[Ord. 447, 1/2/2007, § 301]
1. 
No regulated activities shall commence until the Township approves a plan, which demonstrates compliance with the requirements of this chapter.
2. 
Plans approved by the Township shall be on site throughout the duration of the regulated activity.
3. 
The Township may, after consultation with DEP, approve methods for meeting the state water quality requirements other than those in this chapter; provided, that they meet the minimum requirements of and do not conflict with, state law including, but not limited to, the Clean Streams Law, 35 P.S. § 691.1 et seq.
4. 
For all regulated activities, implementation of water quality controls are required.
5. 
For all regulated activities equal to or greater than 1,000 square feet in area, implementation of peak rate controls and preparation of a SWM site plan are required.
6. 
Impervious Areas.
A. 
The measurement of impervious areas shall include all of the imperious areas in the total proposed development even if development is to take place in stages.
B. 
For development taking place in stages, the entire development plan must be used in determining conformance with this chapter.
C. 
For projects that add impervious area to a parcel, the total impervious area on the parcel is subject to the requirements of this chapter.
7. 
Discharges onto adjacent property shall not be created, increased, decreased, or relocated, or otherwise altered without permission of the adjacent property owner(s). Such discharges shall be subject to the requirements of this chapter.
8. 
All regulated activities shall include such measures as necessary to:
A. 
Protect health, safety, and property.
B. 
Meet state water quality requirements as defined in Part 2.
C. 
Meet the water quality goals of this chapter by implementing measures to:
(1) 
Minimize disturbance to floodplains, wetlands, natural slopes over 15%, and existing native vegetation.
(2) 
Preserve and maintain trees and woodlands. Maintain or extend riparian buffers and protect existing forested buffer. Provide trees and woodlands adjacent to impervious areas whenever feasible.
(3) 
Establish and maintain nonerosive flow conditions in natural flow pathways.
(4) 
Minimize soil disturbance and soil compaction. Cover disturbed areas with topsoil having a minimum depth of four inches. Use tracked equipment for grading when feasible.
(5) 
Disconnect impervious surfaces by directing runoff to pervious areas.
D. 
Incorporate the techniques described in Appendix 23-A of this chapter, "Low Impact Development Practices," whenever practical.
9. 
The design of all facilities over Karst shall include an evaluation of measures to minimize adverse effects.
10. 
The design storm volumes to be used in the analysis of peak rates of discharge should be obtained from the Precipitation-Frequency Atlas of the United States, Atlas 14, Volume 2, US Department of Commerce, National Oceanic and Atmospheric Administration, National Weather Service, Hydrometeorological Design Studies Center, Silver Spring, Maryland, 20910. NOAA's Atlas 14 can be accessed at Internet address: http:/hdsc.nws.noaa.gov/hdsc/pfds/.
[Ord. 447, 1/2/2007, § 302]
1. 
Regulated activities that create less than 1,000 square feet of new impervious area and that meet the area of influence (A) requirements shown in Table 23-1A are exempt from the peak rate control and the SWM site plan preparation requirement of this chapter.
2. 
Regulated activities that create less than 1,000 square feet of new impervious area and that meet the area of influence (A) requirements shown in Table 23-1B are exempt from the rate control requirements of this chapter.
3. 
Use the guidelines in Appendix 23-D to determine the area of influence, A, in acres and the total impervious area, a, in square feet to determine if an exemption is applicable for regulated activities less than 1,000 square feet.
4. 
After the date of adoption of this chapter, if a subdivision and land development plan is submitted that addresses peak rate control and includes a SWM site plan, then the impervious exemption is calculated from the date of approval of that plan, based upon the impervious area shown on the subdivision and land development plan.
5. 
Agricultural plowing and tilling 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.
6. 
Exemptions from any provisions of this chapter shall not relieve the applicant from the requirements in § 23-301, Subsections 6, 7, and 8.
Table 23-1A: SWM exemptions from
Peak Rate Controls and SWM Site Plan preparation for
Area of Influence, A, less than 3 acres.
Area of Influence, A
(acres)
Total Impervious Area, A, Exempt from Peak Rate Controls and from SWM Site Plan Preparation (sq. ft.)
