Town of Willington, CT - Chapter 6 - Required Improvements and Design Criteria

CHAPTER VI _ REQUIRED IMPROVEMENTS AND DESIGN CRITERIA

SECTION 1. DESCRIPTION

a) The Improvements set forth in this Chapter VI shall be required in all subdivisions except where waived by the Commission pursuant to Chapter X of these Regulations. The developer shall also be required to install street signs, monuments, driveway aprons, loam and seeding, and shade trees. The Commission may require the installation of sidewalks, fire hydrants, dry hydrants and fire ponds, and street lights. Such Improvements shall be installed in accordance with Town, State highway, or utility company standards.

b) All construction will be done in accordance with the Standard Specifications and Details for Subdivision on file in the Office of the Town Clerk.

c) The "Rules and Regulations of the State Board of Registration for Professional Engineers and Land Surveyors", dated January 1, 1966, with all revisions, shall apply to all technical work done in conjunction with subdivisions. The technical responsibilities of the Registered Professional Engineer and Land Surveyor in regard to subdivision work are:

1) The design of roads, both horizontal and vertical alignment; drainage systems, including the design and location of structures and pipe; sanitary sewer systems; sewage disposal systems; and water supply and distribution constitute professional engineering and as such shall be sealed by a Registered Professional Engineer. A land surveyor's seal or an architect's seal is not acceptable for this phase of land subdivision design work.

2) The phase of land subdivision which relates to topography maps and the delineation of the boundary lines of the outside perimeter as well as the interior lots and streets constitutes land surveying within the meaning of the statute and as such shall be sealed by a Registered Land Surveyor. A professional engineer's seal or an architect's seal is not acceptable.

d) Roadway widths and curve radii shall be adequate to satisfy emergency vehicle needs. Where deemed necessary by the Commission, drainage easements shall be obtained and all private roadways shall be designed to prevent stormwater flows from entering a Town street. Stormwater detention shall be utilized where required to satisfy the following section.

e) Stormwater Runoff Control.

1) The subdivider shall furnish projections of the increase of stormwater runoff created by the proposed development from the 2_year, 10_year, and 100_year frequency, 24_hour duration Type II distribution storms, as computed in accordance with Technical Release #55, Urban Hydrology, Engineering Division, Soils Conservation Service, USDA, January 1975, as amended.

2) No increase in peak flow from these storms shall be allowed unless downstream increases are compatible with an overall flood plan management system. The following items should be considered in determining whether increased peak flows are compatible with an overall flood plan management system:

A. The timing of peak flows from sub_watersheds.

B. The increased duration of high flow rates.

C. The stability of the downstream channels.

D. The distance downstream that the peak discharges are increased.

3) When stormwater detention structures are required, they shall be designed so that the peak runoff after development shall not exceed the peak runoff prior to development for each of the above flood events. Such structure shall be located upon land to be conveyed to the Town in fee simple or by Drainage Easement, at the discretion of the Commission. .

a) Layout. The street and highway layout shall conform to the Plan of Development for streets and highways.

b) Street Arrangement. The arrangement of streets in the subdivision shall provide for the coordination of principal streets of adjoining subdivisions, and for proper projection of principal streets into adjoining properties which are not yet subdivided, in order to make possible necessary fire protection, movement of traffic, and the construction or extension, presently or when later required, of needed utilities and public services such as sewers, water and drain_ age facilities. When the topographic or other conditions make such continuance impracticable in the opinion of the Commission, the above requirements may be modified. To the maximum feasible extent, pro_ posed streets shall be designed in harmony with existing topography so as to minimize cuts, fills, and other disturbance of the natural landscape.

c) New Streets. Where the subdivision adjoins unsubdivided land susceptible to being subdivided, the Commission may require new streets to be carried to the boundaries of the proposed subdivision. Reservation of title in any land controlling access to streets is prohibited.

d) Reserved Rights_of_Way. When required by the Commission, the developer shall dedicate to the Town reserved rights_of_way for future street connections to adjoining property susceptible of being subdivided. Such reserved rights_of_way shall be included in an agreement by and between the Town of Willington and the developer, and shall include slope rights fifteen (15') feet outside of the street right_of_way. These rights_of_way shall have necessary radial intersections. Lots adjoining these rights_of_way shall be so laid out that access to the house or garage shall not be over the reserved right_of_way.

