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Appendix A
Nashua Revised Ordinances
Artic le XXXI-— Stormwater Management
Hic it Discharge Detection and Himination Plan 19
§ 190-214 § 190-215
ARTICLE XXXI
Stormwater Management
Purpose: The purpose of this article is to protect, maintain and
enhance public health, safety, and general welfare by establishing
minimum requirements and procedures to control the adverse
impacts associated with stormwater runoff, and soil erosion and
sedimentation from site construction and development. Subdivision
and site plans shall include plans for managing stormwater and
controlling erosion and sedimentation as provided herein.
Purpose: This section implements the following Master Plan
recommendations:
The City should strongly consider adopting a soil erosion and
sediment control ordinance, which would comprehensively address
many of the nonpoint sources of water quality degradation discussed
in the Water Resources Protection Plan.
§ 190-214. Applicability.
A. The requirements of this Part 4 apply to any subdivision plan or
site plan, except or to the extent provided in Subsection B.
B. The Planning Board may waive the requirement for all or part of a
stormwater management and erosion control plan if it determines
that a plan is unnecessary because of the size, character, or
natural conditions of a site. All requests for waivers and action
thereon shall be submitted pursuant to § 190-148, along with
supporting technical documentation to demonstrate minimal
environmental impact.
§ 190-215. Stormwater management standards.
The following stormwater management standards shall be applied to
all subdivision and site plans.
A. Untreated stormwater.
(1) No new stormwater conveyances may discharge untreated
stormwater directly to or cause erosion into wetlands or
water bodies.
(2) Rooftop runoff is considered uncontaminated for the
purposes of these standards and therefore does not require
treatment.
B. Postdevelopment peak discharge rates.
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§ 190-215 § 190-215
D.
(1) Stormwater management systems must be designed so that
the ten-year, twenty-four-hour postdevelopment peak
discharge rate does not exceed the ten-year, twenty-four-hour
predevelopment peak discharge rates.
(2) In order to meet this standard, controls must be developed for
the two-year, ten-year and fifty-year, twenty-four-hour storm
events. The hundred-year, twenty-four-hour storm event must
be evaluated to demonstrate that there will not be increased
flooding impacts off site. [Amended 6-26-2018 by Ord. No.
O-18-015]
(3) Measurement of peak discharge rates shall be calculated
using point of discharge or the downgradient property
boundary. The topography of the site may require evaluation
at more than one location if flow leaves the property in more
than one direction. An applicant may demonstrate that a
feature beyond the property boundary is more appropriate as
a design point.
Recharge to groundwater. Annual groundwater recharge rates
shall be maintained by providing infiltration by the use of
structural and nonstructural methods. The annual recharge from
post development site conditions shall mimic the annual recharge
from predevelopment site conditions. Best management practice
(BMP) techniques to achieve recharge requirements include
infiltration, bioretention, dry swale, and _ nonstructural
techniques. Alternative techniques may be used if they meet the
performance criteria stated herein and are approved by the
Planning Board.
Water quality.
(1) For discharges to the Conservation Zone within the Water
Supply Protection District as defined in § 190-24, the runoff
volume to be treated for water quality is calculated as 1.0
inch of runoff multiplied by the total impervious area of the
postdevelopment project site.
(2) For all other discharges, the runoff volume to be treated for
water quality is calculated as 0.5 inch of runoff multiplied by
the total impervious area of the postdevelopment project site.
(3) Removal of 80% of the total suspended solids (TSS),
floatables, greases, and oils. For new developments,
stormwater management systems shall be designed to
remove 80% of the average annual load of total suspended
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§ 190-215 § 190-215
solids (TSS), floatables, greases, and oils after the site is
developed. This standard is met when:
(a) The Planning Board determines’ that _ suitable
nonstructural practices for source control and pollution
prevention are implemented;
(b) Stormwater management best management practices
(BMPs) capture the prescribed runoff volume; and
(c) Stormwater management BMPs are maintained as
designed.
