Article VIII Design Specifications

Permanent monuments shall be of stone or reinforced concrete four inches by four inches by 48 inches, with a drill hole in the center, set in such a manner so that they will not be disengaged by frost; if of concrete, the mix shall be Class A.

[Amended 7-27-2021]

All reference pins shall be of ferrous metal, 1/2 inch in diameter or larger and a minimum of 24 inches in length. The pin may be solid, hollow, round, square or any other standard configuration normally used by surveyors. The pin shall be driven into the ground and shall not protrude above the ground surface more than 1 1/2 inches.

§ 157-39 Street improvements.

[Amended 9-8-1987; 1-24-2012]

General. In general, all new streets within the subdivision and all work to be undertaken thereon shall be designed and constructed according to the specifications adopted by the New Hampshire Department of Transportation. All plans for such improvements shall be submitted for approval or approval with modifications to the City Engineer.

Grading roadway and side slopes. The roadway and side slopes thereof shall be considered as part of a site's improvements and, as such, shall be constructed substantially in accordance with the street cross-sectional design standards. Side slopes shall not exceed one foot vertical rise per every two feet of horizontal length without retaining structure or other special considerations. If the depth of fill is over five feet, the contractor may be required to perform certain operations to ensure that major settlement will occur prior to continuing construction.

All backfill in trenches and fill for roadbeds shall be thoroughly compacted to 95% of optimum density, unless otherwise specified in the approval specifications. All compaction is subject to testing by the City Engineer or designee.

Street construction standards. All streets within the jurisdictional authority of the City, with the exception of state highways, shall be improved in accordance with the following minimum criteria and shall further be arranged and constructed in accordance with the provisions set forth hereinafter:

Base course.

The depth of the base course shall be as shown on the standard road cross section.

Base course shall not be constructed during freezing weather or on a wet or frozen subgrade. Blading and rolling shall be required to provide a smooth, even and uniformly compacted course true to cross section and grade. A minimum slope of the finished base course shall be 1/2 inch per foot or as may be required on curves or on superelevations.

Any portion of the base course material which is not accessible to means of proper compaction with rolling equipment shall be compacted thoroughly by methods satisfactory to the Community Services Department. All yielding or unstable material shall be excavated as directed and brought up to grade with satisfactory material.

(d)

At all times during construction, the subgrade and all ditches shall be constructed and maintained so that the roadbed will be effectively drained to prevent erosion.

(e)

The top four inches of the base course shall not contain stones over three inches in diameter. The gravel pit shall be acceptable to the City.

(f)

In areas with excessive clay, water or loam base, the depth of the base course shall be more than the minimum depth. The base course depth and required base drainage shall then be properly designed by the subdivision engineer and approved by the City Engineer (e.g., by increasing base depth as needed or road underdrains, or both).

(g)

Design depth shall be based on current engineering practices, using percolation results obtained during the wet season, soil-bearing capacity and type.

(h)

Samples of all gravel materials and gradation analysis to be used in project shall be submitted to the City Engineer's office upon request.

Street paving.

Street paving shall be accomplished by placing a minimum of four inches in two courses of hot asphalt concrete for streets that are to become public streets. The minimum thickness of each course shall be as shown on the standard cross section which shall be placed with a self-propelled mechanical spreader and compacted with a minimum ten-ton tandem roller. Paving shall be allowed between April 15 and November 15 only and shall not be placed unless the atmospheric temperature in the shade is above 40° F. and the mixture delivered to the spreader has a temperature above 250° F. Pavement shall not be placed on wet or frozen roadbeds. Unless otherwise specified, paving regulations shall be the same as those specified in the State of New Hampshire Department of Transportation Standard Specifications for Road and Bridge Construction, adopted and approved, latest edition. In special instances, when it has been determined that there is an emergency situation, the above requirements may be waived by the Community Services Director. The Planning Board shall be notified of any waivers by the Director of Planning and Community Development.

The hot-asphalt concrete shall consist of the following materials: the aggregate shall be as indicated in New Hampshire Department of Transportation specifications; bituminous material shall be an asphalt cement AC 85-20100, unless otherwise designated on the plans ordered; and the percentage of bituminous material shall be determined at the plant site to ensure proper control. This is in no way to relieve the contractor from designing a road pavement for a higher classification of traffic which would require a heavy pavement for strength or a different design mix as approved by the Community Services Department.

§ 157-40 Storm sewers and drainage appurtenances.

