City of Lancaster, PA Article III Stormwater Management Standards

§ 260-301 General requirements.

A. Preparation of an SWM site plan is required for all regulated activities, unless preparation and submission of the SWM site plan is specifically exempted according to § 260-502.

B. No regulated activities shall commence until the City of Lancaster issues written approval of an SWM site plan and a stormwater permit.

C. SWM site plans approved by the City of Lancaster, in accordance with § 260-505, shall be on site throughout the duration of the regulated activity.

D. The City of Lancaster may, after consultation with DEP, approve measures for meeting the state water quality requirements other than those in this chapter, provided that they meet the minimum requirements of, and do not conflict with, state law including, but not limited to, the Clean Streams Law.[1] The City of Lancaster shall maintain a record of consultations with DEP pursuant to this subsection. Where an NPDES permit for stormwater discharges associated with construction activities is required, issuance of an NPDES permit shall constitute satisfaction of consultation with DEP.

[1] Editor's Note: See 35 P.S. § 691.1 et seq.

E. For all regulated activities, erosion and sediment control BMPs shall be designed, implemented, operated, and maintained to meet or exceed in light of unique local conditions the purposes and requirements of this chapter and to meet all requirements under Title 25 of the Pennsylvania Code and the Clean Streams Law. Various BMPs and their design standards are listed in the Erosion and Sediment Pollution Control Program Manual (E&S Manual), No. 363-2134-008 (March 2012), as amended and updated.

F. Applicants have the option to propose a regional stormwater management plan or participate in a regional stormwater management plan developed by others. A regional stormwater management plan may include off-site volume and rate control, as appropriate and supported by a detailed design approved by the City of Lancaster in accordance with § 260-301D. A regional stormwater management plan must meet all of the volume and rate control standards required by this chapter for the area defined by the regional stormwater management plan, but not necessarily for each individual development site. Appropriate easement and O&M agreements must be established to ensure the requirements of this chapter and the requirements of the regional stormwater management plan are met.

G. Unless prohibited by the City of Lancaster Building Construction and Floodplain Ordinance,[2] Zoning Ordinance[3] or any ordinance which regulates construction and development within the areas of the City of Lancaster subject to flooding, and any other applicable requirements of the Floodplain Management Act,[4] stormwater management facilities located in the floodplain are permitted when designed and constructed in accordance with the provisions of the BMP Manual, the City Specifications and Guidelines Manual, Stormwater Management Fee Policy and Procedures Manual, other regulatory requirements and the requirements of this chapter.

[2] Editor's Note: See Ch. 109, Building Construction and Floodplain Management.

[3] Editor's Note: See Ch. 300, Zoning.

[4] Editor's Note: See 32 P.S. § 679.101 et seq.

H. Impervious areas:

(1) The measurement of impervious area shall include all of the impervious areas in the total proposed development outside of the right-of-way even if development is to take place in stages or phases. Upon approval of the Director, new public access easements within the proposed development that are requested by the City may be excluded from the measurement of impervious area.

(2) For development taking place in stages or phases, the entire development planned over a five-year period must be used in determining conformance with this chapter.

(3) Any area designed to initially be gravel or crushed stone shall be assumed to be impervious, unless it is designed, approved, and maintained as a pervious cover material (e.g., open-graded gravel walkway or landscape feature) or infiltration system.

I. All regulated activities shall include such measures as necessary to:

(1) Protect health, safety, and welfare of people and property;

(2) Meet the water quality goals of this chapter by implementing measures to:

(a) Protect and/or improve the function of floodplains, wetlands, and wooded areas.

(b) Protect and/or improve native plant communities including those within the riparian corridor.

(c) Protect and/or improve natural drainageways from erosion.

(d) Minimize thermal impacts to waters of the Commonwealth.

(e) Disconnect impervious surfaces by directing runoff to pervious areas, wherever possible.

(3) Incorporate the techniques for low-impact development practices described in the Pennsylvania Stormwater BMP Manual (BMP Manual).

(4) Incorporate green infrastructure stormwater management facilities in accordance with applicable City codes and specifications.

J. A planting plan is required for all vegetated stormwater BMPs.

(1) All trees and other vegetation shall be planted in accordance with the standards and regulations set forth in applicable City codes and ordinances including but not limited to Chapter 202, Parking Lots; Chapter 265, Subdivision and Land Development; Chapter 273, Trees; and Chapter 300, Zoning.

