20201279 Ver 1_Notice of Initial Credit Release/ NCDMS Cools Springs Mitigation Site

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Jeremiah,

The 15-Day As-Built/MY0 review for the NCDMS Cool Springs Mitigation Site (SAW-2020-01400) ended August 22, 2023. Per Section 332.8(o)(9) of the 2008 Mitigation Rule, this review followed
the streamlined review process. All comments received from the NCIRT are incorporated in the email below. There were no objections to issuing the initial 30% credit release of 1,459.080
Warm stream mitigation units and 0.394 wetland mitigation units. Please find attached the current signed ledger. The IRT is not requesting a site visit at this time.

Maria Polizzi, DWR:

1. It is difficult to tell from the photograph, but please confirm whether or not there is undercutting occurring on T2 at Photo Point 8.
2. I am not an engineer, so this may be by design, but multiple log sills shown in photographs look high to me. Is there a specification for log size? Did these turn out as expected?
Also please confirm that all log sills have footer logs.
3. Based on the photograph of the culvert at T3, this culvert does not appear to be embedded. DWR would prefer to see embedded culvert designs on future projects.
4. The riffle at Cross-Section 6 has more rock than DWR would prefer to see. It appears to be just a pile of rocks in the stream rather than a constructed riffle.
5. DWR appreciates the justification for red-line changes provided in Section 2.1.
6. There are a handful of deviations from the design that were captured in the cross-sections, some of which are outside the performance standard requirement for entrenchment ratio (must
stay over 2.2). Below are a few notable examples:

a. UT to Cedar Creek: The entrenchment ratio of 1.3, with a design range of 2.2 to 5 and pre-existing conditions at 1.5. This section became more entrenched.
b. T2: Width/Depth ratio is 27.4 with design at 14. Additionally, the entrenchment ratio is 1.5.
c. T3 R2: The entrenchment ratio is again lower than the pre-existing conditions and significantly lower than the design.
d. T6: Entrenchment ratio is 1.3.

Todd Tugwell, USACE:

1. Table 1.1 – what do the colors mean? I assume mitigation approach. Please label in future reports.
2. We understand that a repair is planned to rebuild a series of three consecutive failing sills on T2 and stabilizing bank erosion on the downstream right bank of UT to Cedar Creek,
which is propsosed to be conducted under a non-notifying NWP. The MY0 report also noted that a repair will occur on T8 in MY1 or MY2. Why would this repair not be conducted at the
same time as the repair on T2 and UT to Cedar Creek? I also don’t believe it is appropriate to state that “all project streams are stable” when in fact several repairs are planned
for failing structures.
3. Please be sure to include a discussion about the prescribed burn damage to planted stems in MY1 and replant if needed.
4. The flow gauges on T2 appears to be lower on the reach than indicated in the approved mit plan. Additionally, the gauges on T6 and T8 also appear to be lower on the reach than the
recommended top third. This was also noted as a comment in the draft mit plan review (reference DWR comment 21). Please note that additional monitoring of flow on intermittent reaches
may be required if questions about flow arise during annual reviews. Please ensure that flow gauges are place in accordance with recommendations on future project.
5. I appreciate the annotation of gate locations on the project maps.

Regards,

Todd Tugwell

Chief, Mitigation Branch

Regulatory Division

Wilmington District, USACE

[phone]

1) Table 1.1 – what do the colors mean? I assume mitigation approach. Please label in future reports.
2) We understand that a repair is planned to rebuild a series of three consecutive failing sills on T2 and stabilizing
bank erosion on the downstream right bank of UT to Cedar Creek, which is propsosed to be conducted under a
non-notifying NWP. The MY0 report also noted that a repair will occur on T8 in MY1 or MY2. Why would this
repair not be conducted at the same time as the repair on T2 and UT to Cedar Creek? I also don’t believe it is
appropriate to state that “all project streams are stable” when in fact several repairs are planned for failing
structures.
3) Please be sure to include a discussion about the prescribed burn damage to planted stems in MY1 and replant if
needed.
4) The flow gauges on T2 appears to be lower on the reach than indicated in the approved mit plan. Additionally,
the gauges on T6 and T8 also appear to be lower on the reach than the recommended top third. This was also
noted as a comment in the draft mit plan review (reference DWR comment 21). Please note that additional
monitoring of flow on intermittent reaches may be required if questions about flow arise during annual
reviews. Please ensure that flow gauges are place in accordance with recommendations on future project.
5) I appreciate the annotation of gate locations on the project maps.

Regards,

Todd Tugwell
Chief, Mitigation Branch
Regulatory Division
Wilmington District, USACE
[phone]

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