Town of Marlborough, CT Design Standards

All proposed lots in a subdivision or resubdivision shall meet all the requirements of the Subdivision Regulations and Zoning Regulations. All proposed lots shall not be approved unless the lots can meet or exceed the minimum buildable lot area requirements at the time of application. Exceptions will be made of lots within an O.S.C.A.R. subdivision or large-lot conservation subdivision application after the determination by the Commission that the O.S.C.A.R. subdivision or large-lot conservation subdivision is the appropriate development pattern.

The minimum buildable lot area requirement is an area of at least 30,000 contiguous square feet having a series of corner angles ranging between 80° and 110°, with each side of the area being not less than 75 linear feet. The minimum buildable lot area shall not include the following: land classified as wetlands or watercourses plus a twenty-foot buffer area, land with no more than 20% of the area shall contain slopes in excess of 20% as measured over fifty-foot intervals, and land within a federally mapped floodplain. The primary subsurface sewage disposal system areas shall be located in the minimum buildable lot area as delineated on plans approved by the Town Sanitarian and Planning Commission.

Lot configuration. The total land area of the subdivision shall be divided into lots of proper dimension and size. Side lines of lots, insofar as practical, shall be either at right angles or radial to street lines. The Commission may require revisions to lot side lines so as to better conform to this provision. No fragments of a lot or remainder areas, and lots regardless of size, which are rendered useless for building according to sound engineering practice, will be permitted within the final subdivision boundary lines. Land of such geophysical nature that cannot be used for building purposes because of danger to health or public safety, because of peril from fire, or flood, or other conditions, such as difficult drainage, difficult configuration, inaccessibility, temporary flooding, erosion, steeply sloping topography, or swamps, or high groundwater level shall not be platted for residential use, or for such other uses which may increase danger to health, life or property or aggravate the flood hazard, until appropriate designs or corrective measures have been prepared by a State of Connecticut registered professional engineer, submitted by the subdivider, and approved by the Planning Commission, and any other applicable state, federal and local agency to eliminate such hazards in accordance with the appropriate specifications declared to be a part of these regulations. Such fragments or remainder areas, and unbuildable lots shall be either incorporated into adjoining full size lots, designated open space, or deeded to the Town, subject to the discretion of the Commission.

Unsuitable land. No house, septic, and structure shall be located on land subject to the following conditions and no more than 40% of the minimum lot size requirement for a conventional subdivision building lot and 50% for an O.S.C.A.R. subdivision lot purposes shall consist of:

Land designated as "floodway" on maps entitled "National Flood Insurance (FIRM) Flood Insurance Map, Town of Marlborough, Connecticut, Hartford County, Panels 1 of 8 through 8 of 8 (See map index for panels not printed.) Proof May 17, 1982, Community Panel Numbers 090148 0001 B through 090148 0008 B, Federal Emergency Management Agency Federal Insurance Administration" of the National Flood Insurance Program, as revised.

Land designated as "floodway fringe" on the above-described maps, except as may be developed in accordance with the requirements of the National Flood Insurance Program.

Land classified as inland/wetlands and/or watercourses area.

Land unsuitable for sanitary disposal by use of septic tank and subsurface disposal system as defined by the Connecticut Department of Health Services Regulations.

Rear lot(s). Rear lots shall not be approved unless such rear lots conform to the Marlborough Zoning Regulations as follows;

Access strip, owned in fee simple, not less than 50 feet in width shall run to an existing or proposed street.

Fifteen-foot side yards shall be maintained along the access strip. The driveway shall not be located in the minimum required side yard. The Commission may waive this requirement when such waiver would result in the reduction of wetland impacts, reducing cutting and filling over two feet, or preserve significant stone walls and/or trees.

Access strips shall be separated by at least one standard building lot except on the arc of a cul-de-sac or dead-end street where they may be one adjoining set of adjoining access strips.

The lot line from which the access strip originates shall be considered the frontage of the rear lot.

The access strip shall not be used in computing the minimum lot size requirements.

The lot shall consist of a minimum of three acres, 120,000 square feet. No part of the rear lot, except the access strip, shall be within 250 feet of the center line of the traveled portion of any street.

Rear lots more than 25 acres in area shall have two access strips spaced a minimum of 600 feet apart.

(8)

Such rear lots shall be numbered consecutively in conformity with other numbered lots in the proposed subdivision.

Adjacent property. Land adjacent to the subdivision which is owned by the subdivider and which is capable of satisfactory subdivision shall be identified and shown on the key map. The Commission may, at its discretion, require additional detail drawings and other information concerning such areas if, in it judgment, a more informed decision will result. The additional information for such adjacent land shall at a minimum include the information specified in the preapplication plan requirements.

Reserved highway right-of-way. When required by the Commission, parcels shall be deeded to the Town reserved for future street connections to adjoining property which is capable of subdivision. The deeds for these parcels and sloping rights on adjoining parcels shall be submitted to Town Counsel for review prior to final approval. The deeds are not to be executed until final approval is granted. Lots adjoining these parcels shall not have access to a house, other principal building or accessory structure over this reserved land. The minimum required yard abutting these parcels shall be considered a front yard for purposes of building and construction. When the adjoining property is subdivided, the developer of said adjoining property shall be required to connect to and construct the street over the reserved parcels. In the event that adjoining subdivisions are developed at the same time, then each developer shall be required to build a portion of the connecting street in proportion to the number of lots in their subdivision.

Public utilities.

Per the Town of Marlborough Highway Construction and Design Standards all locations where sanitary sewers, water lines, gas lines and electric lines are to be furnished, all necessary mains, branch lines to each lot, fire hydrants and necessary equipment shall installed and shall in all cases be placed underground at the cost to the developer. The Commission may permit a waiver(s) based upon evidence pertaining to ledge, significant wetland disturbance, and impacts to stone walls and trees.

All underground public utilities shall be confined to street right-of-way whenever possible. In all other cases, adequate easements shall be deeded to the Town or the respective utility, whichever is appropriate. All proposed utility easements shall be depicted on the subdivision plan. The applicant shall submit a letter of certification from the utility companies that the plans have been reviewed and utilities will be installed as shown on the plans prior to the commencement of construction. Any change from the final subdivision plan may require approval by the Commission depending upon the impact to wetlands, clearing limits, and significant site features.

Open space.

In accordance with Article VI of these regulations, upon consideration of the particular type of development proposed and determination of the needs created by such a development, the Commission shall require the reservation of land for park, playground, open space, or other public purposes in all subdivisions or resubdivisions. Land dedicated for this purpose shall be not be less than 20% of the total area for a conventional subdivision and not less than 40% for an O.S.C.A.R. subdivision.

No privately owned reserve strips of land, which, in the opinion of the Commission, show an intent on the part of the subdivider to control access to land dedicated to public use shall be permitted except where the control of the land comprising such strips is placed definitely within the jurisdiction of the Town or other no-profit land conservation group under conditions approved by the Commission.

Preservation of natural environment.

As a part of the overall design concept applicants shall incorporate the following;

Preservation and potential enhancement of natural features, such as vegetation, natural drainagecourses, trails, scenic points, inland wetlands, lands in the floodplain, steep slopes, habitats of endangered wildlife and other assets of a community nature.

Preservation of all areas of significant tree cover and/or stands, large isolated trees, shrubs, and stone walls which exist on the site. Particular care shall be given to preserve selected trees in order to enhance the landscape features of the development.

The Commission may require additional drawings or exhibits showing the means of protection for the above said assets. Special recommendations of the National Resource Conservation Service (Hartford County Soil and Water Conservation District) shall be incorporated into the plan.