(2) Native or naturalized/noninvasive vegetation suitable to the soil and hydrologic conditions of the development site shall be used unless otherwise specified in applicable state and local codes and regulations, including but not limited to the latest edition of the City GI Design Manual and the PA BMP Manual.

(3) Invasive vegetation may not be included in any planting schedule. [See "Invasive Plants in Pennsylvania" by the Department of Conservation and Natural Resources (DCNR)]

(4) Per § 273-10B and Tree Manual § 4.00-A, an appraisal for all trees within and adjacent to limits of disturbance is required prior to submission of plans.

(5) The limit of existing, native vegetation to remain shall be delineated on the plan along with proposed construction protection measures per standards outlined in Chapter 273, Trees, and the City of Lancaster Tree Manual.

(6) Prior to construction, a tree protection zone shall be delineated in accordance with Chapter 273, Trees, and the City of Lancaster Tree Manual.

(7) All planting shall be performed in conformance with good nursery and landscape practice and per standards outlined in Chapter 273, Trees, and the Tree Manual. Plant materials shall conform to the standards recommended by the American Association of Nurseryman, Inc. in the American Standard of Nursery Stock (ANSI Z60.1).

(a) Planting designs are encouraged to share planting space for optimal root growth whenever possible.

(b) No staking or guying of trees shall be allowed without a maintenance note for the stake and/or guy removal within one year of planting. Use of wire material in staking or guying is not permitted.

K. Areas proposed for infiltration BMPs shall be protected from sedimentation and compaction during the construction phase to maintain maximum infiltration capacity. Staging of earthmoving activities, selection of construction equipment, and other protection measures as described in the City GI Design Manual should be applied.

L. Infiltration BMPs shall not be constructed nor receive runoff from disturbed areas until the entire contributory drainage area to the infiltration BMP has achieved final stabilization, unless otherwise authorized by the City as described in the City GI Design Manual.

M. Volume control storage facilities designed to infiltrate shall avoid the least permeable hydrologic soil group(s) at the development site to the extent practicable.

N. Where required by the Director, a minimum ten-foot-wide access easement for inspection and maintenance shall be provided for all stormwater facilities with tributary areas equal or greater than 1,000 square feet and not located within a public right-of-way. Easements shall provide for ingress and egress to a public right-of-way.

O. When required, drainage easements shall be provided.

P. The City of Lancaster may require additional stormwater control measures for stormwater discharges to special management areas including but not limited to:

(1) Water bodies listed as "impaired" on Pennsylvania's Clean Water Act 303(d)/305(b) Integrated List.

(2) Any water body or watershed with an approved total maximum daily load (TMDL).

(3) Critical areas with sensitive resources (e.g., state-designated special protection waters, cold water fisheries, carbonate or other groundwater recharge areas highly vulnerable to contamination, drainage areas to water supply reservoirs, source water protection zones, etc.).

Q. Roof drains and sump pumps shall be tributary to infiltration or vegetative BMPs, unless otherwise approved by the Director. Use of catchment facilities for the purpose of stormwater reuse is also permitted.

R. Nonstructural BMPs shall be utilized for all regulated activities unless proven to be impractical by the Director.

S. All GI and BMPs shall be implemented on the development site, or on an abutting site with properly executed easements, as may be required by this chapter. However, if the installation of GI and BMPs is proven to be impractical due to existing site constraints, BMPs may be installed off site, within the same drainage basin or sewershed as the development site, upon the approval by the Director.

§ 260-302 Performance standards.

A. All regulated activities except those exempted in § 260-502 and very small projects as defined in § 260-202, shall not increase the postdevelopment total runoff volume for all storms equal to or less than the two-year, twenty-four-hour storm event. At least the first 1 1/4 (1.25) inches of runoff from new impervious surfaces shall also be permanently removed from the runoff flow; that is, it shall not be released into the surface waters of the commonwealth or combined sewer system. As of 2022, 1.25 inches represents 90% of long-term daily rainfall and this depth should be updated at least every five years based on the latest rainfall data. Removal options include reuse, evaporation, transpiration and infiltration. Small impervious areas that are difficult and/or impractical to manage directly may be compensated for by managing an equivalent area from unmanaged/unregulated existing impervious areas on the same site. If no such compensation is feasible, in whole or in part, an area that is less than 500 square feet and less than 10% of the total new impervious area may be exempted.

