ULNRC-06715, Enclosure 3: Attachment a to the NPDES Permit Modification Application

Enclosure 3: Attachment a to the NPDES Permit Modification Application

ML22060A112
Person / Time
Site:	Callaway
Issue date:	03/01/2022
From:	State of MO, Dept of Natural Resources
To:	Office of Nuclear Reactor Regulation
Shared Package
ML22060A108	List: ML22060A110 ML22060A111 ULNRC-06715, Enclosure 3: Attachment a to the NPDES Permit Modification Application
References
ULNRC-06715
Download: ML22060A112 (4)

Text

ULNRC-06715 Page 1 of 4 Attachment A to the NPDES Permit Modification Application

ULNRC-06715 Page 2 of 4 Callaway Energy Center NPDES PERMIT MODIFICATION Attachment A Description of Stormwater Pond closure The storm water detention pond closure project is currently under construction at the Callaway Energy Center under Construction Permit #MO-RA19240. Three separate storm water ponds, as shown below, associated with the current NPDES permit are being decommissioned. These three ponds were originally placed in service during plant construction in the 1980's to control stormwater runoff from various construction areas around the plant site. To reduce maintenance issues with the pond dams, a decision was made to decommission the stormwater ponds. Multiple sample studies were first completed on each pond discharge to prove that the proposed new discharge locations after closure will have no effect on the final effluent limitations. A detailed hydrologic evaluation was also completed on each pond drainage basin area, in order to restore each stormwater basin to its original pre pond alignment. As part of the closure project, each stormwater pond discharge location will be slightly re-located in order to accommodate the pre-pond alignment.

Callaway Energy Center's final effluent limitations on each of the three storm water ponds are currently set as benchmarks, with sampling occurring once per quarter. After sample studies were concluded in early 2021 we expect a reduction in monitoring results at the newly proposed discharge locations versus the monitoring results at the current discharge locations. Because of these findings Callaway believes no changes need to be made to the sampling schedule or benchmark limitations.

Outfall 012 modification As the current Callaway NPDES Permit states, Outfall 012 is storm water discharge from approximately 87 acres (22 acres impervious), draining areas around the majority of the southern portion of the plant proper. This also includes Outfall 013 that was eliminated in the 2010 NPDES permit. As you can see from Drawing

ULNRC-06715 Page 3 of 4 1, the red arrow at Outfall 012 is the proposed new sample and discharge point and the black arrow is the current sample and discharge point.

Proposed new facility description Outfall 012: Stormwater UTM Coordinates: X = 605852; Y=4290489 Legal

Description:

NE 1/4, SE 1/4, Sec. 14, T46N, R8W, Callaway Co.

Receiving Stream: classified tributary to Logan Creek Receiving & First classified Stream & ID: 100K Extent remaining stream (C) WBID #3960 USGS Basin & Sub-watershed No.: Deer Creek - Missouri River (10300102-1606)

Application Design & Storm Flow: 6.6 MGD; daily flow is dependent on precipitation Outfall 014 modification As the current Callaway NPDES Permit states, Outfall 014 is storm water discharge from approximately 100 acres (4 acres impervious), draining areas around the Northwest portion of the plant proper. As you can see from Drawing 1, the red arrow at Outfall 014 is the proposed new sample and discharge point and the black arrow is the current sample and discharge point.

Proposed new facility description Outfall 014: Stormwater UTM Coordinates: X = 605639; Y=4291849 Legal

Description:

NW 1/4, SE 1/4, Sec. 11, T46N, R8W, Callaway Co.

Receiving Stream: tributary to 100K Extent remaining stream Receiving & First classified Stream & ID: 100K Extent remaining stream (C) WBID #3960 USGS Basin & Sub-watershed No.: Cow Creek (10300103-1504)

Application Design & Storm Flow: 4.8 MGD; daily flow is dependent on precipitation Outfall 015 modification As the current Callaway NPDES Permit states, Outfall 015 is storm water discharge from approximately 60 acres (0.6 acres impervious), draining areas around the north and northeast portion of the plant site. As you can see from Drawing 1, the red arrow at Outfall 015 is the proposed new sample and discharge point and the black arrow is the current sample and discharge point.

Proposed new facility description Outfall 015: Stormwater UTM Coordinates: X = 605939; Y=4292059 Legal

Description:

NE 1/4, SE 1/4, Sec. 11, T46N, R8W, Callaway Co.

Receiving Stream: classified tributary to Canyon Lake (L3)

ULNRC-06715 Page 4 of 4 Receiving & First classified Stream & ID: 100K Extent remaining stream (C) WBID #3960 USGS Basin & Sub-watershed No.: Cow Creek (10300103-1504)

Application Design & Storm Flow: 2.8 MGD; daily flow is dependent on precipitation