Bench mark. A permanent bench mark to establish mean sea level vertical control (based on National Geodetic Vertical Datum) shall be placed and approved by a State of Connecticut licensed land surveyor within each subdivision over 10 acres or when otherwise required by the Commission. The location shall be shown on the proposed plan and shall be located within the dedicated right-of-way. Additional benchmarks are required by the Highway Construction and Design Standards.

§ 415-5.3 Subsurface sewage disposal system standards.

Soils testing. Each proposed lot shall be approved by the Town Sanitarian as having sufficient details and data to support a subsurface sewage disposal system, prior to its approval. All percolation tests and deep hole tests shall, where possible, be witnessed by the Town Sanitarian and in all cases be preferred in accordance with the State of Connecticut Public Health Code and Technical Standards for Subsurface Sewage Disposal Systems. All locations shall be specified on the plans. Each proposed lot shall have a percolation test and three deep hole test pits conducted within both primary and reserve sewage disposal areas. Each test pit shall be located in the center of the proposed leaching trench. The Commission or the Town Sanitarian may require additional tests.

Testing period. All percolation tests and deep hole tests for new subdivision or resubdivision lots shall be conducted between September 5 and December 15 and between January 5 and May 15. The Town Health Department may modify these testing periods as seasonal weather conditions warrant. Soils testing for existing lots of record may be conducted all year round unless otherwise directed by the Town Health Department. A report prepared by a State of Connecticut registered professional engineer detailing the results of the percolation tests, deep hole tests and groundwater monitoring shall be presented to the Commission at the time of application. All tests must be taken in the natural soil.

Test pits. Deep test pits shall be dug to a depth of at least seven feet on each proposed building lot unless ledge is found and shall be located on the Plan. Deep test pits data shall show all subsoil conditions, including rock, groundwater and other unsuitable soil conditions.

Percolation test. All percolation tests shall be run for a period of 80 minutes.

Separating standards. The design of subsurface disposal systems shall meet the Connecticut Public Health Code and any requirements of the Health District.

Groundwater monitoring. All lots shall have a standpipe located within the leaching area and groundwater levels shall be monitored weekly from February 1 through May 15. Any test hole where groundwater is above 18 inches for 21 consecutive days shall be an unacceptable location for subsurface sewage disposal.

§ 415-5.4 Street and highway standards.

Intent. The Commission shall ensure that proposed streets are in harmony with existing or proposed thoroughfares shown in the circulation plan of the Plan of Conservation and Development or established through its own deliberations, especially in regard to safe intersections with such thoroughfares, and so arranged and of such width as to provide an adequate and convenient system for present and prospective traffic needs. The Commission shall ensure further that the location number, and routing of proposed streets assure an orderly flow of traffic by providing alternative streets to better distribute vehicle flow to and from residences. All roads shall be designed, constructed, inspected and accepted by the Town in accordance with the current Town of Marlborough Highway Construction and Design Standards.

Street classification.

Streets shall be classified in a street hierarchy system with design tailored to function. The street hierarchy system shall be defined and classified by road function and ADT calculated by trip generation rates prepared by the Institute of Transportation Engineers. It is assumed that each single-family detached dwelling will generate 10.0 average weekday daily trips (ADT). The applicant shall demonstrate to the Commission's satisfaction that the distribution of traffic to the proposed street system will not exceed the ADT thresholds indicated by the Institute of Transportation Engineers for any proposed street types.

The right-of-way shall reflect future development as indicated in the master plan. Local roads shall be laid out so that their use for through traffic will be discouraged. Particular attention should be given to discouraging possible bypasses around traffic signals and major intersections.

Road right-of-way.

Road right-of-way width shall not be less than the various street designations shown in the following schedule: (These standards apply to new roads and to existing roads which shall be upgraded.)

				Boulevard Streets
Designation	Homes Served	R.O.W. (feet)	Pavement Width (feet)	R.O.W. (feet)	Minimum Pavement Width (feet per lane)	Minimum Median Width (feet)
Residential streets
Light	50	50	22-28	70	18	15
Standard	50-150	50	28	70	18	15
Residential collector	150-300	50	28	80	18	20
Collector	N/A	50	30	N/A	N/A	N/A
Arterial	N/A	60	32	N/A	N/A	N/A
Commercial	N/A	50-60	30	80	18	20
Industrial	N/A	60	32	80	18	20

Right-of-way width shall not be reduced from that shown on old plates or as established by utility pole and/or wall locations in the field. Right-of-way and/or pavement widths wider than those shown in the above schedule may be required if deemed necessary by the Commission.

Pavement widths are measured from face of curb to face of curb without on-street parking. Width may be varied up to two feet by the Commission in order to address specific traffic, safety, or environmental concerns.

The median strip for boulevard streets may be left in its natural state if vegetated, or if not, shall be landscaped in accordance with a landscaping plan to be approved by the Planning Commission. In the case of public boulevard streets, the Commission may require that the median strip, and/or streetlighting, street trees, and other street-related improvements within the public right-of-way be maintained by an association composed of the lot owners in the subdivision. The Commission may also allow narrower median strips where appropriate to the design of the subdivision, such as at intersections where medians may taper down to turning lanes or other purposes; where emergency crossover points are proposed or required by the Commission; where a narrower roadway will protect wetlands or other natural resources; or where specimen trees may be preserved by a narrower median strip.

Street layout.

Proposed street design shall bear a logical relationship to the original topography of the property and shall have a location and grade which preserves the natural terrain, significant trees and other physical features. The Commission may require changes to the proposed street layout, including but not limited to rerouting of proposed streets, inclusion of additional streets, or deletion of proposed streets, where, in its judgment, the public's health, safety and welfare will be better protected or better conformity with the Plan of Conservation and Development and § 415-5.2I of these regulations is achieved.

The road pattern within a subdivision shall be orderly. Where appropriate, a collector road shall be indicated for more direct access to residential and light residential streets.

Road block lengths should generally not exceed 1,200 feet and not be less than 600 feet. Minimum block width shall be related to the zoning district requirements for yards and generally shall provide for two tiers of lots.

Improvements to existing streets.

Whenever any subdivision is proposed for land abutting or accessible only by an existing street and the Commission and Town Engineer determine that the approval of the plan would endanger the public safety unless such street was altered and improved along the frontage of the subdivision and/or beyond the limits of the proposed subdivision, the Commission may disapprove such plan and may condition its approval upon completion of the improvements or alterations of such streets by and at the expense of the developer. Improvements include road widening, installation of drainage, road shoulder improvements, and removal of vegetation and rock.

Where a subdivision abuts an existing street which does not comply with the minimum right-of-way or pavement requirements, the Commission may require additional widths where necessary for public safety. Where required, the developer shall dedicate the necessary right-of-way to the Town for street widening and shall show such right-of-way and/or roadway widening on the subdivision plan and street plan and profile. Additionally, the plan shall depict all necessary grading and sloping rights deemed necessary by the Town.

Dead-end streets shall not exceed 1,000 feet in length unless waived by the Commission. The Commission may extend permanent dead-end streets up to a maximum length of 2,000 feet, provided that the applicant can demonstrate to the Commission that the longer road does not create a hazard to the public health, safety and welfare. The Commission may also grant a waiver to allow longer cul-de-sac streets (a) where a loop street provides duplicate access to a portion of the street; or (b) where the cul-de-sac street is a boulevard; or (c) where significant topographic features, such as stream valleys or large wetlands, would cause the creation of a through street to connect with an existing through street in the Town of Marlborough to be impractical or environmentally undesirable. The Commission may require additional design features to provide emergency and maintenance vehicle access, such as the use of adequate turnaround radii at intersections, crossover points in boulevard median strips, or dual use of drainage swales for load-bearing shoulders.

