HomeMy WebLinkAboutCT 2018-0004; THE SEAGLASS; Technical Memorandum Pervious Pavers; 2018-12-03Geotechnical CCCC Geologic CCCC Coastal CCCC Environmental
5741 Palmer Way C Carlsbad, California 92010 C (760) 438-3155 C FAX (760) 931-0915 C www.geosoilsinc.com
TECHNICAL M E M O R A N D U M
Date: December 3, 2018 W.O. 7544-A-SC
To: 2646 Sea Glass, LLC
c/o Prophet Solutions
5845 Avenida Encinias, Suite 138
Carlsbad, California 92008
Attention: Mr. Rodney A. Boone
From: Robert G. Crisman, CEG 1934
David W. Skelly, RCE 47857
Exp. 3-31-20
Subject: Review and Comment Regarding the Planned Pervious Paver Driveway,
“Sea Glass” Project, 2646 State Street, Carlsbad, California
References: 1. “Geotechnical Update for “The Seaglass,” 2646 State Street, Carlsbad, California 92008,”
W.O. 7452-A-SC, Dated May 31,2018, by GeoSoils, Inc.
2. “Geotechnical Evaluation, ‘The Wave,’ 2646 State Street, Carlsbad, San Diego County,
California,” W.O. 6935-A-SC, dated November 3, 2015, by GeoSoils, Inc.
3. “Tentative Map for Condominiums, 2646 State Street, Carlsbad, CA 92008, CT2018-0004,”
Sheet C001, Project No. 2841, Latest Revision Dated October 12, 2018, by Pasco Laret
Suiter, Associates.
In accordance with your request, and in response to a request for information from Pasco
Laret Suiter, Associates (PLSA), the referenced plans, prepared by PLSA (see Reference
No. 3, were review with respect to storm water treatment and the intent of the geotechnical
reports (see Reference No. 1 and 2). Based on our review, and additional engineering
analysis, the following comments and additional geotechnical recommendations are
provided. Unless specifically superceded herein, the conclusions and recommendations
presented in the referenced reports (see Reference Nos. 1 and 2, remain valid and
applicable.
An impervious liner, as recommended in Reference No. 1, located along the base of the
pervious paver driveway section, as shown on sections B and D, on Sheet C001
(Reference No. 3) may be omitted, provided that the following recommendations are
incorporated into the paver design:
GeoSoils, Inc.
2646 Sea Glass, LLC W.O. 7544-A-SC
2646 State Street, Carlsbad December 3, 2018
File:e:\wp12\7500\7544a.rac.mem Page 2
1. Paver driveway subgrade shall slope away from the southern property line (adjacent
offsite building) at a minimum gradient of 2 percent, for a minimum lateral distance
of 10 feet.
2. In order to migitate the potential for the migration of soil subgrade upward into the
“Sub base course” for the pervious paver, a layer of filter fabric, Mirafi HP 570, or
equivalent, should be placed over the subgrade surface prior to base course
placement.
3. The lateral distance of 10 feet at a 2 percent fall may be reduced to 5 feet at a 2
percent fall, if an impermeable liner is placed over the subgrade soil surface within
5 feet of the southern property line (i.e., adjacent offsite building). Impermeable
liners used should consist of a 30-mil polyvinyl chloride (PVC) membrane, and
meets the following minimum specifications:
Specific Gravity (ASTM D792): 1.2 (g/cc, min.); Tensile (ASTM D882):
73 (lb/in-width, min); Elongation at Break (ASTM D882): 380 (%, min);
Modulus (ASTM D882): 32 (lb/in-width, min.); and Tear Strength
(ASTM D1004): 8 (lb/in, min); Seam Shear Strength (ASTM D882) 58.4 (lb/in,
min); Seam Peel Strength (ASTM D882) 15 (lb/in, min).
4. The “perforated sub-drain” shown on Reference No. 3 should be located along the
flow line created at the lower edge of the subgrade surface slope defined in No. 1
or No. 3 above, and extended to a suitable outlet. If a suitable, gravity fed outlet is
not available, then a sump pump system should be installed.
Unless specifically superceded herein, the conclusions and recommendations presented
in the referenced documents remain valid and applicable. The conclusions 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 or
testing performed by others, or their inaction, or work performed when GSI is not
requested to be onsite, to evaluate if our recommendations have been properly
implemented. Use of this report constitutes an agreement and consent by the user to all
the limitations outlined above, notwithstanding any other agreements that may be in place.
In addition, this report may be subject to review by the controlling authorities.
Distribution: Addressee (email)