When the adjoining property is subdivided, the developer of said adjoining property shall be required to connect to and build the street over the reserved right_of_way at his own expense.

e) Street and Pavement Widths. Minimum widths for the various street designations shall be shown in the following table:

Designation Street Width Pavement Width

Arterial Road 70 feet 50 feet

Collector Street 60 feet 32 feet

Local Street 50 feet 26 feet

Commercial Street 60 feet 32 feet

Wherever the preceding street designations are used in these Regulations, the designation for each existing street shall be as set forth in the Willington Zoning Regulations. The designation for each new street will be determined by the Commission after evaluating the following factors:

a) The type of land use permitted in the subject zone, and/or proposed for the subdivision, such as, residential, commercial, industrial, or institutional;

b) The residential density and/or development intensity of any permitted and/or proposed land uses;

c) The number of acres or residential units or non_residential buildings to be served, both immediately and in the future, including potential extensions of existing or proposed streets;

d) The physical characteristics of the property through which the street is proposed, such as topography, surface geology, water table, and the like.

e) The recommendations of the Plan of Development.

Where a subdivision abuts or contains an existing street which does not comply with the specified width requirements, the subdivider shall dedicate the necessary area to the Town for street widening and show such widening on the Final Subdivision Plan.

f) Block Dimensions. The maximum length of block shall be one thousand two hundred (1,200') feet and the minimum length shall be two hundred (400') feet, unless modified in accordance with Section X, Modification, of these Regulations. Special attention shall be given to blocks in industrial and business areas to provide for access to off_street parking and loading areas.

g) Cul_de_sac Streets.

All Cul_de_sac Streets: Cul_de_sac streets shall be equipped with a turn_around which has a minimum right_of_way radius and a minimum pavement radius of one_and_one_half times the minimum width for streets of that classification, but in no event less than sixty (60') feet.

A permanent cul_de_sac street shall not originate at a loop street.

Permanent Cul_de_sac Streets. Where a permanent cul_de_sac street is included in a subdivision, it shall not serve more than fifteen (15) lots unless a greater number is permitted pursuant to Section X, Modification, of these Regulations. A permanent cul_de_sac shall be one which is not proposed to, or is not reasonably capable of, future extension into adjoining property.

Temporary Cul_de_sac Streets. Where the applicant proposes, or the Commission requires, that a cul_de_sac shall be a temporary measure pending future development of adjoining property, it shall be so designed as to be feasible of continuation in the adjacent tract, and the applicant shall provide evidence of such feasibility based on topography, parcel shape, probable future development patterns, and other similar information. A temporary cul_de_sac may serve more than fifteen (15) lots; provided, however, that the Commission may require a temporary emergency access driveway, or may limit the length of a permanent cul_de_sac street, or may require other provisions to limit the risks to life and property which are inherent in single_access subdivision streets.

For any such temporary cul_de_sac street, all portions of the cul_de_sac, including pavement, grass strip and sidewalk that fall outside of the limits of the normal right_of_way width, shall occupy the space by virtue of an easement delivered to the Town before acceptance of the street, which easement shall provide for its automatic termination upon extension and acceptance of the street extension.

The developer extending a street from a temporary cul_de_sac shall be required to remove the existing pavement outside of the standard traveled way, loam and seed said area in which pavement has been removed and install curbs and sidewalks in the original cul_de_sac area in accordance with Town requirements and all at his own expense.

h) Loop Streets. Loop streets shall not originate another loop street or a cul_de_sac street. Loop streets shall not provide access to more than fifteen (15) lots.

No lot within the loop shall have its rear line fronting on the street.

i) Half Streets. The dedication of half streets at the perimeter of a new subdivision is prohibited.

j) Side Slopes. Streets in cut or fill shall be provided with slopes not steeper than two (2') feet horizontal to one (1') foot vertical, or the permanence of the street grade shall be otherwise provided to the satisfaction of the Commission.

In all areas where the side slopes are steeper than four (4') feet horizontal to one (1') foot vertical and slope down from the street, wood, metal beam or other types of guide rails or guide posts approved by the Commission shall be installed in accordance with the Standard Specifications for Subdivisions.

