Attachment 24GEOTECHNICAL
ENVIRONMENTAL
WATER RESOURCES
CONSTRUCTION SERVICES
6399 San Ignacio Avenue, Suite 150 San Jose, CA 95119 (408) 574-4900 Fax (888) 279-2698
www.engeo.com
Project No.
12175.000.000
March 28, 2018
Revised March 29, 2018
Mr. Mike Weisz
Town of Los Gatos
41 Miles Avenue
Los Gatos, CA 95030
Subject: 401-409 Alberto Way
Los Gatos, California
CONSTRUCTION SETTLEMENT & DEWATERING MONITORING RESPONSE
Dear Mr. Weisz:
At your request, we prepared this letter for your project at 401-409 Alberto Way in Los Gatos,
California. Specifically, we are responding to comments that dewatering at the subject project
during construction of the below grade parking structure may cause settlement and foundation
distress to neighboring properties. We previously prepared a letter (Reference 10, attached) to
address these concerns.
As described in the attached letter, it is our opinion that dewatering during construction will have
a negligible effect to offsite properties for the following reasons:
Distance between the proposed basement and offsite properties.
Appropriate management of construction dewatering operations. Although excavation and
shoring methods for construction are unknown at this time, the details of such operations will
be reviewed prior to construction to ensure appropriate methods and practices are employed.
Low risk of settlement of site soils (medium dense to very dense clayey gravels).
We also presented potential monitoring options that could be implemented during construction to
assess the potential for dewatering-related distress to offsite properties. Key aspects of a
monitoring program described in the attached letter include:
A preconstruction survey to establish baseline surface elevations prior to construction.
Periodic surveying of baseline surface points during construction.
A preconstruction photo and video survey to document existing conditions at neighboring
properties.
Installation and monitoring of groundwater wells during construction.
Based on site conditions and the employment of typical monitoring procedures used in dewatering
projects in the San Francisco Bay Area, we do not anticipate that settlement and distress of offsite
ATTACHMENT 24
Town of Los Gatos 12175.000.000
401-409 Alberto Way, Los Gatos March 28, 2018, Revised March 29, 2018
CONSTRUCTION SETTLEMENT & DEWATERING MONITORING RESPONSE Page 2
foundations will pose a significant risk during construction of the subject project. Furthermore,
Items 79 through 81 of the proposed Conditions of Approval for the project (Reference 3,
attached) address the before mentioned construction related settlement and dewatering concerns
and have been agreed to by the Applicant.
If you have any questions regarding the contents of this letter, please do not hesitate to contact
us.
Sincerely
ENGEO Incorporated
Robert H. Boeche, CEG Greg Cubbon, CEG, PE
Uri Eliahu, GE
rhb/gc/ue/dt
Attachments: Selected References
ENGEO, December Supplemental Response Letter (December 12, 2017)
Attachment 17, Draft Resolution from the March 20, 2018 Staff Report (Select Page)
12175.000.000
March 28, 2018
Revised March 29, 2018
SELECTED REFERENCES
1. AMEC; Peer Review – Geotechnical Exploration Report; 401 Alberto Way, Los Gatos,
California; November 4, 2015. AMEC Project No. 0084491960.
2. AMEC Foster Wheeler; Geotechnical Peer Review; 401-409 Alberto Way, Los Gatos,
California; May 8, 2017. AMEC Project No. 084491960.
3. Attachment 17, Draft Resolution from the March 20, 2018 Staff Report.
4. ENGEO; Geotechnical Exploration; 401 Alberto Way, Los Gatos, California; July 17, 2015
(Revised August 13, 2015). ENGEO Project No. 12175.000.000.
5. ENGEO; Response to AMEC Foster Wheeler Peer Review Comments; 401 Alberto Way, Los
Gatos, California; January 11, 2016. ENGEO Project No. 12175.000.000.
6. ENGEO; Supplemental Response to Public Comments; 401-409 Alberto Way, Los Gatos,
California; April 19, 2017. ENGEO Project No. 12175.000.000.
7. ENGEO; Second Supplemental Response to Public Comments; 401-409 Alberto Way, Los
Gatos, California; December 11, 2017. ENGEO Project No. 12175.000.000.
8. ENGEO; November Supplemental Response; 401-409 Alberto Way, Los Gatos, California;
November 2, 2017. ENGEO Project No. 12175.000.000.
9. ENGEO; November 6th Supplemental Response; 401-409 Alberto Way, Los Gatos, California;
November 6, 2017. ENGEO Project No. 12175.000.000.
10. ENGEO; December Supplemental Response; 401-409 Alberto Way, Los Gatos, California;
December 12, 2017. ENGEO Project No. 12175.000.000.
