1. The final plans shall conform to the standards and data requirements set forth for Preliminary Plans in § 22-301(1 through 4) of this Chapter.
2. It shall not be necessary to resubmit supporting maps and data submitted with Preliminary Plan, as set forth in § 22-301(5) of this Chapter, provided that no change has occurred.
3. The following additional data shall be illustrated on the Final Plan:
A. The latest source of title to the land as shown by the deed, page number and book of the County Recorder of Deeds;
B. The total tract boundary lines of the area being subdivided with accurate distances to hundredths of a foot and bearing to 15 seconds. The boundaries shall be determined by accurate survey in the field, to an error of closure not to exceed 1 foot in 10,000 feet. The tract boundary shall be subsequently closed and balanced. The boundary(s) adjoining additional unplatted land of the subdivider (for example, between separately submitted Final Plan sections), however, are not required to be based upon field survey, and may be calculated. The location and elevation of all boundary line (perimeter) monuments shall be indicated, along with a statement of the total area of the property being subdivided. In addition, the Land Surveyor shall certify to the accuracy of the survey, the drawn plan, and the placement of the monuments; [Ord. 360]
C. All lot lines shall be completely dimensioned in feet if straight, and by designating length of arc and radius (in feet) and central angle (in degrees, minutes and seconds) if curved. All internal angles within the lots shall be designated to within 15 seconds;
D. The proposed building setback or the proposed placement of each building;
E. All easements or rights-of-way where provided for or owned by public services and any limitations on such easements or rights-of-way. Rights-of- way shall be shown and accurately identified on the plan. Easements shall either be shown or specifically described on the plan. Easements should be located in cooperation with the appropriate public utilities;
F. Such private deed restrictions as may be imposed upon the property as a condition to sale, together with a statement of any restrictions previously imposed which may affect the title to the land being subdivided;
G. If the subdivision proposes a new access point to a state Legislative Route, the Occupancy Permit number(s) shall be indicated for all such intersections;
H. A certification of ownership, acknowledgment of plan and offer of dedication shall be lettered on the plan, and shall be duly acknowledged and signed by the owner of the property and notarized;
I. A signature block for certification of approval of the plan by the Township Planning Commission and Township Council;
J. A signature block for certification of review of the plan by the Joint Planning Commission;
K. Space shall be left along with lower edge of sheet, in order that the County Recorder of Deeds may acknowledge receipt and recording of the plan when it is presented;
L. If the Final Plan requires more than one sheet, a key diagram showing the relative location of the several sections shall be drawn on each sheet.
4. The Final Plan shall be accompanied by the following:
A. Plans showing:
(1) Location, size, and invert elevation of all sanitary sewer, water distribution and storm drainage systems and the location of all manholes, inlets, and culverts;
(2) Final profiles, cross-sections, and specifications for proposed streets, sanitary sewers, water distribution systems, and storm drainage systems shall each be shown on one or more separate sheets.
B. The existing points of natural drainage discharge onto adjacent property shall not be altered without the written approval of the affected landowners.
C. No stormwater runoff or natural drainage shall be so diverted as to overload existing drainage systems, or create flooding or the need for additional drainage structures on other private properties or public lands, without approved provisions being made by the developer for properly handling such conditions.
D. Storm drainage systems through the subdivision/land development shall be designed to convey the peak runoff that will occur when all tributary areas upstream are developed to the extent reasonably projected during the next 20 years. The calculation of this runoff rate shall take into account the land use and development regulations including runoff controls in effect in the tributary areas.
E. Where a subdivision is traversed by water courses other than permanent streams, there shall be provided a drainage easement conforming substantially with the line of such watercourse. The width of the easement shall be adequate to provide for unimpeded flow of storm runoff based on calculations made in conformance with § 22-406(4) and to provide a freeboard allowance of 1/2 foot above the design water surface level. The terms of the easement shall prohibit excavation, the placing of fill or structures, and any alterations which may adversely affect the flow of stormwater within any portion of the easement. Also, periodic cutting of vegetation in all portions of the easement shall be required.
F. Drainage facilities that are located on State highway rights-of-way shall be approved by PennDOT and a letter indicating such approval shall be directed to the Township Planning Commission.
G. All streets shall be designed so as to provide for the discharge of surface water away from their rights-of-way.
H. When it can be shown to the satisfaction of the Township Engineer that, due to topographic conditions, natural drainage swales on the site cannot adequately provide for drainage, open channels may be constructed conforming substantially to the line and grade of such natural drainage swales. Capacities of open channels shall be calculated using the Manning equation as explained in Appendix A.
I. Storm drainage facilities and appurtenances shall be so designed and provided as to minimize erosion in watercourse channels and at all points of discharge.
5. Stormwater Detention.
A. Stormwater detention facilities shall be used whenever increased runoff from the land development would overload drainage systems or cause significant increases in flood levels in any watercourses downstream. This
will be determined by comparing the increase in runoff caused by the land development with the existing runoff rates and capacity of downstream drainage systems and watercourse.