Cul-de-sac street. The Commission may extend a cul-de-sac street up to a maximum length of 3,000 feet when the applicant can demonstrate the ability to construct a through street in the future in compliance with these regulations that can be extended to a suitable existing Town street.

Stem streets. There may be up to three stem streets of the main cul-de-sac or dead-end street, provided that the total length for each stem does not exceed the length requirements noted above in Subsections F and G. The length of any stem street shall be measured from the street line of the existing through street to the edge of the street line of the circle. Dead ends, hammerheads or similar construction (other than culs-de-sac) shall not be permitted for terminating roads.

Turnaround areas. Cul-de-sac and dead-end arcs shall have a sixty-foot radius at the right-of-way line for local residential streets and a seventy-foot radius at the right-of-way line for commercial and industrial streets. All cul-de-sac streets should have a turnaround at the end consisting of a landscaped island with an outside radius of 35 feet at the center line of the cul-de-sac, or one or more approved building lot(s), and the pavement width shall be the typical pavement width unless the Commission reduces the pavement width due to the number of dwellings served, wetland impacts, and preservation of natural features.

Temporary turnarounds. Where the subdivision adjoins land susceptible to being subdivided, new roads shall be carried to the boundaries of the tract proposed to be subdivided. The road shall end in a temporary turnaround, and all paved area located outside the road right-of-way required for the circle shall be deeded to the abutting lots with a temporary turnaround easement to the Town. Said easement shall remain in effect until the street is extended at which time the easement shall be null and void. When the extension is constructed, the developer of said extension shall remove all pavement beyond the required street width and shall landscape the area as required by the Commission.

Loop streets. The Commission may approve loop streets. The stem of the street shall not exceed 1,250 feet unless the stem is a boulevard. The farthest point of the loop shall not exceed 2,400 feet as measured along the street line from the intersection of the right-of-way of the stem and looped portion of the street.

Private roads.

Private roads shall be constructed to the same design and inspection standards as public roads. The private road right-of-way and all drainage easements shall be owned and maintained by a common interest ownership association in accordance with the Connecticut General Statutes, Section 47-200. Proposed construction shall be bonded in the same manner as a road to be accepted by the Town. An appropriate notation is made on the site plan identifying the private road. The words "private road" must appear on the street signs at the intersections of all private roads.

If a private road is subsequently offered to the Town as a public road, the owner(s) shall be responsible for a final inspection in accordance with these regulations, with work to be sealed by a State of Connecticut registered professional engineer. In addition, the Planning Commission may require further tests to be conducted by the Town Engineer or a private firm of its choosing, and the cost of such tests is to be borne by the owner(s).

Highway geometric design. Connecticut Department of Transportation and American Association of State Highway and Transportation Officials (AASHTO) Design Standards shall be referred to for details and explanation of design.

Intersection design.

No more than two streets shall intersect or meet at any one point to form a four-way intersection. The center line of all roads entering an intersection shall pass through a single point. Unless authorized by the Commission and Town Engineer, intersections of commercial, industrial, and local roads shall be spaced a minimum of 400 feet apart as measured from the center-line points of the intersections. Intersections of arterial and collector roads shall be spaced a minimum of 800 feet apart as measured from the center-line points of the intersections.

Wherever practical, all streets shall intersect at 90° and no street shall intersect any other street at an angle less than 85° or more than 95°. The radii at the right-of-way line of intersecting residential streets shall be a minimum of 25 feet. The radii at the right-of-way line of intersecting residential streets and arterial and collector streets shall be a minimum of 25 feet. All other intersections shall have a minimum radius of 30 feet at the right-of-way line.

Curbing. All streets shall have curbing. The Commission and the Town Engineer may waive this provision when the applicant can demonstrate lack of curbs will not create an erosive condition; benefits wild life; on portions of street with slopes less than 5%.

Clearing limits. All areas within the road right-of-way and the slope rights areas that are necessary for excavation, embankments, and fills, shall be cleared of trees, stumps, brush, rubbish and other objectionable material. The Commission may waive this standard to preserve desirable trees as noted on the approved plans.

Center-line grades. Grades shall not exceed 3% for a distance of not less than 100 feet from the center line of the intersection.

§ 415-5.5 Driveways.

Subdivision lots shall be laid out so as to provide safe access and egress from the street to the garage, carport or parking place for emergency vehicles. No driveway shall be located within 100 feet of an intersection unless waived by the Commission in order to preserve significant natural features. All driveways shall have paved aprons as specified in the Town of Marlborough Highway Construction and Design Standards and as required by Town ordinance. Installation of a driveway apron shall not alter the flow of stormwater in the road gutter or side swale. No driveway runoff shall run directly onto the roadway. It shall be retained on the lot, carried in the roadway side swale, or piped directly to a catch basin or culvert.

Single access driveways.

The apron and drive shall have a maximum grade of 15%, a minimum width of 10% feet, transition curves to meet the existing and proposed street, and a paved apron. Any portion of a driveway with a grade of 7% or more shall be paved with a one-inch bituminous concrete surface course and a two-inch binder course.

Driveways shall not exceed a maximum length of 1,200 feet unless otherwise approved by the Commission after consideration of the recommendation from the Fire Marshal with consideration to the relative location of a water source for fire suppression, the slope of the driveway and the ability for the adequate maneuverability of emergency vehicles. Driveways that exceed 500 feet in length may be subject to additional standards as a means to ensure the reasonable safety of persons occupying or using any premises in the Town. These standards may include, but are not limited to, extra driveway width, pavement treatment, driveway length and turnaround areas. The Commission may prescribe certain conditions or may deny approval for sites that cannot be adequately serviced by emergency vehicle equipment.

Common driveways. The Planning Commission may allow common driveways to be used in subdivision in order to eliminate a potential traffic hazard condition, where there are safety concerns, environmental reasons, aesthetic considerations, such as the preservation of natural streetscapes, or whenever it is necessary to protect an inland wetlands area. Economic reasons will not be justification for the use of common driveways. The Commission may prescribe certain conditions or may deny approval for sites that cannot be adequately serviced by emergency vehicles. In addition, each lot shall demonstrate that an individual driveway can be constructed in accordance with the regulations. The following standards apply to the design and construction of all common driveways, including mews, unless otherwise noted:

The common driveway length shall not exceed 1,000 feet, and the terminus of the common driveway shall contain an area sufficient in size for an emergency vehicle to turn around unless a waiver is obtained from the Planning Commission.

A maximum distance from the proposed fire dropoff point to the rear of any house must not exceed 500 feet. "Dropoff point" is defined as a location at which a water source operation can be managed.

Whenever possible, individual driveway alignment (off of the common driveway) should be designed and situated so that it may be used as a turnaround or dropoff point. No common driveway shall be constructed in any required side yard unless specifically approved by the Commission.

An appropriate easement and maintenance agreement is filed on the Marlborough Land Records with the final subdivision plan to indicate that a right-of-way has been conveyed for the shared portion of the driveway.

A right-of-way easement of at least 30 feet is reserved for the common portions of the driveway.

The common driveway, including the shoulders, shall have an eight-inch-thick rolled gravel subbase installed in accordance with Section 3.02 of the State of Connecticut, Department of Transportation Specification Form 814 as amended.

