This chapter shall be known and may be cited as the "City of Allentown's (Act 167) Stormwater Management Ordinance," which includes a portion of the following watersheds: Jordan Creek, Little Lehigh Creek, Monocacy Creek, and Lehigh River Subbasins.
The governing body of the municipality finds that:
A.
Inadequate management of accelerated runoff of stormwater resulting from development throughout a watershed increases flood flows and velocities, contributes to erosion and sedimentation, changes the natural hydrologic patterns, destroys aquatic habitat, elevates aquatic pollutant concentrations and loadings, overtaxes the carrying capacity of streams and storm sewers, greatly increases the cost of public facilities to carry and control stormwater, undermines floodplain management and flood-control efforts in downstream communities, reduces groundwater recharge, and threatens public health and safety.
B.
A comprehensive program of stormwater management, including reasonable regulation of development and activities causing accelerated erosion and loss of natural infiltration, is fundamental to the public health, safety and welfare and the protection of the people of the municipality and all of the people of the commonwealth, their resources and the environment.
C.
Stormwater can be an important resource by providing groundwater recharge for water supplies and baseflow of streams, which also protects and maintains surface water quality.
D.
Public education on the control of pollution from stormwater is an essential component in successfully addressing stormwater.
E.
Federal and state regulations require certain municipalities to implement a program of stormwater controls. These municipalities are required to obtain a permit for stormwater discharges from their separate storm sewer systems under the National Pollutant Discharge Elimination System (NPDES).
F.
Nonstormwater discharges to municipal separate storm sewer systems can contribute to pollution of waters of the commonwealth by the municipality.
The purpose of this chapter is to promote the public health, safety and welfare within the City by minimizing the damages and maximizing the benefits described in § 538-2 of this chapter by provisions designed to:
A.
Manage stormwater runoff impacts at their source by regulating activities which cause such problems.
B.
Utilize and preserve the desirable existing natural drainage systems.
C.
Encourage infiltration of stormwater, where appropriate, to maintain groundwater recharge, to prevent degradation of surface water and groundwater quality and to otherwise protect water resources.
D.
Maintain the existing flows and quality of streams and watercourses in the municipality and the commonwealth.
E.
Preserve and restore the flood-carrying capacity of streams.
F.
Provide for proper maintenance of all permanent stormwater management BMPs that are implemented in the municipality.
G.
Provide review procedures and performance standards for stormwater planning, design and management.
H.
Manage stormwater impacts close to the runoff source which requires a minimum of structures and relies on natural processes.
I.
Meet legal water quality requirements under state law, including regulations at 25 Pa. Code Chapter 93.4a to protect and maintain existing uses and maintain the level of water quality to support those uses in all streams and to protect and maintain water quality in special protection streams.
J.
Prevent scour and erosion of stream banks and streambeds.
K.
Provide standards to meet the NPDES permit requirements.
A.
This chapter shall only apply to those areas of the City which are located within the Jordan Creek, Little Lehigh Creek, Monocacy Creek, and Lehigh River Subbasins Watershed(s) as delineated on an official map available for inspection at the municipal office.
B.
The following activities are defined as regulated activities and shall be governed by this chapter:
(1)
Land development.
(2)
Subdivision.
(3)
Construction of new or additional impervious surfaces (driveways, parking lots, etc.).
(4)
Construction of new buildings or additions to existing buildings.
(5)
Diversion of piping of any natural or man-made stream channel.
(6)
Installation of stormwater systems or appurtenances thereto.
(7)
Regulated earth disturbance activities.
A.
Impervious cover. Any proposed regulated activity, except those defined in § 538-5B(5) and (6), which would create 10,000 square feet or less of additional impervious cover is exempt from the drainage plan preparation provisions of this chapter. All of the impervious cover added incrementally to a site above the initial 10,000 square feet shall be subject to the drainage plan preparation provisions of this chapter. If a site has previously received an exemption and is proposing additional development such that the total impervious cover on the site exceeds 10,000 square feet, the total impervious cover on the site proposed since the original ordinance date must meet the provisions of this chapter.
