Twentynine Palms City Council
December 12, 2023

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risk. In the event Contractor's insurance is not acceptable to City or copies of insurance certificates or endorsements are not provided, City shall have no obligations to compensate Contractor for such work unless Contractor possesses a notice to proceed from City for this work.
(3) Within sixty (60) days of the commencement of this Agreement, Contractor shall furnish certified copies of the actual policies and endorsements.

Failure to submit such policies shall constitute a material breach of this Agreement entitling City to any and all remedies at law or in equity, including summary termination of this Agreement. If proof of any insurance required under this Agreement is not delivered as required or if such insurance is canceled at any time and no replacement coverage is provided, City shall have the right but not the duty to obtain any insurance it deems necessary to protect its interests under this Agreement, express or implied, in any way relating to City. Any premium for such coverage shall be charged to and promptly paid by Contractor or, at City's option, may be deducted from sums due to Contractor.
(4) In the event of the premature termination of this Agreement for any reason, Contractor agrees to maintain the required insurance coverage until City provides written authorization to terminate the coverage following a review and determination that all liability posed under this Agreement as to the party providing the insurance has been eliminated.
(5) Except as outlined in Section 10(b) (3) above, Contractor will renew the required coverage annually as long as City, or its employees or agents face an exposure from operations of any type pursuant to this Agreement. This obligation applies whether or not the agreement is canceled or terminated for any reason. Termination of this obligation is not effective until City executes a written statement to that effect.
(6) Contractor shall provide proof that policies of insurance required herein expiring during the term of this Agreement have been renewed or replaced with other policies providing at least the same coverage. Proof that such coverage has been ordered shall be submitted prior to expiration. A coverage binder or letter from Contractor’s insurance agent to this effect is acceptable. A certificate of insurance and/or additional insured endorsement as required in these specifications applicable to the renewing or new coverage must be provided to City within five days of the expiration of the coverages.
(g) Notice of Claim or Loss. Contractor agrees to provide immediate notice to City of any claim or loss likely to involve City or its employees or agents which exceeds $2,500 or is likely to exceed that amount arising out of the work performed under this Agreement. City assumes no obligation or liability by such notice, but has the right (but not the duty) to monitor the handling of any such claim or claims if they are likely to involve City. .
(h) Sub-Contractor Insurance Requirements. Contractor agrees to require that all parties,

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including but not limited to sub-Contractors and additional Contractors or professional services with whom Contractor enters into contracts or whom Contractor hires pursuant to or in any way related to the performance of this Agreement, provide the insurance coverage required here, at a minimum. Contractor agrees to monitor and review all such coverage and assumes all responsibility for ensuring that such coverage is provided in conformity with the requirements of this Section. Contractor acknowledges and agrees that upon request, all agreements with sub-Contractors and others engaged in the project contemplated by this Agreement will be submitted to City for review. Contractor agrees and acknowledges that such contracts may require modification as to the insurance requirements necessary to properly protect City.

12. INDEPENDENT CONTRACTOR
(a) Contractor is and shall at all times remain as to the City a wholly independent Contractor. The personnel performing the services under this Agreement on behalf of Contractor shall at all times be under Contractor's exclusive direction and control. Neither City nor any of its officers, employees, or agents shall have control over the conduct of Contractor or any of Contractor's officers, employees, or agents, except as set forth in this Agreement. Contractor shall not at any time or in any manner represent that it or any of its officers, employees, or agents are in any manner officers, employees, or agents of the City. Contractor shall not incur or have the power to incur any debt, obligation, or liability whatever against City, or bind City in any manner.
(b) No employee benefits shall be available to Contractor in connection with the performance of this Agreement. Except for the fees paid to Contractor as provided in the Agreement, City shall not pay salaries, wages, or other compensation to Contractor for performing services hereunder for City. City shall not be liable for compensation or indemnification to Contractor for injury or sickness arising out of performing services hereunder.

13. LEGAL RESPONSIBILITIES
The Contractor shall keep itself informed of State and Federal laws and regulations which in any manner affect those employed by it or in any way affect the performance of its service pursuant to this Agreement. The Contractor shall at all times observe and comply with all such laws and regulations. The City, and its officers and employees, shall not be liable at law or in equity occasioned by failure of the Contractor to comply with this Section.

14. UNDUE INFLUENCE
Contractor declares and warrants that no undue influence or pressure is used against or in concert with any officer or employee of the City of Twentynine Palms in connection with the award, terms or implementation of this Agreement, including any method of coercion, confidential financial arrangement, or financial inducement. No officer or employee of the City of Twentynine Palms will receive compensation, directly or indirectly, from Contractor, or from any officer, employee or agent of Contractor, in connection with the award of this Agreement or any work to be conducted as a result of this Agreement. Violation of this

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Section shall be a material breach of this Agreement entitling the City to any and all remedies at law or in equity.

15. NO BENEFIT TO ARISE TO LOCAL EMPLOYEES
No member, officer, or employee of City, or their designees or agents, and no public official who exercises authority over or responsibilities with respect to the project during his/her tenure or for one year thereafter, shall have any interest, direct or indirect, in any agreement or sub-agreement, or the proceeds thereof, for work to be performed in connection with this Agreement.

16. RELEASE OF INFORMATION/CONFLICTS OF INTEREST
(a) All information gained by Contractor in performance of this Agreement shall be considered confidential and shall not be released by Contractor without City's prior written authorization. Contractor, its officers, employees, agents, or sub-Contractors, shall not without written authorization from the City Manager or unless requested by the City Attorney, voluntarily provide declarations, letters of support, testimony at depositions, response to interrogatories, or other information concerning the work performed under this Agreement or relating to any project or property located within the City. Response to a subpoena or court order shall not be considered "voluntary" provided Contractor gives City notice of such court order or subpoena.
(b) Contractor shall promptly notify City should Contractor, its officers, employees, agents, or sub-Contractors be served with any summons, complaint, subpoena, notice of deposition, request for documents, interrogatories, request for admissions, or other discovery request, court order, or subpoena from any person or party regarding this Agreement and the work performed hereunder or with respect to any project or property located within the City. City retains the right, but has no obligation, to represent Contractor and/or be present at any deposition, hearing, or similar proceeding. Contractor agrees to cooperate fully with City and to provide the opportunity to review any response to discovery requests provided by Contractor. However, City's right to review any such response does not imply or mean the right by City to control, direct, or rewrite said response.

17. NOTICES
Any notices which either party may desire to give to the other party under this Agreement must be in writing and may be given either by (i) personal service, (ii) delivery by a reputable document delivery service, such as but not limited to, Federal Express, which provides a receipt showing date and time of delivery, or (iii) mailing in the United States Mail, certified mail, postage prepaid, return receipt requested, addressed to the address of the party as set forth below or at any other address as that party may later designate by notice:

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To City: City of Twentynine Palms
6136 Adobe Road
Twentynine Palms, California 92277
Attention: City Clerk
To Contractor: Name
Address
City State ZIP

18. ASSIGNMENT
The Contractor shall not assign the performance of this Agreement, nor any part thereof, nor any monies due hereunder, without prior written consent of the City. Because of the personal nature of the services to be rendered pursuant to this Agreement, only Contractor Name shall perform the services described in this Agreement.

Contractor Name may use assistants, under its direct supervision, to perform some of the services under this Agreement. Contractor shall provide City fourteen (14) days' notice prior to the departure of key team members from Contractor's employ. Should he/she leave Contractor's employ, the City shall have the option to immediately terminate this Agreement, within three (3) days of the close of said notice period. Upon termination of this Agreement, Contractor's sole compensation shall be payment for actual services performed up to, and including, the date of termination or as may be otherwise agreed to in writing between the City Council and the Contractor.

19. LICENSES
At all times during the term of this Agreement, Contractor shall have in full force and effect, all licenses required of it by law for the performance of the services described in this Agreement.

20. GOVERNING LAW
The City and Contractor understand and agree that the laws of the State of California shall govern the rights, obligations, duties, and liabilities of the parties to this Agreement and also govern the interpretation of this Agreement. Any litigation concerning this Agreement shall take place in the municipal, superior, or federal district court with jurisdiction over the City of Twentynine Palms.

21. ENTIRE AGREEMENT
This Agreement contains the entire understanding between the parties relating to the obligations of the parties described in this Agreement. All prior or contemporaneous agreements, understandings, representations, and statements, oral or written, are merged into this Agreement and shall be of no further force or effect. Each party is entering into this Agreement based solely upon the representations set forth herein and upon each

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party's own independent investigation of any and all facts such party deems material.

22. SEVERABILITY
The invalidity in whole or in part of any provision of this Agreement shall not void or affect the validity of the other provisions of this Agreement.

23. NO PRESUMPTION REGARDING DRAFTER OF THIS AGREEMENT
The parties acknowledge and agree that the terms and provisions of this Agreement have been negotiated and discussed between the parties and their attorneys, and this Agreement reflects their mutual agreement regarding the same. Because of the nature of such negotiations and discussions, it would be inappropriate to deem any party to be the drafter of this Agreement, and therefore, no presumption for or against validity or as to any interpretation hereof, based upon the identity of the drafter shall be applicable in interpreting or enforcing this Agreement.

24. ATTORNEY’S FEES
If any action at law or suit in equity, including an action for declaratory relief, is brought by either party with respect to this Agreement, the prevailing party shall be entitled to reasonable attorney’s fees, in addition to any other relief to which it may be entitled, and such amount may be added to, and made a part of, such judgment.

25. AUTHORITY TO EXECUTE THIS AGREEMENT
The person or persons executing this Agreement on behalf of Contractor warrants and represents that he/she has the authority to execute this Agreement on behalf of the Contractor and has the authority to bind Contractor to the performance of its obligations hereunder.

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IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be executed the day and year first above written.

CITY OF TWENTYNINE PALMS
By:___________________________
Frank J. Luckino, City Manager
Attest:
________________________________
Cindy Villescas, City Clerk
Approved As to Form:
________________________________
Patrick Munoz, City Attorney
CONTRACTOR: NAME
By:___________________________
(Signature)
______________________________
(Typed Name)
Its:_ ____________________________

By:_____________________________
(Signature)
________________________________
(Typed name)
Its:_____________________________
(Title)

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EXHIBIT A

TASKS TO BE PERFORMED

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EXHIBIT B

PAYMENT SCHEDULE

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EXHIBIT C
CITY’S REQUEST FOR PROPOSAL

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EXHIBIT D
ONTRACTOR’S PROPOSAL

CITY OF TWENTYNINE PALMS

PROPOSAL FOR PROFESSIONAL AUDITING SERVICES
FOR THE FISCAL YEARS ENDING JUNE 30, 2024, THROUGH 2028 (WITH OPTION FOR TWO ONE-YEAR PERIODS)

PREPARED BY

ROGERS ANDERSON MALODY & SCOTT, LLP
735 E Carnegie Drive, Suite 100
San Bernardino, CA 92408
LICENSE #2596
FEIN 95-2662063
NOVEMBER 13, 2023
CONTACT PERSONS:

BRIANNA SCHULTZ, CPA, CGMA
[email protected]
SCOTT W. MANNO, CPA, CGMA
[email protected]
909.889.0871

CITY OF TWENTYNINE PALMS

PROPOSAL FOR PROFESSIONAL AUDITING SERVICES
Table of Contents
Page
Transmittal letter .................................................................................................................................. i Technical Proposal
License to practice in California ................................................................................................. 1 Independence ............................................................................................................................ 1 Firm qualifications and experience ............................................................................................ 1 About our firm
Range of services
Governmental Audit Quality Center
Housing Authority and Successor Agency experience
Single Audit experience
ACFR preparation
Engagement quality control
Equal Opportunity Employer
External quality control review
Disciplinary action
Partner, supervisory and staff qualifications and experience .................................................... 5 Partner and supervisory staff involvement
Staff continuity
Continuing professional education
Assigned personnel
Engagement team resumes
Similar engagements with other governmental entities ............................................................ 12 Specific audit approach .............................................................................................................. 13 Services to be provided
Engagement approach
Audit approach and proposed audit segmentation
Level of staff and approximate number of hours assigned to each segment Sample sizes (including for compliance testing)
Intelligent audit technology
Analytical procedures
Understanding of internal control over financial reporting Approach in determining applicable laws and regulations Auditing in a remote environment
Proposed audit timing
Other information ....................................................................................................................... 20 Identification of anticipated potential audit problems
Why choose RAMS?
Condition of records
Exceptions to Agency’s Professional Services Agreement
Attachment A: Government clients served

-iNovember 13, 2023
City of Twentynine Palms
6136 Adobe Road
Twentynine Palms, CA 92277
Dear Evaluation Committee:

We are pleased to respond, on behalf of Rogers, Anderson, Malody & Scott, LLP, (RAMS) to your request for a proposal regarding professional auditing services. As a recognized industry leader and innovator, our goal for the past 75 years has been to provide honest, objective and high-quality results to all our clients, including governmental organizations such as yours. Our success in these efforts is witnessed by the continued organic growth of our firm and our list of long-term clients, some we have served for over 20 years.

