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Home My WebLink About20020158 Ver 3_Monitoring Report_202309294700 Falls of Neuse Rd, Suite 300 WhARaleigh, NC 27609 moffatt & nichol (919) 781-4626 MEMORANDUM To: Greg Currey (LISACE) From: Brandon Grant (MN) Cc: Tara MacPherson (NC DCM); Holley Snider (NC DWR); Lisa Anglin (Town of Sunset Beach), Dustin Graham (Town of Sunset Beach) Date: September 29, 2023 Subject: Town of Sunset Beach — South Jinks Creek: Nearshore Placement Area Monitoring Report (Year 2 Post -Construction) M&N Job No.: 9269-03 This Memorandum serves as the Town of Sunset Beach's (Town) summary of Year 2 post -construction monitoring results per SAW-2018-02230, Special Condition 15, which requires the Town to conduct a hydrographic survey of the nearshore placement area to evaluate the movement of this material within the nearshore zone. In review, the Town placed approximately 51,000 cy of beach compatible material from the dredging of South Jinks Creek between December 2021 and March 2022. The Physical Monitoring Plan (PMP, see attachment A), of the nearshore placement area includes 19 survey transects starting at Tubbs inlet to the east (00+00) and extends to 301" St to the west (88+00) as shown in Figure 1. The nearshore placement area is 2,000 ft long and 150 ft wide and is approximately 700 ft offshore between transects 54+00 and 70+00. The Town will continue to monitor the nearshore placement area utilizing the same transect lines via topographic and hydrographic survey means in accordance with the PMP with the final survey occurring in September 2024. Survey Schedule The pre -placement conditions survey was taken during two different survey efforts. The first occurred on July 5, 2018, and collected survey data for transects 54+00 through 70+00. The survey data for the remaining transects (0+00 — 50+00 and 74+00 — 88+00) was collected May 9, 2022, approximately two months after project completion. It is assumed that the material placed in the nearshore placement area during the South Jinks Creek Shallow Draft Navigation Project had not migrated outside the nearshore placement area. Therefore, this survey was considered to represent the pre -placement conditions. The first post placement survey was taken on September 2, 2022, approximately 6 months after project completion (March 2022) as required. The second post placement survey was taken on August 8, 2023, approximately 17 months after project completion. The post placement surveys are plotted with the pre - placement condition survey and the nearshore placement area template when present (see Attachment B). September 29,2023 M&N # 926933 Memorandum \ - ~ ,i§�� -■§ e � 2 ■ Figure ISunset ea§Pyi IummAgRa #a seer September 29, 2023 Analysis Methodology M&N # 9269-03 Memorandum Sediment movement and migration trends are analyzed through the comparison of elevation change along the individual transects within the region of the nearshore placement extent offshore (approximately 1300 ft — 1700 ft from the baseline). The transects along the eastern (50+00 and 54+00) and western limits (70+00 and 74+00) of the nearshore placement area of the with the nearshore placement area template. These transects were selected in order to further understand the alongshore movement of sediment outside the extents of the nearshore placement area. Results The material placed within the nearshore placement area continues to remain within the limits of the placement area. Equilibration of the material continues to occur primarily in the cross -shore direction between transects 54+00 and 70+00 (See Transects in Attachment B). This remains consistent for both