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Home My WebLink AboutDRB130159 REV2 Retaining Wall info Hrp�auili-f.nel:il: l lr�,rcchrni:il, lui. �� i0_'Ol',�iiniplL,d�lli-I Glrmi,,,��I S�,nrn,�, l„I��r.iJu�`�.1601 I'L�.nr �)'i0 o�{i-i`1f:.4 IiFPWORTH-PAWLAK GEQ7FCFINICAI. �� ,,��, ,,, ,� , June 12, 2013 Triumpl� Development Attn: Milce Foster 12 Vail Road, Suite 400 Vail, Colorado 81657 n�i it�tilrl�;(uivuh(1n.cuu� Job No. 113 048A SubjecC Reconunendations for Boulder Site Retaining Wall Desigu, Proposed Noell Residence, Lot 6, S�raddle Creek Estates, 1000 Spraddle Creek Road, Vail, Colorado Gent lenten: As requested, we are providing recoimnendations for design of Uoulder site retaining walls at the subject site. The services were su�plemental to our agreement for professional services to Triumpl� Development dated December 21, 2012. The fuidings of our analysis for flie boulder wall designs are presented iu tltis report. Hepwortli-Pawlak Geotecluiical previously performed a subsoil study for the proposed residence and subniitted our findnigs in a report dated April 15, 2013, Job No. 113 048A. Boulder retaining walls are planned at various locations on site to retain cuts and fills. Tl�e walls will be one, two and three tieis with a maxiu�um tier height of 6 feeC. The water feature which will include Uoulder walls will be lvied and have concrete slabs. The overall boulder wall heights are proposed to be up to aUout 16 feet for the teiraced cut walls and aUout 12 feet for the te�raced fill �valls. The l�illside slope Uehiud the garage area will be reCained by soil �i�iling. Based ou our borvtgs at the site, the vatural soi]s are relatively dense, silty sandy gravel and cobbles wifli boulders. No free water �vas encounterecl in our Uoruigs at the site�vhen drilled 'ui March 2013. Boulder walls cTn be used to retain cnts aud fills provided they have adequate section for loca] and overall slope stability. The �valls cau be analyzed as gravity retainnig structures and should be provided with au underdrain systent behmd eadi wall tier to preveut buildup ofliydro-static pressure. A rypical detail for a single tier boulder wall section is provided on tlie attacl�ed Figure 1. A rypical detlil for a two tier boulder�vall section is provided on Figure 2. A rypical detail for the tlu�ee tier boulder wall section is pi'ovided on Figure 3. It l�ave been our experience that properly conshucted boulder�valls �laced on stable slopes will have adequate stabiliry but walls tl�at are too higl� and too steep �vill tend to shift and possibly fail. Geogrid reuiforced fills behind the boulder walls conld be used in are�s to lielp limit wall movemcnt aud fill settlement, and 'u�crease stability. Parl:er 303-�ti41-7119 • C�7l�,ri�l�, 5��rin��s 719-633-5567_ • Sileer�h��rue 970-46N-1NSy Triumph Development June 12, 2013 Page 2 The boulders should be fi�om aUout 2 to 4 feet in diameter (or larger) witl� the larger Uoulders placed �it the bottom of tUe�valls. The uidividual retained �vall heights should Ue no more than 6 feet. The base of the walls sitotild be keyed below flie ground surface at least 1 to 1�L feet. Tl�e walls should bear on tl�e natural soils. Looseued subgrade soils should be moisteiied aud conlpacted prior to the �vall constiliction. Tlie face of tlie walls should Ue battered back at aUout Y (horizontal) Yo 1 (vertical) or flatter. The space betweeu the boulders should be bac]<filled witlt '/ incli drani ci'uslied draui rock. A filter fabric, such as Mirafi 140 N, sllolild separate the on-site soils fi�oui tlie '/ inch drain rock. Fuial slope grades beriveen a�id aUove the walls should Ue no steeper than 2 (horizonfal) to l (veitical). Fill placed behind tite �valls should be compacted to at least 95% staudard Proctor density. Some fill