E. Critical areas land uses with higher potential pollutant loads
require the use of specific stormwater management BMPs, as
detailed in this section. The use of infiltration practices without
pretreatment is prohibited. [Amended 6-26-2018 by Ord. No.
O-18-015]
(1) The following uses are considered to create high potential
pollutant loads:
(a) Any use requiring a National Pollutant Discharge
Elimination System (NPDES) stormwater discharge
permit associated with industrial activity;
(b) Auto salvage yards/auto recycler facilities;
(c) Auto fueling facilities/gas stations;
(d) Fleet storage areas (cars, buses, trucks, public works);
(e) Vehicle service, maintenance and equipment cleaning
areas;
(f) Retail parking lots;
(g) Road salt storage or loading areas if exposed to rainfall;
(h) Commercial nurseries;
(i) Metal rooftops, including roofs made from aluminum, tin,
galvanized steel, copper, or rooftops which contribute
significant pollutant loads;
(j) Outdoor storage and loading/unloading areas of
hazardous substances;
(k) SARA 312 generators if materials or containers are
exposed to rainfall; and
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§ 190-215 § 190-215
(2)
(3)
(4)
(l) The service, repainting, and hull maintenance areas of
marinas.
The following measures are required in addition to BMPs
described in Subsection E(1) above, within areas with high
potential pollutant loads:
(a) Source reduction; and
(b) Pretreatment.
The following are prohibited within areas with high potential
pollutant loads located in a Conservation Zone:
(a) Infiltration trenches;
(b) Infiltration basins; or
(c) Dry wells.
The following restrictions apply to certain BMPs within areas
of high potential pollutant loads: Sand or organic filters,
detention basins, wet ponds or constructed wetlands may be
used only if sealed or lined.
F. Wetland or water bodies.
(1)
(2)
BMPs approved for use within 300 feet of a wetland or water
body unless otherwise prohibited by § 190-24 are limited to:
(a) Extended detention basins;
(b) Wet ponds;
(c) Constructed wetlands;
(d) Water quality swales;
(e) Sand filters;
() Organic filters;
(g) Infiltration basins;
(h) Infiltration trenches; and
(i) Deep sump and hooded catch basins (used with other
BMPs).
Stormwater management systems should incorporate designs
which allow for shutdown and containment in the event of an
emergency spill or other unexpected contamination event.
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§ 190-215 § 190-215
G. Redevelopment. Redevelopment of previously developed sites
must meet the stormwater management standards to the
maximum extent possible to be determined by the Planning
Board. The goal is to reduce impervious area by a minimum of
20% or meet the open space requirement in that zoning district.
The application shall include a certification by a registered
professional engineer as to compliance with this standard.
[Amended 6-26-2018 by Ord. No. O-18-015]
H. Erosion and sedimentation plans. [Amended 6-26-2018 by Ord.
No. O-18-015]
(1) Erosion and sedimentation controls must be implemented to
prevent impacts during construction or post-construction or
land disturbance activities, and shall be properly installed
prior to soil disturbance in the contributing drainage area,
and a plan shall contain the following:
(a) A project narrative including a description of the
development.
(b) Locus map showing property boundaries.
(c) North arrow, scale, date.
(d) Property lines.
(e) Structures, roads, and utilities.
(f) Topographic contours at two-foot intervals.
(g) Critical areas.
(h) Within the project area and within 50 feet of the project
boundary based on Nashua GIS, surface waters,
wetlands, and drainage patterns and watershed
boundaries.
(i) Vegetation.
(j) Extent of 100-year floodplain boundaries if published or
determined.
(k) Easements.
(1) Areas of soil disturbance.
(m) Areas of cut and fill.
(n) Locations of equipment storage and staging.
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§ 190-215
(o)
(p)
(q)
(r)
(s)
(t)
(u)
§ 190-215
Highlighted areas of poorly and very poorly drained soils.
Highlighted areas of poorly and/or very poorly drained
soils proposed to be filled.
Location, descriptions, details, and design criteria and
calculations for all structural, nonstructural, permanent,
and temporary erosion and sedimentation control
measures and BMPs.