the first and second post placement surveys (2022 and 2023). Transect 54+00, which is the last transect within the nearshore placement area along the eastern extent, shows continued cross -shore equilibration of the material placed within the nearshore placement area. Transect 50+00, which is the first transect outside the nearshore placement area along the eastern limit, shows no increase in elevation within the nearshore placement extent offshore (see Figure 2). A similar trend is also noted at Transect 40+00. This is indicative of no longshore movement of material placed within the nearshore placement area to the east towards Tubbs Inlet. The remaining transects towards Tubbs inlet (00+00 — 30+00) show changes in conditions between the surveys within the nearshore bar; however, these changes are most likely attributed to the influence of the Tubbs Inlet ebb shoal bar as it connects to the shoreline and not the migration of nearshore placement material (See Attachment B for Transect Plots). Similar, to the eastern end, the western end transects of 70+00 and 74+00 were compared and showed the same trend of cross shore equilibration of placement material within the nearshore placement area at transect 70+00, with minimal change noted at transect 74+00 (see Figure 3). The remaining transects to the west (76+00 — 88+00) show minimal change offshore of the nearshore bar indicating no longshore movement of material from the nearshore placement area to the west. Summary The placement of dredge material from the South Jinks Creek Shallow Draft Navigation Project remains within the nearshore placement area with equilibration occurring in the cross -shore direction. Longshore migration of this material to the east and west of the nearshore placement area appears to be negligible. The Town will continue to monitor this area until Fall 2024 in accordance with the PMP and will provide results upon completion. 3 September 29, 2023 MTV ;A 012V T, i L7 20 oo 15 00 > 10 a 5 z _ 0 0 -5 0 10 w 15 -20 -25 50+00 M&N # 9269-03 Memorandum 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 Distance from Baseline (ft) 50+00 220509 50+00 220902 54+00 25 20 00 00 15 > 10 a z 5 50+00 230808 ctf 0 0 -5 -10 a>i 15 "' -20 -25 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 Distance from Baseline (ft) 54+00 180705 54+00 220902 54+00 230808------- 54+00 Nearshore Placement Area Template Figure 2 Eastern Limits of Nearshore Placement Area U September 29, 2023 Tn2 L7 20 00 oo 15 0 > 10 a z 5 0 0 -5 -10 -15 "' -20 -25 70+00 M&N # 9269-03 Memorandum 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 Distance from Baseline (ft) 70+00 180705 70+00 220902 70+00 230808------- 70+00 Nearshore Placement Area Template 74+00 LJ 20 oo 15 00 10 Z 5 e 0 c: 0 5 ro -10 w 15 -20 -25 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 Distance from Baseline (ft) 74+00 220509 74+00 220902 74+00 230808 Figure 3. Western Limits of Nearshore Placement Area 5 September 29, 2023 Enclosures: Attachment A: Nearshore Placement Physical Monitoring Plan Attachment B: Nearshore Placement Survey Comparison M&N # 9269-03 Memorandum BY Hydrographic surveys shall be conducted for 3 years post construction to evaluate the material migration of the nearshore placement. Surveys shall be conducted from the MLW line out 1,500 feet to capture the placement area and transport region. A monitoring report shall be provided to the project stakeholders for review and shall evaluate the migration patterns of the placed material. LEGEND SURVEY BASELINE SURVEY AZIMUTHS PLACEMENT AREA TOWN OF SUNSET BEACH - NAVIGATION PROJECT MAINTENANCE DREDGING OF SOUTH JINKS CREEK o' i,000' 