Township of Unity, PA Article III Stormwater Management Performance Standards

§ 99-14 Stormwater management performance districts.

For purposes of stormwater management, the Township is located in the Turtle Creek Watershed, which includes the Stormwater Management Performance Districts shown on the Westmoreland County Integrated Water Resources Plan interactive watershed resource map, which is hereby adopted as a portion of the chapter. The stormwater release rates for real property located within the Township shall be as set forth on the Performance District Maps. For areas not covered by a stormwater performance district, the release rate shall be 80%[1] of the pre-development peak flow as set by the municipality. For more information, refer to www.westmorelandstormwater.org and the Westmoreland County Conservation District's interactive watershed resource map.

[1] Editor's Note: In areas not covered by a Stormwater Performance District, an 80% release rate or less is recommended as a standard. This is to apply a "Factor of Safety" to stormwater calculations; to account for the many variables in site design and stormwater management; and to avoid a land development project inadvertently increasing runoff and causing harm downstream.

§ 99-15 General requirements.

A. Preparation and implementation of a stormwater management site plan is required for all regulated activities, unless preparation of a SWM site plan is specifically exempted.

B. Projects that propose greater than one acre of earth disturbance are subject to NPDES permit requirements and will require a Stormwater Management Plan.

C. No regulated activities, unless exempted hereafter or herein, shall commence until the Township issues written approval of an SWM Site Plan which demonstrates compliance with the requirements of this chapter.

D. Regulated development activities shall be as follows:

Regulated Development Activity Table[1]
SWM Plan Requirement	New Impervious Area for New and Redevelopment	Disturbed Area*	Next Steps
Exempt	Less than 1,000 square feet	AND less than 1 acre	Comply with exemption section of this chapter
Waiver/modification/demonstrated equivalency	Less than 1/2 acre, subject to municipal approval	AND less than 1 acre	Comply with waiver/modification/demonstrated equivalency section of this chapter
Small project (per definition), refer to Appendix C[2]	1,000 square feet to 3,000 square feet	OR 3,000 square feet to 5,000 square feet	Submit Small Project Site Plan complete with all attachments
Stormwater Management Plan meeting the chapter requirements	Greater than 3,000 square feet AND, if exempt, waiver/modification/demonstrated equivalence and small project criteria are not met	OR greater than 5,000 square feet	Consult a qualified professional

[1] Editor's Note: This table is only applicable for projects with earth disturbance less than one acre and that have not had cumulative impacts, within five years preceding the permit application date, that are in excess of the square foot limits.

[2] Editor's Note: Appendix C, Stormwater Best Management Practices Operations and Maintenance Agreement, is included as an attachment to this chapter. See also Appendix D, Small Project Stormwater Management Plan.

§ 99-16 Exemption from performance standards.

A. The following regulated activities are specifically exempt from the Stormwater Management Plan preparation and submission requirements articulated in this chapter:

(1) Agricultural activity limited to plowing or tilling activities, for animal concentrated (heavy) use areas provided the activities are performed according to the requirements of Chapter 102,[1] or conservation practices being installed as part of the implementation of a Conservation Plan written by an NRCS or SCS-certified planner. This exemption does not include any other type of earth disturbance subject to NPDES permit requirements such as earth disturbance equal to or greater than one acre.

[1] Editor's Note: See 25 Pa. Code § 102.1 et seq.

(2) A high tunnel, if proof is provided that the high tunnel is exempt pursuant to the provisions of Act 15 of 2018.[2] Such an exemption does not exempt high tunnels from other requirements applicable under federal, state or municipal laws.

[2] Editor's Note: See 32 P.S. § 680.1 et seq.

(3) Forest management and timber operations, provided the activities are performed according to the requirements of applicable PA DEP regulations and the Code of Unity Township.

(4) Natural resource extraction activities, provided they are done in accordance with applicable PA DEP regulations and the Code of Unity Township.

(5) Roadway resurfacing and maintenance projects, which do not increase impervious area, and underground infrastructure projects are exempt from the provisions of this chapter, provided the activities meet the requirements of all other municipal, state and federal requirements.

(6) Domestic landscaping and/or vegetable gardening.

(7) Voluntary green infrastructure (GI) or the retrofit of stormwater management infrastructure as conversion to green infrastructure BMPs to correct existing problems, that are solely intended to better manage runoff from existing development, are not part of new development or redevelopment, and that do not fall under the requirements of this or other development ordinances.

B. The Township may deny or revoke any exemption pursuant to this section at any time for any project that the Township believes may pose a threat to public health, safety, property or the environment.

§ 99-17 Waivers/modifications/demonstrated equivalency.

A. If the Township, in conjunction with the Township Engineer, WCD, or DEP as applicable, determines that any requirement under this chapter cannot be achieved for a particular regulated activity, the Township may, after an evaluation of alternatives, approve measures other than those in this chapter, subject to the terms of Subsections B, C and D hereafter and provided same are in compliance with all commonwealth laws and regulations. The request for a waiver, modification, or demonstrated equivalency shall originate with the landowner, shall be in writing, include a study of downstream effects, and accompany the Stormwater Management Plan submission to the Township. The request shall provide the facts on which the request is based, the provision(s) of the ordinance involved and the proposed modification or demonstrated equivalency. The Township Engineer and WCD shall review the request to determine if it meets the requirements of the ordinance, including, but not limited to, the provisions set forth in those applicable subsections set forth hereafter. If acceptable to the Township and WCD and the regulated stormwater activity involving earth disturbance is less than one acre AND new impervious surface is less than 1/2 acre, the Township may grant the waiver or modification. If the regulated stormwater activity involves new impervious surface of more than 1/2 acre, then a stormwater management plan meeting the full requirements of this chapter is required. If the regulated stormwater activity involving earth disturbance is equal to or greater than one acre, the plan will be subject to the NPDES requirements of DEP, regardless of the amount of new impervious area.

B. Waivers, modifications, or the use of demonstrated equivalencies of the requirements of this chapter may be approved by the Township if strict compliance with the terms of this chapter will exact undue hardship upon the developer. The burden of proving "undue hardship" shall rest with the developer. In order to prove undue hardship, the developer must prove to the satisfaction of the Township: 1) that strict compliance with this chapter cannot be achieved because of unique physical circumstances or preexisting site conditions peculiar to the land in question; 2) that the modifications or demonstrated equivalency will not be contrary or detrimental to the public health, safety, welfare and/or interest, shall achieve the intended outcome of this chapter, and preserve the purpose of this chapter; 3) that the undue hardship is due to such unique physical circumstances or preexisting site conditions and not the circumstances or conditions generally created by the provisions of this chapter; 4) that there is no reasonable possibility that the property can be developed in strict conformity with the provisions of this chapter; and that the hardship has not been created by the landowner or developer. The cost or financial burden of complying with the terms of this chapter shall not, in and of itself, be considered a hardship.

