Loading...
Memo from SRF 04-20-2011L1 ,i l ENGINEER S PLANNERS DESIGNERS Consulting Group, Inc. SRF No. 7068 MEMORANDUM TO: Members of the TEP, Army Corps FROM: Jeffrey Olson, Associate Scientist, SRF Consulting Group, Inc. DATE: April 20, 2011 SUBJECT: TH 41 UNDERPASS TRAIL; CARVER COUNTY [ Note: This Memorandum, dated April 20, 2011, incorporates additional text concerning sequencing associated with Wetlands #22 as discussed at the Planning Commission Public Hearing held in the Council Chambers of the City of Chanhassen at 7:00 PM on April 19, 2011. Text added to this document after it was originally submitted on April 15, 2011 is in red bold font. ] Dear Members of the TEP, Army Corps, and Associated, The purpose of this Memorandum is to address comments that have been gathered from Members of the TEP and the Corps concerning the TH 41 Underpass Trail Project. This Memorandum will serve as a Permit Application Supplement. Table 1 presents comments and responses to comments. Figures 1 -5 (attached) show "screen shots" of portions of the trail that impact wetlands and call -out boxes that demonstrate instances of wetland impact minimization (side slope steepening, trail profile lowering, and alignment adjustments) and illustrate points made in Table 1. Appendix A, relevant to Comment #7 in Table 1 below, shows proposed MnDOT seed mixes for trail clear zones and side slopes. Per Comment #4 in Table 1, below, we agree that impacts to Wetland #8 would likely be a total take given the small amount of wetland that would remain outside of the trail footprint. We have added 0.06 ac of wetland impact to Wetland #8. The following bulleted points summarize impacts and required mitigation as presented in the permit application - and as amended per this permit application supplement: Permit Application (previously submitted): Wetland Impacts 0.285 ac. Required mitigation 0.57 ac. Revised Application (per this supplement): Wetland impacts 0.345 ac. Required mitigation 0.69 ac) www.srfconsulting.com One Carlson Parkway North, Suite 150 1 Minneapolis, MN 55447 -4443 1 763.475.0010 Fax: 763.475.2429 An Equal Opportunity Employer O N N a ¢ �.•--' V 'C •U Y D © y N pp Cp w is .� ' ° C n 0 y G G '— 3 0 t F o �i3° ca H���a c� ro. c s c .� A V V N U 0 V V U t C 3 V p H L c3 y C �v 3� o O 4x kb� y q W p a o d C ? N N Y 3 a V. 3k 3 Y d o° e F d ° m v 0. . c m C ? a ° a c 3 30E- c a p 3 o 8.. z N� E b.^ o 3g �w o3 y o s c �3x d o C7 y o� ° �yy a0.£ e•o3 y r s o ° u S .0 15 t C Y' V .0 0.'. E dD w 0 'v C U > mop ^�_ cc ° b - s'x°�- = 15 ° C �+ d ° .-. .0 "� 3 O is g' °- =- °.3 '^ u y .r7 V gi V] p er : o c e o g — to O. V 3 m >�cc ° o c3 d W .� G 3 £ ° h 0ota �^ 3 O V C '3 O V V x V V O. 3 0 3 c D 0 0 ° `o ° c e 3 zz O 6 ° v £ -- v & 0 3 a? = rN of C� £ td ioM �+ r v A ry V a' O T V V N 0 £ w C a, �' V .L v y C 3 c c , V b O O y O 3 > t �` 0 G t O y � G V G ° .°_° X0.0 c pq G G Y m >"c °3� v � ���CO 3 5b y o3 ° V 3 u 3tN � sw 3c0 r, •Y a Y Q -- �� •eG e� i w . "o �b ao 3� P c H E y B �:° =x SA o cv o o 8 ° ° V «V m > «' N C O Do b tC a V 0.0 'O V . to 0 £ 2 £ H y a Y EcAa y o�d? 0 ° ^ '0 o ❑ a a e £ a w ��„" p V r .