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5. BASIS OF PLANNING Nutrient Loading Biosolids application to agricultural land should not exceed the annual nitrogen loading required for maximum crop yield and is, therefore, managed according to its fertilizer value. Biosolids may be applied to approved sites above agronomic rates on a one-time basis or less than once per year as long as runoff, nuisance conditions, or groundwater contamination do not occur. Nitrogen accumulation from higher than agronomic rates and annual nitrogen use will determine the acceptable loading rate and frequency. Site Life Site life is important in planning because sites generally have a limited application life based on the chemistry of the soil and the metals loading from the biosolids. Site life is calculated by dividing lifetime biosolids loading limits based on the most limiting constituent by the annual application rate. Seasonal Constraints In western Oregon, where soil damage may occur from application equipment traffic in the wet season, biosolids application should be restricted to the dry season. The main consideration in land-applying on sloping ground is avoiding surface runoff and soil erosion. Grazing Restrictions Grazing animals should not be allowed on pasture or forage nor should livestock feed be harvested for 30 days after application of bulk Class B biosolids or domestic septage. The current biosolids management practices are discussed in section 6.5 in Chapter 6.0. 5.1.5 Reuse Effluent Quality An alternative to direct river discharge of treated effluent during dry weather is to apply treated effluent to meet irrigation demands at agricultural lands, golf courses, and parks. Effluent can also be reused as reclaimed water for specific nonagricultural industrial uses, such as cooling water. The standards for effluent reuse in Oregon are established by the DEQ through OAR Chapter 340 Division 55 (340-55). Treatment and Monitoring Requirements for Effluent Reuse Through OAR 340-55, DEQ has established treatment and monitoring requirements for potential agricultural and nonagricultural uses of the treated effluent. DEQ has classified reclaimed water into four categories and assigned a minimum degree of treatment required: · Level I: Less than biological treatment or biological treatment without disinfection · Level II: Biological treatment plus disinfection · Level III: Biological treatment plus disinfection (stricter coliform limit) · Level IV: Biological treatment, clarification, coagulation, and filtration treatment plus disinfection Limits for total coliform (organisms/100 mL) and turbidity [nephelometric turbidity units (NTUs) have been established for the four categories. These standards serve as a general guideline for defining the anticipated water quality required for the various uses. In MWlvlC_5.0_REV8_VKS.DOC 5-17