At RAMS, we are committed to providing the highest quality audit possible.

We understand the complexity of performing governmental audits and that is why we have a dedicated team of auditors that possess the specialized knowledge and experience to help ensure our audits are planned and executed in a way that maximizes audit efficiency and effectiveness and provides you the highest quality services.

We are aware that City of Twentynine Palms (the City) will be reviewing other proposals during this process, but we believe that RAMS would be an exceptional choice for the audit for the following reasons. Our firm:
 Utilizes Teammate Analytics, a suite of more than 200 Computer Aided Audit Tools (CAATs). This software empowers our audit teams with the ability to perform powerful, meaningful data analysis which builds upon our other robust, substantive audit procedures. This value-added service also helps to identify specific transactions or amounts which may be indicative of fraud.
 Performs an intelligent, risk-based audit (using our CAAT) which enables us to focus on key audit areas allowing us to become more efficient resulting in a higher quality audit at a reasonable fee.  Currently provides auditing services to over 70 governmental agencies and not-for-profit organizations, including over 30 cities, most of which have enterprise activities and over 35 special districts.  Developed a comprehensive remote working environment for our audits. All our staff currently have the tools for working remotely in an effective and efficient manner allowing us to still provide a quality audit. Our ultimate goal is to continue to meet your needs, but in a safe environment.
 Has an established reputation in the governmental and not-for-profit accounting and auditing community for providing excellent, timely service with high quality reporting to our clients.
 Is committed to helping you meet all reporting/auditing deadlines, resolving any issues encountered during your audit (e.g., accounting or auditing, new pronouncements, etc.), and providing you with quality audit services.

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 Understands the audit process can be a stressful experience for you and your staff; we understand that you will have other commitments and your regular workloads during the audit. We make every effort to ensure the audit process, from the interim fieldwork to the preparation of any required financial reports, will be as trouble-free as possible for you and your staff. We accomplish this by comprehensively planning the audit and utilizing our staff and audit technologies in the most efficient and effective manner while keeping disruptions and miscommunications to a minimum.  Has audit team members that are personable and easy to work with, yet still focused on the audit. Through open and responsive communication with all parties involved in the audit process, we work to have the most efficient audit possible by minimizing operational distractions of your staff, while maximizing quality service.
 Has an extensive internal quality control review process to ensure your financial reports meet the highest standards. In addition to the preparation of financial reports by the engagement team and reviewed by the engagement manager, each report is also examined by 2 partners and at least 1 professional proofreader.
 Has assisted many of our clients with the preparation of their Annual Comprehensive Financial Reports, and all our clients that have submitted their reports for the Government Finance Officers Association (GFOA) or California Society of Municipal Finance Officers (CSMFO) awards have received the awards.

Our participation as a GFOA reviewer also indirectly benefits our clients in the quality review process.  Believes that our fee estimate provides a fair and reasonable investment, commensurate with level of service provided and the experience of the audit team members. While we may not be the lowest bidder, that is not our objective. We focus on delivering the best value and price our prospective engagements accordingly.
 Is a local Southern California firm. All our employees live, work, and shop in the region, allowing our local cities to benefit from our sales and property taxes.

As you will see from our proposal, it was prepared in a clear, concise and simple manner in accordance with the request for proposal. We feel our firm, staff and reputation as a leader in governmental auditing exceeds the need for the excess information you may see in other proposals.

Rogers, Anderson, Malody & Scott, LLP is properly licensed to practice in California, including all the assigned professional staff to the engagement. Ms. Schultz, Partner, and Mr. Manno, Partner, are authorized to represent the firm, are empowered to submit the bid and authorized to sign a contract with the City. We understand the work to be done as listed in the section of this proposal titled Services to be provided. In addition, we will be committed to meeting any agreed upon time frames. This proposal is a firm and irrevocable offer for the time of the contract.

We can be reached at: 735 E. Carnegie Drive, Suite 100, San Bernardino, CA 92408, (909) 889-0871, [email protected] or [email protected].

Thank you for the opportunity to present our proposal to the City. We will be committed to exceeding your expectations of an auditor and believe this proposal provides you with information about our firm, the service team members and our customized audit approach. We look forward to having a long and mutually beneficial relationship with the City. Please feel free to contact us if you have any questions regarding this proposal.

Respectfully yours,

ROGERS, ANDERSON, MALODY & SCOTT, LLP

Brianna Schultz, CPA, CGMA
Partner

CITY OF TWENTYNINE PALMS

PROPOSAL FOR PROFESSIONAL AUDITING SERVICES
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License to practice
Rogers, Anderson, Malody & Scott, LLP is licensed to practice in the State of California. Our key professional staff, which includes the partners, managers, and supervisors, are all certified public accountants licensed to practice in the State of California and follow all applicable Board of Accountancy standards.

Independence
Rogers, Anderson, Malody & Scott, LLP is independent of the Agency and any component units, as defined by general standard number two of the generally accepted auditing standards, and by the second general standard for government auditing in the U.S. Government Accountability Office’s Government Auditing Standards.

For the past five (5) years, we have been the Agency’s auditor. We have followed all independence rules as prescribed by the AICPA and Government Auditing Standards, therefore there are no independence or conflict of interest issues.

Firm qualifications and experience
About our firm
We are a local firm founded in 1948 and located at 735 E. Carnegie Drive, Suite 100, San Bernardino, California. We provide a full range of services as expected of a full-service accounting firm. We are one of the oldest, most trusted and respected CPA firms in Southern California, with over 75 years of public practice experience, specializing in governmental agency and not-for-profit
organization auditing, accounting, and management advisory services. Over twenty-one thousand hours per year are
devoted to this area of our practice, which includes cities, redevelopment successor agencies, water districts, other special districts, not-for-profit corporations, and joint power authorities. We do not use our government accounting and auditing practice as “fill work” for the firm, it is one of our primary focuses thus allowing us to provide quality services to local governments.

We understand your desire to engage auditors that have a thorough understanding of the ever-changing complex accounting and compliance issues confronting governments today. Our firm has an extensive history of governmental accounting and auditing. During that time, we have gained valuable experience, acquired an in-depth knowledge of, and obtained the technical expertise needed to perform high quality governmental audits. This expertise has enabled us to provide exceptional, high-quality service and to provide solutions at fees we feel represent our value to our clients. In addition, we use our participation in various industry associations to continuously update our knowledge with respect to issues relating to governmental accounting, auditing, and operations. Any insight we gain is immediately passed on to our clients if we feel they will benefit from it.

Our firm has a total staff of forty people, which includes sixteen certified public accountants. The staff consists of seven partners, four managers, ten supervisors/senior accountants, fourteen staff accountants, and five support staff. The audit staff consists of twenty-three members who devote over 80% of their time to municipal engagements. The engagement team assigned to the Agency’s engagement will consist of the following fulltime staff: one audit partner, one audit manager, one audit supervisor/senior, and two to three staff auditors.

All personnel are out of our San Bernardino office.

CITY OF TWENTYNINE PALMS

PROPOSAL FOR PROFESSIONAL AUDITING SERVICES
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Firm qualifications and experience (continued)
Range of services
Our firm provides various other services in addition to auditing services to governmental entities, including:
 SB 341 compliance (Successor Agencies)
 Internal control agreed upon procedures
 Finance director and accounting support services
 Study and evaluation of financial condition and fiscal policies  Transient Occupancy Tax agreed upon procedures
 Franchise (refuse, cable) agreed upon procedures
 Accounting policies and procedures
 Cash management studies
 Financing and public bond offering assistance
 Franchise agreement assistance (ambulance, cable, television, refuse, etc.) In addition, the firm provides accounting, auditing, attest, and consulting services to for profit and not-for-profit entities. We also provide tax preparation and tax consulting services to individuals, corporations, and partnerships. We provide our municipal audit clients tax consultation at no extra charge.

Governmental Audit Quality Center
As a member of the American Institute of CPAs Governmental Audit Quality Center (the Center), we are committed to adhering to the highest quality standards by voluntarily agreeing to the Center membership requirements, which include designating a partner responsible for the quality of our governmental audit practice, establishing quality control programs, performing annual internal inspection procedures, and making our peer review report findings publicly available. At RAMS, our goal is to continue to enhance our quality initiatives within our governmental audit practice to deliver the highest quality audit services possible.

In addition, the Center provides access to comprehensive resources that will assist us in further enhancing the quality of your audit. The Center membership provides us with timely information on a variety of technical, legislative, and regulatory subjects that we can in turn apply to your audit to help ensure compliance with the appropriate standards and changes in regulations which we pass on to our clients.

Housing Authority and Successor Agency experience
Over the past five fiscal years, the firm has audited the Housing Authorities and Successor Agencies for the following entities:

City of South Pasadena City of San Bernardino
City of Thousand Oaks City of La Verne
City of San Marcos City of San Jacinto
City of Moorpark City of Twentynine Palms
City of Fillmore City of La Mesa
City of Sierra Madre City of Rosemead
City of El Cajon City of Hawthorne
Town of Yucca Valley City of West Covina
City of Poway City of Claremont

CITY OF TWENTYNINE PALMS

PROPOSAL FOR PROFESSIONAL AUDITING SERVICES
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Firm qualifications and experience (continued)
Single audit experience
Most of our municipal clients, and some of our other governmental and not-for-profit clients, have been subject to an audit in accordance with Uniform Guidance. We recently performed single audits for the following entities:

City of San Bernardino City of Menifee
City of El Cajon Elsinore Valley Municipal Water District City of San Marcos City of Imperial Beach
City of Twentynine Palms Town of Yucca Valley
City of Woodlake City of Thousand Oaks
City of Exeter San Joaquin Regional Rail Commission
City of La Verne City of Hawthorne
Our specialized Single Audits Team is led by Managers and Supervisors with Intermediate and Advanced Single Audit Certifications issued by the AICPA guaranteeing a successful and thorough engagement.

ACFR preparation
We have extensive experience in the preparation of Annual Comprehensive Financial Reports (ACFR). For the fiscal years ended June 30, 2021 and 2022, our staff prepared over 25 ACFR’s, with each entity receiving the Certificate of Achievement for Excellence in Financial Reporting from the GFOA. For the fiscal year ended June 30, 2022, again, our staff prepared over 25 ACFR’s for our clients for submittal to the GFOA. In addition, we have helped many cities and special districts develop their first year’s report for submittal. Four of our audit partners and four of our supervisory staff are technical reviewers for the GFOA award program. In addition, we review all the ACFR’s for compliance with the GFOA certificate program checklist, as well as addressing any prior year comments, if applicable, to insure they have been addressed.

External quality control review
As a member of the AICPA Private Companies Practice Section, our firm has participated in the “Peer Review” program since 1993 and has been examined every three years since that date by an outside, independent firm of certified public accountants. Participation in this program ensures that our engagements, firm policies, and audit procedures meet the standards of the AICPA, the Yellow Book, and the California State Board of Accountancy. Throughout our participation in this program, the firm has only received pass ratings from the peer reviewers.

During each review, an independent firm reviews our policies and procedures and then inspects a representative sample of engagement workpapers and reports, including governmental entities and engagements subject to the Uniform Guidance. For the year ended November 30, 2020, our firm received a rating of pass which indicates our auditing practice is suitably designed and complied with to provide reasonable assurance of performing and reporting in conformity with applicable standards. The results provide confirmation that the custom audit approach and procedures we use are technically sound and in compliance with applicable standards.

Disciplinary action
The firm has never had any disciplinary action taken or pending against it with state regulatory bodies or professional organizations, nor has it ever had any pending or settled litigation, civil or criminal investigations.

In addition, we are not aware of any federal or state desk reviews or field reviews of its audits during the last three years.

Our firm does not have a record of substandard work.

CITY OF TWENTYNINE PALMS

PROPOSAL FOR PROFESSIONAL AUDITING SERVICES
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Partner, supervisory, and staff qualifications and experience The quality of service you receive is dependent on the capabilities of the individuals assigned to the engagement, and the manner in which those personnel resources are organized to efficiently focus their abilities on providing you with the requested audit services. These professionals are highly trained and knowledgeable and have a thorough understanding of the environment in which governmental and not-forprofit entities operate. This experience is a critical component in providing the City with an effective and efficient audit.

Our engagement team will provide significant experience coupled with an extensive, practical understanding of governmental accounting and auditing along with a broad business perspective. Each member will have access to a wide range of technical resources and knowledge bases which will enable them to provide the City with practical observations and effective solutions.