The common driveway shall have a six-inch-thick processed aggregate base paving installed in accordance with Section 3.04 of the State of Connecticut, Department of Transportation Specification Form 814 as amended.

(8)

When the slope of the common driveway is 5% or over, that portion of the driveway shall be paved with a one-inch bituminous concrete surface course and a two-inch binder course. The remainder of the common driveway may be required to be paved per recommendation by the Commission, Town Engineer, or Fire Marshal based upon field conditions.

(9)

Except one-way mews, the pavement width shall be a travel lane of 20 feet with gravel shoulders of two feet. The pavement width may be decreased to 16 feet for common driveways less than 200 feet long which allow a clear, and unobstructed view along the entire length of the common driveway. For two-way mews, the standard of this subsection shall apply. For one-way mews, the standard shall be a pavement width of 16 feet, with two eight-inch rolled gravel shoulders (which may be covered with topsoil). One-way mews must be depicted on the plans with suitable "One-Way" and "Do Not Enter" signs. All mews shall be identified with signs indicating the name of the mew and addresses of lots served by it.

(10)

Common driveways with side slopes greater than 4:1 and side slope drops of more than four feet shall have guardrails installed. Guardrail specifications shall be submitted with the subdivision plans and shall be approved by the Town Engineer.

(11)

Where common driveways intersect Town streets, the bituminous pavement shall be extended at least 50 feet from the edge of the existing pavement into the common driveway, and the intersection sight distance (ISD) shall comply with ConnDot and AASHTO design standards.

(12)

Each common driveway serving more than three houses shall have a name to be approved by the Commission (driveway/street names should not be easily confused with another existing street name within the Town). The driveway shall have a street sign with the name and the words "common driveway" at the intersection of the driveway and the Town street.

(13)

Common driveway signs should conform to § 415-5.6D of these regulations.

(14)

A determination should be made at subdivision approval whether there should be illumination at the intersection of the common driveway and the Town street.

(15)

A certificate of zoning compliance shall not be issued until the dwelling unit numbers are posted in a permanent fashion at the intersection of the private driveway and the common driveway and at the intersection of the common driveway and the public street. All required street numbers shall be a minimum of four inches in height and located for optimum visibility.

(16)

No more than four dwelling units should be serviced by a common driveway. The number of homes can further be restricted depending upon the topography.

(17)

The common driveway shall be installed and approved by Town Engineering staff prior to the issuance of a building permit for an individual dwelling unit.

(18)

The driveway shall conform to all of the other requirements of this section of these regulations.

O.S.C.A.R. driveway exceptions.

Width of access strip.

The driveway servicing a rear lot shall maintain the following aggregate setbacks based on the width of the access strips as follows:

Access Width (feet)	Aggregate Setback (feet)
40 to 50	20/narrowest side setback of 8 feet
30 to 39	15/narrowest side setback of 5 feet
25 to 29	10/narrowest side setback of 3 feet
20 to 24	7/narrowest side setback of 3 feet

When a rear lot's access strip is less than 30 feet in width, there shall be a minimum of a fifteen-foot buffer area provided on the abutting lots for the entire length of the access strip.

Modifications. The Commission may modify the above-mentioned setback limits after consideration of the comments from the Fire Marshal and/or such a modification will result in at least two of the following;

Reduction of cuts and fills over four feet.

Preservation of stone walls.

Preservation of significant trees with a caliper over 18 inches.

Reduction of wetland disturbance.

§ 415-5.6 Street monuments, names and signs.

Monumentation.

Street monuments shall be furnished and installed by a State of Connecticut licensed land surveyor at the developer's expense on both sides of the street placed at all block corners, at angle points, and the points of curvature and tangency in street lines and at such intermediate points as directed by the Commission. The location of all monuments shall be indicated on the final subdivision plan; a maximum' distance of 400 feet between monuments is allowable.

Monuments shall be concrete with four one-fourths-inch steel reinforcing rods for metal detection. The monument shall not be less than four inches square and 36 inches long with a brass, stainless steel or aluminum disk with a drill hole or cross marking the point. All monuments are to be set one inch above the finished grade.

Pins. Property pins are to be set one inch above the finished grade and be minimum of one-half-inch steel rod, a minimum of three feet long. They shall be set with the accuracy to a Class A-2 Survey Standards and certified by a State of Connecticut licensed land surveyor. All monuments and pins must be set prior to the endorsement of the final subdivision plan with the exception of those associated with the road right-of-way, including public improvements. Upon completion of the public improvements and prior to the Town accepting such improvements, all the monuments and pins shall be set. Prior to endorsement and acceptance, the applicant shall submit a letter of certification with the original seal and signature of the State of Connecticut licensed land surveyor verifying the installation of the monuments and pins in accordance with the final subdivision plan. All lot corners and angles shall be designated with one-inch steel rod, four feet long, imbedded in the ground or in rock a minimum of three feet.

Street names. There shall be no duplication of existing street names nor shall there be a phonetic resemblance to the names of existing streets within the Town. All street names shall be subject to the approval of the Commission.

Street signs. The developer shall provide and install corrosive-resistant, reflectorized street name signs as specified in the Marlborough Highway Construction and Design Standards. The words "dead end" or "no outlet" must appear on a street sign at the intersection of all cul-de-sac streets.

Traffic markings and signs. To maximize the public's safety, welfare and convenience, the developer shall provide and install all required traffic devices. Such devices shall be designed, located and installed in conformance with the Manual on Uniform Traffic Control Devices for Streets and Highways published by the Federal Highway Administration, U.S. Department of Transportation and the Marlborough Highway Construction and Design Standards.

§ 415-5.7 Standards for storm drainage improvements.

General criteria.

It is the intent of these regulations to implement specific stormwater management practices and measures that achieve the following:

Prevent increases in the volume and flow of stormwater runoff associated with new development so as to prevent an increase in the hazards and costs associated with flooding.

Minimize the erosion potential from a development or construction site so as to prevent deposition of sediment into streams and other receiving waterbodies.

Prevent decreases in groundwater recharge and stream base flows so as to maintain aquatic life, assimilative capacity, and potential water supplies.

Reduce the pollutant load in stormwater runoff from developing and urbanizing areas so as to perpetuate the natural biological functions of streams and other receiving water bodies.

Secure, to the extent practical, multiple community benefits, such as open space protection, increased recreational opportunities, and enhanced landscaping from stormwater management facilities.

(f)

Incorporate decentralized stormwater management systems in any new development designs.

(g)

Minimize the increases in peak rates of stormwater runoff from any development in order to reduce flooding, siltation and stream bank erosion, and to maintain the integrity of stream channels and downstream drainage structures.

(h)

Minimize the increase in nonpoint source pollution caused by stormwater runoff from development which would otherwise degrade local groundwater and surface water quality.

(i)

Minimize the total volume of surface water runoff which flows from any specific site during and following development to not exceed the predevelopment hydrologic regime to the maximum extent practicable.

(j)

Reduce stormwater runoff rates and volumes, soil erosion and nonpoint source pollution, wherever possible, through stormwater management controls and to ensure that these management controls are properly maintained and designed to minimize potential threats to public safety.

(k)

The design and planning of all stormwater management plan facilities shall include detailed inspection procedures and frequencies, maintenance plans and schedules, as well as repair procedures to ensure their continued long-term function. These items shall identify the components of the stormwater management system that need to be inspected and maintained, provide a maintenance schedule for each facility and the equipment necessary to perform that maintenance. Provisions for the periodic review and evaluation of the effectiveness of the maintenance program and the need for revisions or additional maintenance procedures shall be included in the plan.

