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Planning, Conservation, and Development.
SECTION 5.23- DRAINAGE AND STORM SEWERS
5.23.01 General Requirements
The Developer shall be fully responsible for constructing adequate facilities for the control,
conveyance and acceptable disposal of storm water, other surface water and subsurface water,
whether originating within the subdivision area or in a tributary drainage by registered
professional engineer and be subject to the approval and final acceptance by the
- The overall drainage system for residential subdivisions requiring new city streets and
industrial subdivisions shall be designed such that the runoff rate outside of the subdivision
during or after development does not exceed the rate that existed prior to the development.
This may be accomplished by retention/detention basins, infiltration basins or other acceptable
means as determined by the Department of Public Works. Upon determination by the Public Works Department
that direct discharge would be more advantageous this requirement may be waived.
- Where the subdivision storm drainage system is proposed to discharge into a City storm
drainage system, the developer shall make provisions to accommodate the anticipated additional
discharge in the event that the City system is not adequate.
- The storm water drainage system shall be separate and independent of any sanitary sewer system.
5.23.02 Location of Storm Water Facilities
Drainage facilities shall be located in the road right-of-way, where feasible, or in perpetual
unobstructed easements, where necessary. Such easements shall be at least 30 ft. in width.
5.23.02.01 Drainage Rights
When a Proposed Drainage System will carry water across private land outside the subdivision,
appropriate drainage rights must be secured and indicated on the map.
The developer may be required to dedicate, either in fee or by drainage or conservation easement,
land on both sides of existing watercourses to a distance to be determined by the Commission.
5.23.02.03 Natural Drainage ways
Low-lying land along watercourses subject to flooding or overflowing during storm periods shall
be preserved and retained in their natural state as drainage ways.
5.23.03 Drainage Discharge
The discharge of all storm water from a subdivision shall be into suitable streams or other
acceptable and suitable storm water drainage facilities having adequate capacity to carry
the additional water. The drainage design used shall try to improve the quality of the water as
possible prior to discharge.
5.23.03.01 Installation of Appropriate Facilities
Where a new street intercepts an existing street which has no underground drainage system
or has a drainage system of insufficient capacity to carry the additional flow, appropriate
facilities shall be installed by the Developer to intercept and dispose of any drainage
from the new street which would otherwise be discharged onto the surface of the existing
street or into its drainage system.
5.23.04 Under drains
Adequate under-drains shall be constructed whenever, in the opinion of the Director of
Public Works or his/her duly authorized designee, drainage conditions require it. They
may be required even though not shown on the approved construction plans. Design shall be as approved
by the Director or Public Works or his/her duly authorized designee.
5.23.05 Culverts under New Streets
Culverts under streets shall be extended at least to the edge of the right-of-way of the street.
Headwalls, paving, flared-ends, and/or riprap, adequate to prevent erosion, shall be provided at
the ends of all culverts.
5.23.06 Retention and Detention Systems
Measures for the retention and/or detention and controlled release of stormwater runoff from
the subdivision shall:
- Not exceed the rate of runoff for the same site in its underdeveloped state for intensities and
duration of rainfall as specified in Section 5.24.09;
- Have the ability to retain and maximize groundwater recharge. Design of the storm water
runoff control system shall give consideration to providing groundwater recharge; and
- Require that all on site facilities be properly maintained by the owner so that they do
not become nuisances. The city may require that a fence be installed around such facilities. All
runoff control structures, whether dedicated to the City or not, shall be accessible at all
times for City inspection. Where runoff control structures have been accepted by the City for
maintenance, access easements shall be provided.
5.23.07 Drainage Design
All designs shall be based on the maximum ultimate development of the entire watershed as
permitted by the Middletown Zoning Regulations, as amended. All bridges and culverts
shall be designed such that the required head and backwater produced by the structure
shall not cause the flooding of abutting property. The following guidelines shall be adhered to
for storm drainage design:
- Design: All storm drainage systems shall be designed in accordance with the design standards
of Public Works;
- Design Formula: All design formulas shall adhere to acceptable engineering practice,
and the calculations and their method of derivation shall be shown in the material submitted as part of the
final application. Drainage computations showing the following shall be submitted:
- Plans showing the drainage area of the development;
- Calculation showing the area, time of concentration, intensity, coefficient, flow, velocity,
pipe size, and slope of each pipe length; and
- Design criteria: All storm drainage facilities shall be designed based on the standards of
the Department of Public Works; and
- Rainfall intensity: Rainfall intensities used for storm drainage design shall be taken
from the U.S. Weather Bureau "Rainfall Intensity-Duration Frequency Curves", as amended,
for the New Haven rain gauge.
- The drainage system within the street R.O.W. must be directly accessible to each and
every lot fronting that street. A waiver for certain lots may be made by the Public Works
Department when, in their opinion, it is feasible to do so.
5.23.08 Watersheds in Excess of One Square Mile
On watersheds one square mile or over, the design of culverts, bridges and through watercourses
shall be based upon not less than a 100 year storm. On watersheds of less than one square
mile, the design for the through drainage system shall be for not less than a 50 year
5.23.09 Road Drainage System
The drainage system for roads, including catch basins, inlets, pipe, underdrains and gutters within
or abutting the subdivision, shall be designed for not less than a 10-year storm.
5.23.10 Private Drains
Sufficient and adequate facilities shall be constructed on private lots wherever necessary to
prevent the flow of surface drainage from the property the flow of surface drainage from
property on which it originates onto adjacent property in sufficient quantity, concentration
or velocity to cause damage or create neusance on adjoining property.
- The size and location of all private storm drains that connect to the City storm
drain system shall be approved by the Department of Public Works prior to installation.
- Rear yard drains and cellar or foundation drains that are connected to the storm
drainage system must be shown on the final "as-built" plan of the drainage system.
- When storm sewer construction precedes house construction, the piping shall be
installed to a point within the lot not less than six (6) feet from the front