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Imagine EGE

| MAP LEGEND
0.2% Annual Chance
Flood Hazard

| | NH Rivers

NH Water bodies

| | Nashua Wetlands

Conservation Areas

City Parks

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Open Space Map I

Social Pinpoint Mapping

In Social Pinpoint users had

the option to provide feedback
on areas they felt should be
maintained and protected.
The following areas were
highlighted as locations that
residents and visitors would
like to be preserved or further

maintained, and delineated as
conservation land: Pennichuck
Brook and Pond and the
surrounding areas, Holman
Stadium, Arlington Community
Center, Salmon Brook, Mine
Falls, Roby Park, Yudicky Park.

Amherst

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Key conservation land, wetlands, and future flood conce
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https://imagine.nashuanh.gov

While the future is uncertain, it is clear that Nashua will face increased
risk from a wide range of weather and climate scenarios in the coming

decades.

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While Nashua will not be
impacted by sea level rise

and storm surge, the City is at

risk of riverine flooding from
increased precipitation and rising
temperatures leading to increased
snow melt and stormwater

inundation.

What is a ‘0.2%-probability

flood’?

A‘0.2%-Probability flood,’
commonly called a ‘500-year
flood,’ is a flood that has a0.2%
chance of taking place in any given
year. Experts prefer not to use the
“500-year” term since it gives the

impression that a certain level
of flooding will only occur once
every 500 years. In fact, it has a
0.2 percent chance of occurring in
any given year and can even occur
multiple times in a single year or
decade. Over a fifty-year period,
there is almost a one in ten chance
that a 0.2 percent annual chance
flood will occur at least once.
While properties within the
100-year flood plain are generally
required to purchase flood
insurance, properties outside this
zone can still be subject to the
effects of rain and overflow.

Energy and Climate

Across New Hampshire, annual
precipitation has increased 5-20%
and the frequency and magnitude
of extreme precipitation events
have increased. More intense
rainfall events are one of the
reasons for combined sewer
system overflows. In 2018,
discharge amounts in Nashua were
very high. The September 18, 2018
rain event provided 4 inches of rain
overall, at times rain falling at 1
inch per hour; more than combined
sewer pipes can handle. Reducing
overflows is a key strategy in
maintaining the quality of Nashua’s
water.

City-owned hydro dams
generate pollution-free electricity
for Nashua that is readily available.

2014

2015

Year

2016

2017

Oo 250

Nashua now owns two hydro
dams; Jackson Mills and Mine Falls
(acquired in 2017). Owning and
keeping these assets generating as
a community resource is one way
that the City of Nashua is taking
advantage of the resource that is
the Nashua River and continuing
the heritage of powering the
community with it. In addition

to taking advantage of natural
hydroelectric capacity, the city

is home to a growing number

of solar projects with 450 solar
installations in the last 4 years
(residential and commercial), 3
ongoing municipal installations,
and solar at schools including
Fairgrounds Middle School and Dr
Crisp Elementary, and electrifying
the City’s vehicles.

Solar Generation Capacity

500 750 1000 1250 1500 1750

Comprehensive Master Plan

Open Space and Environment

Combined Sewer System
Overflows

Combined sewer systems
are sewers that are designed
to collect rainwater runoff,
household sewage, and
industrial wastewater in the
same pipe. During periods of
heavy rainfall, the amount of
wastewater in a combined
sewer system can go beyond
the amount the system can
take, causing overflows of
dirty, untreated wastewater
into nearby water bodies.
Reducing overflows is a key
SUMeouRcYoAV AO MO ATT One U IATA oaNMaL
quality of Nashua’s water.

2000 2250 £2500

kW of Solar Capacity

Source: https://www.livablenashua.org

Imagine ERITr

Top Goal:

Parks and Natural
Areas

Recognize parks and natural
areas as vital elements of
Nashua’s green network:
Enhance access to and better
connect Nashua’s existing
open space network for
citizens of all ages, abilities,
and incomes.

https://imagine.nashuanh.gov

Action: Improve public
access to open space,
natural resources, and
recreational areas
equitably across the City

Recommendation 1

Timeframe: Mid-term

Seek out public, private
partnerships to allocate funding
to protect public access to the
Pennichuck Brook corridor,
including Pennichuck Pond. The
area is currently unprotected
except as a secondary source of
water for treatment and at risk of
development.

Recommendation 2

Timeframe: Mid-term

Expand planning for Salmon
Brook Corridor by increasing
public access, extending existing
conservation land protection, and
providing a pedestrian trail.

Recommendation 3

Timeframe: Mid-term

Review park and natural area
inventory to determine how
accessible park and natural areas
are for all residents. Seek funding
and build neighborhood parks

in areas of the City that are park
deficient.

Parks and natural areas are two distinct, but equally important,
components of Nashua’s open space program, and play an essential
role in the city, one increasingly appreciated in the wake of the

COVID-19 pandemic.

