ILLINOIS POLLUTION CONTROL BOARD
    October 19, 1978
    ILLINOIS POWER COMPANY,
    )
    )
    Petitioner,
    )
    v.
    )
    PCB 78—8
    ENVIRONMENTAL PROTECTION AGENCY,
    )
    )
    Respondent.
    MR. SHELDON A.
    ZABEL, SCHIFF,
    HARDIN
    & WAITE, APPEARED ON
    BEHALF OF PETITIONER:
    RUSSELL R. EGGERT, ASSISTANT ATTORNEY GENERAL, APPEARED ON
    BEHALF OF THE AGENCY.
    OPINION AND ORDER OF THE BOARD
    (by Mr. Dumelle):
    Petitioner has requested a determination, pursuant to
    Rule 203(i) (5) of Chapter
    3: Water Pollution, that the thermal
    discharge from
    its Hennepin Station has not caused and cannot
    reasonably be expected to cause significant ecological damage
    to the Illinois River.
    A hearing was held on August 16,
    1978
    at the Board’s Chicago office.
    Part VI of the Board’s Procedural Rules sets out the
    requirements for this proceeding.
    Exhibit
    1 contains the
    information required by Rule 602.
    The Agency waived its right
    to file a Recommendation.
    The Hennepin Station is
    a coal—fired electric generating
    facility located on the Illinois River at River Mile 211.9
    near Hennepin, Illinois.
    The plant consists of two units with
    capacities of 77 and 243 megawatts
    (MW)
    respectively.
    A once
    through cooling system is employed using double pass condensers.
    In the period 1972-1976, capacity ranged from 50.1-55.4.
    This
    range is expected to continue with no estimated retirement date
    for either unit.
    Shutdowns are usually under 59 hours in dura-
    tion with the longest on record being 19 days in 1973.
    Under typical operating conditions,
    the flow of cooling
    water
    is 276 cfs with a maximum capacity of 356.5 cfs.
    The
    temperature rise of the cooling water at maximum capacity is
    18.4°F. Temperature of the discharge ranges from 58.0°Fto
    100°F.
    The thermal plume from the Hennepin Station was determined
    to be shoreline attached by a process of elimination and field
    observations.
    Downstream temperature distribution in the
    plume
    31—643
    was determined by modelling.
    Worst case conditions were pro-
    jected by associating low flow with maximum generating capacity
    and actual ambient river temperature.
    The days with the lowest
    recorded river flow (early autumn)
    did not coincide with high-
    est river temperature
    (late summer).
    Even under worst case
    conditions, the 5°Fisotherm is within the standard for mixing
    zones
    in Rule 201 of Chapter
    3: Water Pollution.
    Minimal changes in aquatic biota have been observed in
    the immediate vicinity of the discharge for typical and worst
    case conditions and may be expected to continue to occur.
    These
    changes are not necessarily due to the thermal discharge alone.
    In any event no significant ecological damage to the Illinois
    River has been observed, and none is expected.
    No impact on
    animal life or recreation was observed or anticipated.
    This opinion constitutes the Board’s finding of fact and
    conclusions of law in this matter.
    ORDER
    Petitioner has demonstrated that the thermal discharge
    from its Hennepin Station has not caused and cannot be reason-
    ably expected to cause significant ecological damage to the
    Illinois River.
    IT IS SO ORDERED.
    I, Christan L. Moffett, Clerk of the Illinois Pollution
    Control Board, hereby certify the
    bove Order was adopted on
    the
    J4~
    day of
    _______________,
    1978
    by a vote
    Q~nL~f~~erk
    Illinois Pollutio
    ontrol Board
    .i~~b4*

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