Town of Bloomsburg, PA
Columbia County
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[Ord. 759, 3/8/1993, § 801]
The drainage/stormwater management (hereafter referred to as D/SWM) Plan shall consist of maps and a narrative prepared under the direction of a professional engineer registered in Pennsylvania with experience in D/SWM. The D/SWM plan shall include the following items:
A. 
A narrative including a general statement of the project, the date the project is expected to begin and end, a description of existing and proposed conditions, ownership and maintenance of facilities and conclusions.
B. 
A 7 1/2 minute USGS topographic map, or equivalent, showing the project location and its total watershed(s) and additional maps, as necessary, to clearly show the delineation of all drainage areas, both onsite and offsite, used in all computations for all stormwater management facilities and all storm drainage facilities.
C. 
Project mapping showing existing and proposed facilities such as lots, streets, parking areas, drainage facilities, erosion control facilities, areas of cut and fill, limits of earth disturbance and stormwater management facilities.
D. 
Project mapping showing existing and proposed topographic features as follows:
(1) 
Contours at two foot intervals except in areas where the slope is greater than 15 in which case the contour interval shall be five feet.
(2) 
Boundary lines of the project area.
(3) 
Drainage on the project and adjoining properties including floodplains, floodways, streams, lakes, ponds and easements.
E. 
Calculations for all drainage and stormwater management facilities.
[Ord. 759, 3/8/1993, § 802]
1. 
General. The following design criteria are presented as the minimum acceptable standards available at the time this Chapter was adopted. New and innovative procedures are encouraged and shall be permitted on a case-by-case basis by the Town Engineer/Consultant.
2. 
Drainage.
A. 
Design Storm. All drainage facilities shall be designed to safely convey the ten-year storm. More stringent criteria may be required where the above criteria will aggravate existing problems or create new problems.
B. 
Peak Flow. The rational method shall be used for drainage areas up to 1 1/2 square mile. However, extreme care should be used for watersheds with areas greater then 1/2 square mile, times of concentration greater than 60 minutes or flow paths that include channel storage or diversions. For drainage areas greater than 1/2 square mile, other hydrologic methods should be considered such as the SCS soil cover complex method.
C. 
Rainfall. Design rainfall shall be determined using the Pennsylvania Department of Transportation intensity-duration-frequency curves for Region Four as follows:
(1) 
Rational Method. The appropriate time of concentration and return period shall be used to determine the rainfall intensity.
(2) 
Soil-Cover-Complex Method. The Soil Conservation Service Type II twenty-four-hour rainfall distribution shall be used with the following rainfall depths:
Return Period
24 Hour Rainfall
2 year
3.0 inch
10 year
4.6 inch
25 year
5.5 inch
100 year
7.4 inch
D. 
Runoff Coefficients.
(1) 
Runoff coefficients for the rational method shall be determined using Table 1 in Appendix A.
(2) 
Runoff curve numbers for the SCS Soil Cover-Complex Method shall be determined using Table 2 in Appendix A.
E. 
Time of Concentration. The methods found in Chapter 3 of TR-55 (Reference 1) shall be used to compute times of concentration. The length of flow path for sheet flow shall not exceed 150 feet and the length of flow path for shallow concentrated flow shall not exceed 1,000 feet.
F. 
Allowable Spread of Water. The maximum allowable spread of water on streets is 1/2 of a travel lane.
G. 
Pipe Design. At a minimum, pipe capacities shall be computed using both the Manning Equation for full flow capacity and the Inlet Control Nomographs in Hydraulic Design Series 5 (Reference 2). For inlets, the maximum headwater elevation must be less than the top of grate or top of road. For culverts, the headwater/diameter ratio must be less than or equal to 0.125. Complete outlet control calculations shall be required for special circumstances such as high tailwater conditions, long runs of pipe, excessive bends and other losses, etc.
H. 
Inlet Spacing. The maximum spacing of inlets is 450 feet. On curbed sections, a double inlet shall be placed at the low point on sag vertical curves with an inlet on each side of the low point at a distance not to exceed 100 feet or where the grade is two-tenths feet above the low point.