(1)
The date of the municipal ordinance adoption of the original Act 167 Stormwater Management Ordinance shall be the starting point from which to consider tracts as parent tracts in which future subdivisions and respective impervious area computations shall be cumulatively considered.
Watershed | Watershed Plan Date |
|---|---|
Jordan Creek | 5-1992 |
Little Lehigh Creek | 3-1988 |
Monocacy Creek | 9-1988 |
Lehigh River Subbasins | 2-1997 |
(2)
For development taking place in stages, the entire development plan must be used in determining conformance with these criteria.
(3)
Additional impervious cover shall include, but not be limited to, additional indoor living spaces, decks, patios, garages, driveways, storage sheds and similar structures, any roof, parking or driveway areas and any new streets and sidewalks constructed as part of or for the proposed regulated activity.
(4)
Any additional areas proposed to initially be gravel, crushed stone, porous pavement, etc., shall be assumed to be impervious for the purposes of comparison to the exemption criteria. Any existing gravel, crushed stone or hard packed soil areas on a site shall be considered as pervious cover for the purpose of exemption evaluation.
B.
Prior drainage plan approval. Any regulated activity for which a drainage plan was previously prepared as part of a subdivision or land development proposal that received preliminary plan approval from the municipality prior to the effective date of this chapter is exempt from the drainage plan preparation provisions of this chapter, except as cited in § 538-6C, provided that the approved drainage plan included design of stormwater facilities to control runoff from the site currently proposed for regulated activities consistent with ordinance provisions in effect at the time of approval and the approval has not lapsed under the Municipalities Planning Code. If significant revisions are made to the drainage plan after both the preliminary plan approval and the effective date of this chapter, preparation of a new drainage plan, subject to the provisions of this chapter, shall be required. Significant revisions would include a change in control methods or techniques, relocation or redesign of control measures or changes necessary because soil or other conditions are not as stated on the original drainage plan.
C.
These exemptions shall not relieve the applicant from implementing such measures as are necessary to protect health, safety, property, and state water quality requirements. These measures include adequate and safe conveyance of stormwater on the site and as it leaves the site. These exemptions shall not relieve the applicant from meeting the water quality standards in the ordinance for all development proposed since municipal adoption date of this chapter and the responsibility to secure required permits or approvals for activities regulated by any other applicable code, rule, act or ordinance.
Any ordinance of the municipality inconsistent with any of the provisions of this chapter is hereby repealed to the extent of the inconsistency only.
Should any section or provision of this chapter be declared invalid by a court of competent jurisdiction, such decision shall not affect the validity of any of the remaining provisions of this chapter.
Approvals issued pursuant to this chapter do not relieve the applicant of the responsibility to secure required permits or approvals for activities regulated by any other applicable code, rule, act or ordinance.
Notwithstanding any provisions of this chapter, including exemption and waiver provisions, 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. Such measures shall include such actions as are required to manage the rate, volume, direction and quality of resulting stormwater runoff in a manner which otherwise adequately protects health and property from possibly injury.
For the purposes of this chapter, certain terms and words used herein shall be interpreted as follows:
A.
Words used in the present tense include the future tense; the singular number includes the plural, and the plural number includes the singular; words of masculine gender include feminine gender; and words of feminine gender include masculine gender.
B.
The word "includes" or "including" shall not limit the term to the specific example but is intended to extend its meaning to all other instances of like kind and character.