Where new streets abut private property, necessary slope rights shall be obtained by the subdivider when in cut or fill, and these slope rights shall be shown on the final layout submission to the Commission. The developer shall investigate the effect of cuts or fills on adjacent private property within the slope right area. The developer shall provide the Town with evidence that no drainage problems or other problems will arise on adjacent property due to construction or fill operations.

k) Relation to Topography, Natural/Historic Features. The street of a proposed subdivision shall bear a logical relationship to the topography, and all streets shall be arranged so as to obtain as many of the building sites as possible at or above the grade of the street. Streets shall be designed to maximize the preservation of natural and historic features, except as approved by the Commission; examples include specimen trees, stone walls/fences, historic markers, hedges, and the like.

Number of Intersecting Streets. No more than two (2) streets shall intersect or meet at any one point, and the center line of all streets entering an intersection shall pass through a single point.

Angle of Intersection. Except where impracticable because of topography or other conditions, all streets shall join each other so that for a distance of at least two hundred (200') feet the street is at approximately right angles to the street it joins. In no event shall street intersections be less than eighty_five (85) degrees.

Grades. Grades approaching intersections shall not exceed five (5%) percent for a distance of not less than one hundred (100') feet from the center line of said intersection.

Corner Radii. Intersecting local streets shall have a minimum radius of fifteen (15') feet at the street line. Intersections of local streets with arterial streets and commercial streets shall have minimum radius of twenty (20') feet at the street line. All other intersections shall have a minimum radius of twenty_five (25') feet at the street line.

Distance Between Intersections. Intersections shall be spaced a minimum of two hundred (200') feet apart measured from the points of intersection of the center lines. Two streets intersecting opposite sides of a third street are to have the same points of intersection or else their center lines are to be separated by a minimum of two hundred (200') feet on a third street.

State Highways. The subdivision plan shall be submitted to the State Department of Transportation if a proposed street in the subdivision intersects with a State Highway. State Department of Transportation approval shall be given in writing before approval of the application by the Commission.

Sight Lines. For a distance of fifty (50') feet from the point of two (2) intersecting property lines nearest to the street intersection, all planting, screening and grades shall be so designed and maintained as to assure adequate visibility for approaching pedestrian and vehicular traffic. This sight line shall be shown on the map so as to become a permanent visual easement.

m) Street Name Signs. Street name signs shall be erected at points designated by the Engineer and shall be shown on the Final Subdivi_ sion Plan. They shall be installed in accordance with the Standard Specifications.

n) Traffic Control Signs. Traffic Control Signs shall be erected by the subdivider as directed by the Engineer prior to street acceptance.

o) Street Lights. Street lights shall be installed at all intersections and at the end of temporary or permanent cul_de_sacs. Where power is overhead (i.e., intersections with existing roads), a luminaire which conforms to the type used on comparable streets by the franchised electric company for the area shall be mounted off an existing pole; where power is underground, a decorative luminaire shall be used, as provided by the franchised electric company for comparable rural residential areas, with light poles located a minimum of four (4') feet from the curb. See Section 8.

p) Grades. The minimum grade of all streets shall be one (1%) percent except that in exceptional cases the Commission may permit a minimum grade of one_half (0.5%) percent.

The maximum grades shall be in accordance with the following list:

Classification Grade Range

Collector Streets 7%

Turnarounds 3% (permanent)

Intersections 5% for a distance of 100' from the centerline of the intersection

Design Speed. The various classifications of streets shall be designed for the following design speeds and traffic volumes:

Classification Speed_MPH Traffic Volume_*ADT

Arterial Roads 35_45 over 1,000

Collector Streets 30 200 to 1,000

Local Streets 20 under 200

Commercial ~~ ~~~~~~~~~~

*ADT _ Average Daily Traffic predicted for 20 years after the start of construction. If requested by the Commission, the Developer shall submit a report from an acceptable Traffic Engineer stating predicted traffic volume.

Sight Distance. All changes in grade shall be connected by vertical curves of length sufficient to give the following stopping sight distances:

Design Speed Stopping Sight Distance_Feet

The minimum horizontal sight distance at intersections shall be as follows:

Classification Horizontal Corner Sight Distance_Feet

Collector Streets 300'

Minor Local Streets 200'

q) Horizontal Design Criteria. Where street lines deflect from each other between intersections, the minimum inside radius shall be as follows:

Classification Minimum Horizontal Radius_Feet

Arterial Roads 1,000'

Collector Streets 450'

Commercial Streets 300'

At street intersections, the property lines shall be on a curve with a radius of fifteen (15') feet.

r) Existing Street Improvements.