settlemeut sliould be expected especially for tlie deepei'fill areas. Use of a select granular impo�ted tnaterial such as road Uase and 'uicreasiug compaction to at least 98% of SPD could be done to help limit impacts to settlement sensitive structures. If wall heights are taller or if effective slope of the overall walls is steeper than we have assumed, structural design modifications will be needed. We should oUserve coustniction of the boulder walls Yo evaluate co�npliance with our reconmlendations. Some field modifications to the wall design may be needed. We should also obseive tlte suUgrade conditions belo�v the walls, aud test coinpaction of the wall backfill on a regular basis during consh�uction. Additionally we should review the water feature desigu with respect to our boulder wall details prior to construction. If you liave any questioi�s or need further assistance, please call our office. Suicerely, HEPWOR�� WL�A��y��,flifF��y�NICAL, INC. i J �` j�IM♦ �'�� " l �� ! '� � �� David A. Young, P�. 32-21g � % L /?f� �� DAY/ksev ��'��'�«..��```�` � `� attachments Figure l, ��j4/fNISC4�g�e Tier Boulder Wall Detail Figure 2, Typical Two Tier Boulder Wall Detail Figure 3, Typical Tln�ee Tier Boulder Wall Detail cc: RMT Architects—Pat�l Miller (p,wlui�ui�luaur�hitcc_ls.euu) Beck Builduig Company- Tom Solawetz (fom(ii:beckbuilcls,com) Mom'oe and Netvell— Craig Can'oll (cc;irr��ll�i_monr��e-iicwell.cun� Martin/Marfiu Engifieers—Mark Luna (i\ILunn(a ivarf imu<ntin�_inin.com) Jon�o. �i3oass �tech Maeimum 2'-4' BOUIdBfS � . Z Backs!ope to �Typ� � J � B!end in vnlh �J` ' � NaWral Slope, F= i ?O�-LJ�'� � � J' �� '� �� Filter Fabrlc '�y 1'��=�� (Mirafi 140N or Equiv.) ,��l � � 1 � z, F. / ( f / `�`` ( ) (TYP) ,�. �� H =6' ma� <�};�. � � j .. i DrainGravel I i��_F.�'�- z�;-��-_ � '` m'P� � �� L � , , '�, � ��. � 4" Diameter a r <;:; \ f�� Perforated Drain �� '��' � ' Pipe Sloped to � 2/3 H (min.) �i Graviry Outlet �H=He,9ni�n Fee�� NP) P to 1 1/2' (min. embedment) NOTE: Backslope at top of wall can be graded flatter for pavement and landscape areas. NOT TO SCALE 113 04�A ,�°-��"�� TYPICAL SINGLE TIER FIGURE 1 ��FPw<>Ar�.�=„w�,,�«t�„E�,�h��A� BOULDER WALL DETAIL M�imum Backslope lo Blend in with � NaWral Slope. 'i,j�, ,}/-� 1 /�� l // // �. , ,�`�e>��,L S\I � {: .��'.fx'{.f. > YJ i_,.. � . . �t�� ' f� � f!Ji-i ��c � � H = 6' (m�) i;r,�r, � f �� i .r ZT; ;:�`r.. ' L ��C.--' � '„t � � `,f��`, � � � � � I 5� ° � � I. 2' - 4' Boulders f_� �_,/ , > 2 (�,P) ;,f�x r ��- � � '��;i�� , XY r i I 5��;��. ; � ��-h?-Ci,�i:: I � � S �� ._�'�� Filter Fabri�c � ��"�� (Mirafi 140N or Equiv.) � � � S � � ) � ) �� H = 6' max �t? . z ' j �„ Drain Gravel �� %( ';<` '` ' J � (�P) a �� / � L 4" Diameter �f' . r„4{;, � ��x • Perforated Drain '� �� " �� Pipe Sloped to Gravity Outlet 2/3 H (min.) (H=Height in Feet) (7YP) 1'to 1 1/2' (min. embedment) NOTE: Backslope at top of wall can be graded flatter for pavement and landscape areas. NOT TO SCALE 113 048A ��`��;�`j TYPICAL TWO TIER FIGURE 2 ��_�woH��-�•„w�„K�E�1E�,,,,„�„� BOULDER WALL DETAIL Mamum p Bac%s!opeio � B!entllnW�M1 � Ndl�lql S!OpB. � ' � K�\' �r ' J � �T ��f � � H-a (m�) .��s ` i �.r. � r�� ` � \ 5� � � � � l �� r � � �_ . . � 1 < �\ • � 1� . . J'� � ( � H-s'(m�) Y \II , . L � � ' � J � �, �` 5 �� \ 2'-4'Boulders r \ —'—� m'P) rr-, � , 7.. �i Filler Fabric � � � �\ (Mirafi 140N or Equiv.) � x -j� � � �' f I� (T�'P) 7 F ;f` � H=6'(maej Drain Gravel � � � `` �P '� ' .�� f`... ��1 \ � �/ 4"Diarneter �"� �� , � . . Perforated Draln 1 Pipe Sloped to 1�.� p/3 H(minJ --+� Graviry0ullet I (H=He'gM1tmPC�p I (�P) 1'�0 1 U2'(min.embedmenl) NOTE: Backslope at top of wall can be graded flatter for pavement and landscape areas. NOT TO SCALE 113 048A ��P'�� TYPICAL THREE TIER FIGURE 3 ��waH��-F��w��«to,E��N��:,,� BOULDER WALL DETAIL