C. No waiver, modification or demonstrated equivalency of any regulated stormwater activity involving earth disturbance greater than or equal to one acre may be granted by the Township unless that action is approved in advance by the Department of Environmental Protection (DEP) or the Westmoreland Conservation District (WCD).

D. Applicants may request approval of a demonstrated equivalent stormwater activity for their project in lieu of performing traditional stormwater management. Demonstrated equivalent stormwater activity requests will be evaluated by the Township Engineer and the WCD on a case-by-case basis. Prior approval of a demonstrated equivalent stormwater activity on a site does not set a precedent for future approval of the same or other alternative activities on any site. The approval of a demonstrated equivalent stormwater activity does not excuse the applicant from following standard E&S and SWM practices as applicable on the original site. Demonstrated equivalent stormwater activities shall only be approved when the following criteria are met:

(1) Traditional stormwater management activities on the site are precluded by a particular site limitation, such as contaminated soil, steep slopes, existing buildings/infrastructure, or a combined sewer;

(2) Construction of traditional stormwater management activities on the site would require extra permits or lead to excessive permitting activities and delays;

(3) The site in question does not already have a stormwater management problem; and

(4) The site in question is not already contributing to water quality problems in the receiving stream.

E. Approvable demonstrated equivalent stormwater activities may include the following:

(1) Restoration of an existing degraded wetland, stream channel, floodplain, or riparian buffer, including daylighting of a stream.

(2) Restoration, retrofit or upgrade of an existing stormwater management feature (i.e., an inadequate detention pond, for example).

(3) Creation of new stormwater management features, especially green infrastructure, for a previously unmanaged site.

(4) Providing a water-based benefit to the public other than stormwater management (for example, extend a public sewer to an area not already served).

(5) Treatment of abandoned mine drainage.

F. The proposal for demonstrated equivalency shall be accompanied by documentation or methodology quantifying the equivalency of the proposed project to what would have been originally required. Acceptable documentation or methodology may include use of the Worksheets and Checklist found in PA DEP NPDES permit application, Appendix D, or other approved method which demonstrates that the proposed equivalency:

(1) Controls approximately the same amount of runoff volume as what would originally have been proposed;

(2) Improves approximately the same amount of runoff quality as would have been originally proposed;

(3) Is located within an impaired watershed or stream segment which will benefit from the proposed project. Impairment may include stream impairment, reduced stream buffer, and pollutant loading. Refer to the Westmoreland County Integrated Water Resources Plan at www.westmorelandstormwater.org.

G. The demonstrated equivalent stormwater activity shall:

(1) Be constructed concurrently with the project for which it is being applied;

(2) Be constructed according to plans approved by the Township and the WCD, including any erosion control and stormwater management practices as applicable;

(3) Obtain and have issued all necessary permits;

(4) Be located on land owned by or controlled by the applicant or by a cooperating public or private entity(s) (school, church, club, Township, etc.);

(5) Be protected by a perpetual easement or deed restriction, or landowner agreement;

(6) Be located in the same general watershed as the project for which it is being applied; and

(7) Have an Operation and Maintenance (O&M) Plan and be subject to an Operation and Maintenance Agreement specifying who is responsible for what tasks.

§ 99-18 Small project.

A. When a regulated development activity referenced in the table in § 99-15 of this chapter) creates impervious area between 1,000 and 3,000 square feet, or total earth disturbance between 3,000 and 5,000 square feet, the stormwater management requirements of this section shall be applied.[1]

[1] Editor Note: Refer also to Appendix D, which is included as an attachment to this chapter.

B. For new impervious surfaces, the first one inch of runoff shall be permanently removed from the runoff flow and shall not be released to waters of the commonwealth. Removal options include reuse, evaporation, transpiration and infiltration.

C. Facilities, to the greatest extent possible and subject to Township approval, shall be designed to drain the permanently removed runoff volume in a period no greater than 72 hours. Runoff volumes in excess of one inch shall be safely conveyed to a stable vegetated area, natural watercourse, the curb or gutter line of roadway or existing storm collection/conveyance/control system as applicable.

D. This method may, at the discretion of the Township, be exempted from full compliance with all or parts of the requirements of § 99-26 of this chapter, based on the circumstances of the plan, the nature of the regulated development activity occurring on the property and the effectiveness of the proposed controls.

(1) A Small Project Stormwater Management Plan must be submitted to the Township and the WCD consisting of the following items and related support material needed to determine compliance with §§ 99-19 through 99-24 of this chapter.[2] The Small Project Stormwater Management Plan submitted must contain:

(a) A narrative containing a general description of proposed stormwater management techniques, including calculations, assumptions and criteria used in the design of the stormwater management facilities and BMPs, and construction specifications of the materials to be used for stormwater management facilities and BMPs.

(b) A Stormwater Management Plan, showing the locations of all stormwater management facilities and BMPs, especially green infrastructure, limits of disturbance, including the type and amount of proposed impervious area, structures, roads, paved areas and buildings;

(c) A Small Project Stormwater Management Worksheet;

(d) A signed agreement page for operation and maintenance of stormwater facilities and BMPs in the form attached hereto as Appendix B[3] or, where determined by the Township to be appropriate, a BMP Operation and Maintenance Agreement in the form attached hereto as Exhibit "C"[4]; and

[3] Editor's Note: Appendix B, Landowner Acknowledgement for Small Projects, is included as an attachment to this chapter.

[4] Editor's Note: See Appendix C, included as an attachment to this chapter.

(e) An Erosion and Sediment Control Plan, including all reviews and letters of adequacy from the Conservation District.

[2] Editor Note: The applicant may also utilize those protocols listed in Appendix D, which is included as an attachment to this chapter.

§ 99-19 Development strategies, considerations and general standards.