B. Whenever detention facilities are required under § 22-406(3)(A), facilities will be designed so that the peak runoff rate at all points of discharge from the site, when developed, will not exceed the peak runoff rate at each of those points prior to development.
C. Where detention facilities are included as part of the storm drainage system, the following provisions will apply:
(1) Detention ponds shall be designed so that they return to normal conditions within approximately 12 hours after the termination of the storm, unless the Township Engineer finds that down stream conditions may warrant other design criteria for stormwater release;
(2) The developer shall demonstrate that such ponds are designed, protected and located to assure that public safety is maximized and health problems are prevented;
(3) The developer shall verify that the operation of the detention facilities will not aggravate potential downstream peaking conditions;
(4) Emergency overflow facilities shall be provided for detention facilities to handle runoff in excess of design flows;
(5) If the lands of the proposed land development will remain in common ownership, the developer shall provide written assurances to the Township that the detention ponds will be properly maintained.
6. Calculations of Runoff and Design Storm Frequency.
A. Storm drainage systems required by this Chapter shall be designed to provide protection from a 10 to 100 year storm as determined by the Township Engineer. A 10 year design storm would be appropriate where a storm in excess of the design storm would have minor impact such as inconvenience to traffic on local streets. A 25 year design storm would be appropriate where a storm in excess of the design storm would cause major inconvenience to people and traffic in high use areas such as business districts and major highways. A 100 year design storm would be appropriate where a storm in excess of the design storm would cause damage to existing or future structures or their contents.
B. Stormwater runoff from watersheds of 200 or less acres shall be calculated by the rational method as described in Manual No. 37 of the American Society of Civil Engineers. The rational method of runoff calculation is explained in Appendix A. The area within the perimeter of a ground- mounted solar energy system shall be considered the same as concrete for such calculations. [Ord. 519]
C. Stormwater runoff from watersheds of more than 200 acres shall be calculated using the soil cover complex method developed by the Soil
Conservation Service or other appropriate method acceptable to the Township Engineer.
D. The Manning equation explained in Appendix A shall be used in calculating capacities of watercourses and storm sewers, except culverts which shall be designed using methods acceptable to the Township Engineer.
E. Complete detailed drainage calculations certified by the design engineer shall be submitted to the Township Engineer.
F. Drainage facilities that are located on State Highway rights-of-way shall be approved by PennDOT and a letter indicating such approval shall be directed to the Township Planning Commission. Whenever stormwater control regulations of an “Act 167 - Storm Water Management Plan” that has been adopted by the ‘Township are more restrictive, the more restrictive provisions of such plan shall apply. [Ord. 239]
7. Improvement Specifications.
A. Inlets shall be designed and located to prevent hazardous conditions for vehicles, bicycles or pedestrians.
B. The Township Engineer shall add additional specifications which may be necessary for spacing and type of inlets and manholes, minimum pipe sizes, and materials and construction methods.
8. Perpetual Maintenance Responsibilities.
A. General. All privately owned stormwater management facilities shall be maintained in the manner in which they were originally approved, and such facilities shall be continuously operable and able to meet the purpose for which they were originally designed.
B. Types of Facilities. All private detention basins, whether above or in ground, as well as any piping, outlets, energy dissipaters or other structures required to be constructed as part of the overall development and to serve the purpose of detaining or channeling stormwater from the development into the overall Township or public system shall be regulated by this Part.
C. Vegetation. All vegetation shall be kept at a level not to exceed 6 inches in height, and where vegetation is required within the basin it shall not be allowed to be overrun with weeds and other vegetation not conducive to the operation of the system. This shall include trees, bushes and other growth that would hamper the operation of the system.
D. Fencing. All fencing required by the approved plans of the design of the detention basin shall be maintained in good repair so as to preclude access to the interior, except that provisions shall be made for authorized access for necessary and required maintenance. Any damaged, falling or otherwise deteriorated fencing shall be replaced.
E. Interior Liner. The required interior lining of all detention basins must be maintained pursuant to original impervious design to provide maximum effectiveness of the operation of the system.
F. Inspections. All stormwater management facilities will be subject to an annual inspection by the Township and any violation noted shall be required to be corrected within 10 days of written notification of same. If corrections are necessary, the Township reserves the right of final approval of the proposed corrections. The cost for these annual inspections and the review and inspection of required corrections, if necessary, shall be borne fully by the facility owner and shall be in accordance with the adopted Township fee schedule in effect at that time.
G. Application. The maintenance requirements of this Part shall apply to all privately owned stormwater management facilities regardless of approval and installation date.
[Ord. 390]
(Ord. 52, Art. S-460, 3/8/78; as amended by Ord. 239, 2/7/1990, § 1; by Ord. 390, 11/17/1999, § 1; and by Ord. 519, 6/15/2011, § 2)