To achieve these objectives the applicant must ensure that the quantity and quality of stormwater runoff after development is not substantially altered from predevelopment conditions. More specifically, the applicant must provide drainage analysis to evaluate the impacts of runoff from the proposed development. This analysis must demonstrate that the estimated peak discharge rate under post-development conditions does not exceed that for predevelopment conditions in accordance with these regulations. In general all proposed development that increases the peak rate of discharge of stormwater runoff for post-development conditions must implement drainage control structures to attenuate the proposed flows, such as retention basins, infiltration basins, or other acceptable means.

All stormwater management plans shall include measures to capture and treat stormwater runoff in accordance with the guidelines outlined in the most recent version of the CT DEEP Stormwater Quality Manual and to incorporate low-impact development design elements to the extent that is practical. No application for involving any site development plan will be approved by the Commission unless it includes a stormwater management plan detailing how the stormwater runoff and associated water quality impacts resulting from the development will be controlled and managed during and after construction. The plan must be prepared by an appropriate design professional.

The Commission may impose additional requirements deemed reasonable and necessary to control the volume, timing, rate, and/or quality of runoff if the hydrologic, geologic, topographic, or land use conditions warrant greater control than provided by the applicant. Further the Commission may restrict the use of certain BMPs, and may require pretreatment to exceed the minimum standards established in the most recent version of the CT DEEP Stormwater Quality Manual.

The Commission may waive the requirement of no increase in peak runoff discharge when the applicant provides engineering data that documents that the lack of attenuation will not overburden the ability of the downstream drainage system to adequately handle the increased volume, flow, and/or velocity of stormwater drainage. All stormwater drainage facilities shall conform to the material and construction specifications of the Town's Highway Construction and Design Standards.

Protected watercourses.

Stormwater discharges to critical areas with sensitive resources, such as the Blackledge River, Dickinson Creek, Lyman Brook, Fawn Brook, Flat Brook, Lake Terramuggus and their contiguous wetlands, may be subject to additional performance criteria, or may need to utilize or restrict certain stormwater management practices. Land development that discharges to sensitive waters and wetlands as noted above shall meet enhanced criteria. These may include, but are not limited to:

Nutrient sensitive waters. Enhanced control of nutrients and sediment removal for stormwater discharges shall be required.

Cold water fisheries. Techniques to control temperature increases from stormwater discharges into these streams and water bodies shall be required.

Groundwater. Enhanced recharge and pretreatment of stormwater discharges shall be required to protect groundwater supplies.

Wetlands: controls to minimize impacts to the natural or predevelopment wetland hydrology, including limiting adverse fluctuations in surface and groundwater elevations.

In these cases the Commission may require additional storage capacity, treatment, filtering, infiltration, or other mitigation techniques. The use of nonstructural practices shall be used to the maximum extent practical to meet enhanced criteria. In making its determination to apply enhanced criteria, the Commission shall consider the cumulative impacts of the site development plan.

Surface drainage systems. Subsurface storm drainage may not be required if site conditions are appropriate, erosion control concerns are addressed and a surface drainage system is designed by a State of Connecticut registered professional engineer. Runoff may be collected by a surface system which is approved by the Town Engineer.

Water quality protection. Development shall use the best available technology to minimize off-site stormwater runoff, increase on-site infiltration, simulate natural drainage systems and minimize off-site discharge of pollutants to groundwater and surface water and encourage natural filtration functions. Whenever appropriate, drainage systems should include special engineering design features to minimize pollution from oil, suspended solids and other objectionable materials.

Improvements to existing storm drainage system.

Where the subdivision storm drainage system is proposed to discharge into a new or modified existing municipal separate storm sewer system (MS4) or other publicly, municipally or privately owned storm sewer system, the applicant must demonstrate that the existing storm sewer system has adequate excess hydraulic capacity to convey both increases in peak discharge flow rates and runoff volumes.

In addition, all such discharges shall conform to all the requirements contained in the applicable general permit for the discharge of stormwater and dewatering wastewaters from construction activities, the general permit for the discharge of stormwater associated with industrial activity, or the general permit for the discharge of stormwater associated with commercial activity, as originally issued and reissued. All new or modified site development shall also conform in all respects to the Town of Marlborough Illicit Discharge Detection and Elimination Ordinance, as amended.[1] This shall include all the drainage calculations necessary to demonstrate the capacity of the existing Town drainage system and any proposed improvement. All proposed improvements must be shown on the plans with all appropriate details and notes.

[1]

Editor's Note: See Ch. 301, Stormwater Management, Art. I, Illicit Discharges.

Drainage design formula. All design formula shall adhere to acceptable engineering practices and shall conform to the requirements provided in the Marlborough Highway Construction and Design Standards. For drainage areas less than 50 acres and that do not require stormwater attenuation, the Rational Method may be used for calculating runoff. For drainage areas less than 50 acres that require stormwater attenuation and for any drainage areas greater than 50 acres, runoff shall be calculated by either the Soil Conservation Service TR-20 or TR-55. Drainage computations showing the following shall be submitted to the Commission with the final submission:

Plan showing watershed for the overall site and for each structure.

All calculations for the pre- and post-development hydrology for the site, including hydrographs, time of concentration, rainfall intensity, runoff coefficient, flow, velocity, pipe size and slope of each pipe length.

Design storm criteria.

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

Street storm sewers and minor channels: ten-year storm.

Storm system outfalls and minor culverts: twenty-five-year storm.

Minor stream structures and culverts (drainage area of 200 to 1,000 acres): fifty-year storm

Major stream structures and culverts (drainage area of more than 1,000 acres): 100-year storm.

Positive flood relief through streets and drainage systems shall be provided for a 100-year storm.

The design of stormwater BMPs shall consider public health, safety, and general welfare. These considerations shall include, but not be limited to: preventing flooding of buildings, structures, and travel ways; preventing long-term standing water in and near drainage facilities; minimize the creation of mosquito breeding pools; preventing attractive nuisance conditions and dangerous conditions due to stormwater depth or velocity and/or access to drainage structures, including inlet and outlet openings. In addition, designs shall not result in the creation of aesthetic nuisances due to excessive slopes, cuts and fills, lack of suitable native landscaping and other similar conditions that would detract from the appearance of the surrounding environment.

To the extent that they are feasible, the use of nonstructural stormwater treatment practices are required and shall be selected and designed using the appropriate criteria from the most recent version of the CT DEEP Stormwater Quality Manual or other appropriate design low-impact design manuals acceptable to the Commission.

Rainfall runoff criteria.

Rainfall intensities used for storm drainage design shall be taken from the U.S. Weather Bureau Rainfall Intensity - Duration Frequency Curves for Hartford. Rainfall intensities for TR-55 and TR-20 drainage analysis shall conform to the requirements presented in those respective methods. Methods of computation shall be delineated on the plans.

All drainage structures shall comply with the Marlborough Highway Construction and Design Standards and with standard details outlined in the Guidelines for Erosion and Sedimentation Control, as amended.

General design requirements. Storm drains shall be designed to flow just full and designed to provide a self-cleaning velocity of at least 2.5 feet per second when flowing full. A minimum cover of two feet shall be provided for all storm drainpipes unless otherwise approved by the Commission and Town Engineer. In order to prevent the adverse impacts of stormwater runoff, the Commission has developed a set of performance standards that must be addressed in the design of any new site development plan or modification to an existing site development plan that disturbs 5,000 square feet or more of area.

All stormwater runoff generated from new development shall not discharge stormwater runoff directly into a natural wetland systems, water body, municipal drainage system, or abutting property without adequate pretreatment.