Partner and supervisory staff involvement
All partners and supervisory staff are working professionals and are actively and continually involved in all aspects of their engagements. We believe that partner and supervisory staff involvement in all areas of the audit is a key aspect of the overall audit process. This involvement includes being on-site for interim and yearend fieldwork, thus facilitating a proper, efficient, and effective audit, with minimal disruption of your staff. In addition, the time spent on-site by the partners and supervisory staff ensures they gain an understanding of the entire City’s accounting processes and procedures. This understanding will enable them to evaluate and develop opportunities for efficiency, as well as offer practical and functional advice for improving your accounting processes and procedures.

All professionals on this engagement have worked on audits similar in nature to the City’s, therefore, the City will not have to train our engagement team.

Staff continuity
Continuity of audit staff is a principal concern with our firm. In order to retain our staff, we offer extremely competitive wages, opportunities for advancement, generous medical packages, a retirement plan, bonus opportunities, as well as educational benefits. Even with the benefits we provide, we realize we may lose staff at any given time. Knowing this, we plan to provide staff continuity from year to year, which is in the best interest of the City and our firm. Continuity ensures an orderly, efficient, and less disruptive audit experience.

Since we cannot guarantee staff will remain with us, principal supervisory and management staff, including engagement partners, managers, other supervisory staff, and specialists, may be changed if those personnel leave the firm or are promoted. However, the City reserves the right to accept or reject replacements.

We believe that due to the significant involvement of the partners on all our engagements, any staff transition would have a minimal effect on the audit efficiency and effectiveness of subsequent years.

Continuing professional education
Our team of auditor specialists stays current in this highly technical practice area by adhering to, and typically exceeding, the continuing professional education requirements of Government Auditing Standards as well as the State Board of Accountancy guidelines. All professionals at our firm participate in continuing professional education (CPE) programs, which are sponsored by various organizations including the Government Finance Officers Association, the American Institute of Certified Public Accountants, the California State Society of Certified Public Accountants, the California Society of Municipal Finance Officers and the Association of Government Accountants. Participation in these programs helps us to ensure that our clients are serviced with the best trained and most proficient government auditors and accountants available. In addition, we periodically provide in-house training taught by our partners and senior level staff using published resources.

CITY OF TWENTYNINE PALMS

PROPOSAL FOR PROFESSIONAL AUDITING SERVICES
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Partner, supervisory, and staff qualifications and experience (continued) All staff are required to attend fraud and ethics training. It is our goal to provide our professional staff continuing education which exceeds the minimum standard of 80 hours over two years.

In accordance with our firm’s Quality Control document and Government Auditing Standards (GAS), all staff members who work on audits subject to GAS are required to complete CPE in accordance with GAS standards which require 24 hours directly related to governmental accounting and auditing.

In addition to the required CPE, we also use the following to increase our technical knowledge: view the Governmental Audit Quality Center Annual Webcast Update and other relevant seminars and review monthly publications from the AICPA, the GFOA, and various other resources. We also attend conferences and seminars sponsored by the GFOA, California Society of Municipal Finance Officers, California State Society of Certified Public Accountants and the California Special Districts Association.

In addition, we utilize Accounting Research Manager which gives each staff member access to a variety of resources, including official GASB statements, GASB implementation guides, GASB interpretations, governmental GAAP practice manuals, the GASB Codification along with AICPA accounting and auditing guides.

Assigned personnel
It is our goal to provide you with capable, competent, and personable individuals who offer an extensive background, not only in governmental accounting and auditing, but also in general business practices. By doing so, it allows us to offer practical solutions, as well as provide technical support. This enables you to stay at the forefront of governmental accounting and provides you with the support you need in dealing with the complex issues confronting entities such as yours.

In addition, our engagement team has the managerial and supervisory experience to provide the City with a comprehensive audit of the highest quality, while still focusing on personal service. The resumes of the key engagement personnel assigned to the audit are presented below. The following individuals will be assigned to the engagement for the entire contract period (see staff Continuity section of this proposal):

Brianna Schultz, CPA, CGMA - Partner, Engagement Partner Brianna is a municipal audit partner with the firm and will be the engagement partner. She is licensed to practice as a certified public accountant in the State of California. She has been in public accounting for over 13 years specializing in serving local governments such as yours. As the engagement partner, she will be responsible for overall engagement quality, as well as ensuring that the engagement is performed in the most effective and efficient manner. Brianna will directly oversee all engagement staff while assisting in planning and performing the engagement, as well as reviewing all work-papers prepared during the engagement, in addition to all required reports. Brianna is a working partner and will be actively and continually involved in all aspects of the engagement.

Scott W. Manno, CPA, CGMA - Partner, Concurring Partner Scott is also a municipal audit partner with the firm. He is licensed to practice as a certified public accountant in the State of California. Scott has over 26 years of public accounting experience and has provided accounting, auditing, and consulting services for municipalities, special districts, water agencies, and various not-for-profit organizations. As the concurring partner, Scott will work directly with Brianna in planning and performing the engagement. In addition, he will provide technical consultation for the engagement team.

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Partner, supervisory, and staff qualifications and experience (continued) Brad Welebir, CPA - Partner, Quality Control Reviewer
Brad will be the Quality Control Reviewer. He is licensed to practice as a certified public accountant in the State of California. He has over 20 years of practical, governmental accounting and auditing experience.

Brad will be responsible for the final quality control review of all released opinions and related reports.

Laura Arvizu, CPA - Audit Manager
Laura is a manager with the firm and is licensed to practice as a certified public accountant in the State of California. Laura has over 6 years’ experience in providing accounting and auditing services for municipalities, special districts and various nonprofit organizations. As an audit manager, she will work closely with the engagement partner and manager and be responsible for planning the audit, managing the staff assigned to the engagement, and performing reviews of all workpapers prepared for the engagement. In addition, she will also be responsible for the review of any required reports.

Demi Hite, CPA – Audit Senior
Demi is an audit senior with the firm and is licensed to practice as a certified public accountant in the State of California. She has over 3 years’ experience in providing accounting and auditing services for municipalities, special districts and various nonprofit organizations. As an audit senior, she will work closely with the engagement partner and manager in-charge and be responsible for planning the audit, supervising the staff assigned to the engagement, and performing reviews of all workpapers prepared for the engagement. In addition, she will also be responsible for the preparation of any required reports.

Staff level accountants
All staff accountants employed by us and working on governmental audits are qualified to perform such audits. Prior to “audit season”, our staff are subject to a rigorous training regimen in which we go over all aspects of our audit process and audit programs ensuring staff members have a solid foundation prior to starting fieldwork. Each staff member is encouraged to take on increased responsibility for engagements previously worked on. This enables our staff to grow on each engagement and allows them to continue to gain the skills and knowledge required to perform the audits.

In summary, we want to emphasize the credentials of the above professionals who will be directly responsible for the quality of service that you will receive. Additionally, our audit team has another attribute that is very important, even though it is intangible -- the professionals assigned to the audits have previously worked together as a multi-disciplined team, thus ensuring a smooth, efficient, and effective audit. We are committed to allocating the necessary resources to ensure that we provide continuity of personnel throughout the term of our relationship with the City.

Full engagement team resumes are provided as follows.

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Partner, supervisory, and staff qualifications and experience (continued) Engagement team resumes
Brianna Schultz, CPA, CGMA
Engagement Partner
Professional experience
Ms. Schultz began her career with Rogers, Anderson, Malody & Scott, LLP in July 2014, and had over three years’ experience with another public accounting firm serving the same industry. She primarily provides audits and advisory services to governmental agencies and not-for-profit organizations. Ms. Schultz serves as a technical reviewer for the GFOA ACFR Award program. She also serves as a member-at-large on the CalCPA governmental accounting and auditing committee.

Education/licenses
Bachelor of Science – California State University, San Bernardino Certified Public Accountant – State of California
Chartered Global Management Accountant – American Institute of Certified Public Accountants
Related professional experience
Partial listing of recent relevant governmental agencies served (*includes enterprise fund accounting):

City of Claremont* City of El Cajon*
City of Aliso Viejo City of Live Oak*
City of La Mesa* City of Rolling Hills Estates
City of San Bernardino* City of Yorba Linda*
City of Moreno Valley* City of Yucca Valley
City of Loma Linda* City of Beaumont*
Continuing professional education
Ms. Schultz has completed over 120 hours of continuing professional education courses in the past three years of which the following select courses are relevant to this engagement:
 2022 Single Audit Update: What to Know and How to Prepare  GASB's Lease and SBITA Standards: Practical Implications and Adoption Challenges  ARPA and Infrastructure Bill Impacts and FAQs
Ms. Schultz also obtained the AICPA’s Advanced Single Audit Certificate in 2019 and the Intermediate Single Audit Certificate in 2017.

Professional affiliations
Ms. Schultz is a member of the following professional organizations:
 American Institute of Certified Public Accountants (AICPA)  California Society of Certified Public Accountants (CalCPA)  Government Finance Officers Association (GFOA)
 California Society of Municipal Finance Officers (CSMFO)

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Partner, supervisory, and staff qualifications and experience (continued) Scott W. Manno, CPA, CGMA
Concurring Partner
Professional experience
Mr. Manno began his career with Thomas, Bigbie and Smith in 1995 after serving in the United States Army. He spent six years with the firm primarily working on audits of municipalities, special districts and redevelopment agencies as well as various not-for-profit organizations. He joined Rogers, Anderson, Malody & Scott, LLP in July 2001. Currently, Mr. Manno serves as a technical reviewer for the GFOA ACFR Award program. Since 2010, Mr. Manno has been serving as a technical volunteer on the California Special Districts Association Audit Committee and is also on the Association’s fiscal committee providing accounting and fiscal program guidance. Also, Mr. Manno has done presentations on fraud.

In addition, he is part of the California State Society of Certified Public Accountants Governmental Accounting and Auditing Committee which meets periodically to discuss current events, pronouncements, etc.

Education/licenses
Bachelor of Science, Business Administration – California State University, San Bernardino Certified Public Accountant – State of California
Chartered Global Management Accountant – American Institute of Certified Public Accountants Related professional experience
Partial listing of relevant governmental agencies served (*includes enterprise fund accounting):

City of El Cajon* Town of Yucca Valley City of La Mesa* City of La Verne City of Sierra Madre* City of Fillmore* City of Chino* City of 29 Palms City of Moreno Valley* City of Beaumont* City of San Marcos* City of Loma Linda* City of Claremont City of Perris* City of Exeter* City of Woodlake* City of San Jacinto* City of Menifee City of Rolling Hills Est. City of Poway* Mr. Manno has completed over 170 hours of continuing professional education courses over the past three years of which the following select courses are relevant to this engagement:
 Audits of State and Local Governments
 Government Accounting and Auditing Update
 OMB Supplement Addendum and Latest Covid-19
Professional affiliations
Mr. Manno is a member of the following organizations:
 American Institute of Certified Public Accountants (AICPA)  California Society of Certified Public Accountants (CalCPA)  Association of Government Accountants (AGA)
 Association of Certified Fraud Examiners (ACFE)
 Government Finance Officers Association (GFOA)
 California Special Districts Association (CSDA)
 California Society of Municipal Finance Officers (CSMFO)

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Partner, supervisory, and staff qualifications and experience (continued) Brad A. Welebir, CPA, CGMA, MBA
Quality Control Partner
Professional experience
Mr. Welebir joined Rogers, Anderson, Malody & Scott, LLP in 2004. He primarily provides audits and advisory services to governmental agencies, small to mid-sized businesses, and not-for-profit organizations. Mr. Welebir serves as a technical reviewer for the GFOA ACFR Award program. He also serves as the CalCPA Inland Empire chapter chair of the governmental accounting and auditing committee and as the representative for the chapter at the state committee.