1) Access. Whenever any subdivision is proposed for land accessible only by an unpaved street or an existing Town street which does not conform with minimum requirements of grade, alignment, width and construction set forth in these Regulations, and the Commission determines that approval of the subdivision plan would be contrary to the public safety unless such street was altered or improved where it fronts the proposed subdivision or beyond the limits of the proposed subdivision, the Commission may disapprove such plan or may condition its approval upon alteration of such street by and at the expense of the subdivider, or may disapprove such plan until the Board of Selectman has authorized expenditures for such Improvements.

2) Frontage Improvements. Whenever any subdivision is proposed for land which fronts on an existing Town street which does not conform with the minimum requirements of width and construction set forth in these Regulations, the subdivider shall improve such frontage from the centerline of the street to the required street line, in accordance with Appendix 2 to these Regulations. Where such improvement from the centerline is impractical, the Commission may require improvements of comparable value to be performed along the existing road frontage of the subdivision, or adjacent frontage impacted by the subdivision. In the alternative, the Commission may require that the cost of such improvements shall be paid to the Board of Selectman, or its designated agent, in lieu of the completion of such improvements by the applicant. Such payment shall be held in a separate fund to be used exclusively for the improvement of the subject street in ways which directly benefit the future owners of lots in the subdivision.

In making the determinations set forth in the preceding two paragraphs, the Commission shall take into account the street's ability to handle the increased volumes of traffic which will be generated by the proposed subdivision, the ability of school buses and emergency vehicles to travel the street safely, the drainage conditions of the street, and generally the ability of any vehicle to use the street safely.

s) Scenic Roads; Stone Walls. Frontage improvements, as described in the preceding section, may be modified by the Commission in order to achieve the objectives of the Willington Scenic Roads Ordinance, if and when the same shall be adopted. In addition, the Commission may modify any requirements for improvements described in these Regulations in order to preserve existing stone walls which are a part of Willington's historic character. Any modifications pursuant to this paragraph shall be in accordance with Chapter X of these Regulations.

t) Specification and Details. All street improvements shall be constructed in accordance with the Standard Specifications and Details for subdivision as the same may be amended from time to time.

u) Utilities. For new streets, all utility lines including, but not limited to, those required for electrical, communication, lighting and cable television sources and related facilities shall be placed underground, except surface_mounted transformers, surface_mounted connection boxes and meter cabinets which may be placed above ground, temporary utility service facilities during construction, high capacity electric and communication feeder lines. The subdivider shall make all necessary arrangements with the service utility to provide the underground services. The method of installation shall be approved by the particular utility company and be in conformance with the utility location requirements of these Regulations. The Commission may waive all or part of these requirements of these Regulations in accordance with Chapter X.

v) Watercourses. Where a major watercourse separates an existing street from abutting property to be subdivided, provisions shall be made for carrying such watercourse by means of culverts or other structures of design.

w) Drainage. All curtain and cellar drains are to be tied into the stormwater drainage system, unless the Engineer approves otherwise. Catch basins are to be made of all pre_cast parts (e.g., sumps, reducers, and curb tops with grates). Manholes or center_placed catch basins are not to be used for storm drainage unless approved by the Engineer. Flared end section pipes shall be used at all culvert outlets or inlets, unless headwalls are approved by the Engineer.

x) Dedication of Streets. Approval of Final Subdivision Plan shall not be deemed to constitute or effect an acceptance of any street by the Town. However, the filing of an approved Final Subdivision Plan shall constitute an irrevocable offer of dedication by the owner of the land to the Town.

y) Subdivision Street Work Prior to Acceptance. Prior to Town accept_ ance of new subdivision streets, all catch basins and detention basins are to be cleaned and all roadways swept. The subdivider shall be responsible for any and all maintenance required on unaccepted subdivision streets, including snow removal.

z) Driveways. All driveway openings shall be provided with a one and one_half (1 1/2") inch bituminous concrete apron from the street line to the edge of street pavement or the street face of the curb line. All driveways shall conform with Town driveway standards. See Section 3.g.

aa) Pavement Structure. Streets shall have the following compacted depths:

Subbase. Twelve (12") inches compacted depth in accordance with Connecticut Department of Transportation specifications.

