The Washington City Council Monday night approved a contract with Aquaterra Environmental Solutions, Inc., for design of Phase IV of the Washington Sanitary Landfill.

Phase III of the landfill is expected to be at capacity in spring 2014. The plan is to have Phase IV ready for operation by fall 2013, Dan Boyce, city engineer, told the council.

Aquaterra, Fairview Heights, Ill., also designed Phase III of the project.

The total contract cost is $62,575.

In addition to preparing the bid package for Phase IV, Aquaterra will present a recommendation of a phasing plan for the remaining areas IV and V, evaluate new soil borrow locations, investigate and recommend permit modification options and evaluate landfill expansion options.

Boyce said the city will look at the most cost-effective way to utilize the remaining space at the landfill.

Area IV will be approximately five acres in size.

Construction of the liner system and leachate management system will require up to 10 weeks of work for subgrade preparation, compacted clay liner construction, geomembrane liner installation, geocomposite installation, leachate collection piping installation and placement of a protective soil layer. Surveying services also will be provided.

Several phasing options are being explored, including development of the entire Phase IV landfill cell, development simultaneously of the area IV and V landfill cells, partial development of area IV and partial development of the combined areas IV and V landfill cells.

Another task Aquaterra will take on is a soil borrow source evaluation, which will evaluate up to two new soil borrow locations to the east and south of the landfill. Both parcels are located adjacent to the landfill.

As outlined in the contract, Aquaterra will review the landfill’s existing permit and identify permit modifications for the existing landfill permit that will improve operations and disposal capacity of the landfill. Several potential opportunities for modifications were outlined.

The company also will complete construction drawings and prepare technical specifications and construction bid documents.

Aquaterra will be responsible for soliciting bids for construction for the project.

Final tasks include a landfill expansion evaluation and perform construction quality assurance during the construction.

The ordinance passed unanimously.