HomeMy WebLinkAboutCT 09-01; ROBERTSON RANCH; TEMPORARY PAVEMENT RECOMMENDATIONS; 2009-09-03/ c8 2
Geotechnical—Geologic "Environmental
rlsbad, California 92010 *9 (760)438-3155 FAX(760)931-0915
flORANDUM
DATE: September 3, 2009 W.O. 5353-El-SC
TO: Brookfield San Diego Builders, Inc.
Attention: Mr. Adam Pevney, Mr. Greg McDonnell
FROM: Robert G. Crisman, CEG 1934, Andrew T. Guatelli, GE 2320
SUBJECT: Temporary Pavement Recommendations (Fire Protection), Planning
Area 22 of Robertson Ranch East Village, City of Carlsbad, San Diego
County, California
Reference: "Report of Rough Grading, Planning Area 22 of Robertson Ranch,
East Village, Carlsbad, San Diego County, California," W.O. 5353-El-SC,
dated March 6, 2009, by GeoSoils, Inc.
In accordance with your request, GSI has reviewed the referenced report and site conditions with
respect to the construction of a temporary, all weather access road for fire service vehicles
(75,000 pounds total weight) during site construction. Based on our review and analysis, the
following recommendations are provided.
Pavement Section
Based on our analysis, the following pavement options are provided:
C-
Provide a minimum 2 inches of compacted asphaltic concrete over prepared subgrade.
A thickened, turned down edge, with a minimum embedment of at least 4 inches (6 inches
from top of pavement) should be provided along the edge of pavement to provide lateral
support.
Alternatively, provide a minimum 5 inches of compacted aggregate base over prepared
subgrade. An edge treatment is recommended to provide lateral support for the pavement.
This edging may consist of either a: concrete "mow" strip, or pressure treated wood,
embedded at least 2 inches below the bottom of the base layer.
The edge treatments indicated in the alternatives indicated in 1 and 2 above may be
eliminated if sacrificial shoulders, with a minimum width of at least 3 feet, are provided.
4. As the temporary pavement is to be located within the future permanent pavement right of
way, subgrade preparation should be performed with respect to a future "permanent"
condition in order to minimize any repetitive site work.
Subgrade Preparation
Within street subgrade areas, all surficial deposits of loose soil material shall be removed and
recompacted as recommended. After the loose soils are removed, the bottom is to be scarified
to a depth of at least 12 inches, moisture conditioned as necessary, and compacted to 95 percent
of the maximum laboratory density, as determined by ASTM test designation D 1557.
Deleterious material, excessively wet or dry pockets, concentrated zones of oversized rock
fragments, and any other unsuitable materials encountered during subgrade preparation shall be
removed. The compacted fill material shall then be brought to the elevation of the proposed
subgrade for the pavement. The subgrade shall be proof-rolled in order to ensure a uniform firm
and unyielding surface. All grading and fill placement shall be observed by the project soil
engineer and/or his representative.
Drainage
Positive drainage shall be provided for all surface water to drain away from the pavement, to an
approved drainage channel, or other suitable area. Positive site drainage shall be maintained at
all times. Water shall not be allowed to pond or seep into the ground and saturate pavement
subgrade, otherwise subgrade deformation and pavement distress may occur. Best management
construction practices should be followed at all times, especially during inclement weather.
Limitations
The conclusions and recommendations presented herein are professional opinions. These
opinions have been derived in accordance with current standards of practice and no warranty is
express or implied. Standards of practice are subject to change with time. GSI assumes no
responsibility or liability for work, testing, or recommendations performed or provided by others.
RGC/ATG/JPF/jh
Brookfield San Diego Builders, Inc. W.O. 5353-El-SC
PA 22, Robertson Ranch East Village September 3, 2009
File: e:\wpl2\5300\535301.trpmemO Page 2