October 11, 2012
City to Start Search for Irrigation Partner for Lagoon Land Application Project
Following one of the driest summers on record, free irrigation water figures to be a hot topic of discussion. The City of Memphis is hoping so.
A public hearing has been scheduled for Thursday, October 18th at 6 p.m. at the Memphis City Hall where the city council will discuss evaluations of prospective improvements for the city's wastewater treatment facility.
Land application discharge is one option being considered to alleviate issues with the current lagoon system and to help meet changing environmental regulations.
According to engineer Cary Sayre of Allstates Consultants, LLC., the city would need approximately 150-200 acres of pasture or 350-400 acres of cropland to allow land application of lagoon effluent periodically throughout the year.
The model, which is currently being used in other communities such as Hallsville, Atlanta, St. Elizabeth and Clifton Hill, represents significant cost savings compared to the creation of a new mechanical wastewater treatment facility.
The public hearing will allow interested landowners the opportunity to ask questions regarding the process and discuss the viability of utilizing their ground. Proximity to the current lagoon structure will be a priority to help keep the project costs low.
Irrigation options to be considered will include installation of center pivot sprayers as well as "traveling gun" style mobile units.
The transition is being considered by the city as an option to help meet new ammonia standards that experts predict will be extremely difficult for the current lagoon system to meet.
The option of water aeration systems is hampered by the lack of depth at the lagoon. Traditionally, those ammonia reducing systems require a minimum depth of seven feet. The Memphis lagoon was constructed at a five-foot depth.
Engineers anticipate that land application process would be more cost effective than attempting to raise the lagoon level and install the aeration system.
The first step of the land application process will be to identify irrigation targets for the lagoon effluent.