�� . y7 �y t °r�� n 'o ° s •— Ol CI. V >_ L1. C.7 y0 Q"b iE O V c0 td V '.' V oo d ;— ao u �o0 3� a 3 3�$:° A� a c V - c'L'ia 5: aoiE 1 4 .c c _° � 8 T d Oy • � a 0 _ `� 'O 0. C - 4 g 2£ W V O a C E o U ° O, �D C V SJ Y b , o ' .'J' H Ev A `� 'O _ ' . £U = o VJ O W �- bA 2 F es • 7 4" 0. y ° V t0 N m SO ¢U £ H V 1'j 2 w vl L V C G• « m > N 13 V �� `� a r2 O ° ' 'G 'O 8 O V a at o �3 9 ' x E o o T c c'o o E 66 on � o � 3oG 3 �.� �� 033 �•� 8 3 � � �I, �vaG U aQca `o c 0 a S # c c # A •• E �U dU dU dU dU EC7 E d o E o U E o E 0 E o E o E � E- UU UU u Q u U., U 0 N O N Q d U T Q W w O y 0 y d -a - 0 d >o� '8 �vFo� a eV y w C V .. N > O U D - g V] 0. O b N P. § . _O ^� ° 0 d ° .� T 3 O -gb= FE N .... U y a m N$ O '� .iy uC°i �7.' C i� • OD� C C Vlw T' V S. a AN 0•.= ° 0 ar mho -0 s a ^ 0. 3 is d° 3 v �= T� aCV 0 G V V V •O .k' N E2 Q �F £ •x •O =C 'O 'J .q .-+ c 4 K 8 :--. oo A ctl V N �.� � '� a V V Q N V £ 0.y U- A ffi �3 °# > v S .d OOH° .yg =og� ° 3 = O .� o 3' 7 >" F d .-. "pp �"' �u � O _y m a V y£ w V wl O V A d 0 S td w A F G ° c 'O °> °��oo w O O C A,, C >' C£ O 5 ' 0 - o ❑ .d am a Q o =_� 73os 0 ; ^'_' �g.0Aa�3.c• ' �U�b� e X 3 0 3 c aNa o y ^ 3� 3 o O 2� > A 3 o E 4-- > � o ° c 3 Q ° ° C 3 G A c 3 F E C r;; T S a A C W p U V_ a 3 E Q o w O £ C Y O y O 'a tl G m C U •� C £ U 79 V A a. C A CAA) C• 0 3 s k Q y g C oU �' ❑ C O '°O .� a 3 ' p O p °' �tl 0 0 W .AJ a 0 .- 0 w y° T C O 0 .� � ar C j � O 3'O y ° � A OAS p � 0 C •`i � •d 0 . �y y a �y� V A m Cc,, v o _ L o ° 0 0 3 o A g c > > y ° e v > > 7 , o 0. u j � . QQ�pi c E a c G F y o '� O p O° m Q !pppO b ey "' A J -- . 9 N b T y p z 0000 .o:la N £ 3 V 3 7 0.81 C `i: V y w O V y .R. •d , t X 0. k O ... ... m y •p •ti. A _ y C y j H V > ° y y 'a V T y = _T_ U 6D a� 7 .0 'p U £ £ £ £ C N O •O m ' k'i A 'D 'J R U .0 Q y W O J7 w V b U U F" W E > 4 •- V �'�� W n° A o b c :d .� b° u^ 4 a_`° c C '0 8. o 0. o Q4 3 Cl CV1 7 .00 1. 1 yy A O y ' E t' ! is y' 0. > L 7 w q p V p N '� Cy N- W 7 tCp O C ` C w V O O a.r � Q � y 4 , � '�� CJ '�7 � p V A y � .V. �' y � ❑y m �•- ° £ � $ o a � ° o o� • i 3 '/+ � >��v y ❑5c� 5cdox .d > a`0a ^ C C O' L >� a. r...tin OOaa0. gyp°• C O. ° V v y ° W O O v WI O L 7 'a .O 0. - 4 M O � O $ G � • O i V 7 .: d £ f� " C_ w w O b E p CO E V V • ' d C � o V b £ h 9 0 '�^y ` V j C OC�' C : a b 'oe _° a E v a ao ca v A "u O N C N � • y £ '" £ N C V V 3 F ° 'S - 8, V p w e0 °O C ' E d 0 o ° o V C U C C e 0 a G ea 'j v 1.+ A c°i p Cp b V O 'O •y .C4 o; •� a 0. ? y w 3 H 33 3v yob 3 3�a § k °� �° > n. wa Q O Ln 3 3 3 di eo e ° £a °� o� oI C oCo�o� F ° U C7 U C7 U 0 U p4 U �4 U D4 d U T Q W w O 0 0 E' v E Q w 0 a v �x �' £„y,'O ADO OO bo G° 3y xoy0ov � p c p 3 �g ��3� °. c � as o c_ o. a v ox m o a� °c ° > o en . `�> • E a c• n gb � .E 0- ro E V y V 3 & ° E c �•G c u o .° y° °' ° • 0 0.�. c m f. c.c a '� OO y M V �j O •> crib. 2-8 —�� y . E N 3 y u A e o w , c 3 m x of G v N L . 5$ o c - E o > 4 cd E C O V 18 cy %k M O 8 C p, �y cd V F w m c .^ `3 L as . ° ^ V C `4 o•00 m EA o E vo3 0 3 3 ° $a e x aye E � a ° i � c 8 °� � � c� 3 p = d° o_o o c. 5 y u c �� °a _r�Ec bo ;'o8 �d H y °b aY "' 3 N 3 o 2 0 , c U E�a b �:� o 8bo c3 d 6 ; •E U ec N' V c V c m >� N 0U V a va 1=1 V o^ A `y 6 . 