Education/licenses
Master of Business Administration, Accounting Emphasis – California State University, Fullerton
Bachelor of Arts in Business Administration – La Sierra University Certified Public Accountant – State of California
Chartered Global Management Accountant – American Institute of Certified Public Accountants
Related professional experience
Partial listing of relevant governmental agencies served (*includes enterprise fund accounting):

City of Twentynine Palms City of Loma Linda* City of San Bernardino City of La Verne City of Sierra Madre* City of Fillmore* City of Poway* City of Poway City of Moorpark* City of Rosemead City of Redondo Beach* City of San Marcos* City of Claremont Town of Yucca Valley City of Aliso Viejo City of San Jacinto* Continuing professional education
Mr. Welebir has completed over 120 hours of continuing professional education courses in the past three years of which the following select courses are relevant to this engagement:
 Governmental Accounting and Auditing Update
 Single Audit Update
 Auditing Fraud Risk in the Current Environment
 Annual Conference Sessions
 GAAP Update
Professional affiliations
Mr. Welebir is a member of the following professional organizations:
 American Institute of Certified Public Accountants (AICPA)  California Society of Certified Public Accountants (CalCPA)  Government Finance Officers Association (GFOA)
 California Society of Municipal Finance Officers (CSMFO)  California Special Districts Association (CSDA)

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Partner, supervisory, and staff qualifications and experience (continued) Laura Arvizu, CPA
Audit Manager
Professional Experience
Mrs. Arvizu began her career with Rogers, Anderson, Malody & Scott, LLP in July 2016. During her time with the firm, she has worked primarily on audits of municipalities, special districts and redevelopment agencies, as well as various non-profit organizations. Currently, Mrs. Arvizu serves as a technical reviewer for the GFOA ACFR Award program.

Education
Bachelor of Arts – California State University, San Bernardino Certified Public Accountant – State of California
Related Professional Experience
Partial listing of recent relevant governmental agencies served (*includes enterprise fund accounting):

City of El Cajon* Town of Yucca Valley Nipomo Community Services District
San Bernardino Valley
Municipal Water District*
City of Aliso Viejo City of Imperial Beach West Basin Water District*
Elsinore Valley Municipal
Water District
City of Hawthorne City of Claremont* City of Menifee City of Ojai* City of San Marcos* City of La Mesa* City of Rolling Hills Est. City of 29 Palms Continuing Professional Education
Mrs. Arvizu has completed over 100 hours of continuing professional education courses over the past two years of which the following select courses are relevant to this engagement:
 GASB Update
 Governmental Accounting and Auditing Update
 Frequent Frauds Found in Government
 Government Risk Assessments
Professional Affiliations
Mrs. Arvizu is a member of the following organizations:
 American Institute of Certified Public Accountants (AICPA)  California Society of Certified Public Accountants (CalCPA)  California Society of Municipal Finance Officers (CSMFO)

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Partner, supervisory, and staff qualifications and experience (continued) Demi Hite, CPA
Audit Senior
Professional Experience
Mrs. Hite has over three years of experience in providing accounting and auditing services for municipalities, special districts and various not-for-profit organizations. As an audit senior, she will work closely with the engagement partner and manager and be responsible for planning the audit, supervising the staff assigned to the engagement, and performing reviews of all work-papers prepared for the engagement. In addition, she will also be responsible for the preparation of any required reports.

Education
Bachelor of Arts – California State University, San Bernardino Certified Public Accountant – State of California
Related Professional Experience
Partial listing of recent relevant governmental agencies served (*includes enterprise fund accounting):

City of Rolling Hills Est. Rubidoux CSD Rosamond CSD City of Perris* Beaumont Cherry VWD City of Claremont* City of San Jacinto* City of Ojai* City of South Pasadena* City of La Verne* City of Menifee City of Loma Linda* City of San Marcos* City of Moreno Valley* City of 29 Palms Elsinore Valley Municipal Water District
Continuing Professional Education
Mrs. Hite has completed over 100 hours of continuing professional education courses over the past two years of which the following select courses are relevant to this engagement:
 Intermediate Governmental Accounting
 Discover GFOA Best Practices
 Critical Concepts of Accounting for Capital Assets
Professional Affiliations
Mrs. Hite is a member of the following organizations:
 American Institute of Certified Public Accountants (AICPA)  California Society of Certified Public Accountants (CalCPA)  California Society of Municipal Finance Officers (CSMFO)

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Similar engagements with other governmental entities and client references See Attachment A for a listing of current and recent government clients served.

Entity: City of Loma Linda
Scope of work: Financial Audit/ACFR/RDA/Successor Agency Date: Years ending June 30, 2013 - present
Engagement partner: Mr. Terry Shea/Mr. Brad Welebir
Total hours: Approximately 225 hours each year
Contact person: Ms. Sonia Fabela, Finance Director/Treasurer, (909) 799-2840 Address: 25541 Barton Road, Loma Linda, CA 92354
Entity: City of Aliso Viejo
Scope of work: Financial Audit/ACFR/Single Audit
Date: Years ending June 30, 2016 - present
Engagement partner: Mr. Terry Shea/Mr. Scott Manno
Total hours: Approximately 300 hours each year
Contact person: Ms. Ann Eifert, Director of Financial Services, (949) 425-2520 Address: 12 Journey, Suite 100, Aliso Viejo, CA 92656
Entity: City of La Mesa
Scope of work: Financial Audit/Single Audit/Successor Agency Date: Years ending June 30, 2011 - present
Engagement partner: Mr. Scott Manno/Terry Shea
Total hours: Approximately 340 hours each year
Contact person: Ms. Tammi Royales, Director of Finance, (619) 667-1122 Address: 8130 Allison Avenue, La Mesa, CA 91942
Entity: City of Rolling Hills Estates
Scope of work: Financial Audit/ACFR
Date: Years ending June 30, 2019 - present
Engagement partner: Mr. Scott Manno
Total hours: Approximately 250 hours each year
Contact person: Mr. Mike Whitehead, Admin. Services Director, (310) 377-1577, ext.112 Address: 4045 Palos Verdes Drive North, Rolling Hills Estates, CA 90274 Entity: City of Live Oak
Scope of work: Financial Audit/ACFR
Date: Years ending June 30, 2022 - present
Engagement partner: Ms. Brianna Schultz
Total hours: Approximately 250 hours each year
Contact person: Mr. James Ramsey, Finance Director, (530) 695-2112 Address: 9955 Live Oak Blvd, Live Oak, CA 95953

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PROPOSAL FOR PROFESSIONAL AUDITING SERVICES
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Specific audit approach
Services to be provided
The City desires the auditor to express an opinion(s) on the fair presentation of the financial statements of the City in accordance with generally accepted accounting principles.

In addition, we shall:
 Prepare the Annual Comprehensive Financial Report.
 Apply certain limited procedures related to Management’s Discussion and Analysis and Required Supplementary Information and provide an “in-relation-to" report on the combining and individual fund financial statements and supporting schedules, if applicable.  Provide opinions as to the compliance with the Uniform Administrative Requirements, Cost Principles and Audit Requirements for Federal Awards (OMB Uniform Guidance). RAMS is to provide an "inrelation-to" report on the Schedule of Expenditures of Federal Awards based on the auditing procedures applied during the audit of the financial statements.  Prepare an agreed-upon procedures report over the GANN appropriations limit calculation.  Prepare the Annual Financial Transaction Report (currently we utilize subcontractor Forvis, previously known as Thales Consulting).

Our audit(s) will be in accordance with:
 Generally Accepted Auditing Standards as promulgated by the American Institute of Certified Public Accountants, including requirements found in the most recent AICPA audit guide Audits of State and Local Governments.
 Government Auditing Standards issued by the Comptroller of the United States of America.  Uniform Administrative Requirements, Cost Principles and Audit Requirements for Federal Awards (OMB Uniform Guidance).
 Minimum Audit Requirements and Reporting Guidelines for Special Districts, as issued by the California State Controller.
 Any other applicable standards for other items outlined in the Scope of Work to be performed and/or reports to be issued.

Reports to be issued:
 A report on the fair presentation of the financial statements in conformity with GAAP.  A report on internal control over financial reporting and on compliance and other matters based on an audit of financial statements performed in accordance with Government Auditing Standards (material weaknesses or significant deficiencies).
 A report in compliance with requirements applicable to each major federal program and internal control over compliance in accordance with the Uniform Guidance.  Prepare Management Letter that includes significant and less significant (i.e., reportable and nonreportable) recommendations for improvements to internal control.  We will issue reports to those charged with governance (SAS 114 letters) as required by auditing standards.

RAMS will also perform the following:
 Make an immediate, written notification of all irregularities and illegal acts or indication of illegal acts of which we become aware to the following: City Manager and Attorney.

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Specific audit approach (continued)
Engagement approach
Our engagement approach has been developed and refined over many years. The foundation of our approach revolves around the following:
 Knowledge and experience. We have been auditing governmental entities like the City, both large and small, for over 75 years. This experience has allowed us to gain in-depth knowledge of the governmental environment which in turn allows us to perform a more efficient and effective audit. It also enables us to perform detailed risk assessment procedures allowing us to identify significant audit risk areas within the City and its control environment.
 Intelligent design: As discussed later in our proposal, all our audits are designed to be intelligent using our powerful audit software/data analytic tools (Engagement and Teammate Analytics). This allows us to analyze large amounts of data in seconds increasing both the efficiency and, more importantly, the effectiveness of all our audit engagements.
 Oversight. Professional judgment is not developed overnight. Our partners, managers and supervisors have been deeply involved in governmental audits on a continuous basis for most of their professional careers. By having direct partner and manager oversight, we can design audit strategies that result in effective and efficient audits.
 Timeliness. Deadlines are not just “dates” to us, they are professional commitments. All required deadlines will be met.
 Open communication. Open lines of communication with all parties (the engagement team members and City Management and staff) throughout the audit process helps to eliminate “surprises.” Proper planning and proper use of experienced engagement personnel tend to provide for an effective and efficient audit process. Consequently, inefficiencies, disruptions, and lack of understanding are kept to a minimum.
 Availability. All engagement team members are available throughout the year for any questions or additional consultation. City staff will have direct access to the partner, manager, and other supervisory staff at all times during the engagement, as well as after.  Cost effectiveness. Our customized audit approach and procedures and our experienced auditors help to reduce your overall audit costs while still providing an effective audit and high-quality reports.  Risk based approach. Our detailed risk assessment procedures will consist of activities performed to obtain an understanding of the City and its environment, including its internal control. Evidence from these activities will provide the basis for our assessment of risks of material misstatement at the financial statement and relevant assertion levels. While performing our risk assessment procedures and we may choose to perform further audit procedures concurrently with risk assessment procedures as deemed necessary. In addition, risk assessment procedures will provide some of the necessary evidence about the relevant assertions related to classes of transactions, account balances, or disclosures and about the operating effectiveness of controls.

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Specific audit approach (continued)
As indicated in the previous section of the proposal, the overall objective of the engagement with the City is to conduct an audit of the financial statements in accordance with required auditing standards and the expression of an opinion(s) on those financial statements. Beyond that initial objective, we believe that our engagement approach provides certain other value-added characteristics, at no additional cost, that will benefit the City over the long-term:
 All our audits are designed to be performed in an efficient and effective way to minimize disruption to the office operations.
 We offer practical observations and recommendations relating to internal control issues, implementation of accounting standards and the policies and procedures regarding both.  We identify opportunities for operating efficiencies which can be used to decrease operating costs of the City.

Audit approach and proposed audit segmentation
The following is a summary of the audit team’s audit approach for the engagement. The audit will be divided into the following segments:

Segment 1 - Interim testing - planning, pre-audit administration, and internal control testing During this phase of the audit, our principal objectives will be to gather information about the City and its environment, including its internal control over financial reporting.

In order to achieve the desired objectives of this phase of the audit, we will:
 Meet with the City’s staff in order to determine convenient dates in which we can begin our audit and to discuss the assistance to be provided by the City’s staff.  Hold brainstorming sessions with engagement team members to discuss the susceptibility of the City’s financial statements to material misstatement and fraud.  Review and evaluate the City’s accounting and reporting processes by reviewing the prior year's audit workpapers, any City-prepared documents such as budgets, in-house financial reports, policies and procedures manuals, minutes of governance meetings, etc., and by using various analytical procedures. Analytical procedures will enhance our understanding of the City and will help us identify areas that may need further assessment and additional testing.  Review and retain copies of any pertinent local, state and federal statutes, regulations, or charters that apply to the City.
 Evaluate the design of controls that are relevant to the audit by obtaining a thorough understanding of the City’s internal controls over financial reporting and compliance by documenting key internal control components, utilizing questionnaires, walkthroughs, inquiring of the City’s personnel, and observing and reviewing key supporting documentation (a more thorough explanation of this process is discussed later in the technical proposal).
 Test controls, if control risk is to be assessed below maximum, by selecting a sample of transactions within the audit area being tested and reviewing supporting documentation to determine whether the relevant controls are in place and functioning properly.  Document and review with management, any findings noted during the testing of internal controls and provide a preliminary management letter that will include our recommendations for improving any weaknesses in operations. The letter will also include suggestions for improving the efficiency of the City’s operations.

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Specific audit approach (continued)
 Utilize our powerful audit data analytic software allowing us to analyze large amounts of data in seconds and focusing on areas/transactions that are red flagged.

