# Independent wall-evidence validation — October 20, 2026

This review checked the model's wall derivation and public City/Coastal Commission evidence. No wall or public simulation assets were changed. Public documents establish dated anchors, not a current continuous survey. Model results must retain that distinction.

## Strongest existing-height evidence

| Reach | Best located evidence | Status and interpretation | Current model |
|---|---|---|---|
| Main Island north | City July 24, 2018 completion report, Contract 7066-1: 8.5 ft NAVD88 | Completed City-reported rounded reach height; not a present minimum survey | Appropriate historical anchor, qualified |
| Main Island south, up to Collins Avenue Bridge | Same completion report: 9.0 ft NAVD88 | Completed City-reported reach; do not extend the stated south scope indiscriminately | Appropriate historical anchor, qualified |
| Main Island west | Same report confirms cap construction on west side but supplies no distinct west crest | Nearest north/south value remains inference | Keep nearest-source label; never call measured |
| Grand Canal | City August 8, 2017 rounded existing summary: 8.5 ft NAVD88 | Grand Canal explicitly excluded from cap project | Historical rounded sector fallback, not exact continuous crest |
| Grand Canal at 206/206½ | June 2022 signed topographic survey: upper TW points approximately 8.47 / 8.51 / 8.55 ft NAVD88 | Explicit benchmark NB3-20-92 = 8.364 ft NAVD88; discrete points, not continuous minimum; later PMA/City 8.62-ft summary conflicts with survey | Approximately corroborates rounded 8.5-ft fallback locally; retain 8.62 only as a source-conflict marker |
| Little Island east/south | City August 8, 2017: existing 8.7 / 9.0 ft NAVD88, rounded | Existing values, not proposed; late-1980s raising mentioned | Suitable historical sector anchors; elsewhere still inferred |
| Balboa Peninsula | January 2017 City point layer has explicit TOP WALL/TW observations | Point dates old; source layer does not publish vertical datum; only 528 of 600 records qualify as crest observations | Datum assumed NAVD88 remains unresolved; interpolation/fallback are scenario inputs |

### Completion versus proposal

The July 2018 completion report remains the strongest located primary evidence that the Main Island cap was built. It describes approximately nine inches added on north, south and west, and finished north/south crest levels. Its milestone table erroneously gives a 2017 completion date despite January 2018 start and July 2018 report; retain report date and flag typo. The location-map attachment does not resolve a western crest. Both original DOC and DOCX attachment URLs returned HTTP 200 in this review; the older View.ashx PDF URL returned 410 in the browser, so use the original attachment as a durable alternate.

- [July 24, 2018 completion report, original DOC](https://newportbeach.legistar1.com/newportbeach/attachments/27646a7d-f241-427d-920d-4fc423dd3bbe.doc)
- [Completion location map](https://newportbeach.legistar1.com/newportbeach/attachments/5fafae02-b584-4ceb-b7ba-6836b342d269.pdf)
- [August 8, 2017 report, original DOCX](https://newportbeach.legistar1.com/newportbeach/attachments/cb384fe1-75de-4e30-a9e9-bf79c86d3a90.docx)
- [City January 2017 seawall observations, layer 403](https://nbgis.newportbeachca.gov/arcgis/rest/services/LayerCatalogMap/MapServer/403)

The 2017 summary is explicitly rounded and cannot justify per-inch threshold precision. Its design includes 29 street-end and four public-dock cap gaps, intended for temporary closures. Treating them sealed is the selected scenario, not evidence that barriers are installed, watertight or crest-matched today.

## Local Grand Canal survey and conflicting summary

The retrieved **June 2022 topographic survey** at 206 and 206½ Grand Canal is the strongest located local height evidence. It is signed by **Lore K. Toomey, LS 4459**, June 17, 2022, and explicitly references **NB3-20-92 = 8.364 ft NAVD88**. Upper canal-wall TW labels near the frontage read approximately **8.47 ft north, 8.51 ft midway and 8.55 ft south**. These discrete measurements approximately corroborate the model's rounded **8.5-ft** fallback; they do not certify the current continuous minimum. A parallel lower wall top has separate TW labels near 7.93–7.96 ft and must not be substituted for the higher flood-controlling crest.

The survey is preserved in the [original PMA report, May 25, 2023, PDF page 8](https://ecms.newportbeachca.gov/Web/0/edoc/3163710/01%20-%20Coastal%20Hazards%20Report_2023-05-25.pdf) and [approved plans, PDF page 6](https://ecms.newportbeachca.gov/Web/0/edoc/3173084/20231026_Plans%20Approved.pdf). Enlarged wall and benchmark images are retained beside this report. No 8.62-ft TW label was established on the supplied survey.

PMA report page 3 nevertheless states **8.62 ft NAVD88**, attributing it to that enclosed survey. [City resolution ZA2023-065, October 26, 2023, PDF page 19](https://www.newportbeachca.gov/pln/ZA_Staff_Action/Archive/2023/10-27-2023.pdf) repeats 8.62 and also contains inconsistent 7.7-versus-8.62 overtopping arithmetic. These summaries are a **source conflict, not an independent measured crest**. Do not adopt or test 8.62 as a confirmed correction. The underlying documents are already downloaded; remaining work is survey-to-GIS transformation, feature interpretation, reconciliation and current-condition verification.