Base Course. Six (6") inches of processed aggregate in accordance with Connecticut Department of Transportation specifications.

Surface Course. Three and one_half (3 1/2") inches bituminous concrete placed in a two (2") inch layer and a one and one_half (1 1/2") inch layer; arterial and commercial streets shall have four (4") inches in two (2) equal layers, all in accordance with Connecticut Department of Transportation specifications.

bb) School Bus Accommodations. The Commission may require that accommodations be provided for school bus stops. These accommodations shall include a paved stopping lane, good sight lines, and sufficient right_of_way to provide safe waiting areas.

a) All Land to Be in Lots. No land owned by the subdivider adjacent to the subdivision shall be withheld by the subdivider which is not capable of satisfactory independent subdivision into lots of the size specified. Nor shall there be any fragment of a lot or remainder in the subdivision area of less size than specified for lot dimensions. Fragments and remainders must be incorporated into full size lots complying with all provisions of these Regulations and the Zoning Regulations.

b) No Unapproved Lots. No lot, regardless of size, which is rendered useless for building due to utility easements, right_of_way, watercourses, topography, or lack of compliance with the Public Health Code, shall be shown as building lots on any subdivision. Such property shall be included in adjoining lots.

c) Corner Lots. On corner lots the lot dimensions may be determined from the point of intersection of the two (2) street lines.

d) Side Lines. Side lines of lots shall, insofar as practicable, be either at right angles or radial to street lines. Variations from this rule will be made only where it is impractical to do otherwise, and shall require approval in accordance with Chapter X of these Regulations.

e) Lot Boundary Marker. A lot boundary marker shall be placed by the developer's surveyor on each lot corner and also at any point where a chance of a lot line occurs. Such marker may be a steel rod, iron pin or other equally permanent material and it shall be clearly marked with an indelible paint. The permanent marker location shall be shown on the final subdivision map and must be placed on the site prior to the issuance of a final Certificate of Use and Compliance on the subject lot. Upon the specific request of the applicant in the subdivision application form, the Commission may waive this requirement on extraordinarily large lots or remaining tracts of property in accordance with Chapter X of these Regulations.

f) Lot Size. To ensure that all proposed subdivision lots have an adequate area for on_site water and sewerage systems, house and accessory building locations, driveways and parking area and usable recreation space; to minimize drainage problems and facilitate ground water recharge; and to minimize potentially detrimental encroachments upon watercourses, waterbodies, wetland soils and flood plain areas; all proposed subdivision lots, except for Open Space Subdivisions (if and when authorized by the Willington Zoning Regulations) and Designed Community Residential Developments as permitted under the Willington Zoning Regulations, shall comply with the following Minimum Buildable Area requirements:

1) The area and width of the proposed lots shall conform to the Willington Zoning Regulations and shall be of such shape, size, location and character that buildings can be constructed in conformity with the requirements of such Regulations. Lots shall be able to contain an area as nearly rectangular as possible of 40,000 square feet, such rectangle having no sides less than one hundred seventy_five (175') feet, with no part of that rectangle to be in soils classified as poorly or very poorly drained by the United States Department of Agriculture, Soil Conservation Service as shown on the Willington Inland Wetlands and Watercourses Map, as the same may be amended from time to time. Applications to amend said map shall be made to the Willington Inland Wetlands and Watercourses Commission in accordance with the Regulations of that Commission.

2) The lots shall be as nearly rectangular as is practical and of such character that they can be used for building purposes without danger to the health and safety of the public or the occupants. Any lot which is found to be unsuitable for buildings by reason of water or flooding conditions shall be combined with another lot that is suitable.

g) Driveway Standards. To promote traffic safety and prevent or minimize drainage and icing problems, driveways for all proposed subdivision lots shall be designed and constructed in conformance with the minimum provisions of this Regulation, unless requirements are waived as per the provisions noted below. To enable the Commission to verify compliance, all subdivision proposals shall depict driveway locations, proposed grading, tree and brush removal, drainage improvements and, as appropriate, other construction details. Upon approval, minor on_site modifications may be authorized by the Planning and Engineering staff, provided the required driveway standards are complied with.