A. Proposed land development must consider avoiding, minimizing, and mitigating impacts to the site that may increase stormwater runoff from the proposed project. Applied sequentially, the low-impact development strategies set forth hereafter should be used as an overall guide as a project is planned and carried out. The Westmoreland County Integrated Water Resources Plan also provides an online decision-making tool to assist developers, designers and property owners in addressing all water resources during development and redevelopment and should be consulted.[1]

[1] Editor Note: Refer to www.paiwrp.com and www.westmorelandstormwater.org.

B. All stormwater management plans shall be designed and evaluated using the following standards:

(1) Any landowner and any person engaged in the alteration or development of land which may affect stormwater runoff characteristics shall implement such measures as are reasonably necessary to prevent injury to health, safety or other property. For alteration or development taking place in stages, the cumulative development must be used in determining conformance with this chapter. Such measures shall include actions necessary and reasonable:

(a) To ensure that the maximum rate of stormwater runoff is no greater after development than prior to development activities for the one-, two-, five-, ten-, twenty-five-, fifty-, one-hundred-year storms having rainfall durations of 24 hours. Calculations shall be based on rainfall data obtained from NOAA Atlas 14 or other source approved by the Township.

(b) To manage the water quality, rate, volume and direction of resulting stormwater runoff in a manner which otherwise adequately protects health and property from possible injury.

(c) To notify adjacent property owners or owners of affected properties of any alteration or increase of stormwater flows.

(2) Runoff treatment BMPs must be employed where necessary to ensure the water quality, rate and volume requirements are met.

(3) Volume control BMPs shall be used to maintain existing hydrologic conditions for small storm events by promoting groundwater recharge and/or evapotranspiration. Runoff volume controls shall be implemented using the PA DEP Stormwater BMP Manual 2006 or other approved method such as those listed in the following chart:

Acceptable Computation Methodologies for Stormwater Management Plans
Method	Developed By	Applicability
Win TR-20 (or commercial computer package based on TR-20)	USDA NRCS	Applicable where use of full hydrologic computer model is desirable or necessary
Win TR-55 (or commercial computer package based on TR-55, i.e., VT/PSUHM)	USDA NRCS	Applicable for land development plans within limitations described in TR-55
HEC-1, HEC-HMS	U.S. Army Corps of Engineers	Applicable where use of full hydrologic computer model is desirable or necessary
PennDOT 584 (based on rational method)	PennDOT	Applicable under standards established by PennDOT; not to be used for runoff volume and pond sizing computations.
EFH2	USDA NRCS	Applicable in agricultural areas subject to the program limits
SWMM	EPA	Applicable in urban and suburban areas subject to limits established by EPA
PA DEP BMP Manual 2006	PA DEP	Applicable under standards established by PA DEP
Other methods	Varies	Other methodologies approved by the Township

C. The project plan must specify the permanent stormwater BMPs to be implemented, operated and maintained to meet legal water quality, rate and volume requirements. If methods other than low-impact development (LID) and green infrastructure methods are proposed to achieve the volume and rate controls required under this chapter, the SWM Site Plan must include a detailed justification demonstrating that the use of LID and green infrastructure is not practicable.

D. In order to protect and maintain water quality, additional stormwater runoff created by the development project must be captured, stored and treated. In addition, post-construction stormwater infiltration of runoff must replicate preconstruction infiltration of runoff to the maximum extent possible with the exception of hot spots. As a minimum, this shall be a volume of additional runoff generated by a two-year, twenty-four-hour storm. Preferred BMPs for a hot spot include, but are not limited to, storm inlet filters, proprietary stormwater quality devices, underground detention tanks, detention ponds with forebays, tree planting, green roof. Permeable pavement, infiltration BMPs, and rain gardens are not recommended for hotspots.

E. In addition to the provisions set forth in Subsections A through D as set forth above, all regulated development activities within the Township shall be designed, implemented, operated and maintained to meet the purposes of this article, through:

(1) Erosion and sediment control during the earth disturbance activities (e.g., during construction); and

(2) Water quality, rate and volume protection measures to be implemented after completion of earth disturbance activities (e.g., post-construction stormwater management), including operations and maintenance.

F. No regulated development activities within the Township shall commence until the requirements of this chapter are met.

G. All best management practices (BMPs) used to meet the requirements of this chapter shall conform to the state water quality requirements and any more stringent requirements as determined by the Township.

H. LID and green infrastructure techniques described in the PA DEP Stormwater BMP Manual 2006 or most current edition are encouraged.

I. Proposed projects must comply with the Township's approved MS4 permit, including compliance with the six minimum control measures (MCMs) and with the Township's Pollutant Reduction Plan (PRP).

§ 99-20 Watershed standards.

A. The stormwater management performance standards in this article are intended to implement the provisions, standards and criteria contained in the Pennsylvania Storm Water Management Act (Act 167), 32 P.S. § 680.1 et seq. If there is any discrepancy between the provisions of this article and the provisions, standards and criteria of the Act, or if a stormwater management plan is subsequently approved and adopted by the appropriate governmental agency or body, then the provisions, standards and criteria of the current watershed plan shall govern.

B. Management of stormwater runoff is a key objective of 25 Pa. Code Chapter 93 of the DEP Regulations because runoff can change the physical, chemical and biological integrity of water bodies, thereby impacting rate, volume and water quality. Accordingly, the project plan shall describe how these rate, volume and water quality protection requirements will be met. Infiltration BMPs shall be evaluated and utilized to the maximum extent possible to manage the net change in stormwater runoff generated so that post-construction discharges do not degrade the physical, chemical or biological characteristics of the receiving waters. These BMPs may be used to satisfy all or part of the requirements found within this chapter.

C. Reference should be made to the Stormwater Performance Districts outlined in Appendix A,[1] and the Westmoreland County Integrated Water Resources Plan (IWRP) at www.westmorelandstormwater.org. The project plan shall describe how the proposed project will address performance standards, impairments, and pollutant loading found in the IWRP. For areas not covered by a stormwater performance district, the release rate shall be 80% of the pre-development peak flow as set by the Township.

[1] Editor's Note: Appendix A is included as an attachment to this chapter.

§ 99-21 Design criteria for stormwater management facilities and BMPs.

A. General criteria.

(1) Applicants may select runoff control techniques, or a combination of techniques, which are most suitable to control stormwater runoff from the development site. Refer to the Acceptable Computation Methodologies for Stormwater Management Plans table of this article.[1] All controls must be subject to approval of the Township Engineer and the WCD. The Township Engineer may request specific information on design and/or operating features of the proposed stormwater controls in order to determine their suitability and adequacy in terms of the standards of this chapter.