2,000' PHYSICAL MONITORING PLAN SITE MAP GRAPHIC SCALE IN FEET each SurSek F_1_J___1 Miles Esri, Garmin, GEBCO, NOAA 0 0.5 1 2 NGDC, and other contributors Legend Elevation (ft, NAVD88) • 24.01 - 26.00 -5.99 - -4.00 • 22.01 - 24.00 -7.99 - -6.00 • 20.01 - 22.00 • -9.99 - -8.00 • 18.01 - 20.00 • -11.99 - -10.00 • 16.01 - 18.00 • -13.99 - -12.00 0 14.01 - 16.00 0 -15.99 - -14.00 12.01 - 14.00 0 -17.99 - -16.00 10.01 - 12.00 -19.99 - -18.00 8.01 - 10.00 -21.99 - -20.00 6.01 - 8.00 • -23.99 - -22.00 4.01 - 6.00 • -25.99 - -24.00 2.01 - 4.00 • -27.99 - -26.00 0.01 - 2.00 • -29.99 - -28.00 -1.99 - 0.00 • -31.99 - -30.00 -3.99 - -2.00 • -32.63 - -32.00 Nearshore Placement Area Survey Transects 0 400 800 1,600 Feet 1 inch = 800 feet w� Notes: E -Aerial Imagery: NCOneMap 2020 -Coordinate System: State Plane NAD83 (2011) -Survey Date Sta 54+00 - 70+00: July 2018 -Survey Date Sta 0+00 - 50+00, 74+00 - 88+00: May 2022 Sunset Beach Shallow Draft Navigation Project: Nearshore Placement Area Pre -Placement Conditions Drawn By: Brandon Grant Review By: Sam Morrison Date: 5/19/2022 Map Scale: 1:800 hghq �noffatt & nichol Moffatt & Nichol 4700 Falls of Neuse Rd. Suite 300 Raleigh, NC 27609 919-781-4626 www.moffattnichol.com Su�se� each Miles Esri, Garmin, GEBCO, NOAA 0 0.5 1 2 NGDC, and other contributors Legend Elevation (ft, NAVD88) * 24.01 - 26.00 -5.99 - -4.00 * 22.01 - 24.00 -7.99 - -6.00 • 20.01 - 22.00 -9.99 - -8.00 * 18.01 - 20.00 • -11.99 - -10.00 * 16.01 - 18.00 • -13.99 - -12.00 14.01 - 16.00 • -15.99 - -14.00 12.01 - 14.00 9 -17.99 - -16.00 10.01 - 12.00 -19.99 - -18.00 8.01 - 10.00 -21.99 - -20.00 6.01 - 8.00 • -23.99 - -22.00 4.01 - 6.00 • -25.99 - -24.00 2.01 - 4.00 0 -27.99 - -26.00 0.01 - 2.00 • -29.99 - -28.00 -1.99 - 0.00 • -31.99 - -30.00 -3.99 - -2.00 0 -32.63 - -32.00 Nearshore Placement Area Survey Transects 0 400 800 1,600 Feet 1 inch = 800 feet w� E S' Notes: -Aerial Imagery: NCOneMap 2020 -Coordinate System: State Plane NAD83 (2011) -Survey Date Sta 0+00 - 70+00: Sep 2022 Sunset Beach Shallow Draft Navigation Project: Nearshore Placement Area 6 Month Post -Placement Conditions Drawn By: Brandon Grant Review By: Sam Morrison Date: 10/17/2022 Map Scale: 1:800 hJhq inoffatt & nichol Moffatt & Nichol 4700 Falls of Neuse Rd. Suite 300 Raleigh, NC 27609 919-781-4626 www.moffattnichol.com Beach Su�\Se� Miles Esri, Garmin, GEBCO, NOAA 0 0.5 1 2 NGDC, and other contributors Legend Elevation (ft, NAVD88) • 24.01 - 26.00 -5.99 - -4.00 • 22.01 - 24.00 -7.99 - -6.00 • 20.01 - 22.00 -9.99 - -8.00 • 18.01 - 20.00 -11.99 - -10.00 0 16.01 - 18.00 -13.99 - -12.00 0 14.01 - 16.00 -15.99 - -14.00 0 12.01 - 14.00 -17.99 - -16.00 10.01 - 12.00 -19.99 - -18.00 8.01 - 10.00 -21.99 - -20.00 6.01 - 8.00 • -23.99 - -22.00 4.01 - 6.00 • -25.99 - -24.00 2.01 - 4.00 • -27.99 - -26.00 0.01 - 2.00 • -29.99 - -28.00 -1.99 - 0.00 • -31.99 - -30.00 -3.99 - -2.00 • -32.63 - -32.00 Nearshore Placement Area Survey Transects 0 400 800 1,600 Feet 1 inch = 800 feet N Notes: s -Aerial Imagery: NCOneMap 2020 -Coordinate System: State Plane NAD83 (2011) -Survey Date Sta 0+00 - 88+00: August 2023 Sunset Beach Shallow Draft Navigation Project: Nearshore Placement Area Survey August 2023 Drawn By: Brandon Grant Review By: Sam Morrison Date: 8/10/2023 Map Scale: 1:800 hJhq moffatt & nichol Moffatt & Nichol 4700 Falls of Neuse Rd. Suite 300 Raleigh, NC 27609 919-781-4626 www.moffattnichol.com 25 WE 15 10 -10 -15 -20 25 L- 200 400 600 800 1000 1200 00+00 220509 00+00 1400 1600 1800 Distance from Baseline (ft) 00+00 220902 2000 2200 2400 2600 2800 3000 00+00 230808 25 WE 15 10 Z 5 00 0 Q z 0 0 i -5 10 -15 -20 -25 L- 200 400 600 800 1000 1200 10+00 220509 10+00 