Any regulated activity that meets the following exemption criteria
is exempt from the part(s) of this chapter as specified herein. However,
the requirements of the chapter shall otherwise remain in effect.
The criteria for exemption in this section apply to the total development
proposed, including instances in which the development is proposed
to take place in phases. The date of enactment of this chapter shall
be the starting point from which future development and the respective
proposed impervious surface computations shall be cumulatively considered
and regulated. Exemption shall not relieve an applicant from implementing
such measures as necessary to meet the intent of this chapter.
A. Regulated activities that create DIAs equal to or less than 1,000
square feet are exempt from the peak rate control and the SWM site
plan preparation requirements of this chapter, and therefore, no formal
application to the Borough is required. [NOTE: The Borough has, at
its discretion, the ability to deny exemption from any requirements
of this chapter. Exemption from any requirements of this chapter does
not convey exemption from any requirements of any other applicable
local codes or ordinances (i.e., local building permit requirements).]
B. Regulated activities that create DIAs greater than 1,000 square feet
and equal to or less than 5,000 square feet are exempt only from the
peak rate control requirement of this chapter.
C. Regulated activities meeting the following parcel size and square
footage requirements are exempt from the peak rate control requirements,
but not the volume control or SWM site plan preparation requirements
of this chapter. These criteria shall apply to the total proposed
development even if development is to take place in phases. The date
of the chapter adoption shall be the starting point from which to
consider tracts as "parent tracts" in which future subdivisions and
respective impervious area computations shall be cumulatively considered.
[NOTE: The Borough has, at its discretion, the ability to deny exemption
from any requirements of this chapter. Exemption from any requirements
of this chapter does not convey exemption from any requirements of
any other applicable local codes or ordinances (i.e., local building
permit requirements).]
New Impervious Area Exemption Criteria for Peak Rate Control
|
---|
Total Parcel Size
(acres)
|
Total Parcel Size
(square feet)
|
New Impervious Area Exemption
(square feet)
|
---|
< 0.25
|
<10,890
|
1,500
|
0.25 to 0.5
|
10,890 to 21,780
|
2,500
|
> 0.5
|
>21,780
|
5,000
|
D. Agricultural plowing and tilling are exempt from the SWM site plan requirements including §§
460-16 and
460-17 of this chapter, provided the activities are performed according to the requirements of 25 Pa. Code Chapter 102.
E. Forest management and timber operations are exempt from the rate
control and SWM site plan preparation requirements of this chapter,
provided the activities are performed according to the requirements
of 25 Pa. Code Chapter 102.
F. The Borough may deny or revoke any exemption pursuant to this section
at any time for any project that the Borough determines poses a threat
to public health, safety, property or the environment.
G. The Borough may provide an exemption for regulated activities equal to or less than 1,000 square feet, provided a "fee in lieu of" is provided in accordance with §
460-40.
The green infrastructure and low-impact development practices
provided in the BMP Manual shall be utilized for all regulated activities
to the maximum extent practicable. Water volume controls shall be
implemented using the design storm method in Subsection A or the simplified
method in Subsection B below. For regulated activity areas equal or
less than one acre that do not require hydrologic routing to design
the stormwater facilities, this chapter establishes no preference
for either methodology; therefore, the applicant may select either
methodology on the basis of economic considerations, the intrinsic
limitations on applicability of the analytical procedures associated
with each methodology, and other factors.
A. The design storm method (CG-1 in the BMP Manual) is applicable to
any size of regulated activity. This method requires detailed modeling
based on site conditions.
(1) Do not increase the post-development total runoff volume for all
storms equal to or less than the two-year, twenty-four-hour duration
precipitation.
(2) For modeling purposes:
(a)
Existing (predevelopment) nonforested pervious areas must be
considered meadow in good condition.
(b)
Twenty percent of existing impervious area, when present, shall
be considered meadow in good condition in the model for existing conditions.