C. ACCELERATED EROSION ACT 167 ACT 247 BEST MANAGEMENT PRACTICE (BMP) BEST MANAGEMENT PRACTICE OPERATIONS AND MAINTENANCE PLAN BIORETENTION BUFFER(1) (2) CAPTURE/REUSE CARBONATE BEDROCK CISTERN CITY CLOSED DEPRESSION CONSERVATION DISTRICT CONSTRUCTED WETLANDS CULVERT DAM DEP DESIGN STORM DETENTION BASIN DEVELOPER DEVELOPMENT SITE (SITE) DIFFUSED DRAINAGE DRAINAGE EASEMENT DRAINAGE PLAN EARTH DISTURBANCE ACTIVITY EROSION EXISTING USES FILL FILTER STRIPS FREEBOARD GROUNDWATER RECHARGE HARDSHIP WAIVER REQUEST HOT SPOT LAND USES HYDROLOGIC SOIL GROUP (HSG) IMPERVIOUS SURFACE (IMPERVIOUS COVER) INFILTRATION PRACTICE INFILTRATION STRUCTURE KARST LAND DEVELOPMENT(1) (a) (b) (2) (3) LOADING RATE LOCAL RUNOFF CONVEYANCE FACILITIES LOW-IMPACT DEVELOPMENT LVPC MAINSTREAM (MAIN CHANNEL) MANNING EQUATION (MANNING FORMULA) MARYLAND STORMWATER DESIGN MANUAL MINIMUM DISTURBANCE/MINIMUM MAINTENANCE PRACTICES (MD/MM) MUNICIPALITY NO-HARM OPTION NPDES NRCS OIL/WATER SEPARATOR OUTFALL OWNER PEAK DISCHARGE PENN STATE RUNOFF MODEL (PSRM) PERSON POINT SOURCE PRELIMINARY SITE INVESTIGATION PUBLIC WATER SUPPLIER PUBLIC WATER SYSTEM QUALIFIED GEOTECHNICAL PROFESSIONAL RATIONAL METHOD REACH RECHARGE VOLUME (REV) REGULATED ACTIVITIES REGULATED EARTH DISTURBANCE ACTIVITIES RELEASE RATE RETURN PERIOD ROAD MAINTENANCE RUNOFF SEDIMENT TRAPS/CATCH BASIN SUMPS SEEPAGE PIT/SEEPAGE TRENCH SEPARATE STORM SEWER SYSTEM SHEET FLOW SOIL-COVER COMPLEX METHOD SPECIAL GEOLOGIC FEATURES SPILL PREVENTION AND RESPONSE PROGRAM STATE WATER QUALITY REQUIREMENTS (1) (2) (3) STORAGE INDICATION METHOD STORM DRAINAGE PROBLEM AREAS STORM SEWER STORMWATER STORMWATER FILTERS STORMWATER MANAGEMENT PLAN STREAM SUBAREA SUBDIVISION SURFACE WATERS OF THE COMMONWEALTH SWALE TECHNICAL BEST MANAGEMENT PRACTICE MANUAL AND INFILTRATION FEASIBILITY REPORT, NOVEMBER 2002 TRASH/DEBRIS COLLECTORS VEGETATED BUFFERS VEGETATED ROOFS VEGETATED SWALES(1) (2) WATER QUALITY INSERTS WATER QUALITY VOLUME (WQv) WATERCOURSE WATERSHED WET DETENTION PONDS
The words "shall" and "must" are mandatory; the words "may" and "should" are permissive.
The removal of the surface of the land through the combined action of human activities and natural processes, at a rate greater than would occur because of the natural processes alone.
Act of October 4, 1978, P.L. 864, the "Storm Water Management Act."[1]
Act of 1968, P.L. 805, No. 247, "Pennsylvania Municipalities Planning Code."[2]
Activities, facilities, measures or procedures used to manage stormwater quantity and quality impacts from the regulated activities listed in § 538-5, to meet state water quality requirements, to promote groundwater recharge and to otherwise meet the purposes of this chapter.
Documentation, included as part of a drainage plan, detailing the proposed BMPs, how they will be operated and maintained and who will be responsible.
Densely vegetated, depressed features that store stormwater and filter it through vegetation, mulch, planting soil, etc. Ultimately stormwater is evapotranspirated, infiltrated, or discharged. Optimal bioretention areas mimic natural forest ecosystems in terms of species diversity, density, distribution, use of native plants, etc.
STREAMSIDE BUFFERA zone of variable width located along a stream that is vegetated and is designed to filter pollutants from runoff.
