HomeMy WebLinkAboutCT 2017-0006; ROOSEVELT TOWNHOMES; RESULTS OF PERCOLATION TESTING; 2018-12-03ALLIED EARTH TECHNOLOGY
7915 SILVERTON AVENUE, SUITE 317
SAN DIEGO, CALIFORNIA 92126
PH. (858) 586-1665 FAX (858) 586-1650
(619) 447-4747
ROBERT CHAN, P.E.
December 3, 2018
2569 Roosevelt LLC
4040 McArthur Boulevard
Newport, CA. 92107
Subject:
Gentlemen:
Project No. 17-1106E5
Results of Percolation Testing
Proposed Five Unit Condominium Building Site
2569 Roosevelt Street
Carlsbad, California
DEC 12 2018
CITV _,, ; i ·
In accordance with your request, we have performed percolation tests in the subgrade soils beneath
the proposed driveway on subject property, located at 2569 Roosevelt Street, in the City of
Carlsbad, State of California.
Subject property is more specifically referred to as being a portion of Lot No. 22 of Seaside Lands,
according to Map thereofNo. 1722 (APN 203-101-35-00).
The location of subject property is shown on Figure No. 1, entitled, "Location Map".
The purpose of the percolation testing is to determine the permeability of the subgrade soils
beneath the porous concrete pavement for water infiltration purposes.
Percolation Testing (Simple Open Pit Infiltration Test)
In order to accomplish this purpose, two percolation test borings were excavated in the subgrade
soils beneath the proposed driveway pm the site. The location of these percolation test borings
are shown on Figure No. 2, entitled, "Approximate Location of Percolation Tests".
Two percolation test borings approximately 12 inches in diameter were excavated to a depth of 3
feet. The bottom of the boring was cleared and leveled, and covered with 3 inches of gravel. These
test borings were presoaked for 4 hours prior to performing the percolation tests. During the
testing, a minimum of 6 inches of water was placed in the borings, and the rate of the drop in
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ProjectNo. 17-1106E5 2569 Roosevelt LLC
2569 Roosevelt Street
12/03/18 Page2
water level was recorded at approximately 30 minute intervals. This procedure was repeated until
rates varied generally less than 10 percent.
The stabilized percolation rates are presented below:;
Initial Final Change
Time Depth Depth in Water Percolation
Boring Start Stop Interval to Water to Water Level Rate
# Time Time (Min.) (in.) (in.) (in.) (min.Jin.)
1 9:00 9:30 30 38.0 40.0 2.0 15.0
1 9:30 10:00 30 39.5 41.0 1.5 20.0
1 10:00 10:30 30 39.0 40.4 1.4 21.4
1 10:30 11:00 30 39.2 40.6 1.4 21.4
2 11:30 12:00 30 40.0 42.0 2.0 15.0
2 12:00 12:30 30 41.0 42.7 1.7 17.6
2 12:30 13:00 30 42.0 43.2 1.2 25.0
2 13:00 13:30 30 43.0 44.2 1.2 25.0
Description of Property
Subject property is a rectangular-shaped lot of 9,642 square feet, situated on the west side of
Roosevelt Street, approximately 200 feet south of Laguna Drive. The topography of the general
area may be described as relatively level; with surface drainage in a westerly direction.
An older residence and detached garage currently occupy the site. All existing structures and
improvements will be demolished to accommodate the proposed development.
The property is located in a developed area of Carlsbad. The site is bounded on the east by
Roosevelt Street; and on the north, west and south by existing commercial buildings.
On-Site Soil Conditions
A review of geologic maps as well as observations made during our subsurface exploration
indicates that the general area is underlain by late to middle Pleistocene Old Paralic Deposits Unit
6-7. On subject property, these Old Paralic Deposits were encountered in the form of medium
dense to dense brow/light brown silty fine sands. The Old Paralic Deposits were overlain by a
loose residual/topsoil layer on the order of 12 to 18 inches in thickness.
Project No. 17-1106E5
Groundwater
2569 Roosevelt LLC
2569 Roosevelt Street
12/03/18 Page 3
No groundwater was encountered in the exploratory trenches during the geotechnical
investigation to the maximum depth of exploration at 10 feet; and no groundwater was
encountered to a depth of 25 feet at a nearby site, approximately ½ mile to the southwest.
Conclusion
1. The vertical distance from the subgrade of the on-site driveway to the seasonal high
groundwater mark is greater than 10 feet.
2. The soil through which infiltration is to occur has physical and chemical characteristics
which are adequate for proper infiltration durations and treatment of runoff for the
protection of groundwater beneficial uses.
3. This is a residential project, and the proposed infiltration BMP' s are appropriate.
4. The infiltration BMPs are located a minimum of 100 feet horizontally from any water
supply wells and 25 feet from any septic system or as prescribed by County of San Diego
Department of Environmental Health.
5. A factor of safety of 2 should be applied in the sizing of the infiltration BMPs.
ROBERT
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LOCATION OF
PERCOLATION TESTS
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LEGEND
P# 1.LOCATION OF PERCOLATION ® TESt HOLE -BORING-· · · -