B. The design of all stormwater management facilities over karst shall include an evaluation of measures to minimize adverse effects, where such evaluation shall be carried out in accordance with § 260-405A of this chapter.

C. Infiltration BMPs shall be designed to the maximum extent practicable to fit the site constraints and limitations, and be located to maximize use of undisturbed site soils and areas appropriate for infiltration while still meeting the other requirements of this chapter. Infiltration BMPs shall include pretreatment BMPs unless shown to be unnecessary.

D. Infiltration BMPs intended to receive runoff from developed areas shall be selected based on suitability of soils and development site conditions and shall be constructed on soils that have the following characteristics:

(1) A minimum depth of 24 inches between the bottom of the facility and the limiting zone, unless it is demonstrated to the satisfaction of the City of Lancaster that the selected BMP has design criteria which allow for a smaller separation.

(2) A stabilized infiltration rate sufficient to accept the additional stormwater load and drain completely as determined by field tests conducted by the applicant's professional designer.

(a) The stabilized infiltration rate is to be determined in the same location and within the same soil horizon as the bottom of the infiltration facility.

(b) The stabilized infiltration rate is to be determined as specified in the BMP Manual.

E. The two-, ten-, twenty-five-, fifty-, and 100-year design storm depths shall be the upper bound of the 90% confidence interval from the NOAA Atlas 14 Point Precipitation Frequency Estimates for Lancaster. The twenty-four-hour storm depths as of 2022 are shown in the City GI Design Manual. These values shall be used unless there are updated values at the time of the project application. When required, a NOAA Type C storm distribution shall be used.

F. Runoff from impervious areas shall be drained to pervious areas within the development site, unless the site has 85% or more impervious cover and is a redevelopment, in which case alternative methods of SW management shall be incorporated including but not limited to GI and on-site detention.

G. Stormwater runoff from a development site shall flow directly into a natural drainageway, watercourse, or an existing conveyance system, or onto adjacent properties in a manner similar to the runoff characteristics of the predevelopment flow, unless such predevelopment characteristics were inadequate to control adverse impacts such as erosion, flooding, ponding, etc., as determined by the City.

H. Stormwater flows onto adjacent property shall not be created, increased, decreased, relocated, or otherwise altered without written notification of the adjacent property owner(s) by the applicant. Such stormwater flows shall be subject to the requirements of this chapter, including the establishment of a drainage easement. Copies of all such notifications shall be included in SWM site plan submissions.

I. Existing on-site natural SWM facilities shall be used to the maximum extent practicable.

J. Stormwater runoff shall not be transferred from one subwatershed to another unless they are subwatersheds of a common watershed that join together within the perimeter of the development site, the effect of the transfer does not alter the peak discharge onto adjacent lands and drainage easements from the affected landowners are provided.

K. Minimum floor elevations for all structures that would be affected by a basin, other temporary impoundments, or open conveyance systems where ponding may occur shall be two feet above the 100-year water surface elevation. If basement or underground facilities are proposed, detailed calculations addressing the effects of stormwater ponding on the structure and waterproofing and/or floodproofing design information shall be submitted for approval.

L. All stormwater conveyance facilities (excluding detention, retention, and wetland basin outfall structures) shall be designed to convey a twenty-five-year storm event,* unless otherwise directed by the City so as not to exceed the capacity of the existing City conveyance system. All stormwater conveyance facilities (excluding detention, retention, and wetland basin outfall structures) conveying water originating from off the site shall be designed to convey a fifty-year storm event.* Safe conveyance of the 100-year runoff event* to appropriate peak rate control BMPs must be demonstrated in the design.

* A twenty-four-hour NOAA Type C storm or an IDF Curve Rational Method storm.

M. Erosion protection shall be provided along all open channels, and at all points of discharge. Flow velocities from any storm sewer may not result in erosion of the receiving channel.

§ 260-303 Volume controls.

Volume control BMPs are intended to maintain existing hydrologic conditions for small storm events by promoting groundwater recharge and/or evapotranspiration as described in this section. Runoff volume controls shall be implemented using the Design Storm Method described in Subsection A below and in the City GI Design Manual, or through continuous modeling approaches or other means as described in the BMP Manual, or from other applicable sources acceptable to the City. Small projects may use the method described in Subsection B to design volume control BMPs. All facilities should be designed and constructed in accordance with the City GI Design Manual.