SPECIAL GEOLOGIC FEATURE BUFFERA required isolation distance from a special geologic feature to a proposed BMP needed to reduce the risk of sinkhole formation due to stormwater management activities.
Stormwater management techniques such as cisterns and rain barrels which direct runoff into storage devices, surface or subsurface, for later reuse, such as for irrigation of gardens and other planted areas. Because this stormwater is utilized and no pollutant discharge results, water quality performance is superior to other noninfiltration BMPs.
Rock consisting chiefly of carbonate minerals, such as limestone and dolomite; specifically, a sedimentary rock composed of more than 50% by weight of carbonate minerals that underlies soil or other unconsolidated, superficial material.
An underground reservoir or tank for storing rainwater.
City of Allentown.
A distinctive bowl-shaped depression in the land surface. It is characterized by internal drainage, varying magnitude, and an unbroken ground surface.
The Lehigh County Conservation District.
Constructed wetlands are similar to wet ponds (see below) and consist of a basin which provides for necessary stormwater storage as well as a permanent pool or water level, planted with wetland vegetation. To be successful, constructed wetlands must have adequate natural hydrology (both runoff inputs as well as soils and water table which allow for maintenance of a permanent pool of water). In these cases, the permanent pool must be designed carefully, usually with shallow edge benches, so that water levels are appropriate to support carefully selected wetland vegetation.
A pipe, conduit or similar structure including appurtenant works which carries surface water.
An artificial barrier, together with its appurtenant works, constructed for the purpose of impounding or storing water or another fluid or semifluid or a refuse bank, fill or structure for highway, railroad or other purposes which does or may impound water or another fluid or semifluid.
The Pennsylvania Department of Environmental Protection.
The depth and time distribution of precipitation from a storm event measured in probability of occurrence (e.g., 100-year storm) and duration (e.g., twenty-four-hour) and used in computing stormwater management control systems.
A basin designed to retard stormwater runoff by temporarily storing the runoff and releasing it at the appropriate release rate.
A person, partnership, association, corporation or other entity, or any responsible person therein or agent thereof, that undertakes any regulated activity of this chapter.
The specific tract of land for which a regulated activity is proposed.
See "sheet flow."
A right granted by a land owner to a grantee, allowing the use of private land for stormwater management purposes.
The documentation of the proposed stormwater quantity and quality management controls to be used for a given development site, including a BMP operations and maintenance plan, the contents of which are established in § 538-21.
A construction or other human activity which disturbs the surface of the land, including, but not limited to, clearing and grubbing, grading, excavations, embankments, road maintenance, building construction and the moving, depositing, stockpiling or storing of soil, rock or earth materials.
The removal of soil particles by the action of water, wind, ice, or other geological agents.
Those uses actually attained in the water body on or after November 28, 1975, whether or not they are included in the water quality standards. (25 Pa. Code Chapter 93.)
Man-made deposits of natural soils or rock products and waste materials.
See "vegetated buffers."
The incremental depth in a stormwater management structure, provided as a safety factor of design, above that required to convey the design runoff event.
Replenishment of existing natural underground water supplies.
A written request for a waiver alleging that the provisions of this chapter inflict unnecessary hardship upon the applicant. A hardship waiver does not apply to and is not available from the water quality provisions of this chapter and should not be granted.
A land use or activity that generates higher concentrations of hydrocarbons, trace metals or other toxic substances than typically found in stormwater runoff. These land uses are listed in § 538-15P.
Soils are classified into four HSGs (A, B, C and D) to indicate the minimum infiltration rates, which are obtained for bare soil after prolonged wetting. The Natural Resources Conservation Service (NRCS) of the U.S. Department of Agriculture defines the four groups and provides a list of most of the soils in the United States and their group classification. The soils in the area of the development site may be identified from a soil survey report that can be obtained from local NRCS offices or conservation district offices. Soils become less permeable as the HSG varies from A to D.
A surface which prevents the percolation of water into the ground.