A vegetative separation shall be maintained to provide a disconnection between impervious surfaces and the natural wetland systems of the site and abutting sites.

All stormwater best management practices shall be designed to minimize the need for maintenance, while maintaining water quality discharge treatment standards.

All site development plans shall be designed to minimize the need for stream bank/channel protection for the receiving natural system, but when required, shall include provisions to prevent erosion and scouring of the stream bank/channel.

The design of all stormwater best management practices shall convey stormwater runoff in a manner to allow for the maximum removal of pollutants and reduction in flow velocities.

Stormwater discharges from land uses or activities with a higher potential pollutant loading may require the use of specific pretreatment structural methods and pollution prevention practices.

All site development plans shall include the design of stormwater detention or retention facilities to attenuate the increase in peak rates of stormwater runoff for the two-, five-, ten-, twenty-five- and 100-year, twenty-four-hour duration storm events to provide for a zero post-development increase whenever practical.

(8)

Stormwater management designs shall include an inventory of important natural resources features on the site, and these features shall be shown on the stormwater management plan. Protection and/or conservation of the site natural features shall be a part of the stormwater management plan. The plan shall identify important natural features identified through a natural resources inventory that includes, but is not limited to, the following: natural drainage features, riparian buffers, wetlands, steep slopes, soils with high infiltration capacity, significant forest cover, significant trees and natural communities, including the presence of any threatened and/or endangered species.

(9)

Site design feasibility report.

Stormwater management practices for a site shall be selected on the basis of the physical characteristics of the site. The design professional shall submit a report outlining the stormwater practices options, including low-impact alternatives that were considered and those that were chosen for the design based on the evaluation and analysis of site opportunities and constraints. Among the factors that should be considered:

[1]

Depth to groundwater/ledge.

[2]

Hydrologic functions.

[3]

Contributing drainage area.

[4]

Site vegetation.

[5]

Soil characteristics.

[6]

Topography.

[7]

Location in relation to environmentally sensitive features.

A soils report based on on-site boring logs or soil test pit data shall be submitted with all designs. The number and location of soil borings/test pits and associated soil testing shall be that which is necessary to determine the suitability and distribution of soil types present at the location of the proposed stormwater measures as shown on the site development plan.

(10)

All stormwater designs shall include infiltration for any new site development unless the site design feasibility report and associated soils report demonstrate that the physical characteristics of the site are not suitable. Low-impact design elements utilized for infiltration discharge into a natural system shall utilize native plant species.

(11)

Devices and techniques to reduce stormwater velocities and prevent erosion shall be placed at discharge outlet locations and along or within the full length of any outlet channels to convey and discharge peak design flows in a manner that will not result in scouring or surface erosion, including receiving streams or channels or wetlands so that the natural physical and biological characteristics and functions of the receiving waters are maintained and protected.

(12)

All stormwater management designs shall include a detailed landscaping plan that identifies the types (both common and botanical names), locations, sizes and total number of all proposed plantings. Planting notes and details shall also be provided, as well as a maintenance and management plan to ensure the long-term viability of all plantings. In addition, the landscaping plan shall include a stabilization schedule for the revegetation of all disturbed areas of the site. Any area of land from which the natural vegetative cover has been either partially or wholly cleared or removed by development activities shall be seeded with temporary vegetation within seven days after the suspension of grading work is expected to last a period of 30 days or more. Permanent vegetation shall be fully established by the date of substantial completion of construction. Following the first year after the establishment of permanent vegetation and the completion of all landscaping plantings, an inspection shall be conducted by the Town to confirm their health and survival. Should any permanent vegetation or plantings be determined to be dead or dying following the one-year period, then they shall be revegetated or replaced. A second inspection shall then be conducted by the Town one-year from any subsequent revegetation or replanting.

(13)

To the extent that they are feasible, the use of nonstructural stormwater treatment practices are required and shall be selected and designed using the appropriate criteria from the most recent version of the CT DEEP Stormwater Quality Manual or other appropriate low-impact design manuals acceptable to the Commission.

Catch basin design. The first set of catch basins in a storm drain system shall be located a maximum of 300 feet from the roadway highpoint. Spacing between sets of catch basins shall be a maximum of 300 feet. A drainage structure shall also be placed at each vertical grade change along the storm sewer, at each change in horizontal direction, and at each junction point of two or more storm sewers. The Commission and Town Engineer may require catch basins at a spacing to be based on gutter flow analysis in accordance with CTDOT Form 814A, as amended.

Pipe size. The minimum pipe size for all storm drain systems constructed under these regulations shall be 18 inches inside diameter except catch basin laterals which maybe 15 inches. The material shall be reinforced concrete except when waived by the Commission.

Right to drain. The developer shall obtain drainage rights for flows across adjacent properties in writing. The rights shall include the right for the Town to enter and maintain existing or proposed facilities if the system is to be accepted by the Town.

Drainage easements. Drainage easements shall be a minimum of 20 feet wide for pipes under 24 inches, 30 feet for pipes greater than 24 inches. Easements outside of street lines for culvert inlet/outlets, storm sewer outfalls, and other drainage structures, shall be a minimum of 20 feet by 20 feet centered on the pipe. Easements for outlet pipes shall extend to a suitable existing storm drain or an adequate natural watercourse. Where possible, easements shall be centered on property lines.

Detention/retention facility. The design and construction of all detention/retention facilities shall conform to the Marlborough Highway Construction and Design Standards. Proper and safe access shall be required for maintenance of the facility. Access to the facility shall have a minimum of a thirty-foot-wide easement. Upon completion of the public improvements and acceptance of such public improvements by the Town, responsibility for operation and maintenance of the facility shall be assumed by the Town. Applications including private road development shall include a homeowners' association or similar permanent entity approved by the Commission to maintain and operate the facility. Prior to endorsement of the final subdivision plan, the applicant shall submit a fee for the long-term operation and maintenance of the facilities as determined by the Town.

Intersection drainage. Where the development streets adjoin existing Town streets, the developer must provide drainage at the intersections as directed by the Commission and Town Engineer.

Private drains. Private drains of any kind (subsurface/surface) shall not be permitted to discharge onto or towards the surface of a Town right-of-way, or in a manner which shall change the preconstruction condition on any adjoining property. Connection to a nearby catch basin shall be permitted with prior approval of the Director of Public Works. Such connections shall require recording a hold harmless document on the Land Records of the Town of Marlborough signed by the property owner holding the Town harmless for any future damage caused by backups, broken pipes, or blockage of their drain and his/hers successors in title. Sanitary waste and floor drains are prohibited from entering the storm water system.

Channel rights-of-way. A channel or brook right-of-way, of sufficient minimum width to include a fifteen-foot access strip in addition to the width of the channel or brook from bank top to bank top, shall be dedicated to the Town for drainage purposes, or to the association having the responsibility to maintain such channel, as the case may be. The minimum width shall be 30 feet.

Substantive changes to plan.

No changes shall be made to an approved stormwater management plan without review and written approval by Town staff, or, if any such changes are determined to be substantive, by the Commission. Additional data may be requested to allow for a complete review and evaluation of proposed changes to ensure compliance with the required discharge standards.

§ 415-5.8 Additional standards.

Pedestrian walkways. When required by the Commission sidewalks shall be installed within the street right-of-way wherever possible. The applicant shall provide additional right-of-way width necessary to construct the walkways if it cannot be located within the street right-of-way. Walkways shall be required where deemed essential to provide access to schools, playgrounds, or other community facilities in the proximity of the development. The walkways shall be graded and surfaced as directed.

