Suffolk CountyMassachusetts
Chelsea, Massachusetts
Bedrock sits a median 80 ft down across 21 logs, deeper than the Massachusetts median of 24 ft. 3 of its 14 inventoried bridges are rated poor (21%, against 9% statewide).
- Live · as of Sep 11, 2026
- 9 public sources · method
- ← All towns
Median depth to bedrock
80 ft
middle half 40–120 ft · 21 logs
Bridges rated poor
3
of 14 inventoried
State resilience grants
$90K
1 award on file
Construction projects
26
median $567K · public bid results
01 · Ground
Deep ground: 71% of logs go past 50 ft before rock
From 21 depth-to-rock records inside Chelsea (MassGIS / MGS borings & well logs). Logs cluster where people drill wells and bore for roads, so treat this as the town’s pattern, not a site answer.
Half of Chelsea's logs reach rock between 40 and 120 ft
Depth to bedrock: 10th–90th percentile whisker, middle-half box, median tick; dashed line = Massachusetts median.
median 80 ftMA 24 ft
050100 ft
n = 21 logsSource: MassGIS / MGS borings & well logs
▸ Show the numbers▾ Hide the numbers
| Depth to rock (ft) | Logs |
|---|---|
| 0–5 | 0 |
| 5–10 | 0 |
| 10–20 | 1 |
| 20–50 | 5 |
| 50–100 | 7 |
| 100+ | 8 |
Rock within 10 ft
0%
of logs (23% across Massachusetts). Shallow rock means ledge in excavations, refusal for driven piles and rock anchors rather than soil nails; deep ground means taller shoring and more groundwater. 71% of logs here go past 50 ft.
02 · Bridges
3 of 14 bridges are rated poor — above the Massachusetts rate of 9%
Every highway bridge and large culvert in the 2025 National Bridge Inventory that stands inside Chelsea. Median age 70 years.
43% good, 21% poor
FHWA good / fair / poor rating — the lowest of deck, superstructure, substructure or culvert.
- Good6 · 43%
- Fair5 · 36%
- Poor3 · 21%
n = 14 structuresSource: FHWA National Bridge Inventory 2025
▸ Show the numbers▾ Hide the numbers
| Built | Structures |
|---|---|
| 1910s | 1 |
| 1950s | 12 |
| 1990s | 1 |
The poor-rated bridges
| Carries | Over | Built | Daily traffic |
|---|---|---|---|
| US 1 NB/LOW DECK | CHELSEA LOCAL STRE | 1950 | 42,492 |
| US 1 SB/UPPR DECK | US 1 NB/CHEL LWR DECK | 1950 | 41,655 |
| COUNTY RD | US 1 NE XWAY | 1955 | 16,422 |
03 · Money & permits
26 construction projects on file, median $567K — at or below the state's $1.5M
| Project | Year | Award |
|---|---|---|
| Designing Coastal Community Infrastructure for Climate Change | FY2016 | $90K |
Public construction projects
26
Median estimated value $567K, middle half $277K–$1.8M, against $1.5M across Massachusetts. Capped total $64.5M (each project counted at no more than $100M). Public bid records compiled June 2026, heavy on 2021–22 — a sample, not an annual market.
04 · Dams & disasters
Suffolk County has drawn $567M in federal disaster repair since 2010
FEMA Public Assistance is reported by county, so the figure below is Suffolk County-wide context, not a Chelsea number.
FEMA Public Assistance, Suffolk County
$567M
Federal share obligated across 881 projects in 15 declared disasters since 2010. The largest category is emergency protective measures (97%); roads & bridges took $394K.
05 · Next door
Chelsea and the 3 towns that border it
A dash means no data for that layer, not zero.
| Town | Poor bridges | Rock depth |
|---|---|---|
| Chelsea, MA | 3 / 14 | 80 ft |
| Boston, MA | 41 / 404 | 92 ft |
| Revere, MA | 3 / 30 | 40 ft |
| Everett, MA | 0 / 8 | 75 ft |
Where these numbers come from
Method, sources & caveats
Chelsea is the Census county subdivision 2502513205 (Suffolk County). Every record is placed here by its coordinates, not by the place name the source uses. Construction-project figures come from Massachusetts public bid results, published as town-level counts, medians and capped totals (n ≥ 10).
- Towns are Census county subdivisions: cities, towns, plantations, and Maine/New Hampshire unorganized territories and townships. Every record is placed in a town by its coordinates (point-in-polygon), not by the source's own place label — so a bridge in Roxbury counts for Boston and a well in 'North Waltham' counts for Waltham.
- Bridges: FHWA NBI 2025, highway structures ≥ 20 ft including large culverts. 'Poor' is FHWA's good/fair/poor rating (lowest of deck, superstructure, substructure or culvert ≤ 4). Percent-poor is shown only for towns with at least 5 structures.
- Depth to bedrock is the median of driller- and boring-reported depths in the town, shown only where at least 10 logs exist. Water-well logs over-sample rural lots and hilltops; one town median never describes a particular site.
- Bedrock depths use the same state databases and filters as the Bedrock & soils module (bedrock wells and borings that reached rock, 0 < depth ≤ 400 ft, exact re-filings dropped), but every log is placed in a town by its coordinates rather than the driller's town field, so town counts can differ slightly between the two pages. Connecticut and Rhode Island have no statewide public well-log database with depths.
- Dams: only high-hazard-potential dams whose latest condition assessment is Poor or Unsatisfactory are counted (live NID). Connecticut and Rhode Island assessments may lag.
- FEMA Public Assistance dollars are federal share obligated for disasters declared since 2010, reported by county — they are county context, not a town figure.
- Grant awards are Massachusetts only (EEA Dam & Seawall program, MVP Action grants, CZM Coastal Resilience). Other states' programs are not yet included.
- Ground-related permit counts cover only the municipal portals the pipeline reads (Boston, Cambridge, Somerville, Worcester, Framingham, Providence, Portsmouth, Hartford and a few others) — an absent count means 'not covered', not zero.
- Data as of
- Sep 11, 2026
- Generated
- Sep 11, 2026
- Records
- 367,748
- Refresh
- Live pull · weekly
- U.S. Census Bureau cartographic boundary files — county subdivisions (2024, 1:500k)Public domain
- FHWA National Bridge Inventory (2025 delimited files)Public domain
- USACE National Inventory of DamsPublic domainHigh-hazard dams rated Poor or Unsatisfactory (live NID).
- USGS U.S. Landslide InventoryPublic domain
- MassGIS / Massachusetts Geological Survey — Bedrock Data PointsPublic recordBorings and well logs that reached rock (MassDEP well drillers, USGS, MWRA, MassDOT…); seismic/HVSR and map-derived shallow-bedrock/outcrop points excluded.
- NH DES Water Well Inventory, Maine Geological Survey Wells Database, Vermont DEC well recordsPublic recordBedrock wells only; driller-reported depth to bedrock / overburden thickness.
- OpenFEMA Public Assistance Funded Projects Details (v2)Public domain
- MA EEA / CZM grant awards — Dam & Seawall, MVP Action, CZM Coastal ResiliencePublic record
- Municipal open-data permit portals (Boston, Cambridge, Somerville, Providence, Portsmouth, others)Public recordOnly permits flagged as ground-related (retaining walls, excavation, foundations) are counted.
Published by Earth Support Corp as a public resource. Regional statistics for planning and curiosity. They are not an engineering report, a bid recommendation or a statement about any particular site, firm or project. Spot an error? Tell us and we will correct it. Full method: methodology.