A practice designed to direct runoff into the ground, e.g., French drain, seepage pit, seepage trench or bioretention area.
A structure designed to direct runoff into the ground, e.g., French drain, seepage pit, seepage trench or bioretention area.
A type of topography or landscape characterized by depressions, sinkholes, limestone towers and steep-sided hills, underground drainage and caves. Karst is usually formed on carbonate rocks, such as limestones or dolomites and sometimes gypsum.
Any of the following activities:
The improvement of one lot or two or more contiguous lots, tracts or parcels of land for any purpose involving:
A group of two or more residential or nonresidential buildings, whether proposed initially or cumulatively, or a single nonresidential building on a lot or lots regardless of the number of occupants or tenure; or
The division or allocation of land or space, whether initially or cumulatively, between or among two or more existing or prospective occupants by means of or for the purpose of streets, common areas, leaseholds, condominiums, building groups or other features.
A subdivision of land.
Development in accordance with Section 503(1) of the Pennsylvania Municipalities Planning Code.[3]
The ratio of the land area drainage to the system, as modified by the weighting factors in § 538-18B, compared to the base area of the infiltration system.
Any natural channel or man-made conveyance system which has the purpose of transporting runoff from the site to the mainstream.
A development approach that promotes practices that will minimize post-development runoff rates and volumes thereby minimizing needs for artificial conveyance and storage facilities. Site design practices include preserving natural drainage features, minimizing impervious surface area, reducing the hydraulic connectivity of impervious surfaces and protecting natural depression storage.
Lehigh Valley Planning Commission of Lehigh and Northampton Counties.
Any stream segment or other conveyance used as a reach in any given watershed hydrologic model.
A method of calculation of velocity of flow (e.g., feet per second) and flow rate (e.g., cubic feet per second) in open channels based upon channel shape, roughness, depth of flow and slope. "Open channels" may include closed conduits so long as the flow is not under pressure.
A stormwater design manual written by the Maryland Department of the Environment and the Center for Watershed Protection. As of January 2004, the manual can be obtained through the following website: www.mde.state.md.us.
Site design practices in which careful limits are placed on site clearance prior to development allowing for maximum retention of existing vegetation (woodlands and other), minimum disturbance and compaction of existing soil mantle and minimum site application of chemicals post-development. Typically, MD/MM includes disturbance setback criteria from buildings as well as related site improvements such as walkways, driveways, roadways, and any other improvements. These criteria may vary by community context as well as by type of development being proposed. Additionally, MD/MM also shall include provisions (e.g., deed restrictions, conservation easements) to protect these areas from future disturbance and from application of fertilizers, pesticides, and herbicides.
City of Allentown, Lehigh County, Pennsylvania.
The option of using a less restrictive runoff quantity control if it can be shown that adequate and safe runoff conveyance exists and that the less restrictive control would not adversely affect health, safety and property.
National Pollutant Discharge Elimination System.
Natural Resources Conservation Service, U.S. Department of Agriculture. (Formerly the Soil Conservation Service.)
A structural mechanism designed to remove free oil and grease (and possibly solids) from stormwater runoff.
"Point sources" as described in 40 CFR 122.2 at the point where the municipality's storm sewer system discharges to surface waters of the commonwealth.
One with an interest in and often dominion over a property.
The maximum rate of flow of stormwater runoff at a given location and time resulting from a specified storm event.
The computer-based hydrologic modeling technique adapted to each watershed for the Act 167 plans. The model was "calibrated" to reflect actual flow values by adjusting key model input parameters.
An individual, partnership, public or private association or corporation, firm, trust, estate, municipality, governmental unit, public utility or any other legal entity whatsoever which is recognized by law as the subject of rights and duties.
Any discernible, confined and discrete conveyance, including, but not limited to, any pipe, ditch, channel, tunnel or conduit from which stormwater is or may be discharged, as defined in state regulations at 25 Pa. Code § 92a.2.