12175.000.000
March 28, 2018
Revised March 29, 2018
ENGEO, December Supplemental Response Letter,
401-409 Alberto Way, Los Gatos, California, December 12, 2017
GEOTECHNICAL
ENVIRONMENTAL
WATER RESOURCES
CONSTRUCTION SERVICES
SUBJECT TO ATTORNEY DIRECTION – ATTORNEY WORK PRODUCT
6399 San Ignacio Avenue, Suite 150 San Jose, CA 95119 (408) 574-4900 Fax (888) 279-2698
www.engeo.com
Project No.
12175.000.000
December 12, 2017
Ms. Alicia Guerra
Buchalter Nemer
55 Second Street, Suite 1700
San Francisco, CA 94105
Subject: 401-409 Alberto Way
Los Gatos, California
DECEMBER SUPPLEMENTAL RESPONSE
Dear Ms. Guerra:
At your request, we prepared this supplemental response letter for your project at 401-409 Alberto
Way in Los Gatos, California. Specifically, we are responding to comments that the subject project
should incorporate construction dewatering guidelines that have recently been implemented for
the City of Palo Alto.
The City of Palo Alto recently adopted revised Guidelines for Dewatering During Basement or
Below Ground Garage Construction as outlined in a memorandum of the same name in
May 2017. Pertinent geotechnical items outlined in the document include the following:
Prior to construction, perform pump testing to verify pump rates and determine anticipated
drawdown levels of groundwater and radius of influence of dewatering wells.
During construction, observe groundwater levels in monitoring wells and compare
groundwater drawdown to that from pump testing.
Given the distance of the proposed basement level to neighboring properties and the minimal
amount of dewatering required to construct the basement, we anticipate that the radius of
influence of dewatering wells will have negligible impact on offsite groundwater levels.
Furthermore, as discussed in References 3, 4 and 5, site soils generally consist of medium dense
to very dense clayey gravels. The risk of settlement in these soil deposits as a result of temporary
dewatering is low. Soils of concern for dewatering are generally soft compressible clays, which
are not present at the site.
Based on our experience with dewatering projects in the San Francisco Bay Area, a
preconstruction survey to establish baseline surface elevations prior to the start of dewatering,
periodic surveying of the baseline surface points during construction, and installation and
monitoring of groundwater wells during construction are typical measures employed to assess the
potential for dewatering-related distress to offsite properties. Due to site conditions and our
experience on similar projects, performing pump tests prior to construction is not necessary.
Buchalter Nemer 12175.000.000
401-409 Alberto Way, Los Gatos December 12, 2017
DECEMBER SUPPLEMENTAL RESPONSE Page 2
SUBJECT TO ATTORNEY DIRECTION – ATTORNEY WORK PRODUCT
If you have any questions regarding the contents of this letter, please do not hesitate to contact
us.
Sincerely
ENGEO Incorporated
Robert Boeche, CEG Greg Cubbon, CEG, PE
Uri Eliahu, GE
Attachment: Selected References
SUBJECT TO ATTORNEY DIRECTION – ATTORNEY WORK PRODUCT
12175.000.000
December 12, 2017
SELECTED REFERENCES
1. AMEC; Peer Review – Geotechnical Exploration Report; 401 Alberto Way, Los Gatos,
California; November 4, 2015. AMEC Project No. 0084491960.
2. AMEC Foster Wheeler; Geotechnical Peer Review; 401-409 Alberto Way, Los Gatos,
California; May 8, 2017. AMEC Project No. 084491960.
3. ENGEO; Geotechnical Exploration; 401 Alberto Way, Los Gatos, California; July 17, 2015
(Revised August 13, 2015). ENGEO Project No. 12175.000.000.
4. ENGEO; Response to AMEC Foster Wheeler Peer Review Comments; 401 Alberto Way, Los
Gatos, California; January 11, 2016. ENGEO Project No. 12175.000.000.
5. ENGEO; Supplemental Response to Public Comments; 401-409 Alberto Way, Los Gatos,
California; April 19, 2017. ENGEO Project No. 12175.000.000.
6. ENGEO; Second Supplemental Response to Public Comments; 401-409 Alberto Way, Los
Gatos, California; December 11, 2017. ENGEO Project No. 12175.000.000.
7. ENGEO; November Supplemental Response; 401-409 Alberto Way, Los Gatos, California;
November 2, 2017. ENGEO Project No. 12175.000.000.
8. ENGEO; November 6th Supplemental Response; 401-409 Alberto Way, Los Gatos, California;
November 6, 2017. ENGEO Project No. 12175.000.000.
12175.000.000
March 28, 2018
Revised March 29, 2018
Attachment 17, Draft Resolution from the March 20, 2018 Staff Report (Select Page)
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