Stanley Consultants, Inc.
 

CLIENT

  • Great River Regional Waste Authority;
    Ft. Madison, IA

PROJECT

  • Fort Madison Landfill Leachate Irrigation Disposal System;
    Ft. Madison, IA

AWARDS

  • 1999 First Place Eminent Conceptor Small Budget Category

 
   
 
The Great River Regional Waste Authority (GRRWA) in Fort Madison, Iowa, had been trucking over seven million gallons of landfill leachate annually to a municipal wastewater treatment plant and was in need of a more cost effective alternative to dispose of this regulated waste. In response to this challenge, Stanley Consultants, in conjunction with Ecolotree, Inc. and Fountainhead Irrigation, designed an innovative solution that irrigates the leachate onto a grove of hybrid Poplar trees, resulting in reduction of leachate through evapotranspiration.

This engineered tree system involved the planting of 6,000 trees on five acres of an active landfill cell with an intermediate cap. Liners made of clay composite and 60 ml polyethylene line the landfill cell and a storage lagoon which holds the leachate. The existing drainage system pumps leachate from the cell to the lagoon. The leachate is then automatically irrigated directly onto the trees on a pre-set schedule using a 150-gpm pump system and micro-emitters. Any leachate that is not absorbed by the trees or evaporated seeps back into the landfill, enhancing the conditions for bacteria to decompose the waste. This results in reduced waste volume and improved leachate quality as the trees and other natural processes break down many of the harsh contaminates.

Over 2,000 feet of polyethylene transmission piping was shallowly trenched from the lagoon to the irrigation site. The flexible pipe compensates for the different settling rates of the ground in the landfill cell. The 150 gpm pump system is equipped with a self-cleaning strainer and filtration system that automatically backflushes itself to maintain capacity. The site also includes a flushing hydrant to enable GRRWA to clear the landfill cell’s collection system lines and aid in purging the system prior to winter.

This breakthrough approach to leachate management represents the first time a landfill has been approved by the Iowa Department of Natural Resources (DNR) to irrigate leachate onto an intermediately capped portion of an active landfill. The system has successfully reduced the volume of leachate hauled to a wastewater facility to less than 500,000 gallons annually. The final product is a cost effective leachate management system that meets environmental regulations, exceeds client needs and expectations, and was completed on time and on budget.


 
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