The subdivider shall be required to improve arterial and collector streets only to the width required by the current and immediate needs of his subdivision, consistent with the standards and specifications herein contained.

(d)

Alleys, where permitted or required, shall have not less than a four-inch bituminous concrete surface and a sixteen-inch base course as required for streets.

Where a subdivision will create a public roadway, a sign shall be erected on the site alerting those traveling the roadway that they are on a roadway that is not accepted or maintained by the City of Dover and they travel at their own risk. Said signage shall be located and approved by the City Engineer or Director of Planning and Community Development prior to land disturbance.

[Amended 8-26-2008; 1-24-2012]

All areas of a subdivision shall be graded to prevent ponding of water or eroding of property. In addition to the installation of curbs or gutters along the streets as required by § 157-46, storm sewers or other drainage appurtenances shall be constructed throughout the entire subdivision to carry off water from all inlets and catch basins and be connected to an adequate outfall. The stormwater drainage system shall be separate and independent of the sanitary sewer system and shall be in accordance with drainage laws of the State of New Hampshire. Included in the overall design shall be any work necessary in order to provide adequate and satisfactory drainage along the side of any existing street which is adjacent to the subdivision. The plans and specifications for the disposing of stormwater and the construction thereof shall be approved by the City Engineer. Manholes will be required upon request, to be located between catch basins.

Design.

[Amended 5-24-2016]

Proper sizing of culverts, pipes, etc., shall be by acceptable established engineering practice.

Design storm frequency requirements shall be as follows:

Major streams, rivers, bridges and culverts: 100-year storm or flood of record.

Minor brook culverts: fifty-year storm.

Storm sewers: ten-year storm.

A sample set of the calculations used in sizing the various pipes and a list of the variables used must be submitted to the City Engineer's office. Failure to include this information could result in a delay of the review process.

Standards of construction.

All improvements shall meet the specifications of the American Association of State Highway and Transportation Officials (AASHTO) in regards to material and strength requirements.

Catch basins or drop inlets shall be equal to New Hampshire Standard Type A with three-foot sumps or four-foot sumps with hoods, if required by the City Engineer.

Minimum size pipe shall be 12 inches in diameter for storm drains. Minimum size culvert shall be 15 inches in diameter.

(4)

All pipes shall be one of the following:

[Amended 5-24-2016]

Typical Use	RCP	HDPE	PVC
Culverts	X	X	—
Storm drains	X	X	X
Drive culverts	X	X	—
Underdrain (6-inch)	—	X	X

NOTES:
X	=	Acceptable
RCP	=	Reinforced concrete pipe (Class III minimum)
PVC	=	Polyvinyl SDR 35 pipe
HDPE	=	High-density polyethylene

(5)

There shall be a three-foot minimum cover over all pipes.

(6)

Culvert headwalls/endwalls, when required, shall be either concrete or mortar rubble masonry.

(7)

Erosion protection of ditches or pipe outlets shall be provided where soil and/or velocity conditions warrant protection by paving or use of stone.

(8)

No stormwater pipe, catch basin, drainage inlet or other pipes (floor drains) used to drain surface water shall be connected to any sanitary sewer system.

§ 157-41 Sanitary sewers.

[Amended 1-24-2012]

Each lot in the subdivision shall be provided at the property line with a connection to the public sanitary sewer system. This connection shall be shown with tie-in distances on the as-built plans. The construction of the sewer system shall conform to the approved plans and specifications, and all work must be properly inspected and approved by the City Engineer or representative. In general, the design of municipal sewer lines shall follow the guidelines presented in the Water Pollution Control Federation Manual of Practice No. 9.

In the case of a private wastewater disposal system, both a City and a state permit are required. The system must be designed in accordance with New Hampshire Department of Environmental Services requirements and must be approved and inspected by the City and state. Backfilling before either party has made the inspection will constitute grounds for rejection. Such approval notwithstanding, the Planning Board, on the advice of a sanitary system engineer of its own choice, may approve or disapprove or approve with modifications such plans if it deems such state-approved plans insufficient and may make additional requirements. In no case will discharge of pollutants into surface water or wetlands be permitted, nor will any system which utilizes mechanical or powered devices be permitted unless a copy of a service contract, prepaid at least 12 months in advance, giving the City or any citizen thereof the power to call for repairs, or a bond in lieu thereof, shall be submitted to the Planning Board, and after approval, such contract shall be renewed annually. It shall be understood that failure to renew and/or nonrepaired failure of such sewage system shall be grounds for eviction of residents, whether owners or tenants, unless and until the system is rendered functional.

