Over the past four decades, the number of custom slaughterhouses in Michigan has steadily decreased as the number of livestock producers declined. Those who remain are growing larger as they capitalize on the buy local food craze by providing fresh USDA-approved boxed meats at a meat counter or by adding value to the meats by further processing (i.e., sausages, hams, etc.). All slaughterhouses in the State are regulated by the Michigan Department of Environmental Quality (MDEQ) who issues permits for the proper disposal of the process wastewater for those operations that are not connected to a municipal sewer.
Typical disposal of the process wastewater involves removal of the solids through septic tank filtration and screens followed by storage of the process wastewater in ponds for eventual disposal on crop ground at agronomic rates. Facilities operating in this manner are issued a Groundwater Discharge Permit from MDEQ. However, because the state classifies slaughterhouses as an industry, the storage ponds require double liners and must meet a hydraulic conductivity of 1 x 10-7 centimeters/second.
A process wastewater storage pond is being designed for a slaughterhouse located in Coopersville, Michigan. The existing process wastewater holding pond is not sufficient to hold process water generated at the facility due to the recent expansions in slaughterhouse operations. Therefore, modifications to the existing holding pond and construction of a new holding pond to accommodate the process water generated is underway. The construction of the ponds is scheduled for spring 2017.
This paper evaluates the applicability, economic feasibility compared to geomembrane liners and constructability of pond liners using AquaBlok.
AquaBlok is a man-made clay pellet material that handles like gravel and is placed in varying thicknesses depending on the desired hydraulic conductivity and then hydrated to create a low permeable liner. Advertised as a “composite particle system” each AquaBlok particle contains an individual piece of limestone as its core. When a continuous layer of individual particles is applied, the clay (i.e., a high-quality sodium bentonite coating) surrounding each stone hydrates, swells, and binds together to produce a low-permeable earthen liner when introduced to a water environment.
Based on the current operations and future growth forecast, the slaughterhouse requires a pond(s) with total holding capacity of approximately 1.6 million gallons of process wastewater. This accounts for process wastewater generated in total of eight (8) months period. Soil borings were taken at the site and soil samples were collected to determine geotechnical parameters including hydraulic conductivity. Total of eight (8) soil borings were advanced to an approximate depth of fifty (50) feet below ground surface. Based on the laboratory testing results, the hydraulic conductivity of the native clay did not meet the MDEQ’s minimum 1 x 10-7 cm/s requirement. These results indicate a need for a composite liner for the existing pond as well as the new pond. Two candidate liner materials are being evaluated. They are 1) clay liner that is constructed of AquaBlok and 2) geomembrane liner. Geomembrane are commonly being used for wastewater! holding ponds. AquaBlok is not being frequently used as liners for holding ponds. However, once constructed appropriately, this material would provide a liner with hydraulic conductivity of less than 1 x 10-8 cm/s and appropriate shear and compressive strength. Currently, the economic feasibility of the two methods is being evaluated. Also, the constructability of the AqaBlok liners is being investigated. The ponds are scheduled to be constructed in Spring 2017.
The evaluation of AquaBlok as a liner material for process wastewater holding ponds is being evaluated. The construction of the ponds is scheduled for Spring 2017. This material has promising geotechnical parameters and can provide a liner with a very low permeability once constructed appropriately. A detailed discussion of the material evaluation, liner construction methodology, economic analysis, and regulatory compliance will be presented during the oral presentation.
Use of a geotextile liner is an approved method to construct industrial wastewater storage ponds in Michigan but cost and liner installer availability is typically a detriment to fast installations.
Due to a plant expansion, the design drawings and application to expand the process wastewater pond capacity and to meet the state requirements for minimum liner permeability are currently in review by the state MDEQ. Construction of the new storage pond is planned for spring 2017 pending MDEQ review and approval.
Matthew J. Germane, PE, Senior Project Engineer at Environmental Resources Group, LLC
Mala Hettiarachchi, Ph.D, PE, Senior Engineer at Environmental Resources Group, LLC
Additional information on Michigan's rules for liner construction of industrial wastewater is available at:
The authors wish to acknowledge DeVries Meats, Inc., in Coopersville, MI and their owner, Ken DeVries, whose site the design work and cost evaluations were completed for.