Actual City parcel records, OBJECTIDs 18930 and 18931, share APN **050 191 09** and geometry; they are duplicate 206/206½ address records, not independent frontages. Saved parcel and projected-wall files identify approximately 9.134 m of City wall OBJECTID 124, model samples **CW124-0-00191 through CW124-0-00200**, all 8.5 ft via nearest documented sector. The parcel and wall are separated by 4.115 m, so the frontage is a qualified projection across intervening public space, not an exact parcel intersection or georeferenced survey. Detailed source retrieval and spatial limits follow below.

## Peninsula source conflicts and bounded anchors

**1615 East Bay Avenue, APN 048-231-39.** [CCC April 21, 2022 report 5-21-0908](https://documents.coastal.ca.gov/reports/2022/5/W8c/W8c-5-2022-report.pdf) p10 gives existing 9.5 ft NAVD88 and proposed 10.9. Page12 contains inconsistent existing-cap arithmetic around 6.7–6.84. Do not replace the model automatically from this conflicting summary. The [original exhibits](https://documents.coastal.ca.gov/reports/2022/5/W8c/W8c-5-2022-exhibits.pdf) contain a 2020/2021 topographic survey and should control a spatial reconciliation; saved parcel-clipped wall geometry is a 30-ft frontage anchor, not a survey transformation. No completion evidence was established here.

**2100/2102 East Balboa Boulevard, APNs 048-240-35/38.** [CCC February 20, 2025 report 5-24-0359](https://documents.coastal.ca.gov/reports/2025/3/Th6d/Th6d-3-2025-report.pdf), PDF page9, calls existing wall height a **maximum 8.90 ft NAVD88** and proposes 11.10. A maximum cannot certify the minimum overtopping crest of either 73.5-ft frontage. [Plans](https://documents.coastal.ca.gov/reports/2025/3/Th6d/Th6d-3-2025-exhibits.pdf) and current inspection/as-built confirmation are needed; proposed height must not replace existing input without completion evidence.

**1805/1807 East Bay Avenue.** [CCC September 24, 2026 report, hearing October 7](https://documents.coastal.ca.gov/reports/2026/10/W16b-W16c/W16b-W16c-10-2026-report.pdf) is a new-wall proposal: 7.5-ft NAVD88 coping, 11.0-ft stem, future adaptability 14.4. These distinct features must not be conflated into an existing crest. Report PDF title metadata is wrong; first page identifies Newport applications 5-26-0220/0221. Recent proposed work does not establish completed barriers.

No primary source reviewed supports a Peninsula-wide uniform existing 8.3 or 8.5-ft NAVD88 seawall. The model should continue using spatially sourced observations with explicit assumptions, rather than importing Island numbers.

## Newer plans do not supersede existing-height observations

The [City Harbor & Beaches Master Plan, last updated February 27, 2025](https://www.newportbeachca.gov/home/showpublisheddocument/76788/638851662157830000) schedules Grand Canal/west-end replacement for 2028, east/south Little Island for 2034, north/south Main Island for 2039 and Peninsula street ends for 2027. These are planned start years and estimates, not an as-built survey or proof that every planned task remains unchanged in October 2026. No newer continuous measured crest inventory was established in this review.

## Recommended corrections and validation gates

1. Preserve the benchmark-controlled June 2022 survey at 206 Grand Canal as discrete local crest evidence, and PMA's 8.62-ft summary as a source-conflict marker. Retain the approximately corroborated 8.5-ft regional fallback until survey stations are transformed and current condition checked. Do not adopt 8.62 as a confirmed correction or sensitivity anchor.
2. Expose a source-status distinction: completed historical City reach, dated point with unconfirmed datum, interpolated, nearest inferred, assumed sealed opening. One-meter sampling does not create one-meter surveyed accuracy.
3. Resolve January2017 datum against source survey/control benchmarks before using it for absolute inch thresholds. Do not assign a blanket vertical offset from one parcel.
4. Confirm current cap minima and closure-board tops by benchmark-controlled survey, especially Main Island north/Grand Canal nearest the 8.5-ft scenario peak. Cross-check LiDAR point clouds only with geometric feature identification; bare-earth DEM omits thin walls.
5. Record confirmed survey extent, observation date, reference benchmark/datum realization, feature type and minimum crest along each hydraulic frontage. Do not propagate private-frontage values across neighboring seawalls or promote maximum to minimum.
6. Continue treating sealed gaps and nearest-height connections as selected boundary assumptions. These do not validate leakage, drains, sub-wall seepage, closure condition, storm waves or tide-to-harbor water-level transfer.

This review strengthens provenance but does not establish present property-level flood accuracy or centimeter-level crest accuracy.


## Source retrieval, survey details and spatial applicability

City planning case [PA2023-0111](https://nbgis.newportbeachca.gov/gispub/EnergovPAsReportSing/default.aspx?PLANNUMBER=PA2023-0111) links the archived Laserfiche folder2910910. The archived source is accessible through a JavaScript browser even when search engines fail to index the PDFs. Folder2910911 (03 Application) includes the original coastal study; folder3016618 (08 Plans Approved) includes survey sheets. Planning closeout July8,2025 is archive status, not seawall construction proof.