1400 1600 1800 Distance from Baseline (ft) 10+00 220902 2000 2200 2400 2600 2800 3000 10+00 230808 25 WE 15 10 Z 5 00 0 Q z 0 0 i -5 10 -15 -20 -25 L- 200 400 600 800 1000 1200 20+00 220509 20+00 1400 1600 1800 Distance from Baseline (ft) 20+00 220902 2000 2200 2400 2600 2800 3000 20+00 230808 25 WE 15 10 Z 5 00 0 Q z 0 0 i -5 10 -15 -20 -25 L- 200 400 600 800 1000 1200 30+00 220509 30+00 1400 1600 1800 Distance from Baseline (ft) 30+00 220902 2000 2200 2400 2600 2800 3000 30+00 230808 25 20 15 10 Z 5 00 0 Q z 0 0 i -5 10 -15 -20 -25 L- 200 400 600 800 1000 1200 40+00 220509 40+00 1400 1600 1800 Distance from Baseline (ft) 40+00 220902 2000 2200 2400 2600 2800 3000 40+00 230808 25 WE 15 10 Z 5 00 0 Q z 0 0 i -5 10 -15 -20 -25 L- 200 400 600 800 1000 1200 50+00 220509 50+00 1400 1600 1800 Distance from Baseline (ft) 50+00 220902 2000 2200 2400 2600 2800 3000 50+00 230808 25 WE 15 10 Z 5 00 0 Q z 0 0 v - w 5 10 -15 -20 -25 L- 200 400 600 800 1000 1200 54+00 180705 54+00 220902 54+00 1� 4W 1400 1600 1800 2000 2200 2400 2600 2800 3000 Distance from Baseline (ft) 54+00 230808 - - - - - 54+00 Nearshore Placement Area Template 25 WE 15 10 Z 5 00 0 Q z 0 0 v - w 5 10 -15 -20 -25 L- 200 400 600 800 1000 1200 58+00 180705 58+00 220902 58+00 1400 1600 1800 2000 2200 2400 2600 2800 3000 Distance from Baseline (ft) 58+00 230808 - - - - - 58+00 Nearshore Placement Area Template 25 WE 15 10 Z 5 00 0 Q z 0 0 v - w 5 10 -15 -20 -25 L- 200 400 600 800 1000 1200 62+00 180705 62+00 220902 62+00 1400 1600 1800 2000 2200 2400 2600 2800 3000 Distance from Baseline (ft) 62+00 230808 - - - - - 62+00 Nearshore Placement Area Template 25 WE 15 10 Z 5 00 0 Q z 0 0 v - w 5 10 -15 -20 -25 L- 200 400 600 800 1000 1200 66+00 180705 66+00 220902 66+00 0 1400 1600 1800 2000 2200 2400 2600 2800 3000 Distance from Baseline (ft) 66+00 230808 - - - - - 66+00 Nearshore Placement Area Template 25 WE 15 10 Z 5 00 0 Q z 0 0 v - w 5 10 -15 -20 -25 L- 200 400 600 800 1000 1200 70+00 180705 70+00 220902 70+00 1400 1600 1800 2000 2200 2400 2600 2800 3000 Distance from Baseline (ft) 70+00 230808 - - - - - 70+00 Nearshore Placement Area Template 25 WE 15 10 Z 5 00 0 Q z 0 0 i -5 10 -15 -20 -25 L- 200 400 600 800 1000 1200 74+00 220509 74+00 1400 1600 1800 Distance from Baseline (ft) 74+00 220902 2000 2200 2400 2600 2800 3000 74+00 230808 25 WE 15 10 Z 5 00 0 Q z 0 0 i -5 10 -15 -20 -25 L- 200 400 600 800 1000 1200 76+00 220509 76+00 1400 1600 1800 Distance from Baseline (ft) 76+00 220902 2000 2200 2400 2600 2800 3000 76+00 230808 25 WE 15 10 Z 5 00 0 Q z 0 0 i -5 10 -15 -20 -25 L- 200 400 600 800 1000 1200 78+00 220509 78+00 1400 1600 1800 Distance from Baseline (ft) 78+00 220902 2000 2200 2400 2600 2800 3000 78+00 230808 25 WE 15 10 00 5 00 0 Q z 0 0 i -5 10 -15 -20 -25 L- 200 400 600 800 1000 1200 80+00 220509 1400 1600 1800 Distance from Baseline (ft) 80+00 220902 2000 2200 2400 2600 2800 3000 80+00 230808 25 WE 15 10 Z 5 00 0 Q z 0 0 i -5 10 -15 -20 -25 L- 200 400 600 800 1000 1200 82+00 220509 82+00 1400 1600 1800 Distance from Baseline (ft) 82+00 220902 2000 2200 2400 2600 2800 3000 82+00 230808 25 WE 15 10 00 5 00 0 Q z 0 0 i -5 10 -15 -20 -25 L- 200 400 600 800 1000 1200 84+00 220509 1400 1600 1800 Distance from Baseline (ft) 84+00 220902 2000 2200 2400 2600 2800 3000 84+00 230808 25 WE 15 10 00 5 00 0 Q z 0 0 i -5 10 -15 -20 -25 L- 200 400 600 800 1000 1200 86+00 220509 1400 1600 1800 Distance from Baseline (ft) 86+00 220902 2000 2200 2400 2600 2800 3000 86+00 230808 25 WE 15 10 00 5 00 0 Q z 0 0 i -5 10 -15 -20 -25 L- 200 400 600 800 1000 1200 88+00 220509 1400 1600 1800 Distance from Baseline (ft) 88+00 220902 2000 2200 2400 2600 2800 3000 88+00 230808