For any of the regulated activities described
in this chapter, prior to the final approval of subdivision and/or
land development plans, or the issuance of any permit, or the commencement
of any land disturbance activity, the owner, subdivider, developer
or his agent shall submit a drainage plan for approval.
A.
Impervious cover. Any regulated activity which would
create 10,000 square feet or less of additional impervious cover is
exempt from the detention provisions of this chapter. This criteria
shall apply to the total proposed development even if development
is to take place in stages (i.e., the impervious cover associated
with the total development shall be used to compare to the waiver
minimum, not merely the individual stage impervious cover). Predevelopment
impervious cover is that which is in place as of the effective date
of this chapter. Additional impervious cover shall include, but not
be limited to, any roof, parking or driveway areas and any new streets
and sidewalks constructed as part of or for the proposed regulated
activity. Any areas designed to initially be gravel, crushed stone,
porous pavement, etc. shall be assumed to be impervious for the purposes
of comparison to the waiver criteria.
B.
Prior drainage plan approval. Any regulated activity
for which a drainage plan was previously prepared as part of a subdivision
or land development proposal that received preliminary plan approval
from Lehigh Township prior to the effective date of this chapter is
exempt from the drainage plan preparation provisions of this chapter
provided that the approved drainage plan included design of stormwater
facilities consistent with ordinance provisions in effect at the time
of approval. If significant revisions are made to the drainage plan
after both the preliminary plan approval and the effective date of
this chapter, preparation of a new drainage plan, subject to the provisions
of this chapter, shall be required.
The following items shall be included in the
drainage plan:
B.
Map(s) of the project area showing:
(1)
The location of the project relative to highways,
municipalities or other identifiable landmarks.
(2)
Existing contours at intervals of two feet. In areas
of steep slopes (greater than 15%), five-foot contour intervals may
be used. Off-site drainage areas impacting the project including topographic
detail.
(3)
Streams, lakes, ponds or other bodies of water within
the project area.
(4)
Other physical features including existing drainage
swales, wetlands, closed depressions, sinkholes, and areas of natural
vegetation to be preserved.
(5)
Locations of proposed underground utilities, sewers
and water lines.
(6)
An overlay showing soil types and boundaries based
on the Northampton County Soil Survey, latest edition.
(7)
Proposed changes to land surface and vegetative cover.
(8)
Proposed structures, roads, paved areas and buildings.
(9)
Final contours at intervals of two feet. In areas
of steep slopes (greater than 15%), five-foot contour intervals may
be used.
(10)
Fencing (if required) and landscaping screens.
(11)
Stormwater management district boundaries applicable
to the site.
C.
Stormwater management controls.
(1)
All stormwater management controls must be shown on
a map and described, including:
(a)
Groundwater recharge methods such as seepage
pits, beds or trenches. When these structures are used, the locations
of septic tank infiltration areas and wells must be shown.
(b)
Other control devices or methods such as roof-top
storage, semipervious paving materials, grass swales, parking lot
ponding, vegetated strips, detention or retention ponds, storm sewers,
etc.
(2)
All calculations, assumptions and criteria used in
the design of the stormwater management facilities and in the establishment
of the calculated predevelopment and postdevelopment peak discharge,
including mapping of the watershed areas and indication of runoff
for all points of runoff concentration shall be provided.
(3)
All plans and profiles of proposed stormwater management
facilities including horizontal and vertical location, size, and type
of material. This information shall provide sufficient information
required for the construction of all facilities.
(4)
A map(s) clearly delineating and labeling all drainage
areas used in the design of storm sewer facilities, swales, and retention/detention
basins.
(5)
For all detention and retention basins, a plotting
or tabulation of storage volumes with corresponding water surface
elevations and of the outflow rates for those water surfaces.
(6)
For all detention and retention basins, the design
inflow and outflow hydrographs or the shortcut routing method to determine
the function of the basin.
(7)
For all retention basins which hold 2 1/2 acre feet
or more of water and have an embankment that is 10 feet or more in
height, soil structures and characteristics shall be investigated.
Plans and data prepared by a registered professional, experienced
and educated in soil mechanics, shall be submitted.
(8)
A map(s) clearly delineating any existing wetlands
as classified by a qualified environmental scientist experienced in
wetland determination. Wetland determination shall be performed in
accordance with U.S. Army Corps of Engineers procedures as outlined
in publication TRY-87-1, "Wetlands Delineation Manual," latest edition.
