Township of Potter, PA Article IV Drainage Plan Requirements

§ 173-401 General requirements.

A. From and after the date of enactment of this chapter, a stormwater management plan and other information specified herein shall be submitted to the Township for all lands subdivided or for which land development plans are prepared after the enactment of this chapter. A stormwater management plan and other information specified herein shall be submitted at the same time and together with submission of a preliminary subdivision or land development plan, along with a completed checklist supplied by the Township indicating the items contained within the submission.

B. Such plans and information shall be considered part of said zoning and subdivision documents and shall be reviewed in accordance with procedures established thereunder. Preliminary approval or final approval of a subdivision or land development plan, or the issuance of a zoning permit, shall be contingent upon submission of a stormwater management plan and other materials specified herein, and approval of the stormwater management plan in accordance with provisions of this chapter.

C. All stormwater management plans shall be submitted to the Township Engineer for review and comment. Such review shall include a statement by the Township Engineer specifying the provisions of this chapter, which have not been met by the plan as submitted.

D. Once a stormwater management plan has been approved together with a subdivision or land development plan approval, or together with the issuance of a zoning permit, said stormwater management plan shall be valid only for the subdivision, land development, or zoning permit approved. Any further development on the lot or lots requiring a revision of the approved plan or other construction or activities as defined by Township Zoning Regulations[1] shall require the submission of a new, amended, or revised stormwater management plan and other information specified herein.

[1] Editor's Note: See Ch. 220, Zoning.

§ 173-402 Drainage plan contents.

A. 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 sediment pollution control plan by title and date. The cover sheet of the computations and erosion and sediment pollution control plan shall refer to the associated maps by title and date.

B. 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.

C. Said plan shall be prepared by a registered professional land surveyor, qualified geologist, landscape architect, architect, or engineer licensed in the State of Pennsylvania, with said preparer's seal and registration number affixed to the plan.

D. The following items shall be included in the drainage plan:

(1) Stormwater management report.

(a) General description of project.

(b) General description of permanent stormwater management techniques, including construction specifications and materials to be used for stormwater management facilities.

(c) Complete hydrologic, hydraulic, and structural computations for all stormwater management facilities.

(d) A written maintenance plan for all stormwater features including detention facilities and other stormwater management elements.

(e) Identification of ownership and maintenance responsibility for all permanent stormwater management facilities.

(f) The stormwater management report must include a narrative which clearly discusses the project and summary tables which, at a minimum, provides the following information:

[1] Narrative.

[a] The overall stormwater management concept.

[b] The expected project schedule.

[c] Location map.

[d] Total site area, pre- and post- which must be equal or have an explanation as to why it is not.

[e] Total site impervious area.

[f] Total off-site areas.

[g] Number of stormwater management facilities (ponds), if applicable.

[h] Type of development.

[i] Pre-development land use.

[j] Whether site is underlain by carbonate geology.

[k] Whether site is a water quality sensitive (WQS) development.

[l] Whether site is in a defined sensitive area.

[m] Types of water quality and recharge systems used, if applicable.

[n] Other pertinent information, as required.

[2] Summary tables.

[a] Pre-development hydrologic soil group (HSG) assumptions, curve numbers (CN), computation of average slope, hydraulic length, computed time of concentration.

[b] Required peak rate of runoff.

[c] Post-development.

[d] Undetained areas, areas to ponds.

[e] Land use for each subarea.

[f] Hydrologic soil group (HSG) assumptions, curve numbers (CN).

[g] Time of concentration computed for each subarea.

[h] Post-development peak rate of runoff routed to ponds and out.

[i] Pond maximum return period design data, including maximum water surface elevation, berm elevation, and emergency spillway elevation.

[j] Water quality depth and volume requirements.

[k] Recharge volume requirements.

[l] Morphology requirements.

[m] Capture volumes required.

[3] Reports that do not clearly indicate the above information may be rejected for review by the Township's Engineer or representative and will be returned to the applicant.

(2) Plan information.