[1] Editor's Note: See § 99-19.

(2) If the proposed development site is located in an impaired water shed according to Category four of the PA Integrated Water Quality Monitoring and Assessment Report, or in a watershed with a TMDL according to Category 5 of the same report, the applicant shall identify the source and cause of impairment and shall propose, if required or applicable the use of BMPs to mitigate any impacts to the waters.

(3) The applicant should consider the effect of the proposed stormwater management techniques on any special soil conditions or geological hazards which may exist on the development site. In the event such conditions are identified on the site, the Township Engineer may require in depth studies by a competent geotechnical engineer. Not all stormwater control methods may be advisable or allowable at a particular development site.

(4) The applicant shall consider the effect of the proposed stormwater management techniques on existing stream impairments and pollutant loading. Reference should be made to the Westmoreland County Integrated Water Resources Plan (IWRP) at www.westmorelandstormwater.org.

(5) The applicant shall consider existing conditions on the site for the prior five years to determine prevailing land use and impervious cover, and shall consider 20% of existing impervious cover as meadow for preexisting conditions on redevelopment sites.

(6) The Hydrologic Soil Group (HSG) used for existing soils shall be assumed to be for drained conditions. As an example, a soil identified in the USDA NRCS soil survey as HSG B/D shall be assumed to be HSG B soil unless information, such as infiltration testing and groundwater monitoring data, is presented that justifies the use of HSG D soil.

(7) For post-development conditions of sites that are undeveloped, the HSG for each disturbed soil shall be reduced by one HSG level relative to its HSG reported in the USDA NRCS soil survey in order to account for compaction of the soil due to earthmoving activities, unless specific accommodations are employed, such as deep-tilling (or subsoiling) and soil amendment, to counter against the soil compaction that normally results due to typical earthmoving activities.

(8) The stormwater management practices to be used in developing a stormwater management plan for a particular site shall be selected giving deference to the criteria set forth hereafter in the following order of preference:

(a) Site planning for locating proposed buildings, impervious areas and grading which minimizes disruption of the natural site characteristics especially utilizing low-impact development techniques.

(b) Minimization of impervious areas and promotion of retentive grading.

(c) Implementation of nonstructural measures (refer to the PA DEP Stormwater BMP Manual 2006 or current edition).

(d) Implementation of innovative/green infrastructure structural measures (refer to the PA DEP Stormwater BMP Manual 2006 or current edition).

(e) Stormwater detention/retention structures.

(9) Any BMP which is a dam, culvert, stream obstruction or encroachment or outfall as defined in 25 Pa. Code Chapter 105 shall be designed according to the requirements in those regulations.

(10) Drainage easements shall be provided for all stormwater conveyance and BMPs serving multiple properties and not located within a public right-of-way. Easements shall include ingress and egress to a public right-of-way, and shall be recorded at the county with the final plan. Terms of easement shall prohibit excavation or placement of fill or structures and any alteration that may adversely affect the flow of stormwater within any portion of the easement.

(11) No person shall install, create, modify, remove, fill, landscape or otherwise alter or place any structure, soil, rock, material or vegetation in or on, or otherwise adversely affect, any stormwater management facility or any area within a stormwater easement without the written approval of the Township and approval of the WCD.

(12) Persons engaged in land development activities shall provide the required financial Security and O&M Agreements to the Township as outlined in this chapter.

B. Criteria and considerations for stormwater management facilities and BMPs.

(1) If stormwater management facilities and BMPs are utilized for the development site, the facility(s) shall be designed such that post-development peak runoff rates from the developed site are controlled to those rates defined by a Stormwater Management Performance District for the one-, two-, five-, ten-, twenty-five-, fifty-, one-hundred-year storm frequencies having rainfall durations of 24 hours. Rainfall data shall be obtained from NOAA Atlas 14 or other source as approved by the Township.

(2) All stormwater management facilities and BMPs shall be equipped with outlet/overflow structures to provide rate discharge control for the designated storm frequencies. Provision shall also be made to safely pass the entire post-development one-hundred-year storm without breaching or otherwise damaging the facilities, downstream or neighboring properties.

(3) Release of stormwater flow from a development site must be to an existing stormwater conveyance or easement, whether natural or man-made, that has defined bed and banks. Calculations and information shall be presented as to the ownership, responsible party, capacity, and stability of such conveyance. Release of "sheet flow," as from a level spreader, will be permitted on a case-by-case basis as approved by the Township Engineer and the WCD.

(4) All stormwater management facilities and BMPs shall be designed to control volume and water quality as defined by the Stormwater Management Performance District referenced in Appendix A.[2]

[2] Editor's Note: Appendix A is included as an attachment to this chapter.

(5) Shared stormwater management facilities and BMPs, which provide control of runoff for more than one development site within a single sub-area may be considered and are encouraged. Such facilities shall meet the criteria contained in this section. In addition, runoff from the development sites involved shall be conveyed to the facility in a manner that avoids adverse impacts (such as flooding or erosion) to channels and properties located between the development site and the shared storage facilities.

(6) Where stormwater management facilities and BMPs will be utilized, multiple use facilities, such as wetlands, lakes, ball fields or similar recreational/open space uses are encouraged wherever feasible, subject to the approval of the Township.

(7) Other considerations which must be incorporated into the design of the stormwater management facilities and BMPs include:

(a) Inflow and outflow structures designed and installed to prevent erosion and embankments, cuts, fills and bottoms of impoundment type structures should be protected from soil erosion.

(b) Control and removal of debris both in the storage structure and in inlet or outlet devices.

(c) Inflow and outflow structures, pumping stations and other structures designed and protected, using safety benches, trash racks, energy dissipaters and other means to minimize safety hazards.

(d) Access restrictions include fencing, with at least one lockable ingress and egress gate, in a minimum height of six feet shall be required at the discretion of the Township and the Township Engineer.

(e) Interior slopes of storage ponds not exceeding a ratio of three to one horizontal to vertical dimension with a combination of interior and exterior slopes not exceeding five. Steeper slopes may be approved by the Township Engineer if documented to be stable by a geotechnical analysis prepared by, or under the direction of, and sealed by a licensed geotechnical engineer.