In addition, we will perform the following procedures related to IT General Controls that “touch” financial data:
 Security access (including physical) controls: evaluate the general system security settings and password parameters; evaluate the process for adding, deleting, and changing security access; evaluate the access capabilities of various types of users; evaluate access controls to networks and financial applications; evaluate access controls related to data files; and evaluate physical access to networks, servers, etc.
 Computer operations: Evaluate backup and recovery processes and review processes of identifying and handling operational problems.
 System development and system changes: Evaluate processes related to system development and system changes (if applicable).
 Application testing: We will determine if the testing of application controls is deemed necessary based on our professional judgment in the planning stages of the engagement.

This phase of the engagement for the audit will be performed by the audit senior and two/three staff accountants with direct supervision by the audit manager and partner.

Segment 2 - Year-end testing - substantive testing
During this phase of the audit, our principal objectives will be to assess the risk of material misstatement at the financial statement level and specific assertions, design overall responses to assessed risks and further audit procedures, perform substantive tests, and complete the audit and evaluate audit findings, if applicable.

In order to achieve the desired objectives of this phase of the audit, we will:
 Identify significant risks and develop a detailed audit plan using the results in Segment 1.  Design substantive tests of account balances designed and modified specifically for the City’s operations and assessed level of risk. Substantive procedures will consist of testing material balance sheet accounts, material revenue and expenditure/expense accounts along with various analytical procedures as deemed necessary. In addition, various accounts may be confirmed with outside parties (cash, investments, etc.).
 Determine whether our testing supports the assessed level of risk initially assigned at the financial statement level and at the assertion level.

This phase of the engagement for the audit will be performed by the senior accountant and two/three staff accountants with direct supervision by the audit manager and partner.

If any proposed audit adjustments are noted during this phase, we will discuss and explain them, in detail, with the appropriate level of management prior to posting.

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Specific audit approach (continued)
Segment 3 - Reporting - report preparation/audit conclusion (workpaper review) During this phase of the audit, our principal objectives will be to evaluate whether the financial statements, taken as a whole, are free from material misstatement and form an opinion(s) and issue our report.

In order to achieve the desired objectives of this phase of the audit, we will:
 Determine whether, based on our substantive testing and other procedures, the financial statements, taken as a whole, are free of material misstatement. This will provide the basis for our opinion(s).  Review all audit workpapers to ensure that the audit was performed in accordance with the required standards (GAAS, GAGAS, etc.) and prepare drafts of all required reports by the agreed-upon dates.  Conduct an independent review of the financial statement draft by the engagement’s quality control partner and issue all reports by the agreed-upon dates.

This phase of the engagement will be performed by the audit senior and one staff accountant with direct supervision by the audit manager and partner. In addition, the engagement’s quality control partner will perform a detailed quality control review of the financial statements.

The above procedures are a general list of procedures to be performed. After our initial review of the City and our detailed risk assessment, we will customize the engagement and gear it towards the needs of the City and the audit itself. In doing so, we will determine which procedures to perform relative to our risk assessment.

All our audits are customized to each entity, helping to ensure a complete, effective, and efficient audit. The foundation of the above approach is based on open communication coupled with a strong knowledge of the City's operations and detailed planning at the initial stages of the audit.

Our firm is dedicated to performing a timely audit engagement. Prior to the start of the audit, we will meet with City staff and decide on adequate timeframes, agreed upon by both the City and us, for the performance of the audit and the release of the financial statements. We will dedicate the necessary resources to meet any agreed upon time frames.

Level of staff and approximate number of hours assigned to each segment Sample sizes (including for compliance testing)
Our sample sizes will be determined in accordance with the AICPA's Audit and Accounting Guide, Audit Sampling, and will be selected using professional judgment or our TeamMate Analytics software, depending upon circumstance, as permitted by Statement on Auditing Standards. Our methods are designed to provide the most audit coverage without expending excess time. Our sample sizes will depend upon our preliminary assessment of control risk, our planned substantive testing and analytical procedures as well as our professional judgement.

Segment Partner Manager Senior Staff Total
Segment 1 8 4 19 55 86
Segment 2 12 7 30 72 121
Segment 3 11 9 26 17 63
Totals* 31 20 75 144 270
* = excludes Single Audit hours

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Specific audit approach (continued)
We utilize our Computer Aided Audit Tools (CAAT) software, Teammate Analytics, to draw our audit samples.

The software allows us to generate random samples, systematic samples, stratified samples, attributes samples as well as monetary unit samples (also called probability-proportional-to-size or dollar unit sampling).

Intelligent audit technology
Our audits are designed to be intelligent using our powerful audit software tools (Engagement and Teammate Analytics). In addition, all audit team members are linked to each other using wireless connections which enables them to share information at an almost real-time speed. Below are some of the benefits of our audit technologies:
 We utilize Teammate Analytics, a suite of more than 200 dynamic Computer Aided Audit Tools (CAATs). This allows us to analyze large amounts of data in seconds. Using data received directly from the City, we can perform the following: search for duplicate checks, detect transactions occurring on holidays/weekends or during unusual hours, perform Benford’s Law analysis, and identify instances when a vendor has issued multiple invoices with sequential references along with many other tests. The software empowers our audit teams with the ability to perform powerful, meaningful data analysis which will build upon our other value-added services.
 We can create our own analytical schedules allowing for easy analysis of current balances to prior year balance, current vs budget balance, thus reducing significant City staff time.  Once your trial balances and financial statements are entered into our software, we can observe your financial statements in the field allowing us to notice any variances and address them immediately.  We link the financial statement schedules directly to our audit software trial balances, and as a result, we can provide the City with fund financial statements almost immediately after importing the trial balances.
 We can provide the City with our audited trial balances which show the coding of the financial statement schedules for ease of review for City staff. These reports show each account coded to a specific financial statement line item/function as well as journal entries posted during the audit.  We have the capability to perform effective and efficient audits remotely as well.

Analytical procedures
In order to properly utilize analytical procedures, industry background and knowledge are needed. With our firm’s long history and qualified staff, we believe we have the necessary knowledge and experience to effectively apply analytical procedures. We will utilize analytical review procedures throughout our audit of the City.
 During the interim phase of our audit, we will compare current and prior year unadjusted balances to determine which areas may need additional analysis; we will also compare current year actual amounts to the City’s annual budget (both original and adopted).  During the final phase of our audit, we will perform procedures like those mentioned above, as well as compare certain financial ratios for current and prior years. We will also conduct certain “reasonableness” tests. Any significant variances are investigated further through inquiry and other substantive testing as deemed necessary until resolved to our satisfaction.  Finally, after we have completed our fieldwork, we will compare current and prior year audited balances, keeping in mind expected relationships obtained from our knowledge of the City, similar entities and the general economic environment. In addition, we may choose to use various other analytical techniques such as trend analysis, etc.

Unlike other audit firms, we use analytical procedures to supplement our substantive testing, not supplant them.

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Specific audit approach (continued)
Proposed audit timing
 Entrance
conference
to meet with
management
for pre-audit
planning.
 Preliminary
risk
assessment
procedures.

Anticipated timing of each segment
May August September/October
 Obtain an understanding of
systems, internal controls,
and current-year issues.
 Assess and evaluate design
and implementation of key
internal controls (including
IT related).
 Perform tests of internal
controls as needed.
 Identify control deficiencies
 Perform detailed risk
assessment procedures.
 Draft internal control
comment letter.
 Develop detailed audit plan
- provide management with
a detailed listing of items
needed to perform the audit,
including the timing of when
items are needed.
 Perform substantive audit
fieldwork, including
substantive analytical
procedures.
 Consider whether audit
evidence is sufficient to
form an opinion.
 Conduct exit conference
with management to
discuss proposed entries,
internal control issues, etc.
 Determine whether, based
on our substantive testing
and other procedures, the
financial statements, taken
as a whole, are free of
material misstatement.
 Review all workpapers.
 Evaluate financial
statements and note
disclosures.
 Perform final analytical
procedures.
 Draft required reports.
 Issue final required reports
by or before agreed upon
date.
 Present to governing body
as needed.

Segment 1 -
Planning/internal
control
Segment 2 -
Substantive
testing/analysis
Segment 3 -
Report
preparation/work
paper review
Audit planning

CITY OF TWENTYNINE PALMS

PROPOSAL FOR PROFESSIONAL AUDITING SERVICES
-20-
Other information
Identification of anticipated potential audit problems
One potential problem could be the implementation of any future GASBS. With our deep understanding of governmental accounting and auditing, constant training, and broad resources, we do not anticipate any issues during a GASB implementation. Our approach to any GASB statement implementation would be as follows: gain a thorough understanding of the pronouncement; determine applicability to the City; if applicable, discuss the statement and how it will affect the City with City staff; and provide guidance to City staff on the accounting and financial reporting implications.

Why choose RAMS?
Our firm has a long history of providing high-quality professional services to government entities similar to the City and has a well-respected reputation in the industry, as partly evidenced by our client satisfaction and retention rates. Our staff are committed to the highest standards in performing quality engagements, and you will find they are very personable and easy to work with. At RAMS, you will always work with professionals who are experienced in governmental audits, and thoroughly informed of current issues facing this rapidly changing field. We focus on efficiency in each engagement by emphasizing detailed planning to mitigate or eliminate surprises and maximize the value of our services to our clients. Our knowledge and involvement in the industry lend to our ability to offer year-round guidance and build lasting relationships with our clients. In addition, RAMS possesses the following:

1. Knowledge. We provide highly trained and knowledgeable staff dedicated to client service. We are available throughout the year to answer questions or to provide guidance on any accounting matter.

2. Quality. A commitment to quality on every engagement is our priority.

3. Experience. A client focused team of experienced auditors and accountants will serve the City.

4. Flexibility. A flexible team that will work with your schedule.

5. Value. We provide exceptional client service and quality work at a reasonable and competitive fee.

Condition of records
Our proposed fee assumes the following: the City will be adequately prepared for the audit and the City’s financial operations and working trial balance will be consistent from year to year. If, after we receive the working trial balances, we notice there are excessive new accounts over the prior year; or if there are excessive subsequent journal entries; prepared by client workpapers do not agree to the working trial balances, there are new funds/functions within the City, etc., or other changes that necessitate a significant amount of time to address, we will need to come to an agreed upon change order to address any possible additional costs incurred by the firm. If the need for additional work comes to our attention, we will immediately notify City staff. If you choose to have us perform the additional work, then such work will be performed at the same hourly rates applicable to the audit and set forth in an addendum to the contract between the City and our firm.

Management is also responsible for the implementation of new standards issued by the Governmental Accounting Standards Board. We will provide reasonable assistance in the preparation of the items, but any significant time needed to complete the financial statements will be billed separately.

Our proposed fee is also dependent on all items requested being completed in the format requested or in a mutually agreed upon format and uploaded to the Engagement Organizer hosted by our firm in a timely manner in accordance with the agree-upon audit timeline.

Attachment A
-21-

GOVERNMENT CLIENTS SERVED

GFOA Successor Housing
Government Client Years Served Awards Agency Authority

City of El Cajon 06/30/07 to 06/30/22 Yes Yes Yes
City of Exeter 06/30/17 to 06/30/22
City of Woodlake 06/30/17 to 06/30/22
Town of Yucca Valley 06/30/08 to 06/30/22 Yes Yes Yes
City of La Verne 06/30/11 to 06/30/22 Yes Yes Yes
City of San Jacinto 06/30/11 to 06/30/22 Yes Yes
City of Twentynine Palms 06/30/11 to 06/30/22 Yes Yes Yes City of La Mesa 06/30/11 to 06/30/22 Yes Yes
City of Menifee 06/30/14 to 06/30/22 Yes
City of San Marcos 06/30/14 to 06/30/22 Yes Yes Yes
City of Loma Linda 06/30/13 to 06/30/22 Yes Yes Yes
City of Sierra Madre 06/30/12 to 06/30/22 Yes Yes Yes
City of Hawthorne 06/30/16 to 06/30/22 Yes Yes Yes
City of Aliso Viejo 06/30/16 to 06/30/22 Yes No No
City of Claremont 06/30/16 to 06/30/22 Yes Yes Yes
City of Thousand Oaks 06/30/18 to 06/30/22 Yes Yes Yes
City of South Pasadena 06/30/18 to 06/30/22 Yes Yes Yes City of Rolling Hills Estates 06/30/19 to 06/30/22 Yes
City of Calabasas 06/30/20 to 06/30/22 Yes
City of San Bernardino 06/30/20 to 06/30/22 Yes
City of Ojai 06/30/20 to 06/30/22
City of Beaumont 06/30/20 to 06/30/22 Yes
City of Moreno Valley 06/30/20 to 06/30/22 Yes
City of Lawndale 06/30/20 to 06/30/22
Town of Windsor 06/30/19 to 06/30/22
City of San Dimas 06/30/20 to 06/30/22
City of Imperial Beach 06/30/20 to 06/30/22
City of Brawley 06/30/22
City of Santee 06/30/22
City of Perris 06/30/22
City of Live Oak 06/30/22
City of Yorba Linda 06/30/22
City of Canyon Lake Accounting support
City of Fontana Accounting support
City of Hemet Accounting support
City of Rolling Hills Accounting support
City of Yucaipa Accounting support
City of Angels Camp Accounting support
City of Grand Terrace Accounting support

