Infrastructure resilience · Plymouth & Kingston, MA

When the 1% nor'easter hits Plymouth

What floods, what fails and for how long, what is worth fixing, and what is left to insure. Scenario: MC-FRM 2030 horizon, 1% annual-chance coastal flood, plus a wind-driven power outage.

See the riskFlood depth, exposed buildings, assets

Reduce the riskCascade, measures, benefit-cost

Insure the riskResidual loss, parametric outage cover

For the Town of Plymouth (Planning, DPW, Emergency Management) and a specialty insurer.

The question

A 1% nor'easter brings a coastal flood and a wind-driven outage at the same time. Which services fail, for whom, and for how long?

Hazard

MC-FRM 1% flood, 2030

MA CZM still-water flood depth above ground, in feet, on a ~2 m grid. Includes nor'easters.

Exposure

Parcels & footprints

MassGIS FY2026 assessor parcels and building footprints (>40 m²), Plymouth and Kingston.

Assets

192 essential-service sites

OSM, MassDEP wells, MA critical facilities and FCC tower registrations, each with USGS ground elevation.

History

Real outage records

Plymouth County Oct 2021 nor'easter and March 2018 Riley, used to calibrate restoration. 32,250 households.

Hour 0 is the start of the storm. The 1% coastal flood arrives with high tide at hours 10–20. The model runs hour by hour for 5 days (120 h).

See the risk

527 buildings flood. They are the waterfront, not the town's core services.

Building footprints

527

Parcels

481

Dwelling units

638

Assessed value

$682 M

Plymouth: 398 footprints, $586 M. Kingston: 128 footprints, $96 M. Buildings alone are $376 M. The flooded areas are Water St, Town Wharf, Union St, Saquish, Clark's Island, and Kingston's Landing Rd, River St and Elm St. At the 2070 horizon, 1,038 footprints intersect the 1% extent.

See the risk How deep

277 buildings take a foot or more of water. 15 take six feet or more.

Depth sampled at the footprint centre, MC-FRM 2030 1% event. 126 buildings only touch the flood at their edge.

Deepest sites

Depth	Site	Use	Value
16.8 ft	57–79 Water St	State (environmental police)	$3.0 M
14.5 ft	56 Loring Blvd	Warehouse	$7.7 M
14.3 ft	14 Union St	Marina	$9.2 M
9.1 ft	15 Town Wharf	Restaurant	$0.9 M
8.0 ft	41 Landing Rd, Kingston	Single family	$0.5 M
7.5–6.4 ft	Saquish Head (3)	Single family	$0.6–0.7 M
6.4 ft	45 River St, Kingston	Municipal	$0.7 M
6.2 ft	Clark's Island	Single family	$0.7 M

The deepest values are on wharf and pier structures that stand over water (ground below 0 m). They overstate how deep a normal building would flood.

See the risk Essential services

Almost every core facility sits high and dry. The exposure is indirect.

Inside the flood

4 small unnamed OSM substations: Kingston near the Jones River (~3.6 ft) and 3 near the Wareham/Bourne line (up to 5.5 ft)
1 waterfront telecom mast at 2 m elevation, ~10.9 ft deep. 3 more sites lie within 250 m of the flood.
2 treatment plants on the Wareham/Bourne side, including Mass Maritime (~3 ft). Plymouth's and Kingston's plants are dry.

Not in any dataset

Sewer pump stations and water booster pumps
Downtown underground and pad-mounted power equipment. OSM maps only ~39 km of minor lines across the whole area.

From flood to cascade Hour by hour, first 5 days

Power drives the cascade: 56% of households dark at h18, and the water system loses pressure on day 2.

Hour0day 1

h3–5Distribution lines start failing; booster pumps cut ~1,700 households' water
h7Assisted-living homes lose power (no generator assumed)
h8–10Wells lose power, so the town runs on tank storage. Battery-only cell sites go dark.
h12Downtown sewer pump stations flood: ~6,100 households face use limits
h18Outage peak: ~18,000 households (56%)
h33Tanks run dry: 17,036 households and hydrants lose pressure
h45Nursing homes run out of stored water
h57BID-Plymouth runs out of on-site water (until h61)
h61Water pressure returns after refill
h8890% of households have power back

Cascade on the map

Five service zones, each restored on its own curve

Zones are shaded by the share of households without power. Assets and flooded buildings are coloured by their state at the selected hour. Drag the time slider in the map panel.

Zone (inferred)	Households
South: Manomet, Pinehills, Cedarville (20% worse)	12,568
West Plymouth	6,310
Kingston	5,687
Downtown / waterfront	4,788
North Plymouth	2,897

Restoration priority: feeders to critical facilities come back once their zone falls below 35% out; other facility feeders wait until it falls below 20%. Every backup duration in the panel is an editable assumption.