Proposed lots which cannot be served by a driveway conforming with required standards shall not be approved by the Commission unless requirements are specifically waived in accordance with Chapter X of these Regulations. Said waivers may be approved in situations where no detrimental traffic or drainage impact is anticipated; where the driveway involves unusual site or roadway conditions or where roadway improvements are pending or anticipated.

Unless a waiver is authorized, driveways shall comply with the following standards:

1) Driveways shall conform with any curb cut and driveway standards established by the Zoning Regulations, the Board of Selectman and the Engineer and, as appropriate, the State Department of Transportation.

2) Unpaved driveways shall not exceed a slope of ten (10%) percent; paved driveways shall not exceed a slope of twelve (12%) percent.

3) Driveways shall be designed to prevent stormwater flows from entering a Town roadway and, wherever possible, the Town right_ of_way. Privately owned and maintained drainage diversion swales, detention areas and/or dry wells shall be utilized to the greatest extent possible. Culverts, fifteen (15") inches in diameter at a minimum, shall be used when crossing Town drainageways.

Whenever a private drainage swale or private detention area is utilized in diverting driveway water from the Town right_of_way, the owner of the subject lot(s) shall be responsible for maintaining the depicted swale or detention area and any culverts in accordance with the approved design. To ensure proper maintenance, no Certificate of Use and Compliance shall be issued on the subject lot until a deed restriction, approved by the Willington Planning Staff, is filed on the Land Records. Said deed restriction shall clearly note the maintenance responsibility and, subject to proper notification by the Town, it shall allow the Town to undertake any necessary maintenance activity and charge the property owner for expenses.

4) Driveways shall have a level area at the intersection with the street of at least one car length.

5) Driveway aprons shall be at least fifteen (15') feet in depth and intersect with the street with a twenty_five (25') foot radius.

6) All streets shall be constructed with driveway curb for each lot.

7) Driveways shall intersect roadways at an angle of approximately ninety (90) degrees and shall be located and designed with sightlines as follows: Along State roads, the minimum State recommended sight distance for the established speed limit shall be complied with. A minimum sight distance of four hundred twenty_five (425') feet shall be required along Town arterial streets; a minimum sight distance of three hundred seventy_five (375') feet shall be required along Town collector streets; and a minimum sight distance of three hundred (300') feet shall be required along local streets.

8) Common driveways and loop driveways shall be prohibited.

9) All driveways shall be constructed with a base and surface adequate to support 40,000 pounds of fire fighting vehicles. The design of all driveways shall be reviewed and approved by the Fire Chief.

In addition to the preceding, driveways for rear lots shall be in accordance with applicable provisions of the Willington Zoning Regulations.

10) Driveway sideslopes shall not exceed a slope of 3 to 1 unless retaining walls or other suitable stabilizing provisions are utilized. Guard rails, guide posts, headwalls, flared ends or wider driveway widths shall be used when steep side slopes or culvert crossings present a safety hazard or future maintenance problem. Driveway culverts in the Town right_of_way shall be maintained by the private property owner.

11) Driveway openings shall be located as far as possible from roadway intersections and no closer than seventy_five (75') feet from any roadway intersection, unless some less distance is required to meet the sight line requirements of these Regulations or to comply with the provisions of any permit issued pursuant to the Willington Inland Wetlands and Watercourses Regulations.

12) All driveways shall be substantially completed at the time of the commencement of construction on any lot.

h) Subdivision Lots in Designed Development Zones. Due to the special nature of Designed Development Zones and special regulatory provisions, all subdivision lots within Designed Development Zones shall not be developed until special permit approval is granted in accordance with the applicable provisions of the Willington Zoning Regulations. Each lot must be developed in a coordinated manner consistent with the overall site layout, architectural design and intended uses presented in the application creating a Designed Development District.

i) Underground Petroleum Storage Tanks Prohibited. There shall be no underground tanks on any lot for the storage of any petroleum product.

j) Footing and Curtain Drains. Where required by the Commission due to surface or subsurface water conditions, all dwellings shall be protected from water damage or infiltration by footing and/or curtain drains. All lots for which such measures are required shall be clearly identified on the Final Subdivision Plans. No such footing and/or curtain drains shall discharge water directly onto any adjoining property; all discharges shall be into pre_existing watercourses or inland wetlands, or into existing or proposed drainage structures. The Commission may require the installation of level spreaders or other energy dissipation devices for any points of discharge. Where applicable, evidence of rights to drain shall be provided by the subdivider.