Action: Improve and
provide clear wayfinding
and signage for existing
recreation, open space,
and natural resource
sites across the city for
pedestrians, bikers, and
those travelling by car.

Recommendation 1

Timeframe: Mid-term
Work with graphic designers and
a signage company to streamline
signage for the citywide park and
natural area network.

Recommendation 2

Timeframe: Ongoing

Create a digital map platform and
way-finding app, and printed map
materials to provide residents
and visitors information on how to
access the City’s park and natural
area system.

Action: Improve mobility
throughout recreational
areas for all modes.

Recommendation 1

Timeframe: Near-term/Ongoing

Create bike and pedestrian access
to parks and within all open
Spaces and recreational areas in
the City.

Recommendation 2

Timeframe: Mid-term

Provide bike parking, water
stations, and repair stations at all
park facilities.

Comprehensive Master Plan

Open Space and Environment

Recommendation 3

Timeframe: Mid-term

In conjunction with digital
mapping efforts for park and
natural area access, create and
combine layers for bike and
pedestrian trails so park visitors
can understand the amenities at
parks and natural areas citywide.

Recommendation 4

Timeframe: Long-term

Seek funding to create a rail

to trail network along Daniel
Webster Highway and seek out
new locations to expand rail to
trail networks throughout the City.
When building rail to trail as well
as pure rail and trail networks,
explore how to connect new
networks to existing and future
street bike trails.

139

3.3

3.4

3.5

3.6

3.7

3.8

this task.

Contract Documents — Performed by City. Hoyle Tanner does not have any effort associated with
this task.

Final Engineer’s Opinion of Probable Cost — Performed by City. Hoyle Tanner does not have any
effort associated with this task.

Draft Plan, Specification, and Estimate (PS&E) Submittal —- Performed by City. Hoyle Tanner does
not have any effort associated with this task.

Final PS&E Submittal — Performed by City. Hoyle Tanner does not have any effort associated with
this task.

Project Management — General oversight and management of the PS&E documents and
coordination with NHDOT will be performed by the City. Hoyle Tanner will be responsible for
coordination, scheduling, and monthly tracking of internal team members to meet task, project
milestones and financial requirements of the project, as practicable. This includes monthly
progress reports and invoices submitted electronically to the City.

Bidding —- Management of bidding process and distribution of bid documents will be performed

by the City. Hoyle Tanner will provide assistance with questions and attend the pre-bid
meeting. (10 hours assumed)

Page 4

Imagine EGE

Action: Provide
recreational
opportunities for
residents of all ages and
abilities.

Recommendation 1

Timeframe: Near-term

Invest in universal design retrofits
to playgrounds.

Recommendation 2

Timeframe: Mid-term

Identify trails that are appropriate
for ADA accessibility upgrades.

https://imagine.nashuanh.gov

Action: Conduct
feasibility study to
determine how to
better connect parks
and develop regional
connections or wildlife
corridors.

Recommendation 1

Timeframe: Long-term

As part of a feasibility study,
determine if there are
opportunities to create human
and wildlife trail corridors that
would connect municipal and
private conservation areas all the
way to the Monadnock region.

Recommendation 2

Timeframe: Mid-term

As part of the regional park

connections determine how

to create connections to and
between Mine Falls park and
Nashua River Rail Trail.

Top Goal:
Mitigation of
Climate Change
Impacts

Mitigate the impacts of climate
change on the community.

Action: Incorporate
resiliency planning into
the design, development,
and maintenance of
recreational and open
spaces

Recommendation 1

Timeframe: Mid-term

Create a citywide management
plan to address invasive species
and encourage the use of native
species and pollinator-friendly
landscaping in city owned and
maintained open spaces.

Recommendation 2

Timeframe: Ongoing

Provide training for existing and
future employees to properly
maintain areas with green
infrastructure, invasives, and
pollinators.

Action: Refine and
Implement a robust
climate action and
resilience plan for
Nashua

Recommendation 1

Timeframe: Mid-term
Build upon research from 2017

Climate and Health Adaptation
Plan findings by the NRPC.

Recommendation 2

Timeframe: Near-term

Minimize heat island effect and
determine areas throughout

the city that were identified as
high priority in CHAP such as
the French Hill neighborhood for
green infrastructure.

Recommendation 3

Timeframe: Ongoing

Collaborate with the University
of New Hampshire’s Center for
Infrastructure Resilience to
Climate to determine areas in
Nashua that are most vulnerable
to increased precipitation and
riverine flooding risk.

Comprehensive Master Plan

Open Space and Environment

Action: Update wetland,
flood protection and
stormwater management
ordinances to protect
future flood zones,

and expand flood zone
buffers, and mitigate
increased flood pressure
from new development
and redevelopment
projects.

Timeframe: Near-term/Ongoing

Action: Adapt City
infrastructure to prepare
for climate change

Timeframe: Ongoing

Action: Conduct risk
analysis of City assets’
potential for future
flooding and adopt

risk factor into asset
management practices.

