Section 306.361  Justification of Joint Petition

Except as provided otherwise in subsection (d) if the discharger and the Agency jointly file a petition for exception, exception justifications shall be established in the petition for exception as follows:

a)         An exception justificaiton based upon minimal discharge impact shall include, as a minimum, an evaluation of receiving stream ratios, known stream uses, accessibility to stream and side land use activities (residential, commercial, agricultural, industrial, recreational), frequency and extent of overflow events, inspections of unnatural bottom deposits, odors, unnatural floating material or color, stream morphology and results of limited stream chemical analyses.

b)         Where a minimal impact exception justification cannot be established pursuant to subsection (a), or where an exception will include a modification of otherwise applicable water quality standards, an exception justification shall include, as a minimum, evaluations pursuant to subsection (a) and evaluations of stream sediment analyses, biological surveys (including habitat assessment), and thorough stream chemical analyses that may include but are not limited to analysis of parameters regulated in 35 Ill. Adm. Code 302, analysis of toxics or metals if the collection system tributary to the overflow receives wastes which might contain them, sediment oxygen demand, volatile solids, and diurnal monitoring under both dry and wet weather conditions.

c)         Exception justifications which include projections of the improvement from alternative control programs may include reasonably reliable mathematical models based upon information gathered pursuant to subsection (b).  The reasonable reliability of a mathematical model shall be assessed by reference to factors including but not limited to the model's scientific validity and the consistency with which the model reflects conditions in the stream as determined by monitored data.

d)         Where special circumstances may render any evaluation inapplicable, for reasons of irrelevancy or expense of data collection in relation to the relevancy of the data, the petition shall include a justification for such inapplicability.

(Source:  Added at 7 Ill. Reg. 5682, effective April 19, 1983)