No construction or development shall be permitted in wetlands without
approval from the U.S. Army Corps of Engineers and the Pennsylvania
Department of Environmental Protection, Bureau of Dams and Waterway
Management.
D.
Proposals for the ownership and maintenance responsibilities
for all proposed storm drainage and erosion and sediment control facilities
shall be submitted to the Township for review and approval at preliminary
plan stage. The Township shall be satisfied that sufficient provisions
have been made for adequate and perpetual maintenance of all such
facilities. All drainage facilities to be owned by the developer or
his assigns shall be maintained to retain their design capacity. Such
assurances shall be in a form to act as a covenant that shall run
with the land, and shall provide for municipal maintenance, assessment
of cost and penalties, in case of lack of maintenance.
A.
(1)
The drainage plan shall be submitted by the developer
to the Township as part of the preliminary plan (or final plan if
no preliminary submission is made) submission for the subdivision
or land development.
(2)
Three copies of the drainage plan and supporting documents
shall be submitted. Final stormwater management plans and calculations
shall be signed and sealed by a licensed professional engineer.
C.
For regulated activities specified in § 138-4C(5) and (6) and not requiring site plan or building permit application submission:
(1)
The drainage plan shall be submitted by the developer
to the Lehigh Valley Planning Commission for coordination with the
DEP permit application process under Chapter 105 (Dam Safety and Waterway
Management) of Chapter 106 (Flood Plain Management) of DEP's Rules
and Regulations.
(2)
Two copies of the drainage plan shall be submitted.
A.
The Township Engineer shall review the drainage plan for consistency with the adopted stormwater management plan as embodied by this chapter and against the additional storm drainage provisions contained in this chapter; Chapter 147, Subdivision and Land Development; or Chapter 180, Zoning, as applicable.
B.
The Lehigh Valley Planning Commission shall provide
an advisory review of the drainage plan for consistency with the stormwater
management plans.
C.
For regulated activities specified in § 138-4C(1) and (2), the LVPC shall provide written comments to the Township, within a time frame consistent with established procedures under the Municipalities Planning Code,[1] as to whether the drainage plan has been found to be consistent
with the stormwater management plan.
[1]
Editor's Note: See 53 P.S. § 10101
et seq.
E.
The Township shall not approve any subdivision or land development [regulated activities § 138-4C(1) and (2)] or building permit application [regulated activities § 138-4C(3) and (4)] if the drainage plan has been found to be inconsistent with the stormwater management plan as determined by the Township Engineer.
A modification to a submitted drainage plan for a proposed development site which involves a change in control methods or techniques, or which involves the relocation or redesign of control measures, or which is necessary because soil or other conditions are not as stated on the drainage plan (as determined by the Township Engineer) shall require a resubmission of the modified drainage plan consistent with § 138-19 subject to review per § 138-20 of this chapter.
A.
The Board of Supervisors may hear requests for waivers
where it is alleged that the provisions of this chapter inflict unnecessary
hardship upon the applicant. The waiver request shall be in writing
and accompanied by any requisite fee as set forth on the Township's
fee schedule. A copy of the request shall be provided to each of the
following: the Township, Township Engineer, Township Solicitor and
Lehigh Valley Planning Commission. The request shall fully document
the nature of the alleged hardship and address, at a minimum, the
four requirements listed below.
B.
The Township may grant a waiver from the provisions
of this chapter provided that all of the following findings are made
in a given case:
(1)
That there are unique physical circumstances or conditions,
including irregularity of lot size or shape, or exceptional topographical
or other physical conditions peculiar to the particular property,
and that the unnecessary hardship is due to such conditions, and not
the circumstances or conditions generally created by the provisions
of this chapter in the stormwater management district in which the
property is located;
(2)
That because of such physical circumstances or conditions,
there is no possibility that the property can be developed in strict
conformity with the provisions of this chapter, including the "no
harm" provision, and that the authorization of a waiver is therefore
necessary to enable the reasonable use of the property;
(3)
That such unnecessary hardship has not been created
by the applicant; and
(4)
That the waiver, if authorized, will represent the
minimum waiver that will afford relief and will represent the least
modification possible of the regulation in issue.
(5)
That financial hardship is not the criteria for granting
of a hardship waiver.
C.
In granting any waiver, the Board of Supervisors may
attach such reasonable conditions and safeguards as it may deem necessary
to implement the purposes of Act 167 and this chapter. If a hardship
waiver is granted, the applicant must still comply with the requirements
of Section 13 of the Storm Water Management Act.[1]
[1]
Editor's Note: See 32 P.S. § 680.1
et seq.
