Chapter 8 - Floodplains

PART 1

CONSTRUCTION AND MODIFICATION OF STRUCTURES IN FLOODPLAIN

 

§101.   SUPPLEMENTARY DEFINITIONS FOR DESIGNATED FLOODPLAIN AREA PROVISIONS.

The following are special definitions which shall be used in making reasonable interpretations of the provisions contained in §102 and §103 hereinbelow:

BUILDING - a combination of materials to form a permanent structure having walls and a roof including, but not limited to, all manufactured homes and trailers used for human habitation. [Ord. 93-9]

COMPLETELY DRY SPACE - a space which will remain totally dry during flooding; the structure is designed and constructed to prevent the passage of water and water vapor.

CONSTRUCTION - the construction, reconstruction, renovation, repair, extension, expansion, alteration or relocation of a building structure including the placement of manufactured homes. [Ord. 93-9]

DESIGNATED FLOODPLAIN AREAS - a relatively flat or low land area adjoining a river, stream or watercourse which is subject to partial or complete inundation in a 100 year flood as designated in the Hampden Township Zoning Ordinance [Chapter 27], as amended.

DEVELOPER - any landowner, agent of such landowner or tenant with the permission of such landowner who makes or causes to be made a subdivision of land or a land development and the subdivision of land.

DEVELOPMENT - any manmade change to improved or unimproved real estate, including, but not limited to, buildings or other structures, the placement of mobile homes, streets and other paving, utilities, mining, dredging, filling, grading, excavating or drilling operations, and the subdivision of land or storage of equipment or materials. [Ord. 93-9]

DWELLING - a building designed and constructed for residential purposes in which people live.

ESSENTIALLY DRY SPACE - a space which will remain dry during flooding, except for the passage of some water vapor or minor seepage; the structure is substantially impermeable to the passage of water.

FLOOD - a temporary inundation of normally dry land areas.

FLOOD FRINGE - that portion of the floodplain outside the floodway.

FLOODPROOFING - any combination of structural or nonstructural additions, changes, or adjustments to structures which reduce or eliminate flood damage to real estate or improved real property, water and sanitary facilities, structures and their contents.

FLOODWAY - the channel of a stream together with any adjacent floodplain areas that must be kept free of encroachment in order that 100 year floods be carried without increasing flood heights by more than 1 foot.

LOWEST FLOOR - the lowest floor of the lowest enclosed area (including basement).  An unfinished or flood resistant enclosure usable solely for the parking of vehicles, building access or storage in an area other than a basement area is not considered a building's lowest floor, provided that such enclosure is built with openings in compliance with the provisions of this Part.  [Ord. 93-9]

MANUFACTURED HOME - a structure, transportable in one or more sections, built on a permanent chassis and designed for use with or without a permanent foundation, and attached to required utilities. Said term includes a structure which would otherwise qualify as a recreational vehicle as defined generally herein but which is to be located on a site for more than 180 consecutive days or which is not fully licensed or ready for highway use. [Ord. 93-9]

MANUFACTURED HOME PARK - a parcel (or contiguous parcels) of land which has been planned and improved for the placement of two or more manufactured homes.  [Ord. 93-91

OBSTRUCTIONS - any wall, dam wharf, embankment, levee, dike, pile abutment, projection, excavation, channel, rectification, culvert, building, fence, stockpile, refuse, fill, structure, or matter in, along, across or projecting into any channel, watercourse, or designated floodplain areas, which may impede, retard or change the direction of the flow of water either in itself or by catching or collecting debris carried by such water or is placed where the flow of the water might carry the same downstream to the damage of life and property.

ONE HUNDRED YEAR FLOOD - a flood having a 1% chance of being equaled or exceeded in any given year. [Ord. 93-9]

RECREATIONAL VEHICLE - a vehicle which is built on a single chassis, containing an interior area of 400 square feet or less measured at the largest horizontal projection, which is designed to be self-propelled or permanently towable by a light duty truck, and designed primarily for temporary living quarters for recreational, camping, travel or seasonal use, and not designed primarily as a permanent dwelling. A recreational vehicle is ready for highway use when it is on its wheels or jacking system and is attached (if at all) to its site only by quick disconnect type utilities and security devices, and has no permanently attached additions. [Ord. 93-9]

REGULATORY FLOOD ELEVATION - the 100 year flood elevation plus a freeboard safety factor of 1 1/2 feet.

