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<br />discharges and the effective hydrology. The revised hydrologic analysis resulted in a base flood
<br />discharge of approximately 580 cfs for the project reach.
<br />
<br />The effective HEC-2 hydraulic model was imported into the 'HEC-RAS model using the effective
<br />discharges to create a duplicate effective model. The duplicate effective BFEs matched the effective
<br />BFEs in the FIS report within 0.1 foot. For comparison purposes, the revised discharges were inserted
<br />, into the duplicate effective model to replace the effective discharges. Our review revealed that, as a result
<br />of the decreasing discharges, the, BFEs will decrease in all locations. The maximum decrease in BFE, 1.1
<br />feet, occurred approximately 1,600 feet upstream of the Ermine I;3oulevard Northwest Culvert. ,
<br />
<br />The existing conditions (corrected effective) model was created by incorporating updated topographic
<br />information into the duplicate effective model (with revised discharges). Our review of the corrected
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<br />effective model revealed that the BFEs both increased and decreased compared to the BFEs in the
<br />duplicate effective model (with revised discharges). Themaximum increase in BFE, 0.5 foot; occurred
<br />approximately 1,500 feet upstream of the Ermine Boulevard Northwest Culvert. The maximum decrease
<br />in BFE, 0.7 foot, occurred just downstream of the Ermine Boulevard Northwest Culvert,
<br />
<br />The proposed conditions model was created by replacing the existing 7'2. inch culvert at
<br />Ermine Boulevard Northwestwiththe proposed single 14-feet span by 6-feet rise culvert. Our review of
<br />~he proposed conditions model revealed that the BFEs both increased and decreased compared to the
<br />BFEs in the corrected effective model. The maximum increase in BFE, 0.01 foot, occurred approximately
<br />60 feet downstream of the Ermine Boulevard Northwest culvert. rhe ma,ximum decrease in BFE, 0.7
<br />foot,loccurred approximately 70 feet upstream oft~e Ermine Boulevard Northwest Culvert.
<br />
<br />As a result of the revised hydrolbgic analysis, the updated topographic information, and the proposed
<br />project, the BFEs will decrease compared to the duplicate effective (with effective discharges) BFEs. The
<br />maximum decrease in BFE, 1.1 feet, occurred just downstream of the Ermine Boulevard Northwest
<br />~~ .'
<br />
<br />As a result of the revised hydrologic analysis, the updated topographic information, and the proposed
<br />,project; the BFEs will decrease compared to the duplicate effective (with revised discharges) BFEs. The
<br />maximum decrease in BFE, 0.7 foot, ()ccu~edjust downstream of the Ermine Boulevard Northwest
<br />culvert.
<br />
<br />As a result of the revised hydrologic analysis, the updated topographic information, and the proposed
<br />project, the width of the SFHA will increase in some areas and decrease in other areas compared to the
<br />effective SFHA width along Trott Brook. The maximum increase in SFHA width, approximately 360
<br />feet, will occur just downstream of Ermine Boulevard Northwest. The maximum decrease in SFHA
<br />width, approximately 400 feet, will occur approximately 100 feet upstream of the Ermine Boulevard
<br />Northwest Culvert.
<br />
<br />As a result of the revised hydrologic analysis, the updated topographic information, and the proposed
<br />project, the floodway width will increase in some areas and decrease in other areas compared to the
<br />effective floodway width along Trott Brook. The maximum increase in floodway width, approximately
<br />360 feet, will occur just downstream of Ermine Boulevatd Northwest. The maximum decrease in
<br />floodway width, approximately 100 feet, will occur approximately 600 feet upstream of the
<br />Ermine Boulevard Northwest Culvert.
<br />
<br />Upon completion of the project, your community may submit the data listed below and request that we'
<br />make a fmal determination on revising the effective FIRM, FBFM, and Frs report.
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