVAL: &%vv CITY MANAGER'S APPROVAL: No comments to supplement this report Comments attached Recommendation: Accept the bids and award a contract for City Project 14 -5, Old Miller Dump Vertical Landfill Gas Vents, to the lowest responsible bidder, Belair Builders, Inc., in the amount of $194,313.00. Legislative History: This item was first discussed at the June 11, 2013 City Council Worksession. The City Council approved the plans and specifications and authorized staff to advertise for the public bidding process at their November 26, 2013 meeting. Financial Impact: The following three bids were received and opened by staff at 10:00 a.m. on January 21, 2014: 1. Belair Builders, Inc. $194,313 2. Veit & Company, Inc. $197,073 3. Rachel Contracting, Inc. $205,663 A bid tabulation has been completed by City staff and bid totals verified. The low bid of $194,313 submitted by Belair Builders, Inc. is greater than the total estimated project cost of $174,985. Explanation: Since October 2010, the City and Barr have conducted vapor monitoring at Old Miller Dump and routinely submitted results to the Minnesota Pollution Control Agency (MPCA). The majority of the monitoring has been favorable, indicating the capped dump is restricting vapor migration. However, several perimeter vapor monitoring points in the vicinity of the Block E area have shown elevated methane concentrations since 2010. These methane concentrations have triggered initial contingency actions under the MPCA- approved Response Action Plan (RAP) and additional vapor monitoring points were installed along the perimeter of the Block E area in 2011. Methane concentrations at these new monitoring points are very low and often not detectable, indicating the vapor migration area of concern is relatively limited to the perimeter of the Block E area. According to Barr, there are currently no significant health risks because the Block E area is undeveloped (i.e., there are no buildings for methane to potentially accumulate in). Over the course of the last year, the MPCA has intensified its demands with respect to the methane issue at Block E. On October 29, 2013 the MPCA approved a work plan to install passive vertical vents in the capped dump materials near the area of concern to increase the controlled dissipation of the landfill gas at its source in the dump, in an attempt to alleviate the methane migration that is being observed beyond the dump in the Block E area. This work plan is consistent with MPCA requests for additional landfill gas remedial measures and complies with the terms and conditions of the RAP to address the environmental concerns at the site relative to future buildings. The scope of work includes installation of thirty-three new subsurface vertical landfill gas vents, including a pipe header system connecting the vents and associated pipe cleanouts and vent risers, and incorporation of this new system into the long -term landfill gas monitoring plan for the site. Horizontal spacing of the vertical vents will be approximately 30 feet, consistent with the estimated radius of influence recommended by the MPCA. The vertical vents extend approximately four feet above the ground surface, so the MPCA has approved a subsurface gas collection line connecting the vents together allowing a reduced number of 4 -foot vent risers to help alleviate the aesthetic concern of many vertical vent risers. The plan