[Amended at time of adoption of Code (see Ch. 1, General Provisions, Art. I)]
The determination of the depth to bedrock, the depth to the seasonal high water table and the soil permeability for a possible infiltration location on a site through the use of published data and on-site surveys. In carbonate bedrock areas, the location of special geologic features must also be determined along with the associated buffer distance to the possible infiltration area. See Appendix G.[4]
A person who owns or operates a public water system.
A system which provides water to the public for human consumption which has at least 15 service connections or regularly serves an average of at least 25 individuals daily at least 60 days out of the year. (See 25 Pa. Code Chapter 109.)
A licensed professional geologist or a licensed professional engineer who has a background or expertise in geology or hydrogeology.
A method of peak runoff calculation using a standardized runoff coefficient (rational "c"), acreage of tract and rainfall intensity determined by return period and by the time necessary for the entire tract to contribute runoff. The rational method formula is stated as follows: Q = ciA, where "Q" is the calculated peak flow rate in cubic feet per second, "c" is the dimensionless runoff coefficient (see Appendix C[5]), "i" is the rainfall intensity in inches per hour, and "A" is the area of the tract in acres.
Any of the natural or man-made runoff conveyance channels used for watershed runoff modeling purposes to connect the subareas and transport flows downstream.
The portion of the water quality volume (WQv) used to maintain groundwater recharge rates at development sites. (See § 538-15J.)
Actions or proposed actions which impact upon proper management of stormwater runoff and which are governed by this chapter as specified in Article IV.
Each disturbance activity other than agricultural plowing or tilling of one acre or more with a point source discharge to surface waters or to the municipality's storm sewer system or earth disturbance on any portion of, part or during any stage of a larger common plan of development.
The percentage of the predevelopment peak rate of runoff for a development site to which the post-development peak rate of runoff must be controlled to avoid peak flow increases throughout the watershed.
The average interval in years over which an event of a given magnitude can be expected to recur. For example, the twenty-five-year return period rainfall or runoff event would be expected to recur on the average once every 25 years.
Earth disturbance activities within the existing road cross section such as grading and repairing existing unpaved road surfaces, cutting road banks, cleaning or clearing drainage ditches and other similar activities.
That part of precipitation which flows over the land.
Chambers which provide storage below the outlet in a storm inlet to collect sediment, debris and associated pollutants, typically requiring periodic cleanout.
An area of excavated earth filled with loose stone or similar material and into which surface water is directed for infiltration into the ground.
A conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels or storm drains) primarily used for collecting and conveying stormwater runoff.
Stormwater runoff flowing in a thin layer over the ground surface.
A method of runoff computation developed by NRCS which is based upon relating soil type and land use/cover to a runoff parameter called a "Curve Number."
Carbonate bedrock features, including but not limited to closed depressions, existing sinkholes, fracture traces, lineaments, joints, faults, caves, pinnacles and geologic contacts between carbonate and noncarbonate bedrock which may exist and must be identified on a site when stormwater management BMPs are being considered.
A program that identifies procedures for preventing and, as needed, cleaning up potential spills and makes such procedures known and the necessary equipment available to appropriate personnel.
As defined under state regulations, protection of designated and existing uses (see 25 Pa. Code Chapters 93 and 96), including:
Each stream segment in Pennsylvania has a designated use, such as "cold water fishery" or "potable water supply," which is listed in Chapter 93. These uses must be protected and maintained under state regulations.
"Existing uses" are those attained as of November 1975, regardless of whether they have been designated in Chapter 93. Regulated earth disturbance activities must be designed to protect and maintain existing uses and maintain the level of water quality necessary to protect those uses in all streams and to protect and maintain water quality in special protection streams.
Water quality involves the chemical, biological and physical characteristics of surface water bodies. After regulated earth disturbance activities are complete, these characteristics can be impacted by addition of pollutants such as sediment, and changes in habitat through increased flow volumes and/or rates as a result of changes in land surface area from those activities. Therefore, permanent discharges to surface waters must be managed to protect the stream bank, streambed and structural integrity of the waterway to prevent these impacts.
