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<br />August 17, 2009 <br /> <br />Mr. Ron Bottoms <br />City Manager <br />City of La Porte <br />604 W. Fairmont Parkway <br />La Porte, Texas 77571 <br /> <br />RE: City of La Porte, Texas <br />Fairmont Park East and Brookglen Drainage Study - t\44endum <br />Klotz Associates Project No. 0127.009.000 <br /> <br />Dear Mr. Bottoms: <br /> <br />This letter addendum supplements our report entitled "Fairmont Park Easl'~ Brookglen <br />Drainage Study", City of La Porte ("City"), aiid date.d..... eMay 2009. TIiis addendum <br />./ "",., , <br />summarizes Alternatives 3 & 4 and evaluates Altetqatj.ve 5 for the Fairmont Park East <br />subdivision. <br /> <br />Existing Conditions within Fairmont Park East Subdivisio!l' <br />The Fairmont Park East subdivision wasconstrU~~d,,)V~,th an ~nusual storm sewer design. <br />The subdivision has the main storm sew,~r,pipe sys€lI!;,constructed under Fleetwood <br />Drive. The side street~",on:of'!'1e,etwood Dri~e contain if11ets that are anywhere from 1 to <br />1.9 feet lower in el~y~tion than'tpe intersecting street elevations along Fleetwood Drive. <br />The existing stomr se,};Ytrr inlets,0"and drainage"'system have a 3-year storm capacity and <br />will begin to fill up the"side streetsiduring stoqnevents less than the 3-year storm event. <br />The side str.e. et.,!iwill, continue, to ponllahd th... e depth of water in the side streets will reach <br />1 foot to"alinOs(2'1~.~ geep'b~fqre water backs up onto Fleetwood Drive. If the storm <br />event ~phtinues water c4P packujJ,PIlFJeetwood Drive and will continue to back up in the <br />side streets. The new surVey data obtained by the City of La Porte shows that not only is <br />Fleetwood"Drive higher tfiall the elevations of the side streets Fleetwood also has a high <br />point in the ro~dway betw~en Mulberry Drive and this high point continues north to <br />South Spruce. Tl\~ highe~r point along Fleetwood is between Idlewood and Dogwood. <br />This high point creates, a limitation in the ability for Fleetwood Drive to convey flows out <br />of the subdivision and south to the receiving ditch. See the profile as shown on Exhibit 1. <br /> <br />Previous Study Alternative 3 <br />In the referenced May 2009 original drainage report, Klotz Associates recommended <br />Alternative 3 which proposed to add a parallel storm trunk line under the northbound <br />pavement and adjacent to the existing storm trunk line. The combination of existing <br />storm sewer and proposed parallel trunk line would provide for a 5-year storm event with <br />a capacity of approximately 225 cfs. The two storm sewer lines are to be connected to <br />