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HomeMy WebLinkAboutRe: proposed maintenance work � �- ��3700" NoN1��re �. . , Hennepin County Memo R�� . JU( Z �- ���o �z�I t f Fp�,�NO Date: July 19, 2011 To: MCWD (Attn. Steve Christopher 18202 Minnetonka Blvd. Deephaven, MN 55391) City of Orono (Attn. Lyle Oman 2750 Kelley Parkway, Orono, MN 55356) From: Tony Brough, Hennepin County Environmental Services Subject: 20ll Projects—Lake Improvement Program Attached is the plan sheet and detail for some proposed maintenance work at the North Arm Public Access and Coffee Cove Fishing Area. The areas identified in cross hatch are existing riprap areas that are in need of replenishing. These areas will be replenished with Class 3/4 granite riprap. The walking path and trailer parking areas identified on the plan will be replenished with Class 5 graveL I will be contracting with Minnetonka Portable Dredging out of Excelsior to perfonn this work. Please review the project. If there are any questions or if addirional information is needed you can call me directly at 612-348-4378 or e-mail at anthony.broueh(n�co.hennepin.mn.us. Respectively, � �..__. // � _/_._._� ; � ___-•� Tony Brough / / H.C. Env Services 11�e ,i ' �Bi�I i �if �� 6 ..�yi.� .�.� ��.�. 9 � � � ti s North Arm Public Access and ; . , '� �� �� Hendrickson Channel Project. ��' ��� � .� ��' as�`t � f � � � '- axr H. C. Env Services - 2011 x � ` a�� Replenish Riprap-cross hatch locatior� ,Af ��� � 0 ��" (Class 3/4 granite) _.,��� xµ`�«��' ,�'." "�"�� � 280 ft SW side of channel. � � `'� , 100 ft NW side of channeL -- " Estimated at 0.5 tons per ft. � �� � . 190 tons=~$16,000 �- x ' ,��" Repair small ��� � ' � �i��� r . erosion area. ' ;� "_T1—�i_.� ��' .� ; t �� . - �m,-� ���+-�., � t . , . � �,� -— �x p , ; .. - . Tr , ,. _ > � .. � a , , � t . . � ,�� _ , � r -�.� � � �. _ � � � . � � . _ : . � . rvr � �_ - . � � � � . � � � s�,a i �'_ � � sedlment accumulahor ' � ' - �!� . � � °'_ to prowde proper � ' � _ ' � , * ` drainage to stormwater poi.:.., .'� �� �`� � � � ' � - �" '�„ � � � '��:.: � ��;, �✓p .. ' � � � ,'v� � ,:. 4= � . .}.. � " . y4 • , � o r I _ t �, � : w .� . , ..q � . .g".. k' . � , ;�� �.. ,�` . �� �� � �" ����.�� ��� �.� � , :�� �`R- , �� � � �,,,t�"�,�' � �,� � t„ �n .+�, Replenish walking path gravel # #�`�" , �",�� � x �fl- ��' ' '� -�ww ��" +- ' ' � E. � ''<,� � <r r', with daSs 5. �_ � ,� »` 1700 s ft. �d�, ���:�� , ;� r� � ,. � �� � � :� Q• "���. �e�» „`,� a;°� � � � * 800 sq.ft. � - _` � � �' �'�, � � 3000 sq.ft. � x. ` _. ,- a.. / (Total area=5,500 sq.ft.) , � �.� . : � �v, � � ' � �;, ''�, _r�� �.��- � , .� a A �� � � .�E. �" ,�M�' t/ ��'� *� a .�.�. ''370� � . �� . � y � r '� t Coffee Channel , �: . � ��YG � . ��uGV� ,�.�_�: � �. Fishing Area = �'�t',�� j,�'� ��� � � Replenish 5 ton � � `�� � � � ~�� � ���=° � � � ���x � "�' class 3/4 granite ��:� .�� ��.� �� � ��� ��" �" �,` .r � � , u �� '� riprapat drainage �;"`. "���`��_�� .� �� z � �. � � � � _�,���� � area next to portable ;�T " restrooms. � _ �$�� �, ,�� ,��,r,. � , _. �.. � � , ,, :: "'�w�, � .� � _�`�;r�Jr = �f :� ,� < � « � . � � . , . a :. � � . .� , � �' �. � . � �: �, s�� ��„a "� ' •'sl�' ,„ -*•= � � ...�' ". ��� ���� � . , ^ � �� n � � �" '*� �'""a'�_' ' «' � � .r. .�`� p� , _�°���� , � �!��� � �.,,,,u . � �� ' a. , , » ,.„ "� .. • .. ' .. � ' ' . � „ . � aa ° • ti�... � . �� . . . . ,, �,.. .... .. , ��. � . �� � . �. ...9�',}.. � .. . � ��'. . ��'��� .w. � .. #� `r.: �'�,, . A� ,. . . "sax# ��r'��,-,`, t.�. � � , .¢.:.' ,yY �.�'' � , �r� �;.� �'•t� � , _ � - +�� # M , � � . � , x��"� �� �`� � � � � � � . . , � ��4 `4 � ' � r +e. ... .A V+t fi . � ' � � �� .:+ A �� .. .....SY �. � . � . �*� �� ��' *+� _s ' ' . . . '+. r. . .�.. � . f GENERAL SPECIFICATIONS - RIPRAP CATEGORY • � DETAIL OF STANDARD RIPRAP CONSTRUCTION HENNEPIN COUNTY ENVIRONMENTAL SERVICES Replenish Existing Riprap per Details Listed Below. Existing amount of riprap will vary. .............................................................................................................................................................................................................................. �. ]00 yr floodplain elevation 931.5 . �� , � .� ...................................................2........o,>........................................................................................................................................... � • Ordinary High Water Level 929.4 Bury filter cloth lead at least 12" •..�� . as shown in any exposed soil areas. � .� • Riprap shall be mixed Class 3/4 granite riprap. • Toe boulders will not be touched. Existing slope will not be graded or changed and should maintain a 3:1. Riprap is only to be replenished by setting on existing toe boulders to the top of bank. • Riprap shall not extend higher than the top of bank, above the l 00 year floodplain elevatio�l, and/or will be installed at a lower Depicts existing riprap and elevation to match an existing shoreline contour as directed by toe-boulders. County personnel. • Riprap to be replenished at a ininimum of 1'-0"thick above 929.4 Depicts granite riprap and a maximum of 1'-6"thick below elevation 929.4. replenishing. • No riprap to extend more than 5 ft waterward of OHW or down slope into the navigational area of the channel. lf any falls into channel, it must be removed.