STRUCTURE - anything constructed or erected on the ground or attached to the ground including, but not limited to, buildings, factories, sheds, cabins, manufactured homes, and other similar items. [Ord. 93-9]

SUBSTANTIAL DAMAGE - damage of any origin sustained by a structure whereby the cost of restoring the structure to its before damaged condition would equal or exceed 50% of the market value of the structure as computed before the damaged occurred. [Ord. 93-9]

SUBSTANTIAL IMPROVEMENT - any reconstruction, rehabilitation, addition or other improvement of a structure, the cost of which equals or exceeds 50% of the market value of the structure before the start of construction of the improvement. The term includes structures which have incurred substantial damage, regardless of the extent or amount of actual repair work performed. The term does not include:

(1)        Any project for improvement of a structure to correct existing violations of State or Township health, sanitary or safety code specifications which have been identified by the Township Code Enforcement Official and which are the minimum necessary to assure safe living conditions.

(2)        Any alteration of an historic structure, provided that the alteration will not preclude the structure's continued designation as an historic structure.  [Ord. 93-9]

(Ord. 79-2, 3/6/1979, §1; as amended by ..Ord. 93-9, 4/29/1993, §IA, B)

 

§102.   SPECIAL PROVISIONS APPLYING IN DESIGNATED FLOODPLAIN DISTRICTS.

In order to prevent excessive damage to buildings or structures due to flooding conditions,

the following provisions shall apply to all proposed construction or development occurring

in any of the floodplain areas designated in the Hampden Township Zoning Ordinance

[Chapter 27], as amended:

            A.        Enclosed areas below the lowest floor that are subject to flooding shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwater. Designs for meeting this requirement must be certified by either a registered professional engineer or architect, or meet or exceed all of the following minimum criteria:

(1)        A minimum of two openings shall be provided, each having a total net area of not less than 1 square inch for every square foot of enclosed area subject to flooding.

                                    (2)        The bottom of all openings shall be no higher than 1 foot above grade.

 

 (3)        Openings may be equipped with screens, louvers, valves or other coverings or devices, provided that such devices permit the automatic exit of floodwater. 

[Ord. 93-9]

 

B.         Residential Structure.  Within any designated Floodway (FW), Floodway Fringe (FF) or General Floodplain (FA) Areas, the lowest floor (including basement) of any new or residential structures shall be at least 1 1/2 feet above the 100 year flood elevation.

          C.         Nonresidential Structures.

 (1)        Within any designated Floodway (FW), Flood Fringe (FF) or General Floodplain (FA) Areas, the lowest floor (including basement) shall be at least 1 1/2 feet above the 100 year flood elevation or be designed and constructed so that the space enclosed by such structure shall remain either completely or essentially dry during any flood up to that height.

(2)        Any structure, or part thereof, which will not be completely or adequately elevated, shall be designed and constructed to be completely or essentially dry in accordance with the standards contained in the publication entitled "Floodproofing Regulations" (U.S. Army Corps of Engineers, June 1972), or some other equivalent standard, for that type of construction. All plans and specifications for such floodproofing shall be accompanied by a statement certified by a registered professional engineer or architect which states that the proposed design and methods of construction are in conformance with the above referenced standards. [Ord. 93-9]

            D.        Fill. If fill is used, it shall:

(1)        Extend laterally at least 15 feet beyond the building line from all points.

(2)        Consist of clay, loam or small rock materials only. Sanitary landfills shall not be permitted.

(3)        Be compacted to provide the necessary permeability and resistance to erosion, scouring or settling.

(4)        Be no steeper than one vertical to two horizontal, unless substantiated data justifying steeper slopes are submitted to and approved by the Building Official.

(5)        Be used to the extent to which it does not adversely affect adjacent properties.

E.         Placement of Buildings and Structures. All buildings and structures shall be constructed and placed on the lot so as to offer the minimum obstruction to the flow of water. In so doing, consideration shall be given to their effect upon adjacent property owners and the flow and height of flood waters.

            F.         Anchoring

(1)        All buildings and structures shall be firmly anchored in accordance with Township building codes to prevent flotation, collapse or other movement, thus reducing the threat to life and property and decreasing the possibility of the blockage of bridge openings and other restricted sections of the watercourse.