Crestline Village Water District 04/30/96 to 04/30/22
Crestline-Lake Arrowhead Water 06/30/98 to 06/30/22
San Bernardino Valley Muni Water District 06/30/04 to 06/30/22 Elsinore Valley Municipal Water District 06/30/15 to 06/30/22 Yes Pine Cove Water District 06/30/10 to 06/30/22

Attachment A
-22-
GOVERNMENT CLIENTS SERVED (continued)

CSMFO/
GFOA Successor Housing
Government Client Years Served Awards Agency Authority

Consolidated Fire Agencies 06/30/14 to 06/30/22
Successor Agency to the County of SB 06/30/14 to 06/30/22 Riverside County Habitat Con. Agency 06/30/15 to 06/30/22 Santa Ana Watershed Association 12/31/09 to 12/31/21
Capistrano Bay Community Services
District 06/30/13 to 06/30/22

Ventura County Public Fin Authority 06/30/12 to 06/30/22 Nipomo Community Services District 06/30/16 to 06/30/22 Yes SBIAA 06/30/17 to 06/30/22
San Diego Workforce Partnership 06/30/16 to 06/30/22
Rubidoux Community Services District 06/30/16 to 06/30/22 Conejo Recreation and Park District 06/30/19 to 06/30/22 Upper San Gabriel Valley MWD 06/30/19 to 06/30/22 Yes
March Joint Powers Authority 06/30/19 to 06/30/22
Chino Basin Desalter Authority 06/30/19 to 06/30/22 Yes Mountains Recreation and Conservation 06/30/19 to 06/30/22 Palos Verdes Peninsula Transit Authority 06/30/19 to 06/30/22 Yucca Valley Airport District 06/30/20 to 06/30/22
West Basin Municipal Water District 06/30/20 to 06/30/22 Yes Idyllwild Water District 06/30/11 to 06/30/22
Big Bear Area Regional Wastewater 06/30/12 to 06/30/22 Yes Mojave Water Agency 06/30/19 to 06/30/22 Yes
Beaumont Cherry Valley Water District 12/31/17 to 12/31/20 Yes Rosamond Community Services District 06/30/15 to 06/30/22 Rossmoor Community Services District 06/30/05 to 06/30/22 Rim of the World Park & Rec. District 06/30/06 to 06/30/22 Heartlands Communications Fac Auth 06/30/07 to 06/30/22 Heartlands Fire Training Authority 06/30/07 to 06/30/22 San Joaquin Regional Rail Commission 06/30/22
East Valley Water District 06/30/22
Leucadia Wastewater District 06/30/22
Las Virgenes Municipal Water District 06/30/22
Pomona Valley Transportation Auth 06/30/22
Crestline Sanitation District Accounting support
Running Springs Water District Accounting support
Phelan Pinon Hills Community Services
District Accounting support

STAFF REPORT
TO: City Council
FROM: City Clerk
FOR MEETING: Dec 12 2023
SUBJECT: Selection of Mayor and Mayor Pro Tem.

RECOMMENDATION:

The City Council select a Mayor and Mayor Pro Tem for 2024.

ORDER OF PROCEDURE:

Request Staff Report (City Clerk Presenting)
Council Questions of Staff
Request Public Comment
Council Discussion
Motion/Second
Discussion of Motion
Call the Question
BACKGROUND:

When the City incorporated in November of 1987, the original City Council developed a selection procedure for the Mayor and Mayor Pro Tem seats that would provide stability to the City Council and allow for orderly succession. The selection procedure adopted by the City Council established that the Councilmembers ascend to the Mayor's seat and the order of succession was determined by the number of votes received in the elections.

Since the Mayor and Mayor Pro Tem change annually, as the Mayor Pro Tem ascends to the Mayor's seat, the individual who received the next highest votes became the Mayor Pro Tem. As was indicated earlier, this system allowed for an orderly succession of City Councilmembers.

Notwithstanding the abovementioned procedure, the City Council voted, at the regularly scheduled meeting on May 9, 2023, to go with a succession of Districts in choosing the Mayor and Mayor Pro Tem, beginning with District 5 in 2023, then go to District 1, then 2 and so on.

McArthur Wright, District 5, became the Mayor for 2023 and Steven Bilderain, District 1, became the Mayor Pro Tem. Following the order of succession, District 1, Steven Bilderain, would now step into the Mayor's seat and District 2, Joel Klink, would step into the Mayor Pro Tem seat.

Once the Mayor and Mayor Pro Tem are selected, the meeting is turned over to the newly selected Mayor.

ENVIRONMENTAL:

N/A
ALTERNATIVES: Page 389 of 672
The City Council could choose to nominate and appoint a different Mayor and Mayor Pro Tem.

FISCAL IMPACT:

None.

STAFF REPORT
TO: City Council
FROM: Interim City Manager
FOR MEETING: Dec 12 2023
SUBJECT: Wastewater Alternate Sites and Cost.

RECOMMENDATION:

The City Council provide direction based on the information provided by this Staff Report.

ORDER OF PROCEDURE:

Request Staff Report (Interim City Manager Presenting)
Council Questions of Staff
Request Public Comments
Council Discussion
Motion/Second
Discussion on Motion
Call The Question
ATTACHMENTS:
• Exhibit 1 - WWTP Site
Alternatives - DRAFT
• Exhibit 2 - Collection System
Alternatives - DRAFT
• Capital Cost
EstimateTwentyNine Palms
WRF_ROM
• Site Flows
• 29 Palms Geotechnical
Investigation Report_11-29-23
•
Sewer_Connections_Summary
- DRAFT
BACKGROUND:

At the October 24th, 2023 City Council Meeting the City Council was informed that The City of Twentynine Palms has been allocated $50M from the State for their potential Wastewater Project. $1 million has been deducted towards planning and the balance available is $49 million. This was less than the City Council anticipated they would receive. With the reduced funding, the City Council asked the City Manager to look into cost

of the three different identified site options. The City Council also asked for an estimate of operational cost for the treatment plant.

Option one (Site 1) in the report was the site closest to Desert Knoll Avenue, (Site 2) is approximately 1200' east, (Site 3) is approximately one and a half miles from (Site 1). Exhibit 1 The consultants reduced the area serviced and the number of connections, so the price did not change for each site. The price for each option is $52M. To achieve the same cost for the three alternate locations, the scope of each was adjusted. The original plant was for .9MGD which is approximately 900,000 gallons per day, the new designed plant is for .15MGD which is approximately 150,000 gallons per day. Essentially little capacity for growth. Exhibit 2 and Site Flows.

The Sewer Project must be completed by the end of 2026 per the State of California.

Consultants NV5 and Carollo Engineering's rough estimate is $52M that includes the treatment plant, trunk lines, laterals, connections, and determining how many actual connections will be made would require selection of a site preference. The State does require a minimum of 383 septic to sewer connections if we accept the $49M. The number of connections depends on which option is selected. The consultant report has 437 (Site1) 420 (Site 2) 394 (Site 3) connections in the scope of work.

The consultants' estimates do not include the items listed below, per statements provided in their respective reports, however they confirm all of these items are necessary for an all-in cost estimate.

1. Project Managing Company: 15% of the overall project equals $7,800,000.00. This is based only off of the $52M hard construction cost.

2. Full time inspector to be on site everyday not only inspecting work and safety laws, oversee site deliveries, interview all contractors and employees of contractors ensuring compliance with prevailing wage requirements. $197,000.00 per year.

3. Tribal Inspectors $197,000.00 per year.

4. Road overlays $2,000,000.00 per year.

5. According to the consultants, you should add in CPI of 10% every year which is $6,219,400.00

6. This includes no land cost or easement cost.

Total minimum estimated cost for construction $70,807,000.00, which only includes 1 year of CPI.

Operation cost for treatment plant:

Ongoing plant maintenance costs were much more difficult to estimate. Multiple small municipal systems were surveyed, including Grass Valley, CA, Needles, CA, Yucca Valley, CA, and Groveland Community Services District. These locations were primarily selected based on plant size, and population. Needles operates the smallest plant of these four with a cost of $1,300,000.00, staffed with the lowest number of employees at three. All of these systems are being subsidized in one way or another, sales tax, impact fees, and grant funds. Based on these numbers, it is estimated that each resident connected to the proposed sewer system would have an annual maintenance cost of
Site (1) $2974.00, Site (2) $3095.00 Site (3) $3300.00. This cost estimate is based on the number of connections per site with no subsidies.

ENVIRONMENTAL:

Mitigated Negative Declaration (MND) is complete, but depending on action by the City Council, more studies and reports may be needed.

ALTERNATIVES:

The City Council could choose to:

1. Accept the $49M, select a site and move forward. Page 392 of 672

2. Choose not to accept the $49M.

If the City Council chooses not to continue, they could direct Staff to look into a USGS study, and/or request Staff to develop and seek grants for a Septic Tank Maintenance Program.

FISCAL IMPACT:

To be determined depending on action.

SITE 1
APN
062317111
SITE 2
APN
062317105
SITE 3
APN
062321129

SBCFCD FLOOD CONTROL CHANNEL
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DATE SUBMITTED: NOV 2023 227521-0000132

JOB NUMBER

EXHIBIT
1 SCALE
15092 AVENUE OF SCIENCE, SUITE 200
SAN DIEGO, CA 92128
P: 858.385.0500 WWW.NV5.COM

CITY OF TWENTYNINE PALMS - SEPTIC TO SEWER
WW 1 inch = 300 feet
Trunk Sewer TP SITE ALTERNATIVES
Collector Sewer
20' Contours
Parcels
FEMA 100-Year Floodplain
0 300 Feet
¹
Legend
DRAFT

SITE 1
APN
062317111
SITE 2
APN
062317105
SITE 3
APN
062321129 SBCFCD FLOOD CONTROL CHANNEL
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CACTUS DR

SULLIVAN RD
SR-62
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DATE SUBMITTED: NOV 2023 227521-0000132

JOB NUMBER

EXHIBIT
2 SCALE
15092 AVENUE OF SCIENCE, SUITE 200
SAN DIEGO, CA 92128
P: 858.385.0500 WWW.NV5.COM

CITY OF TWENTYNINE PALMS - SEPTIC TO SEWER
1 inch = 600 feet

WWTP SITE AND COLLECTION

SYSTEM ALTERNATIVES
Phase1A-1
Phase1A-2
Phase1A-3
Parcels
Trunk Sewer
Collector Sewer
20' Contours
FEMA 100-Year Floodplain
0 600 Feet
¹
Legend
DRAFT

29 Palms WWTP Estimate 12/4/2023

SUMMARY OF CAPITAL COSTS
Construction Costs Value Notes

1. Coarse Screens & IPS $ 1,249,698.42

2. Grit Tank & Fine Screens $ 338,408.21

3. Secondary/Tertiary Process Facilities $ 11,476,256.43

4. EQ Tank & Solids Handling Tanks $ 692,189.70

5. Odor Control $ 207,378.77

6. Admin Bldg & Maintenance Bldg $ 1,933,713.32

7. Support Facilities $ 2,585,597.39

8. Site Civil $ 2,200,786.90
Subtotal Construction Costs $ 20,684,029.15
Engineering Costs
Design Services $ 2,068,402.91 10% of Subtotal Construction Costs ESDC Services $ 1,034,201.46 5% of Subtotal Construction Costs Subtotal Engineering Costs $ 3,102,604.37
Subtotal Design-Build Costs $ 23,786,633.52
Other Owner Costs
City Administration and Legal $ 951,465.34 4% of Subtotal DB Costs Owner's Advisor Costs 427,198.01 $ 6% of Subtotal DB Costs1 Owner's Allowance $ 2,378,663.35 10% of Subtotal DB Costs Subtotal Other Owner Costs $ 3,757,326.70
TOTAL PROJECT COSTS $ 27,543,960.22

1. Amendment 1 = $1M was subtracted from 6% value
c:\pw_working\carollo_200000\d0202913\Capital Cost Estimate_TwentyNine Palms WRF_darft 11-28-2023.xlsx 1

Site Flows
Here are the projected average dry weather flows (ADWFs) based on the alternatives shown in the attached exhibits. Projected flow was determined using the same methodology as listed in our PDR.

