03/04/1996 Park Board Packet - Laserfiche WebLink

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r ,,frond information. In London Grove To%vnship. Pennsylvania, ft)r e_xample, the stormwater plan contains Riper Forest Buffer ,fr1 anal},sis of stormwater flour, thermal im- pacts, runoff quality, erosion and sedimenta- RoarioAForest Buffer tion. and groundwater recharge. It further contains a delineation of the outcrop area of Cockeysville Ltarble, a high yielding aquifer sro+a. � � that is vulnerable to groundwater contami- nation. The selection of management prac- tices considers the origins of stormwater(di- I vided into three harmfulness classes) and Cram Fmd Trench ' seems the classifications of streams in the township as Lif.d spreemler as cold water fishery streams, some with exceptional value," and others as trout stocking streams. Figure 6.The"wooded riparian forest buffer"shades the headwater Setting stutdar& stream and keeps it cool.Concentrated storm flows are reconverted to sheet flow through a level spreader and infiltrated in part before they Municipalities have the legal authority to reach the stream. set standards that relate to public health, safety, and environmental quality. Standards are numerical thresholds that separate ac- relates to, and implements, the stormwater ceptable and unacceptable impacts. A stan- plan. It should contain a statement of find- dard that most municipalities have in their ings, explain its legal base, and set forth de- books is that pre-development runoffpeak sign standards and criteria. The ordinance flows not exceed post-developmeaL.peak should come into play whenever a change flows. In older to rotect streams a re- in land use is being sought, giving the de- source, ere need to he additional Stan- veloper a comprehensive set of stormwater dardss—Gr the concerns described above. management requirements, management measures, and design standards and criteria. h A storl lwaUx IIlaila9 ordinance Before development can commence, the de- veloper should be required to make a plan Stormwater management requirements are submission that follows a defined format often part of the subdivision regulations of a and is subject to a review and approval municipality where, together with erosion process. Such a process should permit inter- and sediment control, they take up but a action between parties, and, if necessary, for few pages. In order to achieve clean stream modifications to be made to the plan. There goals, stormwater management should be should be defined permit requirements and addressed through a separate ordinance that procedures including guidelines for fees, a Attenuation at a acres Prior to Concentration Conveyance Pre-Treatment oentantion Eatentied oetention/ Infiltration for Peak R nten tic" for for Reonarpe Control Duality Control Saoondary Impact Mltio If fe.p. Temperature control) Malntenanc• Figure 7.Components of a stormwater management system. JANUARY-FEBRUARY 1994 19