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Home My WebLink AboutB14-0075 Rockfall Risk II�1��.�irli-!':n�L�l: (.i�,�r�,_�ini�:al. lr;c. � ��„�,1�,�,�nu I;��,1]-�� (;I�u•,��.,�,I �E-��iris�,t ��I��r:�.l„r,it-tl( ��i?��Ili:: ��ll�-��-�r�-�'-)iti„ __..'� .�l_r-• �.1f/: li _ ' ' , . -`�i)�'�-I?-� � � March 31, 2014 Blueprint Construction Attn: Mike Rookey 193 Soda Creek Court Dillon, Colorado 80435 (r,;1i't�.el�?�;��.1tC(ir!«ln�iiLe0i1]) Job No. 114 068A Subject: Rockfall Risk Assessment, Proposed Addition to Kent Johnson Residence, Lot 5, Bighorn Estates, 4238 Nugget Lane, Vail, Colorado Gentlemen: As requested, we have reviewed the geologic conditions in the area and observed the subject site on March 20, 2014 to assess the rockfall risk to the residence and adjacent properties as a result of the proposed addition. The findings of our review are presented in this report. The services were performed in accordance with our agreement for professional services to Blueprint Construction, dated March 14, 2014. Project Data: An addition is proposed to the west and south sides of the existing residence which will extend the building footprint by 10 feet and 6 feet, respectively. The Town requires the rockfall review because the property is identified as being potentially impacted by rockfall in their geologic hazard maps. Geologic Conditions: Review of the Town of Vail's official geologic hazards maps (Town of Vail, 2000a, 2000b and 2000c) indicates that potential snow avalanche and rockfall hazards are present on and in the vicinity of Lot 5. Potential debris flow or debris avalanche hazards do not impact the lot. SNOW AVALANCHE Lot 5 is located in the lower part of the "Possible Avalanche Influence Zone" froin the start a�ea located on the valley side to the southwest ofthe subject site which extends down to Nugget Lane on the northeast side of the lot. The hillside is covered with heavy timber. Considering the distance frorn the potential start area and the area not being historically impacted, in our opinion, the risk of snow avalanche reaching Lot 5 is low under current hillside conditions. If this low risk is not acceptable to the building owners then snow avalanche risk mitigation should be feasible without increasing the potential risks to nearby properties. ROCKFALL Lot 5 is located in the lower part of a mapped High Severity Rockfall Hazard Zone which extends down to Nugget Lane on the northeast side of the lot. Rock blocks associated with past rockfalls were not observed on the project site but evidence of past rockfall, if � , . _ ; __ , r� � : I �� _,ul�.) �,p�, .,� -i il�� )-(13�-�J�`.��- � `�i�l'l'l�C�li�l'11C' �)7��.c1(i�5-��)�`i�) � � --d07�" Blueprint Construction March 31, 2014 Page 2 present, may have been removed by prior construction gradi�ig. Snow c,over at the time of our field review was roughly 3 to 5 feet and may have concealed rockfall blocks on- site. Large rockfall blocks were visible uphili of the lot west of the project site. Considering the limited number of rockfall blocks in the neighborhood of Lot 5 and being located at the lower extent of the mapped runout, in our opinion, we estitnate the rockfall severity to be moderate. If a future rockfall were to hit the existing building, it is likely that it would result ui severe damage to the structure and harm to the building occupants. If this rockfall risk potential is not acceptable to the builduig owners or government regulatory agencies then additional site specific rockfall study will be needed to evaluate the potential rockfall risk and feasibility of possible mitigation methods to reduce the risk. Findings and Recommendations: Based on our review of the mapped geologic conditions and the observed site conditions, in our opinion, construction of the proposed addition to the west and south sides of the existing residence will not increase the potential snow avalanche or rockfall risks to the existing residence, adjacent properties or structures including public buildings, roads, street right-of-ways or utility easements or facilities. If you have any questions or need further assistance, please call our office. Sincerely, HEPWORTH—PAWLAK GEOTE HNICAL, INC. � N��' �'�I ��b�s+�T E�.�'' ,,� 0 1�� Fi''L, � 'i't' e S \ o Steven L. Pawlak, P.E. �� j 5 2 2� d , SLP/ljg o� ��J/i �.�`�'S .� �'�,�pE�ONAt��PO References: Town of Vail, 2000a, Official Avalanche Hazard Map, Town of Uail.• Prepared by the Town of Vail, Vail, Colorado (Adopted by the Town Council on October 17, 2000). Town of Vail, 2000b, Official Debr•�s Flow Hazard Map, Town of vail: Prepared by the Town of Vail, Vail, Colorado (Adopted by the Town Council on October 17, 2000). Town of Vail, 2000c, Official Rockfall Hazard Map, Torvn of Vail: Prepared by the Town of Vail, Vail, Colorado (Adopted by the Town Council on October 17, 2000). Job No. 114 068A HPt@C}'1 ' II��,�rurrl�-P:rnl:�l: i.;,-,n�::��ni�_:�I. Ir.c. ��„�,�'„��t�� f:�,�;,.1 1�� (�l�n��J �� i��_,,( ��I�,r:iJ��,�,1(��1•- ��'I,� ��i� �?