< 0.125 acre
1,000
0.2
1,400
0.3
1,900
0.4
2,300
0.5
2,700
0.6
3,100
0.7
3,500
0.8
3,900
0.9
4,200
1.0
4,600
1.1
4,900
1.2
5,200
1.3
5,500
1.4
5,900
1.5
6,200
1.6
6,500
1.7
6,800
1.8
7,100
1.9
7,300
2.0
7,600
2.1
7,900
2.2
8,200
2.3
8,400
2.4
8,700
2.5
9,000
2.6
9,200
2.7
9,500
2.8
9,800
2.9
10,000
Table 23-1B: SWM exemptions from peak rate controls (ONLY) for
Area of Influence, A, 3.0 acres and greater
Area of Influence, A
(acres)
Total Impervious Area, A, Exempt from Peak Rate Controls ONLY (sq. ft.)
3.0
10,300
3.1
10,500
3.2
10,800
3.3
11,000
3.4
11,300
3.5
11,500
3.6
11,700
3.7
12,000
3.8
12,200
3.9
12,500
4.0
12,700
4.1
12,900
4.2
13,200
4.3
13,400
4.4
13,600
4.5
13,800
4.6
14,100
4.7
14,300
4.8
14,500
4.9
14,700
5.0
15,000
>5
15,000
Notes: The area of influence, A, in acres and the total impervious area, A, in square feet are calculated using the guidelines provided in Appendix 23-D.
[Ord. 447, 1/2/2007, § 303]
1. 
Low impact development practices (Appendix 23-A) are encouraged for all regulated activities. Water quality control shall be implemented using the methodologies in Subsections 1A and B below:
A. 
The simplified method is independent of site conditions.
(1) 
Retention and detention facilities shall be sized to capture the first two inches of runoff from all impervious surfaces.
(2) 
The first one inch of runoff shall be permanently removed and shall not be released into the surface waters of this commonwealth. This is the permanently removed volume (PRV). Removal options include reuse, evaporation, transpiration, and infiltration.
(3) 
For projects that meet the exemption criteria in Table 23-1A of § 23-302, the subsequent one inch of runoff shall be detained. This is the extended detention volume (EDV).
(4) 
For projects that do not meet the exemption criteria in Table 23-1A of § 23-302, the one-year twenty-four-hour runoff volume shall be detained.
(5) 
Infiltration of the first 1/2 inch of the PRV is encouraged. This portion of the PRV is the groundwater recharge volume (GRV).
(6) 
The permanently removed volume (PRV) requirement for land areas with existing cover consisting of meadow, brush, wood-grass combination, or woods proposed for conversion to any other nonequivalent type of pervious cover shall be 1/4 inch of runoff.
(7) 
Retention and detention facilities should be designed to drain both the PRV and EDV completely within 48 to 96 hours from the start of the storm.
(8) 
Retention facilities should be designed to accommodate infiltration of the PRV. Infiltration areas should be spread out and located in the sections of the site that are most suitable for infiltration.
B. 
The design storm 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 rainfall.
(2) 
Do not increase peak rate of runoff for (one-, two-, ten-, twenty-five-, one-hundred-year storms (at minimum), predevelopment to post-development; as necessary, provide additional peak rate control as required by Act 167 planning.
(3) 
Existing (predevelopment) nonforested pervious areas must be considered meadow or its equivalent.
(4) 
Twenty percent of existing impervious area, when present, shall be considered meadow in the model for existing conditions.
C. 
In all cases, retention and detention facilities should be designed to completely drain water quality volumes (in the case of the simplified method this includes both the PRV and EDV) over a period of time not less than 48 and not more than 96 hours from the start of the design storm.
The Pennsylvania Stormwater Best Management Practices Manual (1) provides guidance on selection and application of both water quality control methodologies.
[Ord. 447, 1/2/2007, § 304]
1. 
Areas not covered by a release rate map from an approved Act 167 Stormwater Management Plan:
Post-development discharge rates shall not exceed the predevelopment discharge rates for the two-, five-, ten-, twenty-five-, fifty-, and one-hundred-year storms. If it is shown that the peak rates of discharge indicated by the post-development analysis are less than or equal to the peak rates of discharge indicated by the predevelopment analysis for two-, five-, ten-, twenty-five-, fifty-, and one-hundred-year, twenty-four-hour storms, then the requirements of this section have been met.
Otherwise, the applicant shall provide additional controls as necessary to satisfy the peak rate of discharge requirement.
2. 
Areas covered by a release rate map from an approved Act 167 Stormwater Management Plan:
For the two-, five-, ten-, twenty-five-, fifty-, and one-hundred-year storms, the post-development discharge rates will follow the release rate maps in this chapter. For any areas not shown on the release rate maps, the post-development discharge rates shall not exceed the predevelopment discharge rates.