Identification of all permanent control measures.
Identification of permanent snow storage areas.
Identification of snow management measures during
construction.
Description of the combination of sediment and erosion
control measures which are required to achieve
maximum pollutant removal such as:
[1] Sediment basins. For common drainage that serves
an area with 10 or more acres disturbed at one time, a
temporary (or permanent) sediment basin must
provide storage for a calculated volume of runoff from
a drainage area from a two-year, twenty-four-hour
storm, or equivalent control measures must be
provided, where attainable, until final stabilization of
the site. Where no such calculation has been
performed, a temporary (or permanent) sediment
basin providing 3,600 cubic feet of storage per acre
drained, or equivalent control measures, must be
provided where attainable until final stabilization of
the site. When computing the number of acres
draining to a common location, it is not necessary to
include flows from off-site areas and flows from on-
site areas that are either undisturbed or have
undergone final stabilization where such flows are
diverted around both the disturbed areas and the
sediment basin. In determining whether a sediment
basin is attainable, the operators may consider such
factors as site soils, slope, available area on-site, etc.
In any event, the operator must consider public
safety, especially as it relates to children, as a design
factor for the sediment basin, and alternative
sediment controls must be used where site limitations
would preclude a safe design.
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Board of Aldermen — 9/12/17 Page 3
downtown building a stronger, healthier downtown economy adding vitality and strength to downtown. Off Pine
Hill Road will not do that at all.
Another myth is that there has not been a feasibility study and that we don’t know anything about what we’re
doing. That is false. We did a two-year feasibility study paid for initially in large part by the NH Charitable
Foundation because they saw the potential for this kind of project. Two years we engaged Duncan Webb a
leading or maybe the leading consultant on performing art centers in the nation. He does not build centers.
He does not operate them. He serves as a consultant to communities so he can give them straight advice. He
has advised other communities such as Peterborough not to proceed because they didn’t think they could be
financially viable. VVhat he told us was that we should not build something as we originally thought of 1,200,
1,500, 2,000 seats because that would not work. What he told us was that we can successfully operate given
the market, given all of the circumstances a performing arts center with flexible space in the 500 to 700 seat
range. He developed a business plan. The report says how much it will cost to operate this. How much he
thinks it will bring in and he recommended that we develop and raise a $4 million private endowment which
would be used to supplement the cost of the center. The proposal that you have before you is contingency
except for the purchase of the building but proceeding with the vast majority of the project is contingent on
raising $4 million in the private sector.
Finally there’s been this myth that there is no private involvement. There’s no private partnership. Well that is
not true. First of all we have the Currier who wants to join with us. They are certainly a private institution.
They're not the government and it is contingent upon raising $4 million from our own citizens and from
businesses in Nashua. So Mr. Chair | know I’ve gone on a little while but | want to advocate that the Board of
Aldermen pass this and give Nashua a chance to succeed just like all these other communities. We are better
than them and the idea that we can’t succeed when they can is | think totally, totally wrong. So we’ve seen the
energy, the enthusiasm really heat up in downtown Nashua over the last few years. | hope that we don’t throw
a big bucket of ice water on that enthusiasm now. Instead | think we should build on what’s already happened
and make downtown Nashua an even better success than it already is. Thank you Mr. President.
| did say though before | conclude that | would mention another item — I’m sorry — the downtown parking plan
overnight parking that we are going to be moving forward with presenting a plan we think on September 27".
Parenthetically that’s another thing that’s helping downtown. We think we can present a plan to the
Infrastructure Committee at that time. Thank you very much Mr. President.
President McCarthy
I’m going to ask as we go on that we keep applause to a minimum because it actually wreaks havoc with our
poor Legislative Assistant when she listens to the tapes. If you want to applaud, provide someone to do the
transcriptions.
Are there any responses to the remarks of the Mayor?
