Physical climate risk assessment, Mesa Point Residences, Mesa Point, SC

Exposure of four multifamily buildings and the site transformer to six climate hazards under a lower and a higher emissions scenario through 2100, for the IFRS S2 disclosure of Saltgrass Residential Fund I. Building D and the transformer fall below the projected 2100 flood elevation, and riverine flood exposure at Building A is higher than in the 2022 resilience memo.

New construction, 142 units in four buildingsIFRS S2 and TCFD physical riskLower (RCP4.5) and higher (RCP8.5) emissionsSC State Plane NAD83(2011), intl. ft; NAVD 8847 values in the source logPrepared Nov 5, 2026

Summary

Coastal flooding

Building D sits 0.5 ft below the 2100 flood elevation under higher emissions

The coastal BFE of 10.0 ft plus 5.0 ft of sea level rise after 2025 under the 2022 Intermediate-High scenario gives 15.0 ft. Building D has an FFE of 14.5 ft on sheet C-101 Rev C. Under lower emissions the freeboard is 1.0 ft. Transformer T1 (12.0 ft) falls below the 2100 elevation in both scenarios.

Action: raise Building D and the transformer to at least 15.5 ft, or floodproof them to that elevation.

Riverine flooding

Mesa Creek moves from low to medium with the 2025 Preliminary FIRM

The 2022 memo used the 2007 effective FIRM, which showed Building A in shaded Zone X (R-13). The 2025 Preliminary FIRM puts it in Zone AE with a BFE of 18.0 ft (R-11), 1.0 ft below the FFE of 19.0 ft. The 0.2% annual chance elevation of 18.8 ft (R-12) leaves 0.2 ft.

Action: no entries or electrical rooms at Building A below 19.5 ft.

Source log

The memo's design flood elevation rests on an older sea level dataset

R-07 (4.9 ft, 2017 report) and R-05 (5.5 ft, 2022 report) are the same Intermediate-High scenario for 2100 in two versions. The 14.4-ft design flood elevation in the 2022 memo (R-08) was computed from R-07. The other 46 values are current versions or stated assumptions.

Action: update the resilience memo to the 2022 scenarios before the disclosure is filed.

Exposure by hazard, scenario and period

Choose a scenario, a period and a hazard. The map shows the hazard across the site, and each building is colored by the freeboard between its finished floor and the projected elevation. The matrix shows every hazard and column, and the source log has one row for each value the assessment uses.

Scenario
Period
Hazard

Hazard × scenario matrix

Click a cell to show the hazard on the map. Material means high exposure in any column or medium in at least two future columns.

Source log

Hazard screening Acute and chronic hazards, flooding split into four types

Sources and method

Sources

  • C-101_Site_Grading_Plan_RevC.pdfFFE of each building, top of transformer pad, grades and courtyard low point1 sheet
  • Climate_Resilience_Memo_SD_2022-05-17.pdfPrior assessment at schematic design18 pages
  • FIRM_0415J_Effective_2007.pdf, Preliminary_FIRM_0415K_2025.pdfFlood zones and BFEs, effective and preliminary, with the Mesa Creek FIS profile2 panels
  • Geotechnical_Report_Mesa_Point_Residences.pdfSoils, pile foundations and Mesa Creek bank condition64 pages
  • Mesa_Point_Stormwater_Master_Plan_2024.pdf2D ponding depths for the 100-year, 24-hour storm with and without a 20% factor112 pages
  • Town_of_Mesa_Point_Flood_Damage_Prevention_Ordinance.pdfMinimum lowest floor at BFE + 2 ft14 pages
  • Federal datasets2022 and 2017 Interagency Sea Level Rise Technical Reports, CMRA Assessment Tool, NOAA Atlas 14, ASCE Hazard Tool, NRCS Web Soil Survey and USGS 3DEP, retrieved Oct 26–30, 202647 values

Method

  1. Screening. Acute and chronic hazards in four groups (temperature, wind, water, solid mass) were screened for the site. Six hazards were carried forward. The rest are explained in the screening table.
  2. Data. Values were retrieved for a baseline, mid-century and late century. CMRA gives lower (RCP4.5) and higher (RCP8.5) emissions. Sea level rise uses the 2022 Intermediate scenario for lower and Intermediate-High for higher emissions, the pairing CMRA uses. Each value has one row in the source log with source, version and retrieval date.
  3. Flood elevations. For coastal, riverine and pluvial flooding the projected elevation was compared with the FFE. Freeboard of 1.5 ft or more is low, 0 to 1.5 ft medium and below 0 high exposure.
  4. Other hazards. Heat, hurricane wind and bank erosion were rated with indicators and thresholds shown in the detail panel.
  5. Materiality and measures. A hazard is material with high exposure in any column or medium in at least two future columns. Material hazards get adaptation measures, the others are monitored.
  6. Check. Results were compared with the 2022 memo, and the source log was checked so that each dataset is used in one version only.

Assumptions and limitations

  • Future coastal flood elevation is the BFE plus sea level rise after 2025. Changes in surge and wave height are not modeled.
  • FEMA elevations reflect present conditions. The 0.2% annual chance elevation is used as the riverine future-conditions proxy in every future column. The Preliminary FIRM is not yet effective.
  • The stormwater master plan's 20% factor is used in every future column. Sea level rise beyond 2100 is shown as a sensitivity case: 16.0 ft in 2150 under the Intermediate scenario, which leaves Building C 0.5 ft of freeboard.
  • CMRA values are LOCA (CMIP5) projections. If the tool moves to LOCA2 (CMIP6), values and scenario labels change and the log should be refreshed.
  • Wind is rated on the 2024 South Carolina code basis (2024 IBC with ASCE 7-22), which applies to permits submitted from Jan 1, 2027. Through Dec 31, 2026 the state enforces the 2021 IBC, which references ASCE 7-16.
  • The map is schematic. Extents are computed from the grading plan and the USGS 3DEP DEM. Exposure is rated against floor elevations, not against the map image.
  • Thresholds for heat and bank erosion are the assessment's own and should be confirmed with the fund. Wind is rated on the current code hazard. The erosion rating is qualitative and does not replace a geotechnical scour study.
  • The 145 mph basic wind speed is read from the ASCE Hazard Tool and has not been rechecked for the site. The structural engineer of record should confirm it.
  • The flood method (BFE plus sea level rise, and the 0.2% elevation as the riverine future-conditions proxy) is a simplification. A coastal or floodplain engineer should review it before the ratings are used for design.