Title
Resolution to Approve Amendment No. 1 to the Professional Services Agreement with GeoTrans, Inc. ($111,559.00)
Memorandum
Attached for your review and approval is a resolution to approve Amendment No. 1 to the Professional Services Agreement with GeoTrans, Inc. We are requesting an amendment to the existing contract with GeoTrans, Inc. for hydrologic modeling. A conceptual model will be developed for the landfill to provide the basis for analysis and identification of appropriate remediation strategies.
To satisfy the requirements of the Michigan Department of Environmental Quality (MDEQ), the groundwater and air in the vicinity of the landfill must be sampled and analyzed quarterly. GeoTrans has been performing these services at the landfill since July 2007.
For many years the landfill has had an offsite plume of 1,4 dioxane contamination primarily in Southeast Area Park, northeast of the landfill. A slurry wall was constructed along approximately 4/5ths of the boundary of the landfill to eliminate groundwater passing through the landfill and three purge wells were installed to capture the offsite contamination.
Over the past year, the concentration of 1,4 dioxane in monitoring wells north of the landfill has increased. Additional monitoring wells were installed but the cause of the increased concentration remains uncertain. In discussion with our consultants, there are different potential situations that may be contributing to the increased concentration in this area as follows:
Scenario 1: The slurry wall is not working as designed and therefore a source of 1,4 dioxane is not being captured and this source is causing the increase. This would lead us to either close off the northern section of the landfill slurry wall, at an estimated cost of $300,000.00 to $500,000.00, or install additional extraction wells along the northern boundary of the landfill. The capture wells currently discharge to the sanitary sewer system. The closure of the slurry wall would result in a significant reduction flow to the sanitary sewer system and reduce disposal costs. The installation of the additional extraction wells would conversely increase the discharge volume to the sanitary sewer system and increase disposal costs.
Scenario 2: The slurry wall is working as designed, but has influenced the flow of groundwater such that the original plume that left the landfill to the Northeast is slowly moving west. This scenario is not remedied by the actions above, but instead may require no action or may lead to the installation of additional extraction wells in the park.
Because the current conditions contributing to the problem are unknown and there are several remedial options to consider, all with significant costs, it is prudent to complete a hydrologic model and analysis of the landfill groundwater system to support remediation decisions.
Tasks associated with this amendment include surveying and well rehabilitation, identification of transport pathways for movement of the groundwater, pumps tests and analysis of the aquifer, development of a hydrologic model and evaluation of remediation alternatives. A full report will detail the model results and recommended remediation strategies.
Funds were previously approved in the FY06 Capital Budget and can be expended without regards to fiscal year.
GeoTrans, Inc. received Human Rights approval on May 1, 2007 and complies with the living wage ordinance.
Staff
Prepared by: Matt Naud, Environmental Coordinator
Reviewed by: Sue F. McCormick, Public Services Area Administrator
Approved by: Roger W. Fraser, City Administrator
Body
Whereas, On June 4, 2007, the City entered into an agreement with GeoTrans in the amount of $101,392.00 per year for three years to provide professional environmental consulting services at the Ann Arbor Landfill;
Whereas, GeoTrans submitted a proposal to provide additional environmental services requested by the City to develop a hydrologic model and remediation recommendations for a not-to-exceed amount of $111,559.00;
Whereas, Adequate funds to cover the cost of this amendment were previously approved in the FY06 Capital Budget of the Solid Waste Fund and can be expended without regards to fiscal year; and
Whereas, GeoTrans, Inc. received Human Rights approval on May 1, 2007 and complies with the living wage ordinance;
RESOLVED, That the City Council approve Amendment No. 1 to the Professional Services Agreement with GeoTrans in the amount of $111,559.00;
RESOLVED, That the Mayor and City Clerk are authorized and directed to execute said amendment after approval as to form by the City Attorney, and approval as to substance by the City Administrator; and
RESOLVED, That the City Administrator is authorized to take the necessary administrative actions to implement this resolution.