HomeMy WebLinkAboutCUP 2018-0023; BUENA VISTA RESERVOIR SITE (PARK) OFFSITE; FINAL SOILS REPORT; 2021-08-20FINAL REPORT OF TESTING
AND OBSERVATION SERVICES
PERFORMED DURING OFFSITE
IMPROVEMENTS
BUENA VISTA RESERVOIR SITE
(PARK)
CARLSBAD, CALIFORNIA
PREPARED FOR
AUGUST 20, 2021
PROJECT NO. G2225-52-03
LENNAR®
Project No. G2225-52-03
August 20, 2021
Lennar Homes of California, Inc.
15131 Alton Parkway, Suite 365
Irvine, California 92618
Attention: Ms. Lisa Galloway
Subject: FINAL REPORT OF TESTING AND OBSERVATION
SERVICES PERFORMED DURING OFFSITE IMPROVEMENTS
BUENA VISTA RESERVOIR SITE (PARK)
CARLSBAD, CALIFORNIA
Dear Ms. Galloway:
In accordance with your request, we prepared this final report of our testing and observation services
for the offsite improvements for the Buena Vista Reservoir Park site in Carlsbad, California. We
provided compaction testing and observation services on an “on call” basis, as requested by the site
superintendent during construction of offsite improvements. We performed our services during the
period of March 31 through June 29, 2021.
The scope of our services included:
Performing in-place density tests on an “on-call” basis for utility trench backfill operations for
electrical trench.
Performing in-place density tests of subgrade soil for curb/gutter and sidewalk. We also
performed in-place density tests during placement of aggregate base and asphalt concrete.
Providing geotechnical consultation services during improvement operations.
Performing laboratory tests to aid in evaluating the compaction characteristics of soil conditions
encountered and/or used for fill and
Preparing this final report of improvements.
GEOCON
INCORPORATED
GEOTECHNICAL ■ ENVIRONMENTAL ■ MATE RI ALS O
6960 Flanders Drive ■ San Diego, California 92121-297 4 ■ Telephone 858.558.6900 ■ Fax 858.558.6159
Geocon Project No. G2225-52-03 - 2 - August 20, 2021
To aid in preparing this report, we reviewed the following report and plans associated with the project
improvements:
1.Final Report of Testing and Observation Services Performed During Site Grading, Buena
Vista Reservoir Site (Park), Carlsbad, California, prepared by Geocon Incorporated, dated
July 27, 2021 (Project No. G2225-52-03).
2.Improvement Plans for: Buena Vista Reservoir Site (Park), Carlsbad, California prepared by
City of Carlsbad Engineering Department, dated September 10, 2020. (Drawing No.521-1,
Project NO. CUP 2018-0023)
During the construction of site improvements, we observed compaction procedures and performed in-
place density tests to evaluate the dry density and moisture content of the fill materials. We performed
in-place density tests using a nuclear gauge in accordance with ASTM Test Procedure D 6938 for soil
and D 2950 for asphalt concrete. Table I presents the results of the in-place density tests. We used the
referenced plans in the field to identify in-place density test locations for the utility and surface
improvement areas.
We performed laboratory tests on soil samples in accordance with ASTM Test Procedures D 1557,
Maximum Dry Density/Optimum Moisture Content. We also performed laboratory tests on asphalt
concrete samples in accordance with ASTM Test Procedures D 2726 (Hveem Density), D 2041
(Theoretical Maximum Density), D 1560 (Stability), D 6307 (Asphalt Content) and C 136 (Sieve
Analysis). Tables II through IV present the results of the laboratory tests. The results of the laboratory
tests indicate the samples are in general conformance with the Standard Specifications for Public
Works Construction (Greenbook).
The results of the in-place density tests indicate that the subgrade soils for pedestrian sidewalk and
curb/gutter bordering pedestrian sidewalk possess a dry density of at least 90 percent of the laboratory
maximum dry density near to slightly above the optimum moisture content at the locations tested. In-
place density test results indicate that utility trench backfill within the street subgrade area, subgrade
soils for vehicular use sidewalk, subgrade soils for curb/gutter bordering vehicular use sidewalk,
subgrade soils and aggregate base for vehicular pavement possess a dry density of at least 95 percent
of the laboratory maximum dry density near to slightly above the optimum moisture content at the
locations tested. Additionally, the in-place density tests also indicate the asphalt concrete was
compacted to a minimum density of at least 95 percent of the laboratory Hveem density at the
locations tested.
Based on our observations and test results, we opine the construction of site improvements, which is
the subject of this report, has been performed in substantial conformance with the recommendations of
the project geotechnical report. Additional improvement installation performed at the site should be
accomplished in conjunction with our observation and testing services. This office should be notified
at least 48 hours prior to commencing additional grading or backfill operations.
Geocon Project No. G2225-52-03 - 3 - August 20, 2021
Geocon Project No. G2225-52-03 August 20, 2021
TABLE II
SUMMARY OF LABORATORY MAXIMUM DRY DENSITY AND
OPTIMUM MOISTURE CONTENT TEST RESULTS
ASTM D 1557
Sample No. Description
Maximum
Dry Density
(pcf)
Optimum
Moisture Content
(% dry wt.)
2 Reddish brown, Silty fine SAND; trace gravel 135.4 7.9
3 Reddish brown, Silty fine SAND 129.0 9.7
4 Gray, fine to coarse ,Sandy GRAVEL; trace silt 143.3 6.1
7 Grayish brown, Silty GRAVEL; some sand 121.5 10.7
TABLE III
SUMMARY OF LABORATORY ASPHALT CONCRETE TEST RESULTS
ASTM D 2041, D 2726 AND D 1560
Sample
No.
Test 2018
Greenbook
Specifications
Stability
Maximum
Aggregate
Size
(inch)
Theoretical
Maximum Density
(pcf), ASTM D 2041
Hveem
Maximum
Density (pcf),
ASTM D 2726
Air
Voids
(%)
Stability,
ASTM
D1560
AC-01 ½ 156.4 149.4 5 44 35+
TABLE IV
SUMMARY OF LABORATORY ASPHALT CONCRETE GRADATION
AND ASPHALT CONTENT TEST RESULTS
ASTM C 136 AND D 6307
Test Type
¾-Inch Aggregate Greenbook 2018, Specifications
Section 203, Table 203-
6.5.4(A), Type III Class C2 Sample AC-01†
Sieve Analysis (sieve size),
ASTM C136 % passing % passing
¾ inch 100 100
½ inch 99 89-100
⅜ inch 94 70-94
No. 4 71 44-72
No. 8 51 30-54
No. 30 32 10-34
No. 200 9 5-14
Oil Content (%)*, ASTM D 6307 5.4 4.8-6.5
*Green Book and Caltrans refers to as “Asphalt Rubber Binder %.”
†Sample from Superior Ready Mix Escondido