A. The Design Storm Method is applicable to any size of regulated activity that does not meet the definition of "small project" or "very small project."

(1) The Design Storm Method requires detailed modeling based on site conditions to demonstrate that the project will not increase the postdevelopment total runoff volume for all storms equal to or less than the two-year, twenty-four-hour storm event. At least the first 1 1/4 (1.25) inches of runoff from new impervious surfaces shall also be permanently removed from the runoff flow, that is, it shall not be released into the surface waters of the commonwealth or combined sewer system. Removal options include reuse, evaporation, transpiration and infiltration.

(a) Small impervious areas that are difficult and/or impractical to manage directly may be compensated for by managing an equivalent area from unmanaged/unregulated existing impervious areas on the same site. If no such compensation is feasible, in whole or in part, an area that is less than 500 square feet and less than 10% of the total new impervious area may be exempted.

(2) For modeling purposes when demonstrating that the total runoff volume will not increase:

(a) Existing (predevelopment) non-forested pervious areas must be considered meadow in good condition in the hydrologic soils group B soils.

(b) When the existing project site contains impervious area, 20% of existing impervious area to be disturbed shall be considered meadow in good condition in the model for existing conditions, except for repair, reconstruction or restoration of public roadways, or repair, reconstruction or restoration of rail lines, or construction, repair, reconstruction, or restoration of utility infrastructure when the site will be returned to existing condition.

B. Volume control for small projects. At least the first 1 1/4 (1.25) inches of runoff from new impervious surfaces or an equivalent volume from an unmanaged/unregulated impervious area on the same site shall be permanently removed from the runoff flow, that is, it shall not be released into the surface waters of the commonwealth or combined sewer system. Removal options include reuse, evaporation, transpiration and infiltration.

C. If required by the Director, a detailed geologic evaluation of the development site shall be performed in areas of carbonate geology to determine the design parameters of recharge facilities. A report shall be prepared in accordance with § 260-405A of this chapter. When existing karst or poor soil conditions, as determined by the Director, do not allow for the installation of infiltration BMPs, the design volume of stormwater runoff shall be kept out of the combined sewer system and detained on site per the City GI Design Manual guidance on slow-release systems.

D. Unless otherwise noted in the City GI Design Manual, storage facilities shall completely drain the volume control storage over a period of time not less than 24 hours and not more than 72 hours from the end of the design storm. Any designed infiltration at such facilities is exempt from the minimum twenty-four-hour standard, that is, may infiltrate in a shorter period of time, provided that none of this water will be discharged into waters of the commonwealth or combined sewer system.

E. Any portion of the volume control storage that meets the following criteria may also be used as rate control storage;

(1) Volume control storage that depends on infiltration is designed according to the infiltration standards in §§ 260-301 and 260-302.

(2) The volume control storage that has been dewatered and is available within 24 hours from the end of the design storm may be used for rate control. The volume control storage dewatering rate shall be calculated based on the stabilized infiltration rate, the evapotranspiration rate and/or as indicated in the City GI Design Manual.

§ 260-304 Rate controls.

Rate control for large storms, up to the 100-year event, is essential to protect against immediate downstream erosion and flooding.

A. Match predevelopment hydrograph. Applicants shall provide infiltration facilities or utilize other techniques which will allow the postdevelopment 100-year hydrograph to match the predevelopment 100-year hydrograph, along all parts of the hydrograph, for the development site. To match the predevelopment hydrograph, the postdevelopment peak rate must be less than or equal to the predevelopment peak rate, and the postdevelopment runoff volume must be less than or equal to the predevelopment volume for the same storm event. A shift in hydrograph peak time of up to six minutes and a rate variation of up to 5% at a given time may be allowable to account for the timing effect of BMPs used to manage the peak rate and runoff volume. "Volume control" volumes as given in § 260-303 above may be used as part of this option.

B. Where the predevelopment hydrograph cannot be matched, one of the following shall apply:

(1) Postdevelopment rate of runoff from any regulated activity within the Little Conestoga Creek Watershed or Mill Creek Watershed shall not exceed 50% of the peak rates of runoff prior to development for all design storms unless the preexisting hydrograph is not exceeded at all points in time.

(2) For areas covered by the release rate map in Appendix D:[1] For the two-, ten-, twenty-five-, fifty-, and 100-year storm events,* the postdevelopment peak discharge rates will follow the applicable release rate map.

