For any of the activities regulated by this chapter, the final approval of subdivision and/or land development plans, the issuance of any building or occupancy permit, or the commencement of any land disturbance activity shall not proceed until the property owner or developer or his/her agent has received written approval of a drainage plan from the Township, except where exempt from the requirement to prepare a drainage plan pursuant to § 132-5 of this chapter. Drainage plans required and approved by the Township shall be on site throughout the duration of the regulated activity.
The drainage plan shall consist of all applicable calculations, maps, and plans. A note on the maps shall refer to the associated computations and erosion and sedimentation control plan by title and date. The cover sheet of the computations and erosion and sedimentation control plan shall refer to the associated maps by title and date. All drainage plan materials shall be submitted to the Township in a format that is clear, concise, legible, neat, and well organized; otherwise, the drainage plan shall be disapproved and returned to the applicant. The following items shall be included in the drainage plan:
A. 
General.
(1) 
General description of project.
(2) 
General description of permanent stormwater management and water quality techniques, including construction specifications of the materials to be used for stormwater management facilities.
(3) 
Complete hydrologic, hydraulic, and structural computations for all stormwater management facilities.
(4) 
Soil evaluations as they relate to the infiltration device(s) design.
B. 
Maps of the project area shall be submitted on twenty-four-inch by thirty-six-inch sheets and shall be prepared in a form that meets the requirements for recording in the offices of the Recorder of Deeds of Montgomery County. The contents of the maps shall include, but not be limited to:
(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 as approved by the Township Engineer. Critical spot elevations shall be provided where proposed contours do not provide a sufficient level of detail.
(3) 
Existing streams, lakes, ponds, or other bodies of water within the project area.
(4) 
Other physical features, including flood hazard boundaries, sinkholes, streams, existing drainage courses, areas of natural vegetation to be preserved, and the total extent of the upstream area draining through the site.
(5) 
The locations of all existing and proposed utilities, including but not limited to electric, gas, CATV, storm sewers, sanitary sewers, and water lines, within 50 feet of property lines shall be shown on the plans. The applicant should submit a plan showing existing features as referenced in § 136-703C of the Subdivision and Land Development Ordinance, Chapter 136.
(6) 
An overlay showing soil names and boundaries.
(7) 
Proposed changes to the land surface and vegetative cover, including the type and amount of impervious area that would be added.
(8) 
Proposed structures, roads, paved areas, and buildings.
(9) 
The name of the development, the name and address of the owner of the property, and the name of the individual or firm preparing the plan.
(10) 
The date of submission.
(11) 
A graphic and written scale with a minimum scale of one inch equals 50 feet.
(12) 
A North arrow.
(13) 
The total tract boundary and size with distances marked to the nearest foot and bearings to the nearest degree.
(14) 
Existing and proposed land use(s).
(15) 
A key map showing all existing man-made features beyond the property boundary that would be affected by the project.
(16) 
Horizontal and vertical profiles of all open channels and stormwater pipe systems, including hydraulic capacity.
(17) 
Construction details of proposed stormwater management facilities shall include the following as applicable:
(a) 
Cross sections through the facility showing:
[1] 
Side slopes.
[2] 
Bottom slopes.
[3] 
Embankment with slopes identified.
[4] 
Top of berm width and elevation.
[5] 
Emergency spillway elevation.
[6] 
Cutoff trench with side slopes, depth, and bottom width identified.
[7] 
Permanent pool elevation.
[8] 
Water quality storm elevation.
[9] 
Maximum water surface elevation and infiltration bed lining.
[10] 
Outlet structure, outlet pipe, anti-seep collars, and outfall structure.
(b) 
Elevation views of the outlet structure and emergency spillway showing:
[1] 
Maximum water surface elevation.
[2] 
Maximum design flow depth in spillway and resulting freeboard to top of berm elevation.
[3] 
Spillway lining and side slopes.
[4] 
Top width and bottom width of spillway.