SECTION 4. STORM DRAINAGE

4.1 General Hydraulic Design Requirements.

a) Storm drainage systems constructed under these Regulations shall provide for the proper drainage of the tributary area so as to prevent flooding, scouring, siltation or insufficient flows to brooks, lakes, ponds, and other watercourses and waterbodies, and other adverse impacts. The subdivider shall make provisions for preventing the creation of stagnant water within the limits of the proposed subdivision.

b) Storm drains shall be designed to flow full using design formulae approved by the Engineer.

c) Storm sewers shall have a minimum pitch of 0.5%. Variance from this requirement may be granted by the Commission if storm sewers are designed with a minimum self_cleaning velocity of three (3') feet per second with full flowing pipes.

d) A minimum cover of two and one_half (2 1/2') feet shall be provided for all storm drains.

e) No storm drain system shall outlet onto adjoining properties without a drainage easement; nor into a natural watercourse, whether continually flowing or intermittent, so as to exceed the capacity of the watercourse, or to cause erosion, sedimentation, scouring, or other adverse impacts on such watercourse.

f) All storm drain system outlets shall be terminated with an approved outlet structure.

g) The first inlet in a storm drain system shall be located within three hundred fifty (350') feet of the roadway highpoint. A drainage structure, either an inlet or a manhole, shall be provided at three hundred (300') foot maximum intervals on all storm drains with exception of the first inlet. A drainage structure shall also be placed at each grade change along a storm drain, at each change in horizontal direction, and at each junction point of two (2) or more drains.

h) Underdrain outlets shall be connected to drainage structures whenever practical. When impractical, they shall be terminated with an approved endwall. At all underdrain outlets, a "free outlet" condition should be provided.

i) The minimum pipe size for all public storm drain systems constructed under these Regulations shall be 15_inch inside except that culverts of a lesser size may be permitted where recommended by the Engineer.

j) The following types of pipes shall be used for drainage installations:

1) Reinforced concrete pipes or Advanced Drainage Systems (ADS) pipe or equivalent for surface drainage storm sewer systems and cross culverts.

2) Where clearance is limited by existing utilities, pipe arches or oval pipe will be used.

3) On grades over 10% _ use ACCMP.

4) Where uneven support is expected _ use ACCMP.

k) All drainage easements shall include a ten (10') foot access strip in addition to the width of the channel or brook from bank top to bank top. Channels shall be rip_rapped or paved when deemed necessary by the Commission.

l) Drainage easements, outside of street lines, shall be at least thirty (30') feet wide and shall include wording so as to allow inclusion of other utilities such as water and sanitary sewer. Easements for outlet pipes shall extend to a suitable existing storm drain or an adequate natural watercourse. The center line of storm sewer is not to be installed less than ten (10') feet from the edge of the right_ of_way.

m) Where the development streets join existing Town streets, the developer must provide drainage at intersections as necessary, or as directed by the Commission.

n) The size and location of all private storm drains that connect to the Town storm drain system shall be approved by the Commission prior to installation. A waiver must be filed by the developer with the Commission. The waiver shall relieve the Town of Willington of any responsibility for damage resulting from any failure of the private storm drainage system. This waiver shall be part of the deed so as to run with the property as to subsequent purchasers.

o) Rear yard drains and cellar or foundation drains that are connected to storm drainage systems must be shown on the final approved plan of the drainage systems.

p) Details of special or unusual drainage structures shall be submitted to the Commission for review and approval before construction.

q) Where any proposed lot or lots has its required frontage on an existing Town street, and has an existing ditch or waterway along the front of said lot or lots, but within the Town right_of_way, the developer, at his expense, shall install a stormwater pipe drain, of suitable size and material, necessary catch basins and a curb, to conform with the curb line.