5 -2- c ' m U a� 3 i 9 p O 0 ° §QE 3 A L ° c03 : .9 E a ' U L V $U 7 U A v c a er 'O £ 3 E v V c'a �A O E C G 3 x_ H °' m 3 0 `3 ( j d A U °c 1 ai V b a ^ y o U •�ows °'c��' . b �° bo V o � A P. c . •d .g .^ y ca y v� 'c$ O. U C � — O Hga�s E' O U � E >.Y o >o E 3 a pp - 3 > 7 C Q E 4. w V b0 s m y N U L y O w .d 0 O O U E '�. L NC a"c. 00 of O , - O c .°+ N 7 .� .• i. « p O C O x ca .5 •E C >. d 3 O N b pp _ y E a U Q , E � .� O �° 'i vi F D • y > L cOa N _O N at O V U° x d C• O V O ... M y N "' _• C> O' V u �' •p •C 0..0 O • • ° 00 0. •^ O E L V O b N o o•• Go 3 J `� a o o u V 0.O O p w 0 E E'5.N U V 3 G 0 c° 3 o Tb O E> o.£ of C L O co O L m •y � ci •� o • c° c ry, L y > .O y� F U y g o cp •� T 0. b •� C R p ' .� > cvo V 'b E c O Q• >�� o �i Q% K U .n •N .� X .3 b� O O y 'y °O y •p o U O C y O A v _C 0. •+ ' o e v c �� 3 a b on ���vvv E Off" C •V 'F'1' c d A Q td 4 « 4, > C 1 to V "2 ^ ca O 0 7 o a. U Era u N w ° 0 L p' E t y E `- F o U m o$ W 96 ° y° ' C p p 3 of EO. ° •^ V ° c E Q oD O y V ° c V b 3 o O 0 A ,E ou •N 0 o 0 w ❑ V - 0, 0 o p w^ � O N °^ > E a w o• s V U S 3 3 w o.•o F E. c•Esa.�.E3 3 `o e • N L 3 3 x a 0 � pq Pa ; 3 ,,, ao A d _r at -: at V E U E= U �4 U U >4 E' v E Q w 0 a v 2 \ 22$ )]) )f� )k/ =e 7 \!& . //» z ate §&k k 4 \\ 3 \ %§ \ \ ; Isb/ _ \a 2 2 32]` \J \) J; )\ /\ -k )§ \�\ �/ \ E. � �kB . _ O%]7 77 § \)/ E, . - m } u) 2 \ Members of the TEP, Army Corps April 20, 2011 6- Additional Scuuencin2 Test for \\ et[and 422 The follossing test summarizes ssetland- related discussion points at the Planning Commission Public Hearing held on April 19, 2011 in the City of Chanhassen Council Chambers. Sequencing for Welland #S is described in the Memorandum abuse. \1 "etland #22 • Wetland Impact Avoidance. Complete avoidance of impacts at Wetland #22 was not feasible. If the trail were to be realigned to be along the shoulder of the gravel park road, the trail section would be on a piece of road with a tight radius of curvature. The highly curved road has poor horizontal sight distances; thus, recreational use would be unsafe. Moving the trail toward the nearby lobe of Lake Minnewashta to avoid wetland impacts was also not feasible. The narrow tip of Wetland 922 is at the crest of a steep hillside which has already begun to erode. Placing the trail near this hillside would worsen erosion and require considerably wider side slopes. • Wetland Impact Minimization. Currently there is minimal fill at Wetland #22. The width of the impact is just the 10' trail with 2' side slopes on either side and no side slopes. The fill is just the 6" gravel base with bituminous pavement. Further the proposed impact occurs at the narrowest portion of Wetland #22. Where the trail crosses Wetland #22 is coincident with where a current dirt trail crosses the wetland - this dirt trail is currently unvegetated car tire ruts. • Wetland Impact Mitigation. As discussed above and at the Planning Commission meeting. Wetland impacts and proposed mitigation will occur within