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�cr' 14 �_� t � : 1i rr, tr-irr ci�� iic�r• i �� - . � - -`- �_ - - - - - - - - - - � � �� 8300 Nomtan Cer�er Qr�re 55�Wesi 271h Street � t�ira�e8pa/is,MN ii4371026 H'rbbrix,�MN 5574& Pisone;(67�832�'600 Ph�(2�$}2b2-3465 Fll�'1(IE8/11 k��0111�17�/ F�c {612j 83Z•,�01 Far (278)262.3d6� July 10, T995 . Ivix. Joe Offerman � �� 1669 N. Farm Road Long Lake, NIN 55350 � KE: F�ood 'L�vei of Pond Dear Mr. Offerman: We ha�ve reviewed the information which Rae 1'esek has subautted as `�vell as infom�atian collected by R.ick Lestina of our firm during his �cyisit to your property last week. The purpose of our review was to estim.a#e the 100-ye�x fiQod level in orde�' t0 52t minirrt� building elevations on the adjacent property. The pond has a very small tributary area and would be expected to h<<ve a �rery small flovd ir�crease. If we assume that the culvert is open and hinctior►al, the 14C�••year flood level would be 0.7 feet above the pipe i.r�vert or approximately 987.4. HowE:ver, it is becoming standard practice in Ilood control to avoid relying upon a single culvert, unless it is a major structvre with a defined m,aintenance program. When Mr. Lestina made his inspectian, #he culvert was compietely plugged with sedunent at the upstream end. (sroundwrai�r intlow and Iong-term runoff could raise the lewe� of the pond si�ificantly ab•��ve 9$7.4 i#the pipe is plugged. Iv�ar. Gaffron af the Cify�of Orono stated that he would pref�?I �'ldt �t2 ��nimt� ' builciing elevation be above the xunout level since standard mauttenar,r.e procedures cannot guarantee that the culvert wili always be kept opes�_ �ased on this inforniation, I would suggest that the m�T+�*rtuut buildut�; elevation be set tliree inches above the runout elevatioa over �.ong Lake Road _ Based vn the topagraphic map this wouid be Elevation 9915. Beca�;�e of the accuracy iimitaiions af t�e topographic maps, I woul�i kca�� the builder refere3nc�+� the actual minim�ctrn � building elevation to.the ov�flow point of the raad whert cor�s#zuctioii begins. I shouid alsa note th.at a second overflow raute exis#s from the pond to the south, ts�ward the cul-de-sac of ; Farm Road.' Lf the Long Lake Road overflow is too high, the overt�ow to the south might be excavated ta produce another, lower overflow route. • -• � � I hope this inforsnation will help avoid any flood daaZage irt your nei€;iZborhood. Please�.. _ __ ' contact me wzth any questions �: - , ..' . . ' . ' �� r ^ +' � .�.�`Y �..�.e��"�..��.�.�.. ir=�" . ` : ,. .. � . � � . ' . ....-.. '. . . . .. ,y�� . � ._... �...�.'� r:.� ...r:.. � . . � � , .. ! e+.r^`"'^tas'r-1"�:.��.'..�•,. ,..., ' , .,: . . _ . .., ... . � ' . . . � H' W^\.wI �� 1 f ..��. .�.. .�� .. ..�.. ...... .....� ,. � . � .v: }Jr�l� .._• ...�_�.'.�� . . ... . � , .. , . . . . a�.!^� "t...+��.�.1 , Sincerely� , . . •,�--.� '— ' . ` •s _� �" � �=-- . .. . . ..• _a . � . .. . . .. .. .. .. . . . . . • -' �l.L)� �z. r' ..�'T'M. ia Nels P. Nelson, P•�• • .