Creation of stagnant water. Natural or man-made drainage areas shall not be left in such a condition that the normal flow of water is cut off. In the case of ponds, provision shall be made for emergency overflows unless otherwise determined by the Town Engineer.

Tree stumps. The burial of tree stumps and shrubs that have been cleared from the land shall be prohibited within the limits of the subdivision. Disposal must be at an approved off-site location or surface location on site.

Water testing. In areas of known contamination or suspected contamination or in areas of geological concern the Commission and/or Town Sanitarian may require tests to be performed to ensure that there is an adequate safe drinking water supply which meets the criteria of the State of Connecticut Health Code for potable drinking water. If deemed necessary, the placement and approval of the well may be required prior to the issuance of a certificate of zoning compliance for individual lot development or prior to approval of the subdivision application.

Erosion and sediment control plan.

To be eligible for approval, a soil erosion and sediment control plan shall contain proper provisions to adequately control accelerated erosion and sedimentation and reduce the danger from stormwater runoff on the proposed site based upon the best available technology. Such principles, methods and practices necessary for approval are found in the Connecticut Guidelines for Soil Erosion and Sediment Control (1988), as amended. Alternative principles, methods and practices may be used with prior approval of the Commission.

Plans for soil erosion and sediment control shall be developed in accordance with these Regulations using the principles as outlined in Chapters 3 and 4 of the Connecticut Guidelines for Soil Erosion and Sediment Control (1988), as amended. Soil erosion and sediment control plans shall result in a development that minimizes erosion and sedimentation during construction, is stabilized and protected from erosion when completed, and does not cause off-site erosion and/or sedimentation.

The appropriate method from Chapter 9 of the Connecticut guidelines for Soil Erosion and Sediment Control (1988), as amended, shall be used in determining peak flow rates and volumes of runoff unless an alternative method is approved by the Commission. The Commission shall either approve the soil erosion and sediment control plan, as filed, if it finds the plans comply with the requirements and objectives of this section or deny the development proposal when it does not comply with this section.

Site development shall not begin unless the soil erosion and sediment control measures and facilities shall be installed as scheduled according to the approved plan and maintained in effective condition to ensure compliance with the approved plan. Failure to properly install and/or maintain any erosion and sediment control measures shall result in the issuance of a stop-work order until the problem is satisfactorily corrected.

Proper provisions shall be made to prevent surface water from damaging the cut face of excavation or the sloping surface of fills. Also, grading shall not be done in such a way so as to divert water onto the adjoining property without a right to drain agreement.

Inspections shall be made by the Commission or its authorized representative during development to ensure compliance with the approved plan and that control measures and facilities are properly performed or installed and maintained. The Commission may require the permittee to verify through progress reports that soil erosion and sediment control measures and facilities have been installed and are performing according to the approved plan and are being maintained.

Energy conservation. The street design and lot layout should be designed in an energy efficient pattern to encourage solar energy utilization and access and general energy conservation. The applicant shall demonstrate to the Commission that consideration has been given to passive solar energy techniques. These techniques may include, but not be limited to: house orientation, street and lot layout, vegetation, natural and man-made topographical features, and protection of solar access within the development.

Road layout changes. The Commission shall require whatever layout changes it believes are necessary to eliminate or improve any problems relating to health, fire safety, traffic safety, drainage and the provision of future streets, in accordance with these regulations. Such requirements may include, but not be limited to: traffic signs, control facilities and area lighting, improvement of sight distances, conformance to Plan of Conservation and Development street plan, reduction of the number of driveways on streets designated as arterial by the Plan of Conservation and Development or as principal streets in these regulations, widening, repaving or otherwise improving existing streets if the subdivision is to substantially increase traffic flow, additional drainage structures, hydrants, standpipes, water storage and fire ponds, sidewalks.

Field changes and deviations from plan.

All proposed field changes or deviations from specifications or from the approved final drawing must be documented in triplicate on a request for field change approval form, signed by the developer and submitted to the Town Engineer. For proposed changes and deviations of a minor nature, approval by the Town Engineer is required prior to commencing work on said change(s), with such approval being granted only by the Town Engineer's signature on the request for field change approval form. The request for field change approval form will be forwarded to the Commission chairman for information and signature. Copies are to be returned to the developer and Town Engineer.

For proposed changes or deviations which, in the judgment of the Town Engineer, will be a significant alteration of the final approved plan, approval by vote of the Commission is required prior to commencing work on the change. Recommendation for such change or deviation must be received from the Town Engineer, evidenced by his signature on the request for field change approval form. The Commission shall, at its discretion, require revised drawings prior to considering such request. Such significant alterations will be subject to the normal Planning Commission agenda procedures for old business.

The Commission and its authorized representatives reserve the right to require certain specified field changes or deviations from the approved plans when field conditions warrant.

§ 415-5.9 Stormwater management.

The purpose is to establish stormwater management requirements and controls to protect and safeguard the quality of the groundwater and surface water resources of Marlborough, and to reduce adverse impacts associated with increases in peak rates of stormwater runoff.

Objectives:

Incorporate decentralized stormwater management systems in any new development designs.

Minimize the increase in nonpoint source pollution caused by stormwater runoff from development which would otherwise degrade local groundwater and surface water quality.

Design and performance criteria. In order to prevent the adverse impacts of stormwater runoff, the Commission has developed a set of performance standards that must be addressed in the design of any new site development plan or modification to an existing site development plan that disturbs 5,000 square feet or more of area.

A vegetative separation shall be maintained to provide a disconnection between impervious surfaces and the natural wetland systems of the site and abutting sites.

All stormwater best management practices shall be designed to minimize the need for maintenance, while maintaining water quality discharge treatment standards.

The design of all stormwater best management practices shall convey stormwater runoff in a manner to allow for the maximum removal of pollutants and reduction in flow velocities.

Stormwater discharges from land uses or activities with a higher potential pollutant loading may require the use of specific pretreatment structural methods and pollution prevention practices.

Sensitive waters and wetlands: enhanced criteria.

Nutrient sensitive waters. Enhanced control of nutrients and sediment removal for stormwater discharges shall be required.

Cold water fisheries. Techniques to control temperature increases from stormwater discharges into these streams and water bodies shall be required.

Groundwater. Enhanced recharge and pretreatment of stormwater discharges shall be required to protect groundwater supplies.

Wetlands: controls to minimize impacts to the natural or predevelopment wetland hydrology, including limiting adverse fluctuations in surface and groundwater elevations.

Stormwater management plan requirements.

Compliance with federal and state regulations. All stormwater facilities and conveyance systems shall be designed in compliance with all applicable Town, state and federal laws and regulations. It shall be the applicant's sole responsibility to identify and obtain all required permits prior to the start of any construction.

Protection of public health, safety, and general welfare. The design of stormwater BMPs shall consider public health, safety, and general welfare. These considerations shall include, but not be limited to: preventing flooding of buildings, structures, and travel ways; preventing long-term standing water in and near drainage facilities; minimize the creation of mosquito breeding pools; preventing attractive nuisance conditions and dangerous conditions due to stormwater depth or velocity and/or access to drainage structures, including inlet and outlet openings. In addition, designs shall not result in the creation of aesthetic nuisances due to excessive slopes, cuts and fills, lack of suitable native landscaping and other similar conditions that would detract from the appearance of the surrounding environment.