(f) Pond principal spillways consisting of a solid reinforced concrete box (riser) that is designed and constructed to control the flow rate out of the detention facility. Noncorrugated plastic pipe may be used for the riser where the riser height is less than three feet and the plastic pipe is properly anchored to prevent horizontal or vertical displacement. The riser shall be joined by a watertight connection to a horizontal reinforced concrete pipe or high-performance polypropylene pipe (barrel) extending through the embankment and out-letting beyond the downstream toe of the fill. The maximum capacity of the barrel will be the twenty-five-year post-development flow. The construction materials must be approved by the Township Engineer.

(g) Pond dam embankments consisting of all excavation on the project, except such material as may be determined unsuitable by the Township Engineer, which includes, but is not limited to, frozen material, organic material, rock in excess of three inches in diameter, construction debris, sandy or other coarse grained soils, noncompactable soils and excessively wet or dry material. Acceptable material shall conform to the current PennDOT Publication 408 section on embankment material or shall be as approved by the Township Engineer. The pond dam embankment shall be compacted to a minimum 95% standard proctor maximum dry density as per ASTM D698. The embankment shall be constructed and compacted in maximum eight-inch lifts and the principle spillway outfall barrel and anti-seep collar(s) shall be constructed integral with the dam embankment construction.

(h) Landscaping facilities which stabilize disturbed areas and preserves the natural and beneficial values of the surrounding area. Landscaping shall consist of plant species native to southwestern Pennsylvania. No trees or other woody vegetation shall be planted on the fill areas of the pond dam embankment that may result in loosening of the compacted soils of the embankment. Detention basin bottoms shall be vegetated with a diverse native planting mix and may include trees, woody shrubs and meadow/wetland herbaceous plants. Noxious and invasive plants that inhibit plant species diversity shall not be included in the plant mix. PennDOT seed mix Formulas B, C, D and L as per PennDOT Publication 408 latest revision, or approved equivalent mix shall be used for revegetation of embankment areas. Crownvetch and birdsfoot trefoil shall not be used due to their interference with performance of inspections of the dam embankment. For other suitable landscape plant species, refer to Appendix B of the Pennsylvania Stormwater Best Management Practices Manual, latest edition.

(i) Facilities shall be located to facilitate maintenance, considering the frequency and type of equipment that will be required.

(j) Underground detention/retention/infiltration facilities shall be equipped with open grate inlet(s), inspection ports and/or manhole access to facilitate visual inspections and maintenance. Other considerations which should be incorporated into the design of the detention facilities include the following:

[1] Inflow and outflow structures must be designed and installed to prevent erosion, and bottoms of impoundment-type structures should be protected from soil erosion.

[2] All inflow structures into detention/retention ponds must discharge into a pond forebay designed in accordance with the Pennsylvania Stormwater Best Management Practices Manual.

[3] Control and removal of debris both in the storage structure and in all inlet or outlet devices.

[4] Inflow and outflow structures, pumping stations and other structures must be designed and protected to minimize safety hazards.

[5] The water depth at the perimeter of a storage pond should be limited to that which is safe for children. This is especially necessary if bank slopes are steep or if ponds are full and recirculating in dry periods. Restrictions of access (fence, walls, etc.) shall be necessary, depending on the location of the facility.

[6] A safety bench with a minimum width of eight feet must be provided around the entire interior perimeter of the pond at an elevation of six inches minimum above the two-year peak water surface elevation in the pond.

[7] An anti-vortex device and trash rack must be attached to the top of the principal spillway to improve the flow of water into the spillway and prevent floating debris from being carried out of the basin.

[8] The base of the principal spillway must be firmly anchored to prevent its floating. Computations must be made to determine the anchoring requirements. As a minimum, a factor of safety of 1.25 shall be used (downward forces = 1.25 x upward forces).

[9] The barrel of the principal spillway, which extends through the embankment, must be designed to carry the twenty-five-year pre-development flow provided by the riser of the principal spillway with the water level at the crest of the emergency spillway. The barrel shall consist of a reinforced concrete pipe (RCP) or high-performance polypropylene (HPPP) pipe and shall be fully supported along its entire length by a concrete cradle extending to the center line of the pipe and projecting horizontally a minimum of six inches beyond the outside wall of the pipe and vertically six inches below the bottom of the pipe. The connection between the riser and the barrel must be watertight. The outlet of the barrel must be protected to prevent erosion or scour of downstream area. This will include an end section or end wall with a designed rip-rap apron. For principle spillway barrels that pass through compacted fill pond dam embankments, the barrel, cradle and anti-seep collar(s) shall be constructed integral with the dam embankment construction as opposed to cutting into the completed dam embankment to construct the barrel, etc.

[10] Anti-seep collars.

[a] Anti-seep collars shall be used on the barrel of the principal spillway within the normal saturation zone of the embankment to increase the seepage length by at least 10% if either of the following conditions is met:

[i] The settled height of the embankment exceeds 10 feet.

[ii] The embankment has a low silt clay content and the barrel is greater than 10 inches in diameter.

[b] The anti-seep collars must be installed within the saturated zone. The maximum spacing between collars shall be 14 times the projection of the collar above the barrel. Collars shall not be closer than two feet to a pipe joint. Collars should be placed sufficiently far apart to allow space for hauling and compacting equipment. Collars shall consist of reinforced concrete with a minimum thickness of eight inches. Connections between the collars and the barrel shall be watertight.

[11] The emergency spillway must consist of an open channel having a control section at least 20 feet in length. The control section is a level portion of the spillway channel at the highest elevation in the channel. The emergency spillway shall be designed to carry the peak rate of runoff expected from the entire post-development one-hundred-year storm to the stormwater facility. The spillway channel shall be located so as to avoid sharp turns or bends. The channel shall return the flow of water to a defined channel downstream from the embankment. At the discretion of the Township Engineer and/or WCD, the emergency spillway shall include a reinforced concrete grade control wall extending perpendicular to the flow through the spillway with the top of the wall flush with the spillway crest. This control wall shall have a minimum width of eight inches, extend a minimum of 18 inches below the spillway crest and have a length no less than the width of the emergency spillway opening at the top of dam. The emergency spillway shall provide a minimum one foot of freeboard between the water surface of the full one-hundred-year post-development discharge through the spillway and the top of the dam embankment.

C. Criteria for collection/conveyance facilities.

(1) All stormwater runoff collection or conveyance facilities, whether storm sewers or other open or closed channels, shall be designed in accordance with the following basic standards:

(a) All building sites shall use measures to provide drainage away from and around the structure in order to prevent any potential flooding damage as much as practical. Such measures shall include grading the surrounding lawn or pavement area so that it slopes away from the structure by a minimum of 5% slope over a minimum distance of six feet; raising the floor of the structure so that it is a minimum of six inches above the predominant surrounding land elevation and above the designated floodplain elevation for those located within a floodplain; eliminating or waterproofing penetrations thru the structure's walls or foundation; constructing berms, curbs, or swales to divert surface water around the structure; arranging roof and area drains to carry water away from the structure.