* A twenty-four-hour NOAA Type C storm or an IDF Curve Rational Method storm. See Table III-1.

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

C. Normally dry, open-top storage facilities shall completely drain the rate control storage over a period of time greater than or equal to 24 hours but no more than 72 hours from the peak 100-year water surface design elevation.

D. A variety of BMPs should be employed and tailored to suit the development site. Nonstructural BMPs and green infrastructure are preferred. The following is a partial listing of BMPs which can be utilized in SWM systems for rate control where appropriate:

(1) Decreased impervious surface coverage.

(2) Routed flow over grass.

(3) Grassed channels and vegetated strips.

(4) Bio-retention areas (rain gardens).

(5) Concrete lattice block or permeable surfaces.

(6) Seepage pits, seepage trenches or other infiltration structures.

(7) Rooftop detention.

(8) Parking lot detention.

(9) Cisterns and underground reservoirs.

(10) Amended soils.

(11) Retention basins.

(12) Infiltration basins.

(13) Green (vegetated) roofs.

(14) Other methods as may be found in the City GI Design Manual and/or the PA BMP Manual.

E. Small projects are not required to provide for rate control.

§ 260-305 Calculation methodology.

A. Any stormwater runoff calculations involving drainage areas greater than 200 acres and time of concentration (Tc) greater than 60 minutes, including on- and off-site areas, shall use generally accepted calculation techniques based on the NRCS soil-cover complex method.

B. Stormwater runoff from all development sites shall be calculated using either the modified rational method, a soil-cover-complex methodology, or other method acceptable to the City of Lancaster. Table III-1 summarizes acceptable computation methods. It is assumed that all methods will be selected by the design professional based on the individual limitations and suitability of each method for a particular development site.

TABLE III-1 Acceptable Computation Methodologies for Stormwater Management Plans
Method	Method Developed By	Applicability
TR-20 (or commercial computer package based on TR-20)	USDA NRCS	Applicable where use of full hydrology computer model is desirable or necessary
Win TR-55 (or commercial computer package based on TR-55)	USDA NRCS	Applicable for land development plans within limitations described in TR-55
HEC-1/HEC-HMS	US Army Corps of Engineers	Applicable where use of full hydrologic computer model is desirable or necessary
Modified Rational Method (or commercial computer package based on Rational Method)	Emil Kuichling (1889)	For development sites less than 200 acres, Tc < 60 minutes or as approved by the City of Lancaster
EFH2	USDA NRCS	Applicable in rural and undeveloped areas subject to the program limits
Other methods	Varies	Other methodologies approved by the City of Lancaster such as US EPA's Stormwater Management Model (SWMM)

C. If the SCS method is used, Antecedent Moisture Condition one is to be used in areas of carbonate geology, and Antecedent Moisture Condition 2 is to be used in all other areas. A NOAA Type C storm distribution shall be used in all areas.

D. If the Modified Rational Method is used, the National Oceanic and Atmospheric Administration (NOAA) Atlas 14 precipitation data (upper bound of 90% confidence interval) shall be used to determine the rainfall intensity for the appropriate time period.

E. Hydrographs may be obtained from NRCS methods such as TR-55, TR20, or from use of the "modified" or "unit hydrograph" Rational Methods. If "modified" or "unit hydrograph" Rational Methods are used, the ascending leg of the hydrograph shall have a length equal to three times the time of concentration (3 x Tc) and the descending leg shall have a length equal to seven times the time of concentration (7 x Tc).

F. Runoff calculations shall include a hydrologic and hydraulic analysis indicating volume and velocities of flow and the grades, sizes, and capacities of water carrying structures, sediment basins, retention and detention structures and sufficient design information to construct such facilities. Runoff calculations shall also indicate both predevelopment and postdevelopment rates for peak discharge of stormwater runoff from all discharge points.

G. For the purpose of calculating predevelopment peak discharges, all runoff coefficients, both on site and off site, shall be based on actual land use assuming summer or good land conditions. Postdevelopment runoff coefficients for off-site discharges used to design conveyance facilities shall be based on actual land use assuming winter or poor land conditions.