the same Major Watershed (Major Watershed #20). Mitigation will be accomplished at a 2:1 ratio (Mitigation acreage : Impact acreage). JWO/MM Enclosure(s)/Attachment(s) ,.T i f I N 1 � v _o E o G1 to Q ri a i I 1 / I / I v r kn 3 a o \ �� 0 2 � ul w v 0 � \ CL �\ r v N � II I El v c L ` � J U. V 76 d a N N N Q C 2 F- C 7 N V i 3 61 00 � 1i V Rol i r" rn , i E� } I q m " N a a O H v �r � 75 v0�_r� v 3 ` v v o a v - -• Y o o 2 o 0 LU a i Ib. ` LL U ` U AW- i E� } I q rn u � •t v O � L d (Q @ Y v '^ r N L 3 Lo ° Y' c 0 n �rn 3 ' U C a L 3 �+ c =O o 0 c � I LL V f I i I f u N O a H C a v v c N O S F C C 7 is L� Appendix A: Seed Mixes for Clear Z ones an Side Slope A , Mixture: 250 Common Name Bulk Rate % of Mix Component kg/ha lb /ac Ib /ac Brome grass, smooth 11.0 9.8 14.0 Bluegrass, Kentucky " Certified Park" 22.7 20.3 29.0 Bluegrass, Canada 11.0 9.8 14.0 Switch grass 2.4 2.1 3.0 Wheat- grass, slender 3.1 2.8 4.0 Rye - grass, perennial 16.5 14.7 21.0 Timothy 2.4 2.1 3.0 Redtop 2.4 2.1 3.0 Alfalfa, creeping 4.7 4.2 6.0 White Clover 2.4 2.1 3.0 GRAND TOTALS: 78.6 70 100.0 For: General Roadside excluding sandy sites Mixture: 260 Common Name Bulk Rate % of Mix Component kg/ha lb /ac Ib /ac Bluegrass, Kentucky "Certified Park" 35.8 32 32.0 Bluegrass, Canada 11.2 10 10.0 Bluegrass, Kentucky - Low Maintenance 33.6 30 30.0 Fescue, hard 9.0 8 8.0 Rye - grass, perennial 22.4 20 20.0 GRAND TOTALS: 112 100 100.0 For Commercial Turf I Any accepted low maintenance Kentucky Bluegrass EXCEPT "Park ". Mixture: 270 Common Name Bulk Rate % of Mix Component kg/ac Ib /ac Bluegrass, Kentucky - Elite 33.6 30 25.0 Bluegrass, Kentucky - Improved 33.6 30 25.0 Bluegrass, Kentucky - Low Maintenance 33.6 30 25.0 Red fescue, creeping 10.8 9.6 8.0 Rye - grass, perennial 22.8 20.4 17.0 GRAND TOTALS: 134.4 120 100.0 -For: Residential Turf Mixture: 340 Common Name PLS Rate % of Mix Component kg/ha lb /ac Bluestem, big 3.3 3.0 21.5 Bluestem, little 2.8 2.5 18.0 Wild -rye, Canadian 2.2 2.0 14.0 Grama, sideoats 2.2 2.0 14.0 Switch grass 0.6 0.5 4.0 Dropseed, sand 0.6 0.5 3.5 Bluegrass, Canada 1 3.4 3.0 21.5 June grass 0.6 0.5 3.5 Grass Totals: 15.7 14.0 100.0 62.7 Common Name Bulk Rate % of Mix Component kg/ha lb /ac Winter Wheat* 62.7 56.0 80.0 Rye - grass, annual 12.5 11.2 16.0 Wheatgrass, slender 3.1 2.8 4.0 Cover Crop Totals: 78.3 70 100.0 100.0 Dry Forbs Mixture 0.6 0.5 100.0 GRAND TOTALS: 94.6 84.5 100.0 *Oats to be substituted for spring plantings Application: Native mix for Sandy/Dry areas. Mid - height Mixture: 350 Common Name PLS Rate % of Mix Component kg/ha lb/ac Bluestem big 3.4 3.0 21.5 Indian grass 2.8 2.5 18.0 Bluestem, little 2.8 2.5 18.0 Grama, sideoats 3.4 3.0 21.5 Wild-rye, Canadian 2.2 2.0 14.0 Switch grass 1.1 1.0 7.0 Grass Totals: 15.7 14.0 100.0 Common Name Bulk Rate % of Mix Component kg/ha lb /ac Winter Wheat* 62.7 56.0 80.0 Rye-grass, annual 12.5 11.2 16.0 Wheat ass, slender 3.1 2.8 1 4.0 Cover Crop Totals: 78.3 70 100.0 Mesic Forbs Mixture 0.6 0.5 100.0 GRAND TOTALS: 94.6 84.5 100.0 *Oats to be substituted forspring plantings Application: Native mix general roadside areas. 11