[Amended 1-14-2020]

An adequate sanitary sewer shall be designed by a qualified registered engineer to handle all of the present and future development incorporated in a subdivision. A manhole shall be installed at each change of alignment in the pipe and/or beginning or end, as well as each change of grade, but at intervals not to exceed 300 feet. Manhole frames and covers shall be of heavy-duty type. Manholes shall be precast and watertight.

Any sewer lift station required for a subdivision shall be designed by a qualified registered engineer as to its capacity and type. Final approval of the type of station shall be specified by the Community Services Department. All manuals pertaining to said lift station (i.e., operation, service guaranty) shall be turned over to the City. All lift stations shall be duplex, pump-type installations unless specifically approved otherwise. The decision to accept any sewer lift station is entirely a City option and shall be based on the recommendations of the City Engineer, Community Services Director and the Dover Utilities Commission to the Planning Board. The owner of a private system shall maintain a service contract (contact information to be provided to the City) with a licensed service provider to perform the required maintenance. The service contract shall provide for an annual report to the City Engineer detailing the condition of the system, and maintenance report.

All pipes shall be sized and have proper bearing material under them. All trenches shall be opened by the developer for inspection by the Community Services Department prior to approval. House connections shall be made in a workmanlike manner, and tees shall be supplied in the main. Should a tap be required, it shall be completed by use of a mechanical tapping machine. All joints shall be tight-fitting and sealed. Inspections shall be completed on a normal workday within a forty-eight-hour period after notification. Lateral connections shall be through a tee (wye) or cast-iron saddle. All joints of said sewer system shall be cemented or consist of a suitable locking-type joint to prevent the seepage of water either in or out. Minimum slope of a sanitary sewer shall be established to maintain a minimum average velocity of two feet per second.

Materials selected for sewer construction shall be of the following types:

Pipe:

Reinforced concrete: not recommended.

Ductile iron: force mains and heavy loads.

PVC SDR 35 minimum with cement joints: not allowed.

Manholes: may be precast-concrete-sections construction. Manhole covers shall be heavy-duty type and preferably self-sealing.

§ 157-42 Water mains and fire hydrants.

Sewer services: at main, to be wyes or tees; if tapped, must use cast-iron sewer saddles of approved design.

Construction standards shall be clearly emphasized in the specifications, and attention shall be directed to the bedding material and backfill requirements. Suitable compaction as required by the City Engineer shall be provided. All sewer lines laid at a grade less than 0.01 shall be set with a laser. All lateral connections which use sewer saddles shall be tapped with a mechanical tapping machine and suitably sealed. All manholes shall be made watertight with brick inverts. All joints between pipes and with manholes shall be cemented or consist of an adequate locking-type joint to prevent water seepage in or out of the system.

All pipes shall be inspected and approved as required under by § 157-37. Tests to be performed shall include but not be limited to air or smoke testing of lines, water or vacuum testing of manholes and visual television inspection of all mains.

[Amended 9-8-1987; 1-24-2012]

All subdivisions in the City of Dover shall provide municipal water service when available or required by the Planning Board. Installation of all water mains is subject to the approval of the Community Services Department.

[Amended 1-14-2020]

When City water is supplied, each lot shall have a separate connection brought to the lot line, equipped with an outside stop and capped until ready for use. All house service lines shall be connected to the main by the use of tapped couplings. The developer shall provide ties for the end of the service and the outside stop to the City Engineer's office for each lot in the development.

When City water is available and/or required, the system shall be designed by a qualified registered engineer. Each system shall be designed to handle the expected flows, domestic and fire, for present and future development within the subdivision.

In general, the design of City water mains shall follow the guidelines prescribed by the American Waterworks Association (AWWA). In addition, thrust blocks shall be supplied as necessary and gate valves shall be provided on all sides of junctions with other mains. All waterlines shall be installed with a minimum of five feet of cover. The minimum size of a water main shall be eight inches in diameter. The water main shall be sized to provide adequate fire flow to the proposed development and any future development. The design size must be approved by the City Engineer.

Materials selected for water construction shall be American-made, meet American Waterworks Association standards and shall meet the following minimum requirements:

Pipe and fittings. All pipe shall be cement-lined ductile iron pipe, Class 52. All fittings shall be ductile iron. All fittings and pipe shall be American Waterworks Association standard Class 140, coal-tar dipped or greater. All valve boxes shall be ductile iron and of the sliding type, tar-coated, both inside and out. All gate valves shall be Mueller or Clow and must open counterclockwise.

