<br />I
<br />I EXTRAN results indicate the water surface elevation upstream of the Centre A venue embankment
<br />I would be 4993,3 ft, NGYD, Maximum ponded water surface elevations for all return periods,
<br />upstream of both Centre A venue and the BNRR, are summarized in Table 4,2, The water surface
<br />I elevations presented in the table were used as input to the post-project condition HEC-2 models,
<br />in the form of rating curves upstream of Centre A venue and the BNRR,
<br />I Table 4,2 Summary of Pre- and Post-Project Condition Maximum Ponded Water Surface
<br /> Elevations, as Computed by EXTRAN,
<br />I Maximum Ponded Water Surface Elevation (ft, NGVD),
<br /> Return Period Upstream of the lndicated Embankment
<br />I (Years) BNRR Centre Avenue
<br /> Pre-Project I Post-Project Pre-Project I Post-Project
<br />I 10 4989,2 . 4989,0 4989,3 i 4989,8
<br /> 50 4992,2 , 4992.1 4992,5 I 4992,0
<br /> 100 4993,5 I 4993.4 4993,5 I 4993,3
<br />I 500 4995,8 I 4995,7 4995,8 I 4996,3
<br />I The lOO-year post -project condition discharge through the BNRR embankment is 1,487 cfs,
<br />I This represents a reduction of 7 cfs from the pre-project condition discharge computed by the
<br />calibrated EXTRAN model. Table 4,3 summarizes the maximum release rates from the BNRR
<br />I pond for all four return periods analyzed, In all cases, the result is a reduction in downstream
<br />discharge, EXTRAN output for all post-project condition analyses is provided in Section A ofthe
<br /> Technical Addendum,
<br />I
<br /> Table 4,3 Summary of Pre- and Post-Project Condition Peak Release Rates, as Computed by
<br />I EXTRAN,
<br />I Return Period Maximum Release Rate (cfs),
<br /> from the BNRR Detention Pond
<br /> (Years) Pre-Project Post-Project
<br />I 10 970 951
<br /> 50 1,333 1,322
<br />I 100 1.494 1,487
<br /> 500 1,758 1,750
<br />I
<br />I T- OPEN'cocsrtD1"'col,:srtU1 fcma-LOMR final~rpL\\pJ 19 ANdERSON CONsulTiNG ENGiNEERS, INC.
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