Natural resources inventory. Stormwater management designs shall include an inventory of important natural resources features on the site, and these features shall be shown on the stormwater management plan. Protection and/or conservation of the site natural features shall be a part of the stormwater management plan. The plan shall identify important natural features identified through a natural resources inventory that includes, but is not limited to the following: natural drainage features, riparian buffers, wetlands, steep slopes, soils with high infiltration capacity, significant forest cover, significant trees and natural communities, including the presence of any threatened and/or endangered species.

Site design feasibility report.

Stormwater management practices for a site shall be selected on the basis of the physical characteristics of the site. The design professional shall submit a report outlining the stormwater practices options including low impact alternatives that were considered and those that were chosen for the design based on the evaluation and analysis of site opportunities and constraints. Among the factors that should be considered:

Depth to groundwater/ledge.

Hydrologic functions.

Contributing drainage area.

Site vegetation.

Soil characteristics.

(f)

Topography.

(g)

Location in relation to environmentally sensitive features.

Infiltration. All stormwater designs shall include infiltration for any new site development unless the site design feasibility report and associated soils report demonstrate that the physical characteristics of the site are not suitable. Low-impact design elements utilized for infiltration discharge into a natural system shall utilize native plant species.

Overland flood routes. Overland flood routing paths shall be provided to safely convey stormwater runoff from the 100-year, twenty-four-hour duration storm event to receiving water resource or stormwater BMP with adequate hydraulic capacity, such that the runoff is contained within a drainage easement for the flood routing path that does not cause flooding of buildings and abutting properties. There shall be an allowance in all designs for a minimum of one foot of freeboard for all flood conveyance systems and flood control structures.

Stormwater conveyance. Stormwater conveyance systems shall be designed to:

Maximize the flow path from inflow to outflow points;

Include protection of inlet and outlet structures;

Provide for the elimination of or protection from erosive velocities; and

Utilize infiltration systems where applicable.

Velocity dissipation. Devices and techniques to reduce stormwater velocities and prevent erosion shall be placed at discharge outlet locations and along or within the full length of any outlet channels to convey and discharge peak design flows in a manner that will not result in scouring or surface erosion, including receiving streams or channels or wetlands so that the natural physical and biological characteristics and functions of the receiving waters are maintained and protected.

Landscaping/planting plan. All stormwater management designs shall include a detailed landscaping plan that indentifies the types (both common and botanical names), locations, sizes and total number of all proposed plantings. Planting notes and details shall also be provided, as well as a maintenance and management plan to ensure the long-term viability of all plantings. In addition, the landscaping plan shall include a stabilization schedule for the revegetation of all disturbed areas of the site. Any area of land from which the natural vegetative cover has been either partially or wholly cleared or removed by development activities shall be seeded with temporary vegetation within seven days after the suspension of grading work is expected to last a period of 30 days or more. Permanent vegetation shall be fully established by the date of substantial completion of construction. Following the first year after the establishment of permanent vegetation and the completion of all landscaping plantings, an inspection shall be conducted by the Town to confirm their health and survival. Should any permanent vegetation or plantings be determined to be dead or dying following the one-year period, then they shall be revegetated or replaced. A second inspection shall then be conducted by the Town one year from any subsequent revegetation or replanting.

Nonstructural stormwater practices. To the extent that they are feasible the use of nonstructural stormwater treatment practices are required and shall be selected and designed using the appropriate criteria from the most recent version of the CT DEEP Stormwater Quality Manual or other appropriate design low-impact design manuals acceptable to the Commission.

Structural stormwater practices. All structural stormwater management facilities shall be selected and designed using the appropriate criteria from the most recent version of the CT DEP Stormwater Quality Manual. For other structural stormwater controls not included in the CT DEP Stormwater Quality Manual, or for which pollutant removal rates have not been provided, the effectiveness and pollutant removal of the structural control must be documented through prior studies, literature reviews, or other means acceptable to the Commission, before approval of any design utilizing such structural stormwater controls.

Discharge to municipal stormwater system. If any stormwater runoff from a new or modified site development plan is discharged to a municipal separate storm sewer system (MS4) or other publicly, municipally or privately owned storm sewer system, the applicant must demonstrate that the existing storm sewer system has adequate excess hydraulic capacity to convey both increases in peak discharge flow rates and runoff volumes. In addition, all such discharges shall conform to all the requirements contained in the applicable general permit for the discharge of stormwater and dewatering wastewaters from construction activities, the general permit for the discharge of stormwater associated with industrial activity, or the general permit for the discharge of stormwater associated with commercial activity, as originally issued and reissued. All new or modified site development shall also conform in all respects to the Town of Marlborough Illicit Discharge Detection and Elimination Ordinance, as amended.[1]

[1]

Editor's Note: See Ch. 301, Stormwater Management, Art. I, Illicit Discharges.

Operation, inspection and maintenance plan agreement and schedule.

An enforceable operation, inspection and maintenance plan agreement and schedule shall be executed to ensure that the stormwater management plan facilities function as designed and approved. The agreement shall designate the responsible party for the long-term maintenance of the approved stormwater management facilities and include a provision passing the responsibility for such maintenance to successors in title. This agreement shall include easements to the Town allowing access to all stormwater management plan facilities at reasonable times for periodic inspection by the Town and/or its agent to ensure that the facilities are being properly maintained and in good working order. Said easements shall be executed and recorded on the Marlborough Land Records with filing of the final endorsed plan.

The design and planning of all stormwater management plan facilities shall include detailed inspection procedures and frequencies, maintenance plans and schedules, as well as, repair procedures to ensure their continued long-term function. These items shall identify the components of the stormwater management system that need to be inspected and maintained, provide a maintenance schedule for each facility, and the equipment necessary to perform that maintenance. Provisions for the periodic review and evaluation of the effectiveness of the maintenance program and the need for revisions or additional maintenance procedures shall be included in the plan.

All stormwater management facilities must undergo, at a minimum, an annual inspection to document maintenance and repair needs and to ensure compliance with the requirements of the CT DEP Stormwater Quality Manual and any additional conditions assigned by the Commission. Any maintenance and/or repair needs found must be addressed in a timely manner by the owner and a reinspection made confirming the completion of the identified items. The owner shall submit to the Commission annually a copy of the inspection report and if necessary any reinspection reports. If the responsible party fails or refuses to fully address all items identified in an inspection report after 30 days' notice from the Commission of such failure to comply, the Commission shall commence enforcement action to achieve compliance.

Substantive changes to plan. No changes shall be made to an approved stormwater management plan without review and written approval by Town staff, or, if any such changes are determined to be substantive, by the Commission. Additional data may be requested to allow for a complete review and evaluation of proposed changes to ensure compliance with the required discharge standards.

Decision guidelines.

The Commission shall, when reviewing all site development plan applications, take into consideration the general objectives of the public health, safety, welfare, convenience and the protection of property values as well as the particular protection of the immediate neighborhood in which the application is proposed.

The Commission shall ensure conformance to all requirements of the district in which the site is located and to the standards contained below:

The site and all buildings, structures and uses shall be accessible for fire, police and other emergency vehicle service which shall be accomplished through the review and report submitted by the Town Fire Marshal.

The site and all buildings, structures and uses shall comply with the State Building Code, specifically in regard to the requirements for handicapped access.

Parking, loading facilities, traffic circulation within the site, and entrance and exit driveways shall be adequately and properly located for maximum pedestrian and vehicular safety.

Landscaping on the site shall comply with the intent and the standards of Article XIII of Chapter 340, and all refuse collection areas, parking, service and loading areas shall be suitably screened and/or enclosed by plantings, wall and fencing from the adjacent areas and public rights-of-way.