§ 157-43 Street markers and traffic signs.

Hydrants. All hydrants shall be Eddy manufacture and subject to the following additional details. All hydrants shall be of iron body. All hydrants shall be the improved type with breakable flanges, painted red body with silver reflective domes and nozzles. All hydrants shall open counterclockwise, with the direction of opening cast on the head of the hydrant. All hydrants shall have a valve opening of 5 1/4 inches, hose nozzles conforming to the national standard of nozzles and 2 1/2 inches and steamer nozzle 4 1/4 inches. Hydrants shall be long enough to accommodate a minimum bury of 5 1/2 feet and equipped with six-inch pipe connections. All hydrants shall be plugged.

Construction standards shall be clearly emphasized in the specifications. Attention should be directed to bedding and backfill requirements. Various gates and other fittings shall be installed in conformance with manufacturer's specifications. Hydrants shall be installed not less than one foot nor more than three feet from the curb and so installed that the center of the hydrant steamer nozzle shall be at least 18 inches above the finish grade. All hydrant gate valves shall be installed with anchoring tees to the water main with the top of the box flush with finish grade.

The Director of Community Services shall be notified at least 48 hours prior to any construction involving water mains. All new pipes shall be inspected as provided by § 157-37. Tests to be performed shall include but not be limited to water sampling and testing for contamination.

[Amended 1-14-2020]

[Amended 1-24-2012; 7-27-2021]

All regulatory signs shall be installed in conformance with the Manual on Uniform Traffic Control Devices. A permanent street marker shall be placed at each intersection designating the names of the streets entering said intersection and shall comply with the specifications as provided by the City. All street signs shall be of the approved size, color and type set forth by the Community Services Department and shall be purchased at a nominal rate from the Department or other suitable source of supply. The signs shall be installed at the expense of the developer and done to the satisfaction of the Community Services Department. If a roadway is to remain private, a private sign marker shall be added to the street sign.

§ 157-44 Telephone and electric service lines; streetlights.

[Amended 1-24-2012; 12-18-2012]

For subdivisions that include the construction of a new road, all utility lines for telephone and electric service shall be placed underground in the right-of-way or in rear lot easements. Where telephone and electric service lines are placed underground entirely throughout a subdivided area, said conduits or cables shall be placed within easements or dedicated public ways in a manner which will not conflict with other underground services. They shall be a minimum of five feet from any other utility. Wherever possible, underground services will be placed under grassed areas rather than paved areas. Further, all transformer boxes shall be located so as not to be unsightly or hazardous to the public. Additionally, all streetlighting fixtures and poles shall be approved by the Community Services Director or designee. The most energy-efficient streetlighting shall be installed.

§ 157-45 Sidewalks.

[Amended 8-11-1992; 11-28-1995; 12-18-2012]

A sidewalk is required on at least one side of a street in the urban core and may be required by the Planning Board on both sides of the street where it is deemed appropriate. Sidewalks shall be of bituminous concrete or portland cement concrete. Bituminous concrete shall not be less than 2 1/2 inches in thickness and placed over a six-inch gravel base. Portland cement concrete sidewalks shall not be less than four inches in thickness, reinforced by eight-by-eight, six-by-six wire mesh and placed on a suitable base not less than 12 inches thick. Portland cement concrete sidewalks that cross driveways shall be not less than six inches thick and meet all the standards listed above. All sidewalks shall be five feet in width and constructed adjacent to the property line within the street right-of-way. Sidewalks shall be designed to be free from obstruction; all streetlights, street trees, mailboxes, newspaper bins, trash receptacles, or any other type of obstruction shall be placed in the grass area between the sidewalk and the curb.

§ 157-46 Curbs.

[Amended 8-11-1992; 11-28-1995]

All new and improved streets within the urban core shall be provided with granite curbs. When the curb forms one edge of a sidewalk, the granite curbing shall be vertical and five inches by 17 inches. Curbs used to define driveway entrances shall be tapered as per standard road cross section graphic.

Granite slope edge curb shall be installed as specified in Section 609 of the State of New Hampshire Standard Specifications for Road and Bridge Construction, minimum cross section of stone to be four inches by 12 inches.

§ 157-47 Private roads.