(2)        All air ducts, large pipes and storage tanks located at or below the regulatory flood elevation shall be firmly anchored in accordance with accepted engineering practices to prevent flotation.

G.        Floor, Walls and Ceilings. Where located at or below the regulatory flood elevation:

(1)        Wood flooring shall be installed to accommodate a lateral expansion of the flooring, perpendicular to the flooring grain, without incurring structural damage to the building.

(2)        Plywood shall be of "exterior" or "marine" grade and of a water-resistant or waterproof variety.

(3)        Walls and ceilings in nonresidential structures shall have sufficient wet strength and be so installed as to survive inundation.

(4)        Window frames, door frames, door jambs and other components shall be made of metal or other water-resistant material.

            H.        Electrical System.

(1)        All electric water heaters, electric furnaces, electric air conditioning and ventilating systems, and other electrical equipment or apparatus shall be permitted only at elevations above the regulatory flood elevation.

(2)        No electrical distribution panels shall be allowed at an elevation less than 3 feet above the level of the 100 year flood elevation.

(3)        Separate electrical circuits shall serve lower levels and shall be dropped from above.

            I.          Plumbing.

(1)        Water heaters, furnaces and other mechanical equipment or apparatus shall be permitted only at elevations above the regulatory flood elevation.

(2)        No part of any onsite sewage disposal system shall be constructed within any designated floodplain district.

(3)        Water supply systems and sanitary sewage systems shall be designed to preclude infiltration of flood waters into the system and discharges from the system into flood waters.

(4)        All gas and oil supply systems shall be designed to preclude the infiltration of flood waters into the systems and discharges from the systems into flood waters. Additional provisions shall be made for the drainage of these systems in the event that flood water infiltration occurs.

            J.          Paints and Adhesives.

                                   (1)        Where located at or below the regulatory flood elevation:

(a)        adhesives shall have a bonding strength that is unaffected by inundation (i.e., "marine" or water-resistant quality).

(b)        All wooden components (doors, trim, cabinets, etc.) shall be sealed with a "marine" or water-resistant quality or similar product.

(c)        Paints or other finishes shall be capable of surviving inundation (i.e., "marine" or water-resistant quality).

K.        Storage. No materials that are buoyant, flammable, explosive, or in time of flooding could be injurious to human, animal or plant life, shall be stored below the regulatory flood elevation.

L.         Drainage Facilities. Storm drainage facilities shall be designed to convey the flow of surface waters without damage to persons or property. The system shall insure drainage at all points along streets and provide positive drainage away from buildings. The system shall also be designed to prevent the discharge of excess runoff onto adjacent properties. 

M.        Sanitary Sewer Facilities. All new replacement sanitary sewer facilities and private package sewage treatment plants (including all plumbing stations and collector systems) shall be designed to minimize or eliminate infiltration of flood waters into the systems and discharges from the systems into the flood waters, and should be located and constructed to minimize or eliminate flood damage and impairment.

N.        Streets. The finished elevation of proposed new streets shall be no more than 1 foot below the regulatory flood elevation. Profiles and elevations of proposed new streets shall be submitted to the Township to determine compliance with this requirement.

O.        Utilities. All utilities such as gas lines, electrical and telephone systems being placed in designated floodplain areas should be located, elevated (where possible) and constructed to minimize the chance of impairment during a flooding occurrence.

P.               Special Flood Damage Control Provisions for Manufactured Homes and Manufactured Home Parks in the Designated Floodplain Areas.

(1)        Manufactured homes are prohibited to be located within any Floodway Area (FW).

(2)        All manufactured homes and any additions thereto lawfully within any floodplain area shall be:

(a)        Placed on a permanent foundation.

 

            (b)        Elevated so that the lowest floor is at least I 1/2 feet above the elevation of the 100 year flood.

 

(c)        Anchored to resist flotation, collapse or lateral movement.

[Ord. 93-9]

Q.        Existing Structures in Designated Floodplain Districts. Structures existing in any designated floodplain area prior to the enactment of this Part, but which are not in compliance with these provisions, may continue to remain subject to the following:

(1)        Existing structures located in a designated Floodway Area shall not be expanded or enlarged, unless the effect of the proposed expansion or enlargement on flood heights is fully off-set by accompanying improvements.

(2)        Any modification, alteration, reconstruction or improvement of any kind to an existing structure to an extent or amount of less than 50% of its market value shall be elevated and/or floodproofed to the greatest extent possible, in accordance with subsection (A)(1) above.

