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KOECHLEIN CONSULTING ENGINEERS, INC.
Geotechnical and Materials Engineers
Lakewood—(303)989-1223
Grand Junction—(970)241-7700
Date: 9/29/10 Sheet: 1 of 1
Job No. 10-039 Attachments: Fig. l
Subject: Foundation Stabilization
Pro'ect: Lionshead Transit Center, Vail, Colorado
During our site visit on 9/28/10, water was observed in the base of the retaining wall footing in the area of Gridlines E-
E.6/E-0.8. The soils in the base of the excavation were soft due to the presence of the water. The water was being
directed to a sump where it was being removed.
Because the soils are soft, we recommend that the foundation subgrade be stabilized prior to the construction of the
retaining wall footing. The foundation subgrade could be stabilized by waiting until the soils have had the opportunity to
dry out or the wet soils may be removed and replaced with angular rock. The use of a geogrid in combination with the
angular rocic will reduce the amount of wet soils that need to be removed. It has been our experience tbat in granular
soils, a minimum of].5 feet of the soft, wet soils should be removed and replaced with angular rock in combination with
a geogrid. If a geogrid is not used a minimum of 3 feet of the soft, wet soils should be removed and replaced with
angular rock.
The angular rock should be placed at a 1 to 1 (Horizontal to Vertical) slope from the outside of the new footing. In areas
where the new footing abuts an existing footing, the natural soils at the edge of the existing footing should be excavated
no steeper than at a 1 to 1 slope (H to V). The attached figure presents our foundation stabilization recommendations
when using geogrid.
While we have had success in stabilizing wet granular soils with 1.5 to 3 feet of angular rock, it is possible that additional
rock may be required. The stabilized subgrade should be observed by a representative from our office to verify that the
subgrade has been properly stabilized. In addition, any water flowing into or within the excavation must be controlled
and pumped out of the excavation during construction.
Scott B. Myers, P.E.
Prepared by
KOECHLEIN CONSULTING ENGINEERS, INC.
Geotechnical and Materials Engineers
�
I I NEW CONCRETE FOOTING
COMPACTED STRUCTURAL FILL I I
� �
I TENSAR BX1200 OR EQUIVALENT
�L _ (INSTALLED AS PER MANUFACTURERS
I— —I RECOMMENDATIONS)
'i _III— �
- ��_���_���= , 1 ��
(��—���- � ` 1
\
SOFT OR LOOSE —�I� � � �� 1'-6"MIN. SOFT OR LOOSE
SOIL � COMPACTED ANGULAR ROCK � SOIL
� %"TO 1"tN SIZE
� \
/ `�
- ��-����-����� ��.���
=1 I 1.=1 I 1=1 I 1=1 I 1=1 I 1= •-��-���-���-_
" -I I 1=1 I i—1 I i- NATURAL SOIL
EDGE OF EXCAVATION
(EXCAVATE AS PER
OSHA REGULATIONS)
CROSS-SECTION PERPENDICULAR TO NEW WALL
TENSAR BX1200 OR EQUIVALENT
(INSTALLED AS PER MANUFACTURERS
RECOMMENDATIONS)
— — — — — — — — — — — — — — — — — — — — — — — — — —
EXISTING CONCRETE FOOTING
� NEW CONCRETE FOOTING
— — — — — — — — — — — — — — — — — — — — — — —
_ _ _ _ _ � _ _ _ _ _ _ _ _ �
1'-6"MIN. � .�
COMPACTED ANGULAR ROCK
%Z"TO 1"IN SIZE L��)I
��=���—�
_ -- - _I I I-i��-� ------------ - � I I1=1I1=
�=1 I I.-1 I 1=1 I 1=1 I 1=1 I 1= - li I I 1=1 I 1=1 I I-I I I,;
" -I I�—I I i—I i i- NATURAL SOIL �I,,—I I I=I I I=I I I-
'-1 I I-I I i-
CROSS-SECTION PARALLEL TO NEW WALL AND ABUTTING EXISTING WALL
FOUNDATION STABILIZATION RECOMMENDATIONS
JOB NO. 10-039 FIG. 1