(b) Developers proposing a land development or subdivision shall arrange internal drainage within the subdivision so that surface water is safely directed and channeled away from all structures within and adjacent to the development site.

(c) Developers shall provide to all persons constructing a structure within a land development site, standards, including drawings and specifications to ensure that those persons adhere to the general site plans and stormwater management plans for the development. Persons constructing a structure within a land development site shall submit to the Township Engineer and WCD drawings, calculations, and other information to show how they will meet the stormwater management requirements of the development site.

(d) Lots located on the high side or low side of streets shall extend roof, trench and area drains to a stable vegetated area, natural watercourse, the curb or gutter line of roadway or storm collection/conveyance/control system (if applicable) in accordance with the approved stormwater management plan for the development site.

(e) For all building sites and lots, the inclusion of rain barrels, rain gardens, dry wells and other strategies for infiltration of roof runoff close to its source is encouraged.

(f) Collection/conveyance facilities should not be installed parallel and less than 10 feet from the top or bottom of an embankment, greater than or equal to 15 feet in height to avoid the possibility of failing or causing the embankment to fail, unless documented to be stable by a geotechnical analysis.

(g) All collection/conveyance facilities shall be designed to convey the twenty-five-year storm peak flow rate from the contributing drainage area to the nearest suitable outlet such as a stormwater control facility, curbed street, storm sewer or natural watercourse. However, the one-hundred-year design storm may be required as determined by the Township Engineer where it is necessary for the storm system to convey the one-hundred-year design storm to the stormwater management facility.

(h) Where drainage swales or open channels are used, they shall be suitably lined to prevent erosion and designed to avoid erosive velocities.

(i) Wherever storm sewers are proposed to be utilized, they shall comply with the following additional criteria:

[1] Where practical, same shall be designed to traverse under seeded and planted areas. If constructed within 10 feet of road paving, walks or other surfaced areas, drains shall have a narrow trench and maximum compaction of backfill to prevent settlement of the superimposed surface or development.

[2] Preferably, same shall be installed after excavating and filling in the area to be traversed is completed, unless the drain is installed in the original ground with a minimum of three feet cover and/or adequate protection during the fill construction.

[3] Designed:

[a] With cradle when traversing fill areas of indeterminate stability.

[b] With anchors when gradient exceeds 20%.

[c] With encasement or special backfill requirements when traversing under a paved area.

[4] Designed to adequately handle the anticipated stormwater flow and be economical to construct and maintain. The minimum pipe size shall be 15 inches in diameter, with the exception of roof drains, foundation drains, internal french drains and/or sump pumps, or similar conveyances.

[5] Drain pipe, trenching, bedding and backfilling requirements and appropriate grates, catch basins, stormwater inlets, manholes and other appurtenances shall conform to the requirements of the Township and/or applicable PennDOT specifications, Publication 408.

[6] All corrugated metal pipe shall be polymer coated, and with paved inverts where prone to erode. Pipe within a Township right-of-way shall be reinforced concrete pipe or high-performance polypropylene pipe with a diameter sufficient to accept existing and reasonably anticipated future stormwater capacity and in no event less than the minimum diameter of 15 inches.

[7] All storm pipes constructed within existing Township rights-of-way or in new developments whose roads and associated storm sewers may be taken over by the Township are to consist of straight runs of pipe only, both horizontally and vertically, between storm structures such as inlets, manholes and/or end walls. No storm sewers consisting of blind elbows, blind tees or pipe joint deflections, such as for pipes following the horizontal curve of a roadway, will be acceptable for takeover by the Township.

[8] Storm inlets and structures shall be designed to be adequate, safe, self-cleaning and unobtrusive and consistent with Township standards with sufficient capture and conveyance capacity and spacing of inlets and cleanouts for maintenance.

[9] Where a proposed sewer or conveyance connects with an existing storm sewer or conveyance system, the applicant shall demonstrate that sufficient capacity exists in the downstream system to handle the additional flow.

[10] Storm sewer outfalls shall be equipped with energy dissipation devices to prevent erosion and conform with applicable requirements of the Pennsylvania DEP for stream encroachments (Section 7 of the Dam Safety and Encroachments Act, 32 P.S. § 693.1 et seq., and the rules and regulations promulgated thereunder at 25 Pennsylvania Code §§ 105.441 to 105.449). Exit velocities of the design storm for the stormwater conveyance systems must be considered in the design of the energy dissipation devices.

[11] Storm inlets shall include castings with the message "Dump No Waste. Drains to Stream" or similar message as approved by the Township Engineer cast into or permanently affixed to the casting and positioned in a manner that is legible to pedestrian traffic.

D. Criteria for riparian buffers.

(1) If a riparian buffer is required by PA DEP as part of an NPDES permit, then DEP regulations will govern.

(2) If a riparian buffer is used to meet stormwater management requirements and/or MS4 pollutant load reduction credits, it shall meet the following requirements:

(a) In order to protect and improve water quality, a riparian buffer easement must be created and recorded as part of any subdivision or land development that encompasses a riparian buffer.

(b) Except as required by Pa. Code Title 25, Chapter 102, the riparian buffer easement shall may be measured to a minimum of 35 feet measured from the top of the nearest bank (on each side), or an average of 35 feet with no distance from top of bank less than 25 feet.

(c) Minimum management requirements for riparian buffers shall require:

[1] Existing native vegetation to be protected and maintained within the riparian buffer easement.

[2] Whenever practicable, invasive vegetation to be actively removed and the riparian buffer easement shall be planted with native trees, shrubs and other vegetation to create a diverse native plant community appropriate to the intended ecological context of the site.

[3] No earth disturbance beyond which is necessary to establish or maintain a planted buffer.

(3) The riparian buffer easement shall be recorded in the Westmoreland County Recorder of Deeds Office, run with the land, limit the use of the property located therein and shall be enforceable by the Township. The easement shall allow for the continued private ownership by the property owner and shall counted as part of the minimum lot area required by Chapter 118, Zoning, unless specified otherwise in an applicable Township ordinance.