(a) Plans for tracts of less than 20 acres shall be drawn at a scale of one inch equals no more than 50 feet; for tracts of 20 acres or more, plans shall be drawn at a scale of one inch equals no more than 100 feet. Plans shall be submitted on the following sheet sizes: 18 inches by 24 inches, 24 inches by 36 inches, or 36 inches by 42 inches. All lettering shall be drawn to a size to be legible if the plans are reduced to half size. All sheets comprising a submission shall be on one size.

(b) The following information, unless specifically exempted in writing by the Township Engineer, must be shown on the plans, prepared in a form that meets the requirements for recording in the Office of the Recorder of Deeds of Centre County, Pennsylvania. The contents of the map(s) shall include, but not be limited to:

[1] 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.

[2] The date of submission and revision.

[3] The location of the project relative to highways, municipalities or other identifiable landmarks.

[4] Existing contours at intervals of two feet. In areas of steep slopes (greater than 15%), five-foot contour intervals may be used.

[5] Existing streams, lakes, ponds, or other bodies of water within the project area.

[6] Other physical features including flood hazard boundaries, sinkholes, closed depressions, wetlands, streams, existing drainage courses, areas of natural vegetation to be preserved, and the total extent of the upstream area draining through the site. In addition, any areas necessary to determine downstream impacts, where required for proposed stormwater management facilities must be shown.

[7] The locations of all existing and proposed utilities, sanitary sewers, and water lines within 20 feet of property lines.

[8] An overlay showing soil names and boundaries, including rock outcrops.

[9] Total area of impervious surfaces proposed.

[10] Proposed structures, roads, paved areas, and buildings.

[11] Final contours at intervals of two feet. In areas of steep slopes (greater than 15%), five-foot contour intervals may be used.

[12] Graphic and written scale.

[13] North arrow.

[14] The total tract boundary and size with distances marked to the nearest foot and bearings to the nearest degree.

[15] Existing and proposed land use(s).

[16] Key map showing all existing man-made features beyond the property boundary that would be affected by the project and the extent of the watershed or sub-area that drains through the project site.

[17] Horizontal and vertical profiles of all open channels, including hydraulic capacity.

[18] Overland drainage paths.

[19] Access easements around all stormwater management facilities that would provide ingress to and egress from a public right-of-way.

[20] Note on the plan indicating the location and responsibility for maintenance of 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] Construction detail of any improvements made to sinkholes and the location of all notes to be posted, as specified in this chapter.

[22] Complete drainage systems for the site, including details for construction. All existing drainage features which are to be incorporated in the design, shall be so identified. If the site is to be developed in stages, a general drainage plan for the entire site shall be presented with the first stage and appropriate development stages for the drainage system shall be indicated.

[23] Location and selected plan material used for vegetative filter paths to sinkholes, and the location of all notices to be posted.

[24] 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.

[25] A note indicating that as-built drawings will be provided by the developer for all stormwater facilities prior to occupancy, or the release of the surety bond.

[26] The following signature block for the registered professional preparing the stormwater management plan:

"I, ____________________, hereby certify that the Stormwater Management Plan meets all design standards and criteria of the Spring Creek Act 167 Stormwater Management Ordinance."

[27] The following signature block for the Township Engineer reviewing the stormwater management plan:

"I, ____________________, have reviewed this Stormwater Management Plan in accordance with the Design Standards and Criteria of the Spring Creek Act 167 Stormwater Management Ordinance."

[28] The location of all erosion and sedimentation control facilities.

(3) Supplemental information.

(a) A soil erosion and sediment pollution control plan, where applicable, including all reviews and approvals, as required by PADEP.

(b) Soils investigation report, including boring logs, compaction requirements, and recommendations for construction of detention basins.

(c) Karst features identification and analysis reports and a hydrogeologic assessment of the effects of runoff on sinkholes.

(d) The effect of the project (in terms of runoff volumes and peak flows) on adjacent properties and on any existing Township stormwater collection system that may receive runoff from the project site.

(e) A declaration of adequacy and highway occupancy permit from the PENN DOT District Office when utilization of a PENN DOT storm drainage system is proposed.

(f) All permits required by the PADEP, Army Corps of Engineers, and other regulatory agencies.

(4) Stormwater management facilities.

(a) All stormwater management facilities must be located on a plan and described in detail.

(b) 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.