H. Criteria and assumptions to be used in the determination of stormwater runoff and design of management facilities are as follows:

(1) Runoff coefficients (C) shall be based on the information contained in Appendix B-1[1] if the actual land use is listed. If the actual land use is not listed in Appendix B-1, runoff coefficients shall be chosen from other published documentation, and a copy of said documentation shall be submitted with the SWM site plan.

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

(2) Runoff curve numbers (CN) shall be based on NRCS' Urban Hydrology for Small Watersheds (TR-55) or the most current PA DEP Post-construction Stormwater Management Spreadsheet (derived from TR-55).

(3) Times of concentration (Tc) shall be calculated based on the methodologies contained in Chapter 3 of TR-55 and the following design parameters:

(a) Sheet flow: The maximum length for each reach of sheet or overland flow before shallow concentrated or open channel flow develops is 100 feet. Flow lengths shall be justified based on the actual conditions at each development site. Sheet flow may be determined using the nomograph in Appendix B-2[2] when using the Modified Rational Method, or the Manning's kinematic solution using Equation 3-3 in Chapter 3 of TR-55.

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

(b) Shallow concentrated flow: Travel time for shallow concentrated flow shall be determined using Figure 3-1 and Equation 3-1 from TR-55, Urban Hydrology for Small Watersheds.

(c) Open channel flows: At points where sheet and shallow concentrated flows concentrate in field depressions, swales, gutters, curbs, or pipe collection systems, the travel times to downstream end of the development site between these design points shall be based upon Manning's Equation (Eq. 3-4 from TR-55) and/or acceptable engineering design standards as determined by the Municipal Engineer.

(4) The applicant may use stormwater credits for nonstructural BMPs in accordance with the BMP Manual. The allowable reduction will be determined by the City of Lancaster.

(5) Peak rate control is not required for off-site runoff. Off-site runoff may be bypassed around the site provided all other discharge requirements are met. If off site runoff is routed through rate control facilities, runoff coefficients for off-site discharges used to design those rate control facilities shall be based on actual land use assuming winter or poor land conditions.

I. Times of concentration (Tc) shall be calculated based on the methodology recommended in the respective model used, except that Tc for channel and pipe flow shall be computed using Manning's Equation. Supporting documentation and calculations must be submitted for review and approval.

§ 260-306 Riparian corridors.

A. In order to protect and improve water quality, a riparian corridor easement and vegetation management plan shall be created and recorded as part of any subdivision, land development, or large stormwater project that encompasses a riparian corridor.

B. As required by Pa. Code Chapter 102, the riparian corridor easement shall be measured to the limit of the 100-year floodplain, or 35 feet from the top of the streambank (on each side), whichever is greater.

C. Minimum management requirements for riparian corridors.

(1) Riparian corridor vegetation shall be assessed and reported per § 273-10B regarding tree appraisal requirements. Existing native vegetation shall be protected and maintained within the riparian corridor easement.

(2) Whenever practicable invasive vegetation shall be actively removed and the riparian corridor 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. Invasive species management shall be required when invasive species reach either 10% of riparian corridor area coverage or 10% of total plant numbers.

D. The riparian corridor easement shall be enforceable by the City of Lancaster and shall be recorded in the Lancaster County Recorder of Deeds Office, so that it shall run with the land and shall limit the use of the property located therein. The easement shall allow for the continued private ownership and shall count toward the minimum lot area as required by Zoning, unless otherwise specified in the City Zoning Ordinance.[1]

[1] Editor's Note: See Ch. 300, Zoning.

E. Any permitted use within the riparian corridor easement shall be conducted in a manner that will maintain the extent of the existing 100-year floodplain, improve or maintain the stream stability, and preserve and protect the ecological function of the floodplain, and shall be in accordance with the provisions of all applicable City codes and ordinances including but not limited to Chapter 109, Building Construction and Floodplain Management, and Chapter 300, Zoning.

F. The following conditions shall apply when public and/or private recreation trails are permitted within riparian corridors:

(1) Trails shall be for nonmotorized use only and shall be constructed of permeable materials when feasible.

(2) Trails shall be designed to have the least impact on native plant species and other sensitive environmental features (e.g., wetlands, streams, lakes, ponds and other waterbodies, existing drainage courses, karst features).

G. Septic drainfields and sewage disposal systems shall not be permitted within the riparian corridor easement and shall maintain a minimum distance of 100 feet from the top of streambank. This provision shall not relieve any person from complying with all other City ordinances governing sewers, sewer systems and sewage disposal.