[5] 
Size and elevation of all controls devices in the outlet structure.
(c) 
Additional details to construct the stormwater management facility, including but not limited to:
[1] 
Low flow channels with dimensions.
[2] 
Energy-dissipating and sediment-removal devices, with dimensions.
[3] 
Under drains.
(18) 
Overland drainage paths and drainage areas tributary to the proposed facilities.
(19) 
A twenty-foot-wide access easement around all stormwater management facilities that would provide ingress to and egress from a public right-of-way.
(20) 
A note on the plan indicating the location and responsibility for maintenance of the stormwater management facilities that would be located off site. All off-site facilities shall meet the performance standards and design criteria specified in this chapter.
(21) 
A construction detail of any stabilization techniques to be applied to sinkholes and the location of all notes to be posted, as specified in this chapter.
(22) 
A statement, signed by the landowner, acknowledging the stormwater management system to be a permanent fixture that can be altered or removed only after approval of a revised plan by the Township. The statement shall be incorporated as a deed restriction with proof of a recorded revised deed submitted to the Township with the as-built survey for all stormwater management facilities included in the approved drainage plan.
(23) 
The following signature affidavit for the Township must be included on the plan:
"(Township Official or Designee), on this date ________, has reviewed and hereby concludes that the drainage plan meets all design standards and criteria of the Towamencin Township Stormwater Management Ordinance No. ________."
(24) 
The drainage plan shall include an operation and maintenance plan for all existing and proposed stormwater management/BMP facilities, addressing long-term ownership and maintenance responsibilities for such facilities, including schedule for operation and maintenance activities.
(25) 
The location of all erosion and sedimentation control facilities and BMPs.
C. 
Supplemental information.
(1) 
A written description of the following information shall be submitted.
(a) 
The overall stormwater management concept for the project.
(b) 
Stormwater runoff computations as specified in this chapter.
(c) 
Stormwater management techniques to be applied both during and after development.
(d) 
Expected project time schedule.
(2) 
A soil erosion and sedimentation control plan, where applicable, including all reviews and approvals, as required by the Montgomery County Conservation District.
(3) 
A geologic assessment of the effects of runoff on sinkholes as specified in this chapter.
(4) 
The effect of the project (in terms of runoff volumes and peak flows) on adjacent properties and on any existing Township stormwater collection systems that may receive runoff from the project site.
(5) 
A declaration of adequacy and highway occupancy permit from the PennDOT District Office when utilization of a PennDOT storm drainage system is proposed.
D. 
Stormwater management facilities.
(1) 
All stormwater management facilities must be located on a plan and described in detail.
(2) 
When groundwater recharge methods such as seepage pits, beds or trenches are used, the locations of existing and proposed septic tank infiltration areas and wells must be shown.
(3) 
All calculations, assumptions, and criteria used in the design of the stormwater management facilities must be shown.
(4) 
All stormwater management/BMP facility easements required by this chapter must be shown on the drainage plan, including the bearing and distance of each segment of the easement's boundary.
For all activities regulated by this chapter, the steps below shall be followed for submission. For any activities that require a PADEP joint permit application and regulated under Chapter 105 (Dam Safety and Waterway Management) or Chapter 106 (Floodplain Management) of PADEP's Rules and Regulations, require a PennDOT highway occupancy permit, or require any other permit under applicable state or federal regulations, the permit(s) shall be part of the plan.
A. 
The drainage plan shall be submitted by the developer as part of the development plan submission for the regulated activity. If the plan is part of a land development or subdivision application, the plans should be submitted in accordance with the provisions of the Subdivision and Land Development Ordinance.[1] All other projects should be submitted as referenced in the following sections.
[1]
Editor's Note: See Chapter 136, Subdivision and Land Development.
B. 
Four copies of the drainage plan and related application documentation shall be submitted to the Township. Two copies of the plan will be forwarded by the Township to the Township Engineer for review.
A. 