Grounded in history

Restoration is calibrated to Plymouth County's two worst recent nor'easters

Plymouth County customers out, 6-hourly, from EAGLE-I outage records. Oct 2021 peaked at 176,404 (62.6%) with 90% restored 72 h after the peak. Riley peaked at 140,915 (50.0%) with 90% restored after 83 h.

Longest outages in the modelled event

Flooded buildings	> 5 days
Power, south coast (to 90%)	~90 h
Downtown waterfront businesses	h4–87
Mobile service degraded	h9–74
Booster-zone water	69 h
Town-wide water pressure	28 h

Total power outage

~960k

household-hours without power, about 29 h per customer, close to the October 2021 level.

Reduce the risk 11 measures, ranked by benefit-cost

Backup power at the wells is the best buy by far

Recommended package: the top 5 (green)

~$10 M

service losses avoided per event

$12.5 M

up front, plus ~$115k a year

≈3.3

combined benefit-cost ratio

Well & booster generators, auto-transfer at the 5 largest wells: ~547k water household-hours avoided, $2.2 M
Distribution automation (~30 switches, Eversource): restoration ~15% faster, $1.5 M
Assisted-living generators at 5 homes, ~300 frail residents: $0.75 M
Sewer pump station flood-proofing (~4): protects 6,099 households, $2.4 M
Raise utilities in 225 homes flooded 1–6 ft: $5.6 M

All costs, values and effects are planning-level assumptions, not quotes or utility data. Burying the downtown feeders (≈0.5) would put new equipment in the flood zone.

Reduce the risk Cascade before vs after the package

Water, sewer and care facilities stay up. The power peak does not move.

BeforeAfter packageHours from storm start, 5 days

Power: same peak of ~18k households. 90% restored at ~h78 instead of h88, 99% at ~h95 instead of h109, ~845k household-hours instead of ~960k. Adding cell-site generators would close the remaining mobile gap.

Insure the risk What remains after the package

The residual is flood damage and long power outages, and much of the second is uninsured today

Building flood damage, 1% event

$22.5 M

Down from ~$27 M. Measured on assessed value, so replacement cost would be higher. Excludes contents and business interruption. This is NFIP or private flood cover. About 15 wharf and Saquish buildings at ≥6 ft suit insurance or buyout.

Power outage remaining

~845k

household-hours per event. Business-interruption losses from them are largely uninsured unless policies include utility-service-interruption cover.

Not addressed by any measure

Waterfront gear & roads

Flooded Eversource underground equipment on the waterfront (out h10–68 in the model) and roads blocked by fallen trees (until h36).

Parametric outage cover: a structure for discussion

Pay out fast on an observable index instead of adjusting each loss. Not priced in this analysis.

Trigger: Plymouth County customers-out share, using EAGLE-I records (the series used for calibration).
Severity tiers: hours from peak until 90% of customers are restored.
Frequency anchor: outages this size occurred ~0.18 times a year (2 events in 11 years of records).
Buyers: downtown waterfront businesses, care homes and the Town, to cover the outage hours the package leaves.

Event (Plymouth County)	Peak out	To 90%	To 99%
Oct 26–27 2021 nor'easter	62.6%	72 h	94 h
Riley, Mar 2–3 2018	50.0%	83 h	100 h
Skylar, Mar 13 2018	23.0%	37 h	53 h
Grayson, Jan 4 2018	3.0%	3.5 h	6 h

Method, caveats, next steps

Planning-grade results. Five checks would firm them up.

Caveats

MC-FRM gives still-water depth without wave crests. It is not comparable with FEMA flood elevations and is not regulatory.
Ground elevations come from the 10 m USGS terrain model, not floor or equipment height. Depth is sampled at one point per footprint.
Dependencies are inferred from location and service areas, not utility network models. Pump stations, booster pumps and downtown power equipment are unmapped. Shelters are assumed to be Plymouth North and South High Schools. Kingston water is not modelled.
Every backup duration, cost and value is an assumption. Lost service is valued at $17, $11.40, $6.60 and $1 per household-hour (power, water, sewer, mobile), with a 25-year life and a 3.1% discount rate.
Outage history counts customer accounts, not people. Assessed value is not replacement cost.

Next steps

DPW: confirm whether Plymouth Water wells already have generators. If they do, measure 1's ratio drops sharply. Check this first.
DPW + Eversource: map sewer pump stations, booster pumps and downtown underground equipment.
Emergency management: confirm shelter designations and assisted-living occupancy and generators.
Planning: survey basements and utility locations in the 225 homes flooded 1–6 ft.
Insurer: back-test a customers-out parametric trigger on the EAGLE-I history, and pair it with flood cover for the residual.