Collection System Alternative 2025 ADWF (MGD)
Phase 1A-1 (WWTP Site 1 at APN 062317111) 0.154
Phase 1A-2 (WWTP Site 2 at APN 062317105) 0.149
Phase 1A-3 (WWTP Site 3 at APN 062321129) 0.146
Each collection system alternative (phase) has a rough order of magnitude construction cost opinion of approximately $24.5 million, excluding costs for full lane or full road width grind and overlays, sewer easements, private sewer systems other than a lateral, and construction management/inspection.

`
City of Twentynine Palms
Phase I Wastewater Collection System
Twentynine Palms, California
Project No.: 227522-0000190.00
NV5 West, Inc.
15092 Avenue of Science, Suite 200
San Diego, CA 92128

GEOTECHNICAL INVESTIGATION
November 29, 2023
Prepared For:

City of Twentynine Palms
6136 Adobe Road
Twentynine Palms, California 92277

227522-0000190.00 NV5.COM | i
Mr. Larry Bowden November 29, 2023
Interim City Manager Project No.: 227522-0001415.01
City of Twentynine Palms
6136 Adobe Road
Twentynine Palms, CA 92277
Subject: Geotechnical Investigation Report
Project: City Twentynine Palms
Phase I Wastewater Collection System
Twentynine Palms, California 92277
Dear Mr. Bowden:

This report presents the results of NV5 West, Inc.’s (NV5) geotechnical investigation for the subject project. The purpose of this investigation was to evaluate the subsurface conditions for the proposed Phase 1 Wastewater Collection System project located in Twentynine Palms in San Bernardino County, CA. NV5 understands the preliminary design for the Phase 1 Wastewater Collection System includes the installation of approximately 27 miles of new gravity sewer pipelines, one small lift station near the north end of Luckie Park and approximately 0.6-mile of new force main pipeline. NV5 understands that the geotechnical investigation for the centralized wastewater treatment plant (WWTP) is not part of the current scope of work and will be completed at a later date, The results of the geotechnical field exploration, laboratory tests, and preliminary geotechnical engineering recommendations and conclusions for the subject project are presented herewith.

Based on the subsurface exploration, subsequent testing of the subsurface soils, and engineering analyses, it was concluded that the construction of the proposed project is geotechnically feasible. The geotechnical information presented herein is intended to assist the project design team and construction contractor(s) in their understanding of the geotechnical factors affecting the proposed project. The geotechnical recommendations should be incorporated into the project design and implemented during construction.

NV5 appreciates the opportunity to provide this geotechnical engineering service for this project and looks forward to continuing its role as your geotechnical engineering consultant.

Respectfully submitted,
NV5 West, Inc.

Sean Roy, PG, CEG Carl Henderson, PhD, PE, GE
Senior Geologist CDO/ VP, Geotechnical Services West

CH/SR/JR
Distribution: (1) Addressee, via email

227522-0000190.00 NV5.COM | ii

TABLE OF CONTENTS
Page

1.0 Introduction.............................................................................................................................. 1

2.0 Scope of Services .................................................................................................................... 1

3.0 Site and Project Description ................................................................................................. 2

4.0 Geotechnical Desktop Study (2021) .................................................................................... 3

5.0 Field Exploration Program ..................................................................................................... 3 Exploratory Drilling ........................................................................................................................... 3

6.0 Laboratory Testing .................................................................................................................. 6

7.0 Geologic and Soil information .............................................................................................. 6 Regional Geologic Setting ............................................................................................................... 6 Site-Specific Geologic and Soil Information ................................................................................. 7 Groundwater ................................................................................................................................... 20 Faults ................................................................................................................................................ 21

8.0 Seismic and Geotechnical Hazards ................................................................................... 22 Fault Rupture .................................................................................................................................. 22 Seismic Shaking ............................................................................................................................. 23 Liquefaction and Seismically-Induced Settlement ................................................................... 24 Landslides and Slope Instability .................................................................................................. 24 Subsidence ...................................................................................................................................... 24 Tsunamis, Inundation Seiche, and Flooding .............................................................................. 25 Expansive Soils ............................................................................................................................... 25 Erosion ............................................................................................................................................. 25

9.0 Conclusions and Design Recommendations .................................................................... 26 General ............................................................................................................................................. 26 Rippability/Excavatibility .............................................................................................................. 26 Earthwork ........................................................................................................................................ 26 Temporary Excavations and Shoring ........................................................................................... 26 Dewatering ...................................................................................................................................... 28 Trench Bottom Stability ................................................................................................................. 28 Pipe Zone Backfill .......................................................................................................................... 28 Trench Backfill Placement and Compaction ............................................................................. 30 Lift Station Recommendations .................................................................................................... 31 Jack and Bore Considerations ...................................................................................................... 38 Corrosion Potential ........................................................................................................................ 39

11.0 Limitations ............................................................................................................................. 42

12.0 Selected References ............................................................................................................ 43

227522-0000190.00 NV5.COM | iii

FIGURES
FIGURE 1 – SITE LOCATION MAP
FIGURE 2 – VICINITY MAP
FIGURE 3 – EXPLORATION LOCATION MAP
FIGURE 4 – REGIONAL GEOLOGIC MAP
FIGURE 5 – SITE FAULT MAP
FIGURE 6 – REGIONAL FAULT MAP
FIGURE 7 – FLOOD HAZARD MAP
FIGURE 8 – LATERAL SURCHARGE LOADS
FIGURE 9 – THRUST BLOCK DETAIL

APPENDICES
APPENDIX A – GEOTECHNICAL DESKTOP STUDY PREPARED BY NV5 (2021) APPENDIX B – FIELD EXPLORATION LOGS
APPENDIX C – LABORATORY TEST RESULTS
APPENDIX D – PRELIMINARY SCREENING STUDY OF GROUNDWATER RECHARGE SITES, TWENTYNINE PALMS, CALIFORNIA PREPARED BY NV5 (2022)
APPENDIX E – TYPICAL EARTHWORK GUIDELINES

227522-0000190.00 NV5.COM | 1

1.0 INTRODUCTION
This report presents the results of the geotechnical engineering investigation for the proposed Phase 1 Wastewater Collection System project located throughout in Twentynine Palms, California. The approximate project limits are presented in Figure 1, Site Location Map and Figure 2, Vicinity Map.

The purpose of this study was to evaluate the subsurface conditions and to provide preliminary geotechnical recommendations for the design and construction for the proposed wastewater management system improvements. This report summarizes the data collected and presents NV5’s findings, conclusions, and geotechnical recommendations.

This report has been prepared for the exclusive use of the client and its consultants/contractors to describe the geotechnical factors at the project sites which should be considered in the design and construction of the proposed project. In particular, it should be noted that this report has not been prepared from the perspective of a construction bid preparation instrument and should be considered by prospective bidders only as a source of general information subject to interpretation and refinement by their own expertise and experience, particularly with regard to construction feasibility. Contract requirements as set forth by the project plans and specifications will supersede any general observations and specific recommendations presented in this report.

2.0 SCOPE OF SERVICES
The purpose of the geotechnical investigation was to evaluate the geotechnical conditions at the various project areas and provide recommendations, from a geotechnical standpoint, regarding the proposed development. NV5 conducted geotechnical investigation services consisting of three tasks which included the following tasks:
• Review of available background data, including published maps (geologic, fault, and flood), fault maps, and literature pertaining to the project limits. • A site reconnaissance to observe the general surficial site conditions and to select boring locations.
• Preparation of San Bernardino County boring permit application for borings greater than 20 feet below ground surface (bgs).
• Preparation of a City of Twentynine Palms encroachment/traffic control permit application. • Coordination with entities having an interest in the field exploration activities including San Bernardino County, the City of Twentynine Palms, the drilling subcontractor (Veteran Drilling), traffic control subcontractor (California Traffic Control), private utility locating subcontractor (GPRS), and Underground Service Alert (USA).
• Coordination with the Client representatives, City Inspectors, and subcontractors. • Conducting a subsurface investigation for the proposed Phase 1 Wastewater Collection System project, which included the drilling, logging, and sampling of forty-one (41) exploratory borings located throughout project areas to final depths ranging between approximately 15 to 31.5 feet below ground surface (bgs).

227522-0000190.00 NV5.COM | 2
• Performing laboratory testing on selected representative bulk-disturbed and relatively undisturbed drive-samples of the materials obtained during the field exploration program to evaluate their pertinent geotechnical engineering properties. • Performing an assessment of general seismic conditions and geologic hazards affecting the site areas and their possible impact on the subject project. • Engineering evaluation and analysis of the geotechnical data collected to develop geotechnical recommendations for the design and construction of the proposed development. Specifically, the following items were addressed:
ο Evaluation of general subsurface conditions and description of types, distribution, and engineering characteristics of subsurface materials.
ο Evaluation of project feasibility including excavatability, excavation stability, and suitability of on-site soils for backfill.
ο Determination of seismic design parameters.
ο General construction considerations for the proposed improvements and appurtenant features.
• Preparation of this report, including reference maps and graphics, summarizing the data collected and presenting NV5’s findings, conclusions, and preliminary geotechnical recommendations for the design and construction of the proposed project.

3.0 SITE AND PROJECT DESCRIPTION
NV5 understands that the City is using a phased approach for construction of the wastewater collection and treatment system. A total of five (5) construction phases were initially proposed, whereas this report covers only Phase 1. The approximate limits of the Phase 1 study area are presented on Figure 2, Vicinity Map; Figure 3, Exploration Location Map; Figure 4, Regional Geologic Map; Figure 5, Site Fault Map and Figure 7, Flood Hazard Map. NV5 understands the preliminary design for the Phase 1 Wastewater Collection System includes the installation of approximately 27 miles of new gravity sewer pipelines, one small lift station near the north end of Luckie Park and approximately 0.6-mile of new force main pipeline. NV5 understands that the geotechnical investigation for the centralized wastewater treatment plant (WWTP) is not part of the current scope of work and will be completed at a later date, As noted in the document titled City of Twentynine Palms Phase 1 Wastewater Collection System Preliminary Design Report as prepared by NV5 (dated May 09, 2023), the following general project description is provided.
“In coordination with the City, the limits of the proposed ultimate service area for the ultimate centralized wastewater collection system were generally developed to exclude areas within the City limits that have very-low density residential land use which have a minimum lot size of 2.5 acres. These sparsely populated areas constitute a small portion of the City’s current water use and subsequently have a smaller impact on groundwater quality. The proposed ultimate service area includes the majority of residential, commercial, industrial, and public land use areas within the City limits, except for some small commercial and residential land use areas in the western portion of the City and north of the hilltop on Adobe Road.”

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The following general surface development is present within the proposed Phase 1 service area. • The downtown area east of Donnel hill and adjacent areas that are part of the “Four Corners” neighborhood. This area has a mixture of single-family residential, multi-family residential, and commercial land use.
• The two large multi-family military housing developments on Two Mile Road and Joe Davis Drive.
• The single-family residential area in the eastern portion of the “Chocolate Drop” neighborhood.

The area within the proposed ultimate service area generally slopes from the southwest to the northeast but has several hills and ridgelines throughout. A substantial portion of the proposed service area drains to the earthen flood control channel which bisects the City and the proposed Phase 1 service area. The channel was developed and is maintained by the San Bernardino County Flood Control District (SBCFCD) and drains to a natural desert wash area to the northeast.

4.0 GEOTECHNICAL DESKTOP STUDY (2021)
In 2021, NV5 completed a geotechnical desktop study for proposed City of Twentynine Palms – Septic to Sewer project located throughout the City of Twentynine Palms in San Bernardino County, California.

A copy of the report completed for the geotechnical desktop study is presented in Appendix A, Geotechnical Desktop Study (2021).

5.0 FIELD EXPLORATION PROGRAM
Before starting the field exploration program, a field reconnaissance was conducted to observe site conditions and mark out the locations for the planned subsurface explorations. As required by law, Underground Service Alert was notified of the locations of the exploratory borings. In addition, services of a private utility locating subcontractor were utilized, prior to drilling. NV5 additionally coordinated the drilling schedule with the San Bernardino County Drilling services were provided by Baja Exploration.

EXPLORATORY DRILLING
The subsurface conditions at the project site were explored from June 5th through 15th, 2023 and August 23, 2023, by drilling, logging, and sampling forty-one (41) exploratory borings (B-1 through B41) to final depths ranging between approximately 15 to 31.5 feet below the existing ground surface (bgs). The approximate locations of the explorations are shown on Figure 3, Exploration Location Map.

A summary of approximate boring locations with respect to proposed site improvements is provided in the table below.