Timeframe: Mid-term

141

Imagine EGE

Action: Expand the use
of green stormwater
infrastructure (GSI) or
low impact development
(LID) on city property
and create incentives to
encourage the use of GI
throughout the city.

Recommendation 1

Timeframe: Ongoing

Create citywide guidelines for
how to implement stormwater
management and green
infrastructure, including planting
plans, preferred materials, and
maintenance suggestions.

Recommendation 1

Timeframe: Long-term

Provide educational training for
residents and city maintenance
workers to encourage adoption
and understand how to maintain
GI.

https://imagine.nashuanh.gov

Action: Update
ordinances to protect
areas at risk of current
and future climate
hazards and reduce
the climate impact of
development

Timeframe: Mid-term

Action: Research and
develop an ordinance
that requires a reduction
in impervious surfaces.

Recommendation 1

Timeframe: Ongoing/Near-term

Require the use of low impact
development techniques, porous
pavement, vegetative buffers,
and islands in large parking areas
of new construction or when
redeveloping a site.

GREEN STORMWATER
INFRASTRUCTURE (GSI)

What is Green Stormwater
Infrastructure (GSI) and how will it
help Nashua accomplish its goals?
GSI is a set of tools and practices that
mimic natural methods of storing,
infiltration and/or filtering stormwater.
As more development occurs across
the City of Nashua, continued
integration of these practices into new
and redeveloped areas will mitigate
flooding, contribute to adaptation to
increased rainfall, and where plants
are present, will help filter urban
stormwater before returning it back to
groundwater reservoirs.

Where should it be employed?

How does each of these methods
work?

Enhanced Tree Wells : filters water
through a tree pit with well-drained,
amended planting soil

Vegetated Filters : turf or planted
surfaces used to slow runoff and trap
sediments between paved area and
GSI

Bioswale : moves and filters water
through a linear soft or hard-edged
channel with amended soils. In
streetscapes, streetscapes employ
underdrains

Pavement Reduction: restores and
infiltrates water through the reduction
of impervious cover to a permeable
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Permeable Surfaces : opens voids in

Comprehensive Master Plan

the surface and subbase allow water
to drain while still providing a rigid
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Underground Chambers : stores

and infiltrates stormwater volumes
underground while maximizing
useable surface space

Raingarden: Shallow depressions
that temporarily hold and filter water
through existing or amended soils
Infiltration Basin : landscape space
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water through a side slope or hard-
edged depression with amended sols,
pipes, and structures

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Imagine TERIAL

HEALTHY CITY-WIDE
FOREST CANOPY

As the city looks to retrofit parts of the
urban core and develop new areas,
planning to provide for a healthy tree
canopy will improve the quality of life
for the residents using and living in
these spaces over time.

Urban Core +

Development Areas:

Tree Planting in urban and developing
environments gets more challenging
as space gets more constricted. A
healthy urban canopy can contribute
to many of the City of Nashua’s goals,
including the creation of inviting
pedestrian space for residents,
stormwater pollutant filtration, and
the reduction of island effect to name
a few. Some key considerations for a
healthy urban canopy include:

New Trees:

Continuous Tree Wells: Consider
planting trees in continuously
connected tree wells either with
structural soil or tree grates to
safeguard the soil from compaction.

Tree Protection Measures

Tree Maintenance

yr

The expanded soil volumes from
extended wells will help encourage
healthy root growth and will contribute
to higher rates of urban tree resiliency.
Permeable Pavement at Tree Wells:
As described in the GSI section,
permeable pavement can help address
stormwater challenges, but when used
in conjunction with tree plantings in
streetscapes, permeable pavement
also helps expand the amount of
rainfall available to tree roots and
expands the resiliency of urban trees.
Silva Cells or Structural Soils:
Compaction of Soil is one of the
biggest challenges for urban

trees. Consider advocation for
structural soils or silva cells as new
developments and tree wells are
planned.

Right Tree, Right Place: Consider
consulting an arborist or landscape
arborist to choose the correct

species of urban tree for the
challenges of each specific location
with consideration for availability

of sunshine, water, salt exposure,
overhead wires and/or soil volumes
and drought tolerance.

New Tree Support: Newly planted
trees require special care and

https://imagine.nashuanh.gov

attention, and it is recommended

to use a combination of contractor
planting and watering guarantees (two
year minimum) as well as harnessing
the resources of the community

by encouraging neighbors to help
monitor, water, and support the newly
planted trees.

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Tree Protection Measures: As
development occurs, special attention
will need to pe paid to the protection
of the City’s existing trees which are
cherished assets for the community.
Proper tree protections include
maintaining proper tree protection
fencing during construction, as well as
monitoring by arborists or landscape
specialists for the duration of the
construction period.

City Tree Survey : Consider conducting
a regular city-owned tree survey. Tree
health monitoring will help the city
respond to tree health challenges and
patterns over time.

Tree Maintenance: Regular pruning
and early action tree training programs
are very successful in expanding tree
life cycles and minimizing the effects
of storm damage as the tree matures.

Continuous Tree Wells

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