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<br />B.
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<br />Design Slrllle~' Recomll1elltllltioll~
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<br />After review cflhl' advantages and disadvantages ofa variety of storm water storage and conveyance
<br />options, the Advisory Board selected a design strategy which inc1ude dlocal,neighhorhood, and regional
<br />components. When developing the design strategy, the Advisory Board recognized the stratcl0 may nol
<br />be applicable to all situation.. and ,,>;ceptian, should be made for special conditions or cases. Fur
<br />example, if regional detention facilities unreasonably burden onc landowner, multiple parallel ponds
<br />with unit release rates maybe substilutcd
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<br />Analysis of the jurisdictional and land use maps of the study area sugge~1s the study
<br />TOughly divided into Cily of Lafayette, open space areas, and Eric Planning Area,
<br />conveyance improvements will differ in each ofthesejurisdic!ions
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<br />area may be
<br />Stormwater
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<br />I. City of Lafayette
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<br />The City of Lafayette has indicated small, non. regional detention facilities will primarily be used for
<br />stonnwater control in the study area Small detention facilities cannot be evaluated accurately with the
<br />hydrologic model of the scale used in this study, Therefore, no ahernative evaluation ofstonnwater
<br />control for lands located within the City of Lafayette city limits will be made, and it is assumed
<br />hydrographsrepres.enta!ive of future conditions will leave the cit y limits undetained,
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<br />2. Open Space Areas
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<br />The design .1rategy for large open space areas relatively unaffected by development is to minimize
<br />stormwater improvements in these areas, Detention facilities will be used to take advamage of
<br />inadvertenl ddentiun upstream of road croSSing:; to reduce culvert sizes and attenuate flood peaks
<br />Conveyance will maintain natural channel and floodplains in undeveloped open space areas and, when
<br />the open space area is slightly impacted by development, a 2.year stable channel will beconstfllcted
<br />while the natural lloodplain will be maintained
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<br />J. EriePlanningArtll.
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<br />The design strategy within the Erie Planning Area recognize~ a variety of con~traims within the area,
<br />including such items as existing developmems, existing stOflnwater infrastructure, flooding problems,
<br />activ,; "moving target d<,vdopnlt'nl", planning lim;tatio!ls (such as ma.\imizing available land, zoned for
<br />commercial use), and lands which could be rca~onably used for drainage facilitics. The overall dramage
<br />design strategy which will be followed in the f>lanning Area is summarized in Table 12 below
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<br />C. AllernaleAnalysis
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<br />,\Iternate stormwater conveyance systems I.'.cre designed to help conyev flood flows safely and reduce
<br />projected tuture loo-year rlondpeak magnimdcs to rhose of existing conditions, AltcfTlate SlOrmwater
<br />cOI1\'evance systems were rested by modifYing the future c"n<.!iti wlhydwlogic ~I(,del
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<br />Table 12. Drainage Desi1i:n Guidelines f'or Erie Planning Area.
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<br />f)elentionf;,ciliti""
<br />. Local detention limit to p~ved are~s 0.5 acre or larger. or. in conjunction with water quality (along with
<br />.\1DCIA (minimize directly connected impervious areas) lit mdustrial areas,
<br />. Neighborhood detention in parks: provide detention volume for the IO-ye~r event and water quality, u,e
<br />owrtlow spillway for cvent, greater than the lO-yoarevent, flow depths in pOl1ds less than S.fecr and no I
<br />crickle channolto be compatible with park. design dovmstream conveyance to safely convey full lOO-year
<br />d!Scharge
<br />. Regional detCl\tion facilities use for flood peak reduction from the minor and major ove"t
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<br />Con"'ryuncePucilitie..
<br />. Preserve lOO-yeartloodplam for Coal Creek and BouldnCreek
<br />. Do not use hard cbannels,
<br />. Open space areas:
<br />. maintain naturnl channel and floodplains in undeveloped open space areas
<br />. construct 2-yearstable channel in partially developed open space areas and mamtain natural
<br />floodplain,
<br />. Sllbdivision(moderateandhighdensitydevclopmonlS)andcommercialand industrial areas;
<br />. encourage MDCIA (minimize dllectly connected impervious areas) on lot, but provide nO credit
<br />for runoff reduction,
<br />. strects (major storm) and stann sewers (minor storms) convey drainage in (atchm~nt areas of!
<br />appro~imately20acre, I
<br />. curb and gutter for all Slreets, .
<br />. top offoundationsrobea minimum of l.foot above the top of curb or 6-inches abo vethe majof'
<br />storm strecrdisch"rge. whichever is gre,1ter,
<br />. grass lined ~wales for conveyance of discharges from Catchment areas great~' than approximately i
<br />20~in~. I
<br />. S\Jbdivision (low density),
<br />. roadside swales and MDCIA mctho<fs or storm sewers ~nd neighborhood detention fucilities; no
<br />credit should be given for runoff reduction.
<br />. for homes within 50.fe<.Jtoftheroad.topoffoundalionstobe"tl~ast6-inchesabovetlleelevation
<br />efthe major storm street di,ch.rge.
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<br />Rt'adw/l.y (md RuilrOl,d Crt'... Flow
<br />. When possible, in ro.1dways, combine cuh'en with detention for lOO-yeal event, rele"se at appro\imMely
<br />the flood peak of the IO-yearfutl1f~evcnt,
<br />. Establish wetklnd in detention are. when possible
<br />. Design roads to function.s ~n emergencvoverflow 5plllwaywhich can possthe lOO-ye~r event at. depth
<br />of less tha.o one foot
<br />. D~sign all railroad crossmgs to convey th~ IOO.year ~vellt followmg railro.1d guidelines
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<br />l'ron..-Catd,m"f1tJJivCT_,-jOn.<
<br />. Consider when there is substantial discharge onto dc\'eloped landsw ithoul a defined fl(!\'i path
<br />. U..,asalastresen
<br />. Utilize flow limiters so thJt onl" des'l;Il flows will be diwf1ed (hkher d,scharges to follow histo/le flow
<br />path)
<br />. Obtain legal epinion priOl to constnletlOl1
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<br />IV.]
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