RESPONSE TO REMARKS OF THE MAYOR - None
RECOGNITION PERIOD
R-17-124
Endorsers: Mayor Jim Donchess
Board of Aldermen
EXTENDING CONGRATULATIONS TO THE NASHUA SILVER KNIGHTS BASEBALL TEAM
Given its first reading;
MOTION BY ALDERMAN COOKSON THAT THE RULES BE SO FAR SUSPENDED AS TO ALLOW
FOR THE SECOND READING OF R-17-124
MOTION CARRIED
§ 190-215 § 190-215
(2)
(3)
(4)
(5)
[2] Drainage locations which serve 10 or more disturbed
acres at one time and where temporary sediment
basins or equivalent controls are not attainable,
smaller sediment basins and/or sediment traps should
be used. At a minimum, silt fence, vegetative buffer
strips, or equivalent sediment controls are required
for all downslope boundaries (and for those side slope
boundaries deemed appropriate as dictated by
individual site conditions).
[3] Drainage locations serving less than 10 acres may
utilize smaller sediment basins and/or sediment
traps. At a minimum, silt fence, vegetative buffer
strips, or equivalent sediment controls are required
for all downslope boundaries (and for those side slope
boundaries deemed appropriate as dictated by
individual site conditions) of the construction area
unless a sediment basin providing storage for a
calculated volume of runoff from a two-year, twenty-
four-hour storm or 3,600 cubic feet of storage per
acre drained is provided.
Whenever practical, natural vegetation shall be retained,
protected or supplemented. Priority shall be given to
preserving natural drainage systems, including perennial and
intermittent streams, wetlands, swales, and drainage ditches
for conveyance of runoff leaving the project area.
Examples of BMPs for erosion and sedimentation control are
staked straw bales, filter fences, hydroseeding, and phased
development. Many stormwater BMP technologies (e.g.,
infiltration technologies) are not designed to handle high
concentrations of sediments typically found in construction
runoff and must be protected from construction-related
sediment loadings. Construction BMPs must be maintained
while construction or land disturbance activities continue.
Measures shall meet as a minimum the best management
practices set forth in the "New Hampshire Stormwater
Manual, Volumes 1 through 3" and any published DES
regulations.
Off-site surface water and runoff from undisturbed areas shall
be diverted away from disturbed areas where feasible or
carried nonerosively through the project area. Integrity of
downstream drainage systems shall be maintained.
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§ 190-215 § 190-215
(6)
All temporary erosion and sediment control measures shall be
removed after final site stabilization. Trapped sediment and
other disturbed soil areas resulting from the removal of
temporary measures shall be permanently stabilized within
30 days.
I. Stormwater management measures.
(1)
(2)
(3)
(4)
J.
Structural stormwater management measures to achieve
recharge, water quality, and peak discharge control shall be
structural BMPs designed in accordance with the
requirements of the following:
(a) New Hampshire Stormwater Manual, Volumes 1 through
3. [Amended 6-26-2018 by Ord. No. O-18-015]
(b) Best Management Practices for Urban Stormwater
Runoff, published by NH DES, 1996, as amended.
(c) Innovative Stormwater Treatment Technologies Best
Management Practices Manual, published by NH DES,
May 2002, as amended [Reference:
http://www.des.state.nh.us/wmb/was/manual/]
The performance criteria specified in the Design Manual with
regard to general feasibility, conveyance, pretreatment,
environment and landscaping, and maintenance shall be
considered in the selection of a structural BMP.
Structural stormwater management practices shall be
selected to accommodate the unique hydrologic and geologic
conditions of the site. Design computations must document
these conditions.
Nonstructural management measures may reduce or
eliminate the need for structural BMPs to meet recharge,
water quality, and peak discharge control requirements.
These techniques shall include runoff prevention methods
(RPMs), are encouraged and shall be designed in accordance
with the guidelines in the documents listed in Subsection I(1)
above. These techniques may include disconnection of
rooftop and nonrooftop runoff, vegetated bio-cells and bio-
islands, infiltration edges, dividers, or islands, planters, and
raingardens.
Allowable nonstormwater discharges. The following
nonstormwater discharges are authorized, provided it has been
determined that they are not significant contributors of pollutants
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