4.2 Drainage Design Formulae.

a) Peak discharges for the design of storm drains shall be derived using the rational method for drainage areas of less than 1,000 acres, where:

Q = peak discharge in cubic feet per second

c = weighted runoff coefficient in percent

i = rainfall intensity in inches per hour

A = gross area tributary to the drain under design

b) Peak discharges for the design of storm drains shall be derived using the SCS method for TR 20 or TR 55 formula for drainage areas of more than 1,000 acres, where:

S = potential maximum retention after

I = initial abstraction (in.)

c) Design discharges for major channels and brooks may, with the concurrence of the Commission, be based on a flood hydrograph or flood flow formula type of analysis. [amended effective 3/11/82]

d) Hydraulic design shall be based on the Manning Formula:

Q = discharge in cubic feet per second

n = roughness coefficient

r = hydraulic radius

A = wetted area of conduit

4.3 Design Storm Criteria.

a) All storm drainage facilities shall be designed based on the following storm return frequency criteria:

1) Residential Drainage Systems:

Storm Sewers and Minor Ditches _ 10 year storm

Major Ditches and Channels _ 50 and 100 year storm

2) Commercial Districts:

All Drainage Facilities _ 50 and 100 year storm

3) Industrial Parks:

All Drainage Facilities _ 50 and 100 year storm

b) Rainfall intensities used for storm drainage shall be taken from Plate No. 4S.

c) Time of concentration shall be derived for all storm drains constructed.

d) Weighted runoff coefficients shall be derived based on the following criteria:

1) Areas Containing Roads, Roofs,

Parking Lots, Sidewalks and Driveways 90%

2) Areas Containing Lawns and Natural Ground 15% to 40%

e) Off_site drainage and the ultimate development of adjoining land shall be addressed and calculations provided in the design of a storm drainage system for the subject site. All off_site impacts, alterations, easements, and similar information shall be shown on the subdivision plans.

SECTION 5. INSPECTION

a) All subdivision Improvements to be dedicated to the Town shall be inspected by the Commission or such agent as may be designated by the Commission, in consultation with the Board of Selectmen. The developer shall, prior to the commencement of construction, arrange with the Commission and the Board of Selectmen for the employment of a clerk of the works to supervise the installation of all improvements. Such clerk of the works shall be an individual(s) approved by the First Selectmen; shall be answerable and report, as requested, to the Commission and the Board of Selectmen, acting by and through the First Selectmen; and all fees and expenses of such clerk of the works shall be payable to the Town in accordance with An Ordinance Establishing Fees For Planning and Zoning.

b) Inspections shall be made at the following stages of construction:

1) When rough grading is complete.

2) When drainage and all other underground facilities are installed, but prior to any backfilling.

3) During construction of street base courses.

4) During construction of bituminous concrete surface and binder courses.

5) During the placing of concrete for sidewalks.

6) When curbing is complete.

7) A final inspection shall be made when all Improvements are complete, and before acceptance by the Town.

c) For details on inspections, see the inspection schedule and fee schedule appended to these Regulations.

d) The developer shall not proceed to work on any stage subsequent to the first stage until such inspection has been made by the Commission or its appointed agent, on the preceding stage and approval in writing has been obtained on the preceding stage. At least forty_ eight (48) hours' notice, excluding Sundays and Holidays, shall be given by the developer to the Commission or its appointed agent for each inspection.

SECTION 6. STREET BOUND STONES

Street bound stones shall be placed at all block corners, at angle points, and the points of curves in streets and at such intermediate points as may be necessary to identify the street line in the field. The location of all street monuments shall be indicated on the final subdivision plan. They shall be installed and their accuracy certified by a Licensed Land Surveyor. The monuments shall be made of concrete, and shall be thirty (30") inches in length. The top shall be four (4") inches square with an "H" cast into it. The base shall be six (6") inches square. The monuments shall be set with the top two (2") inches above finish grade.

SECTION 7. FLOOD HAZARD REQUIREMENTS

All subdivision proposals greater than fifty (50) lots or five (5) acres, whichever is lesser, and all proposed subdivision activity impacting Zones on the Town's current National Flood Insurance Program Hazard Boundary Map (PHBM), which is on file in the Planning Office and the Office of the Town Clerk, shall comply with all applicable standards and requirements cited in Section 3.18 of the Willington Zoning Regulations. All applicable requirements of said Section 3.18 shall be in addition to all standards and requirements contained in these Subdivision Regulations.

In addition, for all subdivisions containing lots located in special flood hazard areas, as defined in the Willington Zoning Regulations, the following requirements shall apply:

a) The subdivision plan shall be consistent with the need to minimize flood damage.