- [Original PMA coastal report, May25,2023, City record3163710](https://ecms.newportbeachca.gov/Web/0/edoc/3163710/01%20-%20Coastal%20Hazards%20Report_2023-05-25.pdf): downloaded HTTP200 application/pdf,4,830,840bytes. PDFp3 states8.62 and attributes it to the enclosed survey; PDFp8 contains the actual survey. Some enclosed sheet dates are later than report cover; retain individual dates.
- [Approved plans, City record3173084](https://ecms.newportbeachca.gov/Web/0/edoc/3173084/20231026_Plans%20Approved.pdf): downloaded HTTP200 application/pdf,15,068,485bytes. PDFp6 is the same topographic survey, unrotated and easier to inspect. Approval stampOctober26,2023; CityPDFcreationJuly8,2025 is archive packaging, not survey date. Record3173085 is a duplicate approved-plan file.
- [Direct archived project folder](https://ecms.newportbeachca.gov/Web/Browse.aspx?dbid=0&id=2910910). Exact retrieval metadata retained in `206-grand-canal-ecms-browser.json` and `206-grand-canal-ecms-folders.json`; planning-case HTML is also retained.

### What the actual survey establishes

The topographic survey of Lot 4, Block 7, Section 5 is by **Lore K. Toomey, LS 4459**, dated **June 2022**, signed **June 17, 2022**. Its legend defines **TW = TOP OF WALL**. Benchmark **NB3-20-92, elevation 8.364 ft NAVD88**, an aluminum disk, identifies its seawall/bridge/Marine Avenue location. This establishes an explicit local datum tie absent from the January2017 GIS point layer, but does not establish survey error bounds, current condition or datum correctness of every other City survey.

Visible canal-wall top measurements near the206frontage are approximately **8.47ft atnorth,8.51ft midway,8.55ft atsouth**, with neighboring beyond-frontage values8.48north and8.53south. A parallel lower top line is also explicitly labelledTW at roughly **7.93–7.96ft**. Both must be interpreted geometrically: the lower exposed step/top is not automatically the flood-controlling upper crest. Property-side pilaster tops9.00/9.04ft are different structures, not canal protection crest. Ground/finished-surface6.62ft labels must not become wall heights.

I visually inspected the original survey sheet and enlarged wall/benchmark areas. **No 8.62-ft TW label was established on the supplied survey.** Therefore the PMA summary and downstream City 8.62-ft wording remain a source conflict; the underlying survey appears to support rounded 8.5 ft, within 0.05 ft / 1.52 cm at these three sampled upper-crest locations. These are discrete points, not a verified continuous minimum between them. Their decimal precision is not independently proven measurement accuracy.

### Spatial comparison with the model

The actual City parcel does not intersect the City inventory wall: minimum gap**4.11474m**, consistent with intervening boardwalk/public space and approximate GIS alignment. It would be false to call a constructed intersection an exact survey frontage. The nearest City wall is **OBJECTID124**, Little Island's canal side. Projecting the parcel's9.141m bay-facing edge onto that wall gives a**9.134m** approximate frontage, endpointsWGS84:

- south: **[-117.8887976874,33.6060264782]**
- north: **[-117.8887937720,33.6061087913]**

Saved as `206-grand-canal-wall-frontage.geojson`, explicitly labelled projection rather than intersection. Intersecting1m model samples are **CW124-0-00191 throughCW124-0-00200**, all8.5ftNAVD88 via `nearest-documented-sector` sourced toGrandCanal. Exact extracted model segments are in `206-grand-canal-modeled-frontage.geojson`. These are not georeferenced survey points; no fabricated exact locations were assigned to the8.47/8.51/8.55 measurements.

A defensible next step is a survey-to-GIS transformation using surveyed parcel-corner ties/bearings, then preserve the original TWpoints and identify the flood-controlling upper wall. Any interpolation should retain approximate transformation and discrete-survey provenance. This evidence does not justify overwriting the entire Little Island or GrandCanal reach.

### Working 2017 primary-source fallback

The original CityAugust8,2017 staff attachment **DOCX** remains HTTP200 and contains the full rounded height table, local copy`data/source/balboa-island-heights-2017.docx` with extracted text. Use [original attachment](https://newportbeach.legistar1.com/newportbeach/attachments/cb384fe1-75de-4e30-a9e9-bf79c86d3a90.docx) as fallback for the410View.ashxURL. [Legistar matter5202 attachmentsAPI](https://webapi.legistar.com/v1/newportbeach/matters/5202/attachments) independently locates the attachment. A working attachment confirms document availability, not new2026measurements.


### Audit trail

The initial search located the City/PMA 8.62-ft summary first. Following the City's archived planning-case links then retrieved the enclosed June 2022 survey, whose visible TW measurements differ from that summary. This report now leads with the underlying survey and retains the conflicting summary solely for traceability. No production wall height was changed at either stage.