(3)        Any modification, alteration, reconstruction or improvement of any kind to an existing structure to an extent or amount of 50% or more of its market value shall be undertaken only in full compliance with the provisions of this Part.

            R.         Waiver.

(1)        Requests for waiver to the strict application of the provisions of this Part may be granted by the Township in accordance with the following procedures and criteria:

            (a)        No waiver shall be granted for any construction, improvement, development, use or activity within any      floodway area that would cause any increase in the 100 year flood elevation.

            (b)        If granted, a waiver shall involve only the least modification necessary to provide relief.

            (c)        In granting any waiver, the Township may attach whatever reasonable conditions and safeguards it considers necessary in order to protect the public health, safety and welfare and to achieve the objectives of this Part.

(d)       Whenever a waiver is granted, the Township Building Official shall notify the applicant in writing that:

1)         The granting of the waiver may result in increased premium rates for flood insurance.

2)         Such waiver may increase the risks to life and property.

(e)        A complete record of all waiver requests and related actions shall be maintained by the Township Building Official. A report of all waivers granted during the year shall be included in the annual report to the Federal Insurance Administration.

                        (2)        Notwithstanding any of the above, however, all structures shall be designed and constructed so as to have the capability of resisting the hydrostatic and hydrodynamic loads and pressures, and effects of buoyancy of the 100 year flood.

(Ord. 79-2, 3/6/1979, §2; as amended by Ord. 93-9, 4/29/1993, §lC-E, and 15-06, 4/2/2015)

 

§103.   SUPPLEMENTARY ADMINISTRATIVE PROVISIONS FOR ACTIVITIES IN DESIGNATED FLOODPLAIN DISTRICTS.

1.         Plan Requirements.

A.        In addition to the permit application requirements normally required under other Township ordinances, the Township Building Official shall require the following specific information to be included as part of the application for a building permit and waiver requests:

(1)        A plan which details the existing and proposed contours and elevation (in relation to mean sea level) of the ground and the lowest floor of proposed construction, 100 year flood elevations and other associated factors such as pressures and impact forces, etc., storage elevations, size of the structure, location and elevations of streets, water supplies, sanitary facilities, soil types and floodproofing measures, including specific reference to the level of the floodproofing in relation to a 100 year flood.

(2)        A document, certified by a registered professional engineer or architect, which states that the proposed construction has been adequately designed to withstand the flood depths, pressures, velocities, impact and uplift forces and other hydrostatic and hydrodynamic and buoyancy factors associated with a 100 year flood. Such statement shall include a description of the type and extent of floodproofing measures which have been incorporated into the design of the structure.

(2)        Review of County Planning Commission. A copy of all applications and plans for construction and/or improvements in any designated floodplain to be considered for approval shall be submitted by the Township Building Official to the County Planning Commission for review and comment prior to the issuance of a building permit. The recommendations of the County Planning Commission shall be considered by the Township Building Official for possible incorporation into the proposed plan.

(3)        Other Permit Issuance Requirements. Prior to the issuance of any building permit, the Township Building Official shall review the application for permit to determine if all other necessary Township or governmental permits, such as those required by State and Federal laws, have been obtained, including those required by Act 537, the Pennsylvania Sewage Facilities Act, the Dam Safety and Encroachment Act, and the Federal Water Pollution Control Act Amendments of 1972, Section 404, 33 U.S.C. §1334. No permit shall be issued until this determination has been made. [Ord. 98-7]

 (4)        Start of Construction. For purposes of implementation of these provisions, construction shall be considered to have started with the first placement of permanent construction of the site, such as the pouring of slabs or footings or any work beyond the stage of excavation. For a structure without a basement or poured footings, the start of construction includes the first permanent framing or assembly of the structure or any part thereof on its pilings or foundation, or the affixing of any prefabricated structure or manufactured home to its permanent site. Permanent construction does not include land preparation, land clearing, grading, filling, excavation for basement, footings, piers or foundations, erection of temporary forms, the installation of piling under proposed subsurface footings, or the installation of sewer, gas and water pipes or electric or other service lines from the street.

(Ord. 79-2, 3/16/1979, §3; as amended by Ord. 93-9, 4/29/1993, §IF; and by Ord. 98-7, 8/27/1998)

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