(c) All calculations, assumptions, and criteria used in the design of the stormwater management facilities must be shown.

[1] A sketch of the berm embankment and outlet structure indicating the embankment top elevation, embankment side slopes, top width of embankment, emergency spillway elevation, perforated riser dimensions, pipe barrel dimensions and dimensions and spacing of antiseep collars.

[2] Design computations for the pipe barrel and riser.

[3] A plot or table of the stage-storage (acre-feet vs. elevation) and all supporting computations.

[4] Flood routing computations.

[5] A detailed plan of the trash rack and anti-vortex device.

(d) Record set (as-built) plans: At the completion of the project, and as a prerequisite for the release of the guarantee or issuance of an occupancy permit, the owner or his representative shall:

[1] Provide certification of completion from a registered professional verifying that all permanent facilities have been constructed according to the plans and specifications and approved revisions thereto; and

[2] Provide a set of approved stormwater management plan drawings showing all approved revisions and elevations and inverts to all manholes, inlets, pipes, and stormwater control facilities.

§ 173-403 Plan submission.

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 PENN DOT 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 preliminary plan submission for the regulated activity.

B. Four copies of the drainage plan and stormwater management report shall be submitted.

C. Distribution of the drainage plan will be as follows:

(1) Two copies to the Township accompanied by the requisite municipal review fee, as specified in this chapter.

(2) One copy to the Township Engineer.

(3) One copy to the County Planning Commission/Department.

§ 173-404 Drainage plan review.

A. The Township Engineer shall review the drainage plan for consistency with the adopted Spring Creek Watershed Act 167 Stormwater Management Plan. 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 submission or land development against the Township subdivision and land development ordinance provisions not superseded by this chapter.

C. For activities regulated by this chapter, the Township Engineer shall notify the Township in writing, within 60 calendar days, whether the drainage plan is consistent with the stormwater management plan. Should the drainage plan be determined to be consistent with the stormwater management plan, the Township Engineer will forward an approval letter to the developer, or developer's agent who submitted the plan, with a copy to the Township Secretary.

D. Should the drainage plan be determined to be inconsistent with the stormwater management plan, the Township Engineer will forward a disapproval letter to the developer, or developer's agent who submitted the plan, with a copy to the Township Secretary citing the reason(s) for the disapproval. Any disapproved drainage plans may be revised by the developer and resubmitted consistent with this chapter.

E. For regulated activities specified in § 173-104C and D of this chapter, the Township Engineer shall notify the Township Building Permit Officer in writing, within a time frame consistent with the Township Building Code and/or Township Subdivision Ordinance,[1] whether the drainage plan is consistent with the stormwater management plan 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.

[1] Editor's Note: See Ch. 184, Subdivision and Land Development.

F. For regulated activities requiring a PADEP joint permit application, the Township Engineer shall notify PADEP whether the drainage plan is consistent with the stormwater management plan 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 § 173-104A and B of this chapter if the drainage plan has been found to be inconsistent with the stormwater management plan, as determined by the Township Engineer. All required permits from PADEP must be obtained prior to approval.

H. The Township Building Permit Office shall not issue a building permit for any regulated activity specified in § 173-104 of this chapter if the drainage plan has been found to be inconsistent with the stormwater management plan, 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 developer shall be responsible for completing an "as-built survey" of all stormwater management facilities included in the approved drainage plan. The as-built survey and an explanation of any discrepancies with the design plans shall be submitted to the Township Engineer for final approval. In no case shall the Township approve the as-built survey until the Township receives a copy of an approved declaration of adequacy, highway occupancy permit, and any applicable permits from PADEP.

J. The Township's approval of a drainage plan shall be valid for a period not to exceed three years. This three-year 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 has not been approved within this three-year time period, then 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 § 173-406 of this chapter.

§ 173-405 Modification of plans.

A. A modification to a 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 is 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 § 173-403 of this chapter and be subject to review as specified in § 173-404 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. 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.

§ 173-406 Resubmission of disapproved drainage plans.

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 § 173-403 of this chapter and be subject to review as specified in § 173-404 of this chapter. The applicable municipal review fee must accompany a resubmission of a disapproved drainage plan.