�i�_��E ,�iti , - .-,-,_. ;1..rr: �� - _ - +i�?-�)r�-;;-I�•f � ,�, i March 31, 2014 Blueprint Construction Attn: Mike Rookey 193 Soda Creelc Court Dillon, Colorado 80435 (i;�.i::�_,�;;�.,ilr!%c_�.�iil<ii L�oll�) Job No. 114 068A Subject: Rockfall Risk Assessinent, Proposed Addition to Kent Johnson Residence, Lot 5, Bighorn Estates, 4238 Nugget Lane, Vail, Colorado Gentlemen: As requested, we have reviewed the geologic conditions in the area and observed the subject site on March 20, 2014 to assess the rockfall risk to the residence and adjacent properties as a result of the proposed addition. The findings of our review are presented in this report. The services were performed in accordance with our agreement for professional services to Blueprint Construction, dated March 14, 2014. Project Data: An addition is proposed to the west and south sides of the existing residence which will extend the building footprint by 10 feet and 6 feet, respectively. The Town requires the rockfall review because the property is identified as being patentially impacted by rockfall in their geologic hazard inaps. Geologic Conditions: Review of the Town of Vail's official geologic hazards maps (Town of Vail, 2000a, 2000b and 2000c) indicates that potential snow avalanche and rockfall hazards are present on and in the vicinity of Lot 5. Potential debris flow or debris avalanche hazards do not impact the lot. SNOW AVALANCHE Lot 5 is located in the lower part of the"Possible Avalanche Influence Zone" froin the start area located on the valley side to the southwest of the subject site which extends down to Nugget Lane on the northeast side of the lot. The hillside is covered with heavy timber. Considering the distance fiom the potential start area and the area not being historically impacted, in our opinion, the risk of snow avalanche reachulg Lot 5 is low under current hillside conditions. If this low risk is not acceptable to the building owners then snow avalanche risk mitigation should be feasible without increasing the potential risks to nearby properties. ROCKFALL Lot 5 is located in the lower part of a inapped High Severity Rockfall Hazard Zone which extends down to Nugget Lane on the northeast side of the lot. Rock blocks associated with past rockfalls were not observed on the project site but evidence of past rockfall, if E',ar1<er i�!�-ti'��-71 1) � (�uL��ra�l�.� �l,rin�=; 7 l�)-6 3 3-»6' o Si l��erthc�l-n� �)l0-�}(��5-f 9��) _ Blueprint Construction March 31, 2014 Page 2 present, may have been removed by prior construction grading. Snow cover at the tune of our field review was roughly 3 to 5 feet and may have concealed rockfall blocks on- site. Large rockfall blocks were visible uphill of the lot west of the project site. Considering the limited number of rockfall blocks in the neighborhood of Lot 5 and being located at the lower extent of the mapped runout, in our opinion, we estimate the rockfall severity to be moderate. If a future rockfall were to hit the existing building, it is likely that it would result in severe damage to the structure and harm to the building occupants. If this rockfall risk potential is not acceptable to the building owners or government regulatory agencies then additional site specific rockfall study will be needed to evaluate the potential rockfall risk and feasibility of possible mitigation methods to reduce the risk. Findings and Recommendations: Based on our review of the mapped geologic conditions and the observed site conditions, in our opinion, construction of the proposed addition to the west and south sides of the existing residence will not increase the potential snow avalanche or rockfall risks to the existing residence, adjacent properties or structures including public buildings, roads, street right-of-ways or utility easements or facilities. If you have any questions or need further assistance, please call our office. Sincerely, HEPWORTH—PAWLAK GEOTE HNICAL, INC. N��' �'� �`C�dt�e,.�.11r. �� T E ��i'f` A � Steven L. Pawlak, P.E. �� 1 5 2 2� o , SLP/ljg o��/� ��`�'t �',�q pfo00�O��PdO References: Town of Vail, 2000a, Official Avalanche Hazard Map, Town of Vail: Prepared by the Town of Vail, Vail, Colorado (Adopted by the Town Council on October 17, 2000). Town of Vail, 2000b, Official Debris Flotiv Hazard Map, Town of Vail: Prepared by the Town of Vail, Vail, Colorado (Adopted by the Town Council on October 17, 2000). Town of Vail, 2000c, �cial Rockfall Hazard Map, Town of Vail: Prepared by the Town of Vail, Vail, Colorado (Adopted by the Town Council on October 17, 2000}. Job No. 114 068A Ge PteCh