The URL can be used to link to this page

Home My WebLink About20070721 Ver 2_Monitoring Report_20240924Jennings Environmental 7 Samuel Ashe Drive, Asheville, NC 28805 1 919-600-4790 1 greg@jenningsenv.com September 24, 2024 Regulatory Agencies: RE: CITY OF HENDERSONVILLE NORTH FORK RESERVOIR SEDIMENT RELEASE DOWNSTREAM MONITORING REPORT The attached monitoring information is provided to satisfy permit conditions regarding documentation of downstream impacts associated with sediment release through the bottom valve opening of the North Fork Reservoir dam. The valve was installed and opened for bottom release in August 2023 following completion of dredging operations. The intent of the bottom release is to discharge cool water with natural sediment concentrations while maintaining sufficient water volume in the reservoir for the City's water supply. The Jennings team visually monitored the six permanent downstream cross -sections quarterly since the October 2023 monitoring report. No fine sediment accumulation was observed at any of the cross - sections during the monitoring period. An annual cross-section survey was completed on September 20, 2024. The monitoring data and visual observations of the 6 cross -sections indicated no substantial accumulation of fine sediment on the stream channel bed downstream of the reservoir. Future monitoring through 2026 will consist of quarterly visual observations and annual cross-section surveys per the approved monitoring plan. Please contact me with any questions. Respectfully Submitted, A,rj b, �—� Gregory D. Jennings, Ph.D., P.E., President Jennings Environmental PLLC Attachment: Channel Bed Survey Information and Photographs Jennings Environmental PLLC is licensed with the North Carolina Board of Examiners for Engineers and Surveyors and is authorized to practice engineering under the provisions of Chapter 89C and 55B of the General Statutes of North Carolina. License Number P-1932. North Fork Reservoir Sediment Release Program Downstream Channel Bed Monitoring City of Hendersonville Cross Section 1 — Riffle 98 97 IL 96 w 0 95 y a� —Ar- May 2023 W 94 --*--sep-23 —F 5ep-24 93 0 5 10 15 20 25 30 35 40 45 Distance (feet) *Channel bed measured perpendicular to flow with laser level and tape from a fixed benchmark North Fork Reservoir Sediment Release Program Downstream Channel Bed Monitoring City of Hendersonville May 2023 September 2023 A 74°E (T) O 35.419540°,-82.674764, ±62ft ♦ 2449ft September 2024 View of Cross -Section 1 Facing Downstream May 2023 — Before dredging and bottom release opening September 2023 — After dredging and bottom release opening September 2024 — Year 1 Cross -Section Survey North Fork Reservoir Sediment Release Program Downstream Channel Bed Monitoring City of Hendersonville Cross Section 2 — Pool 97 96 95 w 0 94 y a� W —&-- 1iav 2023 93 t Sep-23 —K--Sep-24 92 0 5 10 15 20 25 30 35 40 45 Distance (feet) *Channel bed measured perpendicular to flow with laser level and tape from a fixed benchmark North Fork Reservoir Sediment Release Program Downstream Channel Bed Monitoring City of Hendersonville May 2023 September 2023 ® 76°E (T) * 35.4196341,-82.674808° ±32ft ♦ 2454ft September 2024 View of Cross -Section 2 Facing Downstream May 2023 — Before dredging and bottom release opening September 2023 — After dredging and bottom release opening September 2024 — Year 1 Cross -Section Survey North Fork Reservoir Sediment Release Program Downstream Channel Bed Monitoring City of Hendersonville Cross Section 3 — Pool 99 98 97 96 w 95 .p 94 93 W 92 —�lfay 2023 91 t Sep-23 —K--Sep-24 90 0 5 10 15 20 25 30 35 40 Distance (feet) *Channel bed measured perpendicular to flow with laser level and tape from a fixed benchmark North Fork Reservoir Sediment Release Program Downstream Channel Bed Monitoring City of Hendersonville May 2023 September 2024 September 2023 View of Cross -Section 3 Facing Downstream May 2023 — Before dredging and bottom release opening September 2023 — After dredging and bottom release opening September 2024 — Year 1 Cross -Section Survey North Fork Reservoir Sediment Release Program Downstream Channel Bed Monitoring City of Hendersonville Cross Section 4 — Riffle 98 97 96 w 95 0 94 W —ir—lfav 2023 93 +Se-p-23 —K--Sep-24 92 0 5 10 15 20 25 30 35 40 Distance (feet) *Channel bed measured perpendicular to flow with laser level and tape from a fixed benchmark North Fork Reservoir Sediment Release Program Downstream Channel Bed Monitoring City of Hendersonville May 2023 September 2024 View of Cross -Section 4 Facing Downstream September 2023 May 2023 — Before dredging and bottom release opening September 2023 — After dredging and bottom release opening September 2024 — Year 1 Cross -Section Survey North Fork Reservoir Sediment Release Program Downstream Channel Bed Monitoring City of Hendersonville Cross Section 5 — Riffle 98 97 96 ,-, w 95 0 94 W flfay 2023 93 t5ep-23 92 —K--Sep-24 0 5 10 15 20 25 30 35 Distance (feet) *Channel bed measured perpendicular to flow with laser level and tape from a fixed benchmark North Fork Reservoir Sediment Release Program Downstream Channel Bed Monitoring City of Hendersonville May 2023 0 39-NE (T) O 35.419855°,-82.674022" ±26ft ♦ 2449ft September 2024 View of Cross -Section 5 Facing Downstream September 2023 May 2023 — Before dredging and bottom release opening September 2023 — After dredging and bottom release opening September 2024 — Year 1 Cross -Section Survey North Fork Reservoir Sediment Release Program Downstream Channel Bed Monitoring City of Hendersonville Cross Section 6 — Pool 97 96 95 94 93 .p 92 91 W 90 —*-- May 2023 t Sep-23 89 —K--Sep-24 88 0 10 20 30 40 50 Distance (feet) *Channel bed measured perpendicular to flow with laser level and tape from a fixed benchmark North Fork Reservoir Sediment Release Program Downstream Channel Bed Monitoring City of Hendersonville May 2023 ® 44-NE (T) OO 35.420185°,-82.673978" ±108ft ♦ 2450ft September 2024 View of Cross -Section 6 Facing Downstream September 2023 May 2023 — Before dredging and bottom release opening September 2023 — After dredging and bottom release opening September 2024 — Year 1 Cross -Section Survey North Fork Reservoir Sediment Release Program Downstream Channel Bed Monitoring City of Hendersonville Representative Site Photos — September 2024 Dredge Spoil Stockpile Area View Facing Downstream from the Dam View Facing Upstream Towards the Dam Reservoir