This Standard Operating Procedure (SOP) “Biosolids Land Application ” has been established to provide procedures and guidelines for the land application of biosolids from wastewater treatment facilities.

Ag Tech drivers transport biosolids from various wastewater treatment facilities to the Donley Farms in Yuma, Arizona. The biosolids are received in both liquid and dewatered forms in specially designed trailers. Following the National Code of Good Practice, the biosolids are either land applied by spreading and discing or re-liquefied and applied via subsurface injection to permitted farm fields. Subsurface injection is Ag Tech's preferred method of land applying biosolids. Subsurface injection is more aesthetically pleasing and reduces vectors and objectionable odors. Subsurface injection also reduces the potential of unauthorized persons coming in contact with the biosolids. After application of biosolids, the land is prepared for planting using standard farming practices.

1. The success of the land application project depends on the effectiveness of Ag Tech’s monitoring. Highlights of this monitoring process are as follows:
2. A quadrant numbering system designed by Ag Tech using a seven-digit number to identify every parcel. These numbers are used to track applications and monitor the critical parameters.
3. A flexible database has been developed to track application rates, cumulative applications and yield data.
4. Trained, motivated and properly supervised employees.

1. Sub-Surface Injection: Ag Tech drivers arrive at a predetermined mixing station and unload the biosolids into a man-made pit/tank. The biosolids are then mechanically mixed and diluted to prepare for field application. The biosolids are re-liquefied to a minimum of 10% solids concentration using Ag Tech's proprietary re-liquefying process. The biosolids are now ready for field application. The biosolids are pumped through flexible piping directly to the tractor applying the biosolids. Ag Tech uses “direct deep chisel injectors” to subsurface inject to a depth appropriate for the crop being grown. The Biosolids are applied at the appropriate agronomic rate.
2. Surface Spreading: The biosolids are off loaded at the application site in cake form. The biosolids are then skip loaded into a manure spreader and spread at the appropriate agronomic rate for the crop being grown. Following the surface spreading the biosolids are disced into the soil at the appropriate depth.

5.0 Regulations

Application site inspections are conducted on a periodic, as-needed basis by the generator. These inspections are performed in accordance with the Code of Good Practice for the Land Application of Biosolids. Application site inspections are conducted by the regulating authorities (U.S. EPA, ADEQ) on an annual basis or as often as they deem necessary.