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Table 1 –Field Explorations and Improvement Locations
Field
Exploration
Identification
Approximate Street
Location
Approximate Depth
to Invert Elevation of
Alignment Near
Boring, feet
Approximate Final
Drilling Depth Below
Existing Grade, feet
Approximate
Field Exploration
Surface
Elevation
Approximate
Roadway
Alignment
Station Per
Design Drawings
B-1
South of intersection
Spit Rock Ave. &
Cactus Dr.
8 20 2018 62+30
B-2
West of intersection
Tamarisk Ave. &
Cactus Dr.

14.3 20 2009 39+75
B-3
West of intersection
Adobe Rd. and Old
Dale Rd.

16.6 20 1993 12+00
B-4
East of intersection
Old Dale Rd. & Palo
Verde Ave.

16.2 20 1978 58+90
B-5
Northwest of
intersection Inn Ave.
and National Park Dr.

13.1 18.5 1965 10+00
B-6
Desert Knoll
Shoulder and 62
intersection
12 31.5 1948 30+50
B-7 Southbound edge of
Desert Knoll 13.7 31.5 1948 28+50
B-8
East of intersection
Desert Knoll Ave. and
Buena Vista Dr.

17.3 31.5 1935 10+10
B-9
South of intersection
Joe Davis Dr. and
Desert Knoll Ave.
10 20 1934 23+25
B-10
East of intersection
Ocotillo Ave. and S.

Slope Dr.
9 20 1979 36+60
B-11 East of Aztec Ave.
and Buena Vista Dr. 18.3 20 1957 29+75
B-12
North of intersection
Gorgonio Dr. and
Ocotillo Ave.

18.1 23 1976 10+10
B-13
West of intersection
Cholla Ave. and
Buena Vista Dr.

18.3 20 1995 52+50
B-14 Northbound Tamarisk
Ave. 19.1 31.5 2011 11+40
B-15
West of intersection
Adobe Rd. and Sun
Valley Dr.

8.5 15 2004 36+10
B-16
West of intersection
Hillside Ave. and Sun
Valley Dr.

8.8 16.5 2084 61+40
B-17
West of intersection
Mesquite Spring Rd.
and Wildcat Way

11.1 16.5 2138 28+00
B-18
North of intersection
Joe Davis Dr. and
Desert Knoll Ave.
12 18 1969 33+45
B-19
West of intersection
Halsey Ave. and Two
Mile Rd.

8.1 15 1902 35+45
B-20 Southbound
Tamarisk Ave. 19.1 31.5 2016 13+80
B-21 Northbound Bullion
Ave. shoulder 19 31.5 2080 22+90

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Field
Exploration
Identification
Approximate Street
Location
Approximate Depth
to Invert Elevation of
Alignment Near
Boring, feet
Approximate Final
Drilling Depth Below
Existing Grade, feet
Approximate
Field Exploration
Surface
Elevation
Approximate
Roadway
Alignment
Station Per
Design Drawings
B-22 South of 29 Palms
Hwy. and Oasis Ave. 12 18 2022 14+50
B-23
South of intersection
Joshua Dr. and
Desert Queen Ave.

13.9 20 2017 17+05
B-24
South of intersection
Joshua Dr. and
Smoketree Ave.

14.2 20 2003 25+05
B-25
East of intersection
Tamarisk Ave. and
Cedar Dr.

9.5 20 2009 24+00
B-26
South of intersection
Cactus Dr. and Palo
Verde Ave.

16.4 20 1984 59+25
B-27
South of intersection
Verbana Dr. and
Cienega Dr.

8.3 19.5 1964 21+30
B-28
East of intersection
Gorgonio Dr. and
Cienega Ave.
14 21.5 1957 21+90
B-29
West of intersection
Bagley Ave. and Spit
Rock Ave.
8 16.5 2036 39+25
B-30
West of intersection
Yucca Ave. and El
Paseo Dr.

8.3 16.5 2044 38+30
B-31 West of Sunnyslope
Dr. and Alpine Ave. 12.2 20 2168 157+50
B-32
South of intersection
Granite Ave. and
Juniper Ave.

12.4 18.3 2148 15+20
B-33
Northeast of
intersection Desert
Trail Dr. and Larrea
Ave.

11.5 20 2123 11+00
B-34
Northeast of
intersection Desert
Trail Dr. and L Luna
Ave.
8 19.5 2165 115+90
B-35
East of intersection
Hillside Ave. and
Sunnyvale Dr.

8.7 16.5 2056 52+90
B-36
East of intersection
Bagley Ave. and
Sunnyslope Dr.
8 15 2028 38+60
B-37
East of intersection
Ocotillo Ave. and
Desert Trail Dr.

8.2 15 2010 17+70
B-38 South of Marine Ave.
and Joe Davis Dr. 17.8 20 1916 33+90
B-39
North of intersection
Wainwright Ave. and
Joe Davis Dr.

16.2 20 1898 18+50
B-40
South of intersection
Utah Trail and Two
Mile Rd.
12 18.5 1872 18+00
B-41
East of intersection
Alpine Ave. and El
Paseo Dr.

13.4 20 2172 78+85

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The exploratory borings were drilled using a truck mounted drilling rig and advanced using 8-inch diameter hollow-stem augers. The materials encountered in the exploratory borings were continually observed, classified, and logged by an NV5 engineer/geologist in general accordance with the Unified Soil Classification System. The logs of the exploratory borings are presented in Appendix B, Field Exploration Logs. Subsequent to logging and sampling, the exploratory borings that extended greater than 20 feet bgs were backfilled with cement grout with up to 6% bentonite. The exploratory borings that extended less than 20 feet bgs were backfilled with soil cuttings. Exploratory borings located in asphalt were patched with Aquaphalt™ cold patch.

Representative bulk-disturbed and relatively undisturbed drive samples were retrieved during exploratory drilling at selected depths appropriate to the investigation. The samples were labeled in the field and transported to the laboratory for observation, evaluation, and testing. The drive samples were obtained using the California Modified Split Spoon (CAL) and Standard Penetration Test (SPT) samplers, as described in Appendix B, Field Exploration Logs.

6.0 LABORATORY TESTING
Laboratory testing was performed on selected representative bulk-disturbed and relatively undisturbed drive samples of the materials obtained from the exploratory borings to aid in the material classifications and to evaluate engineering properties of the materials encountered. The following tests were performed:
• In-situ Density and Moisture Content (ASTM D2937 and ASTM D2216); • Particle Size Analyses (ASTM D6913);
• Sand Equivalence (ASTM D2419);
• Maximum Dry Density and Optimum Moisture Content (ASTM D1557); • R-Value Test (ASTM D2844);
• Direct Shear (ASTM D3080); and
• Corrosivity test series, including sulfate content, chloride content, pH-value, and resistivity (CTM 417, 422, and 532/643)
Testing was performed in general accordance with applicable ASTM standards and California Test Methods (CTM). A general summary of the laboratory testing program and the laboratory test results are presented in Appendix C, Laboratory Test Results.

7.0 GEOLOGIC AND SOIL INFORMATION

REGIONAL GEOLOGIC SETTING
The project site is located in southern San Bernardino County traversing the Mojave Desert Geomorphic Province at the northern end of the site and the Transverse Ranges Geomorphic Province at the southern end of the site. The Mojave Desert province is characterized by isolated mountain ranges separated by expanses of desert plains. The province is known for its interior drainage systems and many playas. There are two important fault trends that control topography, a prominent NW-SE trend and a secondary east-west trend (apparent alignment with Transverse Ranges is significant).

The province is topographically controlled by the two major active fault zones known as the Garlock (to

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the north) and the Southern San Andreas (to the south). As such, many major secondary faults and fault zones traverse the interior of the province, and at a transverse manner to the previously mentioned fault zones.

The Transverse Ranges province are characterized by east-west trending mountain ranges bordered by relatively straight-sided, sediment-floored valleys. The western limit of the province is the offshore island group of San Miguel, Santa Rosa, and Santa Cruz. The eastern limit extends into the Mojave Desert and includes the San Bernardino Mountains on the east side of the San Andreas Fault. The Pinto Mountain fault zone crosses the project area at the south end of the Phase 1 project area and the Pisgah-Bullion Mountain – Mesquite Lake fault lies approximately 0.5-mile to the east-northeast of the Phase 1 project area.

SITE-SPECIFIC GEOLOGIC AND SOIL INFORMATION
Typical geologic stratigraphy in the site vicinity include erratic outcrops of Precambrian-age igneous and metamorphic rocks and Mesozoic-age granitic and metamorphic rocks that make up the underlying “basement” bedrock, with vast and massive bedded Cenozoic-age and Quaternary-age sedimentary deposits covering the desert valley floors. The general geologic conditions in the project vicinity are displayed in Figure 4, Regional Geologic Map.

Reference to the regional geologic map Geologic Map of the Twentynine Palms Quadrangle, San Bernardino and Riverside Counties, California, by T.W. Dibblee, Jr., 1968, indicates that the site vicinity is predominantly underlain by Quaternary-age relatively younger surficial sediments and older surficial sediments.

These relatively younger surficial sediments derived from the adjacent highlands are described as unconsolidated and undissected fill found in the valley areas and flood plains of stream channels, and are mapped as windblown sand (Qs), younger alluvium (Qa), and micaceous clay and silt (Qc). The older alluvial surficial sediments (Qoa) are described as older valley fill materials derived from mountains to the west and south. These materials are found at slightly elevated positions and are much more dissected and lie unconformably on pre-Tertiary aged rocks.

Detailed descriptions of the earth materials encountered at our field exploration locations are presented in Appendix B, Field Exploration Logs. Asphalt concrete (AC) was encountered at ground surface in thirty-three (33) of the exploration locations and ranged between approximately 3 to11 inches in thickness. Aggregate base (AB) was encountered beneath AC at one (1) of the field exploration locations (B-9) with an approximate thickness of 5 inches. • Fill: Fill materials were encountered near surface at all field exploration locations, with the exceptions of B-6, B-33 and B-38, to final depths ranging between approximately 0 to 7 feet in depth. As observed, the fill soils were generally characterized as follows:

o Light brown to dark brown with varying amounts of orange oxidation, dry to moist, loose to medium dense, Silty SAND (SM), Silty SAND with Gravel (SM), Well Graded SAND (SW), Well Graded Sand with Silt (SW-SM), Poorly Graded SAND (SP), Poorly Graded SAND with Gravel (SP), Poorly Graded SAND with Silt (SP-SM), Sandy SILT (ML), with variable amounts of subangular fine-to-coarse gravel and trace cobble-sized clasts.

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• Quaternary-Aged Alluvium (Qa): Alluvial deposits were encountered beneath fill at twenty-one (21) of the forty-one (41) field exploration locations. As observed, these materials were generally characterized as follows:
o Light brown to dark brown with varying amounts of orange oxidation and white mottling, dry to moist, loose to very dense with varying amounts of cementation, Silty SAND (SM), Silty SAND with Gravel (SM), Well Graded SAND (SW), Well Graded Sand with Silt (SW-SM), Poorly Graded SAND (SP), Poorly Graded SAND with Gravel (SP), Poorly Graded SAND with Silt (SP-SM), and Clayey SAND (SC), with variable amounts of subangular fine-to-coarse gravel and trace cobble-sized clasts.

Although not encountered in the exploratory borings during the current investigation it is anticipated that occasional boulder-sized clasts may be encountered in the alluvial materials.
• Quaternary-Aged Older Alluvium (Qoa): Older alluvial deposits were encountered beneath fill at twenty (20) of the forty-one (41) field exploration locations. These materials were generally characterized as follows:
o Light gray to dark brown with some black mottling, dry to moist, loose to very dense, Silty SAND (SM), Well Graded SAND (SW), Well Graded Sand with Silt (SW-SM), Poorly Graded SAND (SP), Poorly Graded SAND with Silt (SP-SM), and hard Sandy SILT (ML), with variable amounts of subangular fine-to-coarse gravel. o Although not encountered in the exploratory borings during the current investigation it is anticipated that occasional cobble- to boulder-sized clasts may be encountered in the older alluvial materials.

Additionally, the following table presents general descriptions of subsurface material encountered at the field exploration locations.

Table 2 – General Description of Subsurface Conditions
Encountered at Field Exploration Locations
Field
Exploration
Identification
Approximate
Street
Location
Approximate
Final Drilling
Depth
Below
Existing
Grade, feet
Approximate
Field
Exploration
Surface
Elevation
Approximate
Roadway
Alignment
Station Per
Design
Drawings
Approximate
Depth to Invert
Elevation of
Alignment Near
Boring, feet
Approximate
Elevation Below
Existing Grade
as Encountered
in Field
Exploration, feet
Material Description as
Encountered in Field
Exploration
B-1
South of
intersection
Spit Rock Ave.
& Cactus Dr.
20 2018 62+30 8.0

0.3 to 3.