As used in this chapter, the following terms shall have the meanings indicated:
The Board of Supervisors (BOS) of the Township of Lehigh, Northampton County.
An underground reservoir or tank for storing rainwater.
The Northampton County Conservation District.
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 (formerly the Pennsylvania Department of Environmental Resources).
The magnitude of precipitation from a storm event measured in probability of occurrence (e.g., fifty-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 a predetermined rate.
A person, partnership, association, corporation or other entity, or any responsible person therein or agent thereof, that undertakes any regulated activity as defined in § 138-4 of this chapter.
The specific tract of land for which a regulated activity is proposed.
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 management controls, if any, to be used for a given development site, the contents of which are established in § 138-18.
The removal of soil particles by the action of water, wind, ice, or other geological agents.
The incremental depth of a stormwater management structure, provided as a safety factor of design, above that required to control or convey the design runoff event.
Replenishment of existing natural underground water supplies.
The area comprised of the Hokendauqua Creek Watershed and Lehigh River Sub-Basin 3 (Dry Run and four direct drainage subareas). See map in Appendix A[1] (provides area located within Lehigh Township only).
A surface which prevents the percolation of water into the ground.
A structure designed to direct runoff into the ground (e.g., French drain, seepage pit or seepage trench).
Any natural channel or manmade conveyance system which has the purpose of transporting runoff from the site to the mainstem.
Any stream segment or other conveyance in a Single Release Rate, Dual Release Rate or Conditional No Detention I subarea used as a reach in any DEP approved Act 167 study area hydrologic model. In Conditional No Detention II subareas the main channel is the Lehigh River.
A method for 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.
Lehigh Township, Northampton County, Pennsylvania.
National Pollutant Discharge Elimination System Regulations.
U.S. Department of Agriculture (formerly the Soil Conservation Service).
The maximum rate of flow of storm runoff at a given point and time resulting from a specified storm event.
The computer-based hydrologic modeling technique adapted to the Watershed for the Act 167 Plan. The model has been "calibrated" to reflect actual recorded flow values by adjusting key model input parameters.
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 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[2]), "i" is the rainfall intensity in inches per hour, and "A" is the area of the tract in acres.
Any natural or man-made runoff conveyance channels used for modeling purposes to connect subareas and transport flows downstream.
Actions or proposed actions which impact upon proper management of stormwater runoff and which are governed by this chapter as specified in § 138-4.
The percentage of the predevelopment peak rate of runoff for a development site to which the postdevelopment peak rate of runoff must be controlled to protect downstream areas.
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.
That part of precipitation which flows over the land.
The former Soil Conservation Service, U.S. Department of Agriculture, now known as the "NRCS."
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 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."
A reservoir routing procedure based on solution of the continuity equation (inflow minus outflow equals the change in storage for a give time interval) and based on outflow being a unique function of storage volume.
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 the applicable Act 167 stormwater management reports 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.
Any plan for managing stormwater runoff adopted by Northampton County for a watershed as required by the Act of October 4, 1978, P.L. 864 (Act 167), and known as the "Storm Water Management Act."
[3]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, transfer of ownership or building or lot development.
A low-lying stretch of land which gathers or carries surface water runoff.
Lehigh Township, Northampton County.
The area comprised of the Trout/Bertsch Creek Watershed and Lehigh River Sub-Basin 1 (three unnamed creeks and direct drainage areas). See map in Appendix B[4] (provides area located in Lehigh Township only).
Any channel of conveyance of surface water having defined bed and banks, whether natural or artificial, with perennial or intermittent flow.
[1]
Editor's Note: Appendix A is included at the end of this chapter.
[2]
Editor's Note: Appendix C is included at the end of this chapter.
[3]
Editor's Note: See 32 P.S. § 680.1 et seq.
[4]
Editor's Note: Appendix B is included at the end of this chapter.