(4) Any permitted use within the riparian buffer easement shall be conducted in a manner that will maintain the extent of the existing one-hundred-year floodplain, improve or maintain the stream stability, and preserve and protect the ecological function of the floodplain.

(5) Stormwater drainage pipes and all other linear utility lines as approved by the Township shall be permitted within the riparian buffer easement, but shall cross the easement in the shortest practical distance. Other stormwater management facilities and BMPs are not permitted within the riparian buffer easement.

(6) When public and/or private recreation trails are permitted within riparian buffers:

(a) Trails shall be for nonmotorized use only.

(b) Trails shall be designed to have the least impact on native plant species and other sensitive environmental features.

(7) Septic drain fields and sewage disposal systems shall not be permitted within the riparian buffer easement and shall comply with setback requirements established under 25 Pa. Code Chapter 73.

E. Criteria for stream restoration projects.

(1) A stream restoration project may eligible for stormwater management and/or MS4 load reduction credits if it meets the following qualifying criteria:

(a) Existing conditions, such as channel or stream bank erosion and an actively enlarging or incising urban stream condition, are documented prior to restoration.

(b) Projects should be located on first- to third-order (small) streams to be effective.

(c) The project addresses a minimum of 100 linear feet of stream channel and both sides where need to do so is evident.

(d) Upstream impervious area should be sufficiently treated to address peak flows that may exceed engineering design thresholds or compromise channel form and function.

(e) A comprehensive approach employing a mix of techniques appropriate to the site, creating long-term stability of the streambed, stream banks and floodplain is utilized.

(f) Armored length of streams (i.e., using riprap or gabions) are used to maintain channel stability, and the same length is not included in the load reduction calculation.

(g) The project maximizes floodplain reconnection, with minimal channel invert elevation increase (i.e., bank height ratio = 1.0 or less) to achieve the objective.

(h) The project includes a minimum thirty-five-foot permanent riparian buffer.

(i) The project includes an O&M plan identifying O&M activities, frequencies and responsible parties.

§ 99-22 Design standards for grading activities.

A. Excavation standards.

(1) No excavation shall be made with a cut face steeper in slope than two horizontal to one vertical except under one or more of the following conditions:

(a) The excavation is located so that a line having a slope of two horizontal to one vertical and passing through any portion of the cut face will be entirely inside the property lines of the property on which the excavation is made.

(b) The material in which the excavation is made is sufficiently stable to sustain a slope steeper than two horizontal to one vertical and a written statement of a professional engineer, licensed by the Commonwealth of Pennsylvania and experienced in erosion control to that effect is submitted to the Code Official and approved by him. The statement shall state that the engineer has inspected the site and that the deviation from the slope specified above will not result in increased risk of injury to persons or damage property.

(c) A retaining wall or other approved support designed by a registered professional engineer and said design approved by the Code Official is provided to support the face of the excavation.

(2) The Code Official may require an excavation to be made with a cut face less (flatter) in slope than two horizontal to one vertical if he finds that the material in which the excavation is to be made is unusually subject to erosion or if other conditions exist which, under applicable engineering practice, make such flatter cut slope necessary for stability and safety.

(3) Excavations adjacent to any footing, foundation, or structure shall not extend below the angle of repose or natural slope of the soil under the nearest point of the same unless such footing, foundation, or structure is first properly underpinned or protected against settlement.

(4) Before commencing any excavation which will in any way affect an adjoining property or structure thereon, the person making or causing the excavation to be made shall notify, in writing, the owners of adjoining buildings not less than 30 days before such excavation is to be made. Adjoining properties and structures shall be protected as provided in the Unity Township Building Code and/or as required by the Code Official.

B. Fill standards.

(1) No fill shall be made which creates any exposed surface steeper in slope than two horizontal to one vertical, except under one or more of the following conditions:

(a) The fill, in the opinion of the Code Official, is located so that settlement, sliding, or erosion of the fill material will not result in property damage or be a hazard to adjoining property, streets, alleys, or structures.

(b) A written statement of a professional engineer licensed by the Commonwealth of Pennsylvania and experienced in erosion control to that effect is submitted to the Code Official and approved by him. The statement shall state that the site has been inspected by such engineer and that the deviation from the slope specified above will not result in increased risk of injury to persons or damage property.

(2) The Code Official may require that the fill be constructed with an exposed slope less (flatter) than two horizontal to one vertical if he finds that under the particular conditions such flatter slope is necessary for stability and safety.

(3) Whenever a fill is to be made of materials other than clean soil or earth, the grading permit shall be subject to the following additional limitations and requirements:

(a) The fill shall be completed within a reasonable length of time, said time limit to be determined by the Code Official and to be specified on the grading permit.

(b) Clean soil or earth shall be placed over the top and exposed surfaces of the fill to a depth sufficient to effectively conceal all materials, other than clean soil or earth, within the fill.

(4) When the fill is other than clean soil or earth, the Code Official may require clean soil or earth to be placed over the top and exposed surfaces of the fill to a depth sufficient to conceal all materials at the end of each day's operations.

(5) No fill of any kind shall be placed over trees, stumps, or other material which would create a nuisance or be susceptible to attracting rodents, termites, or other pests.

(6) All fills shall be compacted to provide stability of material and to prevent undesirable settlement.

(7) The fill shall be spread in a series of layers, each not exceeding 12 inches in depth, and shall be compacted by a sheep's-foot roller or other approved method after each layer is spread.

(8) Where fills are placed on slopes of 5% or more, benching of the surface shall be required and indicated on the cross sections.

(9) The Code Official may require tests or other information if, in their opinion, the conditions or materials are such that additional information is necessary.

(10) The movement of earth in the course of farming or agricultural work or private landscaping.

C. Ground cover.

(1) In order to prevent erosion, the permit holder shall be required to provide adequate surface treatment by installing ground covering of such kind and character as may be approved by the Code Official.

(2) The ground covering shall be grass, crown vetch, or other approved variety of vegetation.

D. Drainage.

(1) Adequate provisions shall be made to prevent any surface waters from damaging the cut face of an excavation or the sloping surface of a fill.

(2) The Code Official shall require such drainage structures or pipes to be constructed or installed which are necessary to prevent erosion damage and to satisfactorily carry off surface waters.

(3) All drainage provisions shall be of such design so that the peak discharge for all stormwater outfalls on site shall be in conformance with the performance standards set forth herein.