3. 
Stormwater.
A. 
Design Storm. The maximum peak rate of runoff for the proposed conditions shall not exceed the maximum peak rate of runoff for the existing conditions for the two-, ten-, and twenty-five-year storms. More stringent criteria may be required where the above criteria will aggravate existing problems or create new problems.
B. 
Hydrographs. Hydrographs shall be calculated using the following methods:
Drainage Area
Method
Less than 10 acres
Modified Rational Method
10 to 20 acres
Modified Rational Method or SCS Soil Cover-Complex Method
Greater than 20 acres
SCS Soil Cover-Complex Method
C. 
Rainfall. Refer to subsection (2)(C).
D. 
Runoff Coefficient. Refer to subsection (2)(D).
E. 
Time of Concentration. Refer to subsection (2)(E).
F. 
Routing. The design of the facility shall be verified by routing the proposed two-, ten-, twenty-five-, and one-hundred-year hydrographs through the facility using the storage indication method or modified Plus method.
G. 
Emergency Spillway. An emergency spillway must be provided to safely pass the 100 storm with one foot of freeboard between the maximum pool elevation and the top of the dam.
H. 
Riser Pipe. The riser pipe shall be designed to withstand buoyancy forces if it becomes clogged.
I. 
Fencing. Any ponds with slopes steeper than three to one shall be enclosed by a chain link fence not less than four feet in height.
J. 
Pond Bottom. The minimum slope of any surface on the bottom of any pond shall be 1 1/2%. Also, low-flow channels shall be constructed from any pipe or swale leading into the pond to the principal spillway.
K. 
Access. All facilities shall have access roads, gates and easements where necessary.
[Ord. 759, 3/8/1993, § 804]
1. 
General. Following are the minimum acceptable construction standards. Other standards will be accepted on a case-by-case basis by the Town Engineer/Consultant.
2. 
Drainage and Stormwater.
A. 
Pipe.
(1) 
Pipes shall be constructed in accordance with the specifications as set forth in the Pennsylvania Department of Transportation, Publication 408, as amended. (Reference 3)
(2) 
Pipes, trenching and backfill shall be in accordance with RC-30 of Roadway Construction Standard Drawings. (Reference 4)
(3) 
Pipe thickness and reinforcement shall be in accordance with approved engineering calculations. Minimum pipe gauge for C.M.P. shall be 16 gauge.
(4) 
Pipe sizes shall be in accordance with that shown on approved drawings. Minimum pipe size for drainage facilities shall be 15 inches in diameter for onsite collection. Pipes utilized for upstream conveyance of offsite flows shall have a minimum size of 18 inches.
(5) 
Pipes shall be constructed and set to line and grade as shown on approved drawings.
(6) 
Pipes shall be inspected by the Town Engineer/Consultant or his agent prior to backfilling.
B. 
Inlets.
(1) 
Inlets shall be constructed in accordance with the specifications as set forth in the Pennsylvania Department of Transportation, Publication 408, as amended, and as detailed on the Roadway Construction Standard Drawings (RC-34).
(2) 
Inlet tops shall be precast concrete top units with a ten-inch hood or equivalent in order to place inlet in a two sump condition, and shall be compatible with type of curbing installed.
(3) 
All inlets shall have weep holes placed at the appropriate elevations to completely drain the subgrade prior to placing the base course and surface course.
(4) 
Inlets shall be inspected by the Town Engineer/Consultant or his designated agent after completion of all work.
C. 
Manholes.
(1) 
Manholes shall be constructed in accordance with the specifications as set forth in the Pennsylvania Department of Transportation, Publication 408, as amended, and as detailed on the Roadway Construction Standard Drawings (RC-39).
(2) 
Manholes shall be inspected by the Town Engineer/Consultant or his designated agent after completion of all work.
D. 
Miscellaneous Structures and Facilities. Miscellaneous structures and facilities shall be constructed in accordance with Pennsylvania Department of Transportation Publication 408 and Roadway Construction Standards where applicable.