[Amended 3-23-2010]

Private roads shall be designed and constructed pursuant to the following criteria:

	3 and 4 Parcels	5 or More Parcels in R-12, R-20, R-40, RM-SU, RM-U or Nonresidential Districts
Right-of-way width (feet)	30	50
Road width (feet)	16	24 to 32*
Base course	12 inches bank-run gravel (A)	12 inches bank-run gravel (A) 6 inches crushed gravel (B) 1 1/2 inch binder and inch topcoat (C) 3-foot gravel shoulder (D) (A road profile shall be submitted with subdivision applications. Said profile shall be rendered by a qualified registered engineer.)

Standard Roadway Cross Section

NOTES:
*	The width of the roadway shall be determined by the site's physical characteristics and the layout and density of the proposed development.

The subdividing of lots along such rights-of-way shall only be approved upon the condition that no City services will be rendered until said private right-of-way is built in accordance with the City street construction specifications. (See Articles VII and VIII.)

Culs-de-sac shall be designed and constructed as depicted below:

W	=	Required roadway width.
R	=	Required radius width.

The physical constraints of a specific tract shall dictate the Board's consideration thereon.

§ 157-48 Required changes.

Changes in the terms and specifications contained in Planning Board approval of the improvement aspects of a subdivision application may be required in the event subsequent excavations reveal subsurface conditions which require special attention, e.g., underground water requiring side drains, etc. All such changes must be approved by the City Engineer, Director of Planning and Community Development and the Community Services Director.

§ 157-49 As-built plans.

[Amended 1-14-2003; 8-26-2008]

The developer shall be responsible for submitting an as-built drawing of the project to the City Engineer's office. The drawings shall include all items as required in the final plan with as-built locations, dimensions and sizes. Also included on the as-built drawings shall be water and sewer locations, depths and ties. The as-built drawings shall be submitted in Mylar and digital formats and shall be tied into the City's GIS coordinate system.

If a street is to become a public roadway, prior to the City Engineer processing the request and advising the City Council on whether to accept street or not, the developer shall be responsible for submitting a recordable deed and any associated fees to the City Engineer's office. Once the City Council has accepted the street, the developer shall be notified, and the City Engineer shall record the deed with the Strafford County Registry of Deeds within 10 days of acceptance. Upon registration, a signed, original copy of the deed shall be filed with the City Clerk's office and a copy submitted to the developer.

§ 157-50 Driveways.

[Added 5-8-2018]

The provisions of this section apply to the construction, reconstruction, alteration, surfacing or resurfacing of any driveway which intersects with the right-of-way of any City-owned, City-maintained way and/or other private way. Section 125-8 of the City Code, referring to permit requirements, applies to all paving contractors or related construction enterprises engaged in the retailing of driveway paving services to the general public within Dover's City limits.

[Amended 1-14-2020]

It shall be unlawful to construct, reconstruct, alter, surface or resurface any driveway in a manner which affects the size, elevation or grade of such driveway until the Community Services Director has reviewed and approved of such construction or alteration and has issued a written permit for such work. No permit shall be required for any existing driveway, entrance or approach unless the grade, elevation, location or width of said driveway is changed. For purposes of this section, any driveway so constructed, reconstructed, altered, surfaced or resurfaced as indicated above which abuts or is clearly designed to provide access to a public way as defined by RSA 259:125 shall be presumed to be situated within the right-of-way.

Pursuant to this section, a written construction permit application must be obtained from and filed with the Community Services Department by any landowner or by his/her paving contractor, if he/she is employing one, affected by the provisions of this section.

Before any construction or alteration work is commenced, said permit application shall have been reviewed and approved and a construction permit issued by the Community Services Director. Said permit shall:

Describe the location, area and width of the driveway, as well as the entrance, exit or approach. The location shall be selected to most adequately protect the safety of the traveling public.

Describe any drainage structures, traffic control devices and channelization islands to be installed by the applicant.

Establish grades that adequately protect and promote street drainage and permit a safe and controlled approach to the street in all seasons of the year.

(d)

Include any other terms and specifications necessary for the safety of the traveling public.

The following construction standards must be adhered to for driveways:

Unless an all-season sight distance of 400 feet in both directions along the street can be obtained, the Community Services Director shall not permit more than one access to a single parcel of land, and this access shall be at that location determined to be safest. The Community Services Director shall not give final approval for use of any additional access until it has been demonstrated that the 400-foot, all-season sight distance has been approved.

Within 20 feet of the point where the driveway intersects the public right-of-way, the maximum slope of a driveway to four or fewer dwelling units shall not exceed 12% and the maximum slope for other driveways shall not exceed 8%.