The Township Engineer shall review the drainage plan for consistency with this chapter. The Township shall require receipt of a complete plan, as specified in this chapter.
B. 
The Township Engineer shall review the drainage plan for any subdivision or land development against the Township Subdivision and Land Development Ordinance[1] provisions not superseded by this chapter.
[1]
Editor's Note: See Chapter 136, Subdivision and Land Development.
C. 
For activities regulated by this chapter, the Township Engineer shall notify the Township, in writing, whether the drainage plan is consistent with this chapter. Should the drainage plan be determined to be consistent with this chapter, the Township Engineer will forward an approval letter to the Township with a copy to the developer.
D. 
Should the drainage plan be determined to be inconsistent with this chapter, the Township Engineer will forward a disapproval letter to the Township with a copy to the developer citing the reason(s) for the disapproval. Any disapproved drainage plan may be revised by the developer and resubmitted consistent with this chapter.
E. 
For regulated activities specified in § 132-4D(1) through (4) of this chapter, the Township Engineer shall notify the Township, in writing, within a time frame consistent with the Township Building Code and/or Township Subdivision and Land Development Ordinance, of whether the drainage plan is consistent with this chapter and forward a copy of the approval/disapproval letter to the developer. Any disapproved drainage plan may be revised by the developer and resubmitted consistent with this chapter.
F. 
For regulated activities requiring a PADEP joint permit application, the applicant shall request that the Township notify PADEP of whether the drainage plan is consistent with this chapter and forward a copy of the review letter to the Township and the developer. PADEP may consider the Township Engineer's review comments in determining whether to issue a permit.
G. 
The Township shall not approve any subdivision or land development for regulated activities specified in § 132-4D(1) and (2) of this chapter if the drainage plan has been found to be inconsistent with this chapter, as determined by the Township Engineer. All required permits from PADEP must be obtained prior to, or as a condition of, final plan approval.
H. 
The Township shall not issue a building permit for any regulated activity specified in § 132-4 of this chapter if the drainage plan has been found to be inconsistent with this chapter, as determined by the Township Engineer, or without considering the comments of the Township Engineer. All required permits from PADEP must be obtained prior to issuance of a building permit.
I. 
The Township's approval of a drainage plan prepared in conjunction with a regulated activity that is not a subdivision or land development shall be valid for a period not to exceed one year. This time period shall commence on the date that the Township signs the approved drainage plan. If stormwater management facilities included in the approved drainage plan have not been constructed, or if an as-built survey of these facilities pursuant to § 132-32E of this chapter has not been approved within this time period, the Township may consider the drainage plan disapproved and may revoke any and all permits. Drainage plans that are considered disapproved by the Township shall be resubmitted in accordance with § 132-22 of this chapter.
J. 
The Township's approval of a drainage plan prepared in conjunction with a subdivision or land development shall remain valid and protected from any change in Township codes and ordinances for a period of five years from the date of preliminary subdivision and/or land development plan approval, pursuant to the provisions of the Pennsylvania Municipalities Planning Code.[2]
[2]
Editor's Note: See 53 P.S. § 10101 et seq.
A. 
A modification to a previously submitted drainage plan for a development site that involves a change in stormwater management facilities or techniques, or that involves the relocation or redesign of stormwater management facilities, or that becomes 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 § 132-19 of this chapter and be subject to review as specified in § 132-20 of this chapter.
B. 
A modification to an already approved or disapproved drainage plan shall be submitted to the Township, accompanied by the applicable review fee. A modification to a drainage plan for which a formal action has not been taken by the Township shall be submitted to the Township, accompanied by the applicable Township review fee.
A disapproved drainage plan may be resubmitted, with the revisions addressing the Township Engineer's concerns documented in writing, to the Township Engineer in accordance with § 132-19 of this chapter and be subject to review as specified in § 132-20 of this chapter. The applicable Township re-review fee must accompany a resubmission of a disapproved drainage plan.