B. The simplified method (CG-2 in the BMP Manual) provided below is
independent of site conditions and should be used if the design storm
method is not followed. This method is not applicable to regulated
activities greater than one acre or for projects that require design
of stormwater storage facilities. For new impervious surfaces:
(1) Stormwater facilities shall capture at least the first two inches
of runoff from all new impervious surfaces.
(2) At least the first one-inch of runoff from new impervious surfaces
shall be permanently removed from the runoff flow; i.e., it shall
not be released into the surface waters of this commonwealth. Removal
options include reuse, evaporation, transpiration, and infiltration.
(3) Wherever possible, infiltration facilities should be designed to
accommodate infiltration of the entire permanently removed runoff;
however, in all cases at least the first 0.5 inch of the permanently
removed runoff should be infiltrated.
(4) This method is exempt from the requirements of §
460-17, Rate controls.
In areas of carbonate geology, a geologist shall certify to
the following:
A. No stormwater management facility will be placed in, over, or immediately
adjacent to the following features:
(1) Closer than 100 feet from sinkholes.
(2) Closer than 100 feet from closed depressions.
(3) Closer than 100 feet from caverns, intermittent lakes, or ephemeral
streams.
(4) Closer than 50 feet from lineaments in carbonate areas.
(5) Closer than 50 feet from fracture traces.
(6) Closer than 25 feet from bedrock pinnacles (surface or subsurface).
B. Stormwater resulting from regulated activities shall not be discharged
into sinkholes.
C. If the developer can prove through analysis that the project site is an area underlain by carbonate geology, and such geologic conditions may result in sinkhole formations, then the project site is exempt from recharge requirements as described in §
460-16, Volume control. However, the project site shall still be required to meet all other standards found in this chapter.
D. It shall be the developer's responsibility to verify if the project
site is underlain by carbonate geology. The following note shall be
attached to all stormwater management plans and signed and sealed
by the developer's geologist: "I, __________, certify that the proposed
stormwater management facility (circle one) is/is not underlain by
carbonate geology."
E. Whenever a stormwater management facility will be located in an area
underlain by carbonate geology, a geological evaluation of the proposed
location by a geologist shall be conducted to determine susceptibility
to sinkhole formation. The evaluation may include the use of impermeable
liners to reduce or eliminate the separation distances listed in the
BMP Manual. Additionally, the evaluation shall, at a minimum, address
soil permeability, depth to bedrock, seasonally high groundwater table,
susceptibility for sinkhole formation, suitability of stormwater management
facilities, subgrade stability and maximum infiltration capacity in
depth of water per unit area.
F. A detailed soils evaluation of the project site shall be performed
to determine the suitability of recharge facilities. The evaluation
shall be performed by a qualified professional, and at a minimum,
address soil permeability, depth to bedrock, susceptibility to sinkhole
formation, and subgrade stability. The general process for designing
the infiltration BMP shall be:
(1) Site evaluation to determine general areas of suitability for infiltration
practices.
(2) Provide field test throughout the area proposed for development to
determine appropriate percolation rate and/or hydraulic conductivity.
At least one infiltration test must be included in each soil group
and at least one infiltration test must be conducted for each five
lots proposed for development. Infiltration tests must be taken at
the location and depth of all proposed infiltration structures.
(3) Design infiltration structure for required storm volume based on
all available data.
G. Extreme caution shall be exercised where infiltration is proposed
in geologically susceptible areas such as strip mine or limestone
areas. It is also extremely important that the design professional
evaluate the possibility of groundwater contamination from the proposed
infiltration/recharge facility and recommend a hydrogeologic justification
study be performed if necessary. Whenever a basin will be located
in an area underlain by limestone, a geological evaluation of the
proposed location shall be conducted to determine susceptibility to
sinkhole formations. The design of all facilities over carbonate formations
shall include measures to prevent ground water contamination and,
where necessary, sinkhole formation. The infiltration requirement
in the high quality/exceptional waters shall be subject to the Department's
Chapter 93 and antidegradation regulations. A detailed hydrogeologic
investigation may be required by the Borough and where appropriate,
the Borough may require the installation of an impermeable liner in
detention basins.