A method of routing or moving an inflow hydrograph through a reservoir or detention structure. The method solves the mass conservation equation to determine an outflow hydrograph as it leaves the storage facility.
Areas which lack adequate stormwater collection and/or conveyance facilities and which present a hazard to persons or property. These areas are either documented in Appendix B[6] of this chapter or identified by the municipality or Municipal Engineer.
A system of pipes or other conduits which carries intercepted surface runoff, street water and other wash waters, or drainage, but excludes domestic sewage and industrial wastes.
The surface runoff generated by precipitation reaching the ground surface.
Any number of structural mechanisms such as multichamber catch basins, sand/peat filters, sand filters, and so forth which are installed to intercept stormwater flow and remove pollutants prior to discharge. Typically, these systems require periodic maintenance and cleanout.
The plan for managing stormwater runoff adopted by Lehigh County for watersheds situated within the City as required by the Act of October 4, 1978, P.L. 864, (Act 167), as amended, and known as the "Storm Water Management Act."
A watercourse.
The smallest unit of watershed breakdown for hydrologic modeling purposes for which the runoff control criteria have been established in the stormwater management plan.
The division or redivision of a lot, tract or parcel of land by any means into two or more lots, tracts, parcels or other divisions of land including changes in existing lot lines for the purpose, whether immediate or future, of lease, partition by the court for distribution to heirs or devisees, transfer of ownership or building or lot development; provided, however, that the subdivision by lease of land for agricultural purposes into parcels of more than 10 acres, not involving any new street or easement of access or any residential dwelling, shall be exempted.
Any and all rivers, streams, creeks, rivulets, impoundments, ditches, watercourses, storm sewers, lakes, dammed water, wetlands, ponds, springs and all other bodies or channels of conveyance of surface water, or parts thereof, whether natural or artificial, within or on the boundaries of this commonwealth.
A low-lying stretch of land which gathers or carries surface water runoff. See also "vegetated swale."
The report written by Cahill Associates that addresses the feasibility of infiltration in carbonate bedrock areas in the Little Lehigh Creek Watershed. The report is available at the Lehigh Valley Planning Commission offices.
Racks, screens or other similar devices installed in a storm drainage system to capture coarse pollutants (trash, leaves, etc.).
Gently sloping areas that convey stormwater as sheet flow over a broad, densely vegetated earthen area, possibly coupled with the use of level spreading devices. Vegetated buffers should be situated on minimally disturbed soils, have low-flow velocities and extended residence times.
Vegetated systems installed on roofs that generally consist of a waterproof layer, a root-barrier, drainage layer (optional), growth media, and suitable vegetation. Vegetated roofs store and eventually evapotranspirate the collected rooftop rainfall; overflows may be provided for larger storms.
Vegetated earthen channels designed to convey stormwater. These swales are not considered to be water quality BMPs.
Broad, shallow, densely, vegetated, earthen channels designed to treat stormwater while slowly infiltrating, evapotranspirating, and conveying it. Swales should be gently sloping with low-flow velocities to prevent erosion. Check dams may be added to enhance.
Any number of commercially available devices that are inserted into storm inlets to capture sediment, oil, grease, metals, trash, debris, etc.
The volume needed to capture and treat 90% of the average annual rainfall volume. (See § 538-15B.)
Any channel of conveyance of surface water having defined bed and banks, whether natural or artificial, with perennial or intermittent flow.
The entire region or area drained by a river or other body of water, whether natural or artificial.
Basins that provide for necessary stormwater storage as well as a permanent pool of water. To be successful, wet ponds must have adequate natural hydrology (both runoff inputs as well as soils and water table which allow for maintenance of a permanent pool of water) and must be able to support a healthy aquatic community so as to avoid creation of mosquito and other health and nuisance problems.
[4]
Editor's Note: Said appendix is included as an attachment to this chapter.
[5]
Editor's Note Said appendix is available from the City offices.
[6]
Editor's Note: Said appendix is available from the City offices.
