Laserfiche WebLink
Metadata
Document management portal powered by Laserfiche WebLink 9 © 1998-2015 Laserfiche. All rights reserved.
'� � � <br />; r-� <br />, � <br />'�: <br />,In considering the proposal of the developer, it is somewhat difficult to apply properly <br />accepted and sound.a_torm.sewer deeign pra;ctice to the matter. The existing 24" concrete <br />ditch line h�s a very flet gr�tde (0.15%) a�d a history of set�.ling and sedimentation prob- <br />l�ms accord�,n.g to informstiqn received from Ramsey County maintenance personnel. Further, <br />; , , ..> ' ` _ <br />its r�ted capacity, when clean and flowing fu�.l, is only 9 c.f.s. (cubic feet per second) <br />whieh. is but ,a fraction of that required' by tfie 140 acre direct drainage area when discharge <br />,gf�e capacity i.s; calculated by any of the methods in general use today. A discharge type <br />� pi,pe capaci�ty caf 10Q c.f,s. or more would be n�ces�sary i.f substantial impounding basins were <br />� �r �itt d.` The' unusued and , pluggec� off . 36" line wou ld pxovide an additiona 1 28 c. f. s, <br />.,� not, to, b� p ,A �, <br />or wh�n;cambined witk� existing 24" line, ��otal of 37 c.f.a. <br />. <br />���. A fuicthez aspect �o consider is �hat present Ditch No. 5 system is functionin� due to two <br />, . ., <br />,. <br />`.x. � condit3.ons :`; <br />1. Th�C the land now being drained i� only s1�.ght�.y developed, therefore providing <br />�. � . arily l�imited and da�.ayed surface runof� . <br />�; ;. : <br />�f� 2.:; Thet the remnants of old Wilson Lake'are functioning as impounding basins and <br />'� accepting r�pid runoff and then gradual.ly metexing off the impounded waters to <br />}� �Dit`Gh ,No . 5. �h�se two remai�ing ponds are capable of providing temporary s fi.or- <br />,.,, . < . :,; : _ <br />� ` age of betwaen-7 �nd l0 acre-feefi. `(one acre-foot is that water resulting from <br />� oi�e-ac�ce o£ land with a depth of wgter of one foot thereon) <br />'' . Th'e "modifications to Langdon L�ake wou�.d have little or no, effect on the area flowing directly <br />to�Ditch No. 5;aince it would b� mandatory tk�a� drainage waters impounded in the lake could <br />,. . <br />be released to the di�ch only fol,lowing rainfall and at such times as the�ditch was receiving <br />very 1'imi�ted flows from it� di,rect tribut�xy a�ea . This wou�.d be a very similar situatian . <br />ta the rel�tion�hip of Zimm�erman Lake to County Ditch No: 4 and`a control overflow structure <br />would be required to pr�vent f�.ow from Langdon Lake reaching the ditch until runoff from.the <br />�. datrectly draix►ed areas was completed. - <br />''` �ii;summat;ion, iC may.be ��ated that if the wequested�site is rezoned by the Village followed : <br />_5_ ° <br />