E. Maintenance.

(1) The owner of any property on which an excavation or fill has been made shall maintain in good condition and repair all retaining walls, cribbing, drainage structures, fences, ground cover, and other protective devices as established by permit, and, further, the continued use of said area shall be contingent upon the maintenance and upkeep of same in a condition satisfactory to the Township, and subject to such further conditions as the Township may prescribe.

(2) The certificate of completion may at any time be revoked by the Board of Supervisors, in accordance with the procedures set forth hereafter, if the conditions of the permit are not being observed or if conditions exist that prejudice or pose a threat to the health, safety, and welfare of any person, persons, or property.

F. Protection of adjacent property and utilities.

(1) Prevention of slides or washes. Materials shall not be permitted to roll, slide, flow, or wash onto adjacent private or public property. Where necessary, walls, cribbing, silt fence, or benching shall be utilized to comply with this requirement.

(2) Horizontal distance of excavation or fill slope from property or easement line.

(a) The horizontal distance from the toe or top of the excavation or fill slope line shall be five feet or 1/2 of the vertical height of the fill or excavation from any adjoining property or easement line, whichever is greater, but such distance need not exceed 10 feet.

(b) The Code Official shall have the authority to modify this requirement in instances where it is demonstrated that such modification is needed to secure desirable interrelationships between properties and will not result in a condition detrimental to the adjacent property.

(3) Support and protection of public utilities and public streets.

(a) A plan shall be in effect for proper support and protection from drainage resulting from the operation for all public and private utilities, whether on the surface, beneath the ground surface, or overhead, and, when necessary, for the repair, replacement, or relocation of such utilities.

(b) The surface and other facilities or public streets shall be fully restored by the permit holder in the event of such damage.

(c) The permit holder shall correct any damage to the utility involved before the Code Official issues the completion certificate.

G. Fencing. Should the nature of land operations, in the opinion of the Code Official, create a hazard to persons or property unless adequately fenced, the permit holder shall construct such fences or guide rails as safeguards to persons using adjoining property, public or private.

H. General requirements.

(1) Any excavations within a floodway or floodplain must follow the guidelines as set forth in the floodplain management regulations of the Township Code.

(2) A temporary construction fence not less than four feet in height, or a design approved by the Code Official and/or meeting other Township fence requirements, shall be placed at the top of all cuts or fills with slopes in excess of two horizontal to one vertical.

(3) The permit holder and owner of a property shall be responsible to protect and clean up lower properties of silt or debris washing from his property as a result of the regrading of his property.

(4) In order to prevent the denuding of the landscape, large trees and other natural features constituting important physical, aesthetic, and economic assets to existing or impending suburban development shall be preserved.

(5) All grading, excavating, or fill shall be performed so that no unnecessary dust shall be raised. The Code Official may enforce reasonable dust-control regulations and may revoke any permit issued under this chapter until proper dust-control regulations are met.

I. Certificate of completion.

(1) If, upon final inspection of an excavation or fill, it is found that the work authorized by the permit has been satisfactorily completed in accordance with the requirements of this chapter, a certificate of completion covering such work and stating that the work is approved shall be issued to the permit holder by the Code Official.

(2) The Board of Supervisors shall have the power to revoke any certificate of completion upon the recommendation of the Code Official that the work covered by the certificate has been materially extended or altered without a permit to do so, or that any retaining walls, cribbing, drainage structures, fences, or other protective devices shown on the approved plans and specifications submitted for a permit have not been maintained in good order and repair.

(3) Before such revocation, the Code Official shall first give written notice to the permit holder and to the owner of the property involved, specifying the defective condition and stating that, unless such defective condition is remedied, the certificate may be revoked. If the defective condition is remedied, the certificate shall not be revoked. Such conditions shall be corrected within 30 days' notice to the owner to correct the same, or within a shorter period of time established by the Code Official if exigent circumstances warrant.

(4) Following the issuance of a certificate of completion, and provided that as a minimum 90% of the proposed homes are constructed, the developer's completion guarantee bond will be released by the Township.

J. During any stage of the regulated earth disturbance activities, if the Township or its designee determines that any BMPs are not being implemented in accordance with this chapter, the Township may suspend or revoke any existing permits or other approvals until the deficiencies are corrected.

§ 99-23 Erosion and sedimentation controls.

A. No regulated development activities within the Township shall commence until approval by the Township and the WCD of an erosion and sediment control plan for construction activities.

B. Any earth disturbance activity of 5,000 square feet or more requires an erosion and sedimentation control plan under 25 Pa. Code § 102.4(b). Refer to the PA DEP Erosion and Sediment Pollution Control Manual 2012 or the most recent version of same.

C. In addition, under Title 25 Pa. Code Chapter 92, a DEP NPDES construction activities permit is required for regulated development activities.

D. Evidence of any necessary permit(s) for regulated development activities from the appropriate DEP regional office or Westmoreland Conservation District must be provided to the Township. The issuance of an NPDES construction permit (or permit coverage under the Statewide General Permit (PAG-2)) may be found to satisfy the requirements under Subsection A above conditioned upon review and approval by the Township.

E. A copy of the erosion and sediment control plan and any permit required by DEP or the Township shall be available at the project site at all times.

§ 99-24 Water obstructions and encroachments.

A. No regulated development activities which require a Chapter 105 (Water Obstructions and Encroachment) permit from either PA DEP or the Westmoreland Conservation District shall commence until all permits, PA DEP or WCD approval, and Township approval have been received.

B. Evidence of any necessary Chapter 105 permit from PA DEP/WCD shall be provided to the Township.

C. Any proposed development shall avoid the long and short term adverse impacts associated with the occupancy and modification of floodplains as designated by FEMA, to the extent possible wherever there is a practicable alternative to reduce the risk of flood loss, minimize the impacts of floods on human safety, health and welfare, and restore and preserve the natural and beneficial values served by floodplains.

D. Any proposed development found to be within the base floodplain of a waterway shall be in compliance with Chapter 57, Floodplain Management, of the Unity Township Code, and shall include the identification of impacts, an evaluation of practicable alternatives outside the floodplain, and, when impacts cannot be avoided, the development of measures to minimize the impacts and restore and preserve the floodplain as appropriate.

E. Any proposed stormwater management plan should be consistent with the provisions of the PA Flood Plain Management Act 166 of 1978, 32 P.S. § 679.101 et seq., and applicable municipal floodplain ordinances, and when impacts cannot be avoided, the development of measures to minimize the impacts and restore and preserve the floodplain is appropriate.