[Ord. 759, 3/8/1993, § 804]
Compliance with this Chapter does not preclude the need to obtain other permits and approvals as required by the Town, Columbia County, the Columbia County Conservation District, the Commonwealth of Pennsylvania, the Federal government and other agencies. Other permits and approvals may include an erosion and sedimentation pollution control plan, earth disturbance permit, water obstruction and encroachment permit, dam safety permit, submerged lands license agreement, §§ 401 and 404 of the Clean Water Act, and others. The most stringent of all pertinent requirements shall apply.
[Ord. 759, 3/8/1993, § 805]
Prior to the granting of final approval of the D/SWM by the Town, the applicant shall either provide for the dedication of the permanent facilities to the Town or have a written agreement providing for the ownership and maintenance of said facilities.
A. 
Facilities Dedicated to Town. It shall be the Town's responsibility to maintain any facilities that are dedicated to the Town. Upon construction of the facilities which the developer or owner wishes to dedicate ownership to the Town and before their acceptance by the Town, the applicant shall provide to the Town an amount determined by the Town, which at a rate of 6% per annum, will provide sufficient interest income per year to cover the annual maintenance of such facilities, which the developer or owner wishes the Town to accept for future maintenance.
Example:
Maintenance $250 per year = $4,166.67 deposit.
Maintenance $500 per year = $8,333.33 deposit.
Prior to the Town approving the final D/SWM plan upon which the facilities are shown for dedication to the Town, the developer or owner shall provide to the Town satisfactory surety as approved by the Town Solicitor to ensure the payment of the said required maintenance amount at the completion of construction and prior to acceptance by the Town Engineer/Consultant.
B. 
Facilities Maintained by Private Entity.
(1) 
In cases where permanent facilities are owned by a private entity such as homeowners' association, such entity shall be responsible for maintenance. In this case, a legally binding agreement between the entity and the Town shall be made providing for maintenance for all permanent facilities, including the inspection by the Town of all such facilities deemed critical to the public welfare, annually and after each major flood event.
(2) 
If the Town determines at any time that any facility has been eliminated, altered or improperly maintained, the entity shall be advised of corrective measures required and given a reasonable period of time to take necessary action. If such action is not taken by the entity, the Town may cause the work to be done and lien all costs against the entity.
C. 
Facilities Maintained by Individual Lot Owners. When the facilities are located on individual lots, and when they are the responsibility of that landowner to maintain, a description of the facility or system and the terms of their required maintenance shall be recorded with the deed to the property.
D. 
If the Town determines at any time that any facility has been eliminated, altered or improperly maintained, the owner of the property shall be advised of corrective measures required and given a reasonable period of time to take necessary action. If such action is not taken by the property owner, the Town may cause the work to be done and lien all costs against the property.
[Ord. 759, 3/8/1993, § 806]
1. 
Stormwater management facilities located in close proximity to Fishing Creek and the Susquehanna River may be waived in order to facilitate drainage prior to stream flooding. All conveyance facilities between the project and the stream must have adequate capacity to safely pass the proposed twenty-five-year storm or they must be improved to pass the proposed twenty-five-year storm.
2. 
Any proposed activity regulated by or subject to the stormwater requirements of this Chapter which would create 10,000 square feet or less of additional impervious cover shall not be required to adhere to the stormwater provisions in § 22-802(3)(A) of this Part. Development which is planned to occur in stages or phases will be considered in its entirety for the purposes of determining exemption. Semi-pervious areas shall be considered as impervious for purposes of this exemption. Waivers shall not be provided for any diversion of watercourses or watersheds.
3. 
Where, owing to special conditions, a literal enforcement of the provisions of this Part will result in unreasonable hardship, the Town, on the recommendation of the Town Engineer/Consultant and Zoning Officer, may make such reasonable variance thereto or waiver thereof as will not be contrary to the public interest and so that the spirit of this Part shall be observed and substantial justice done. A request for a variance or waiver shall be submitted in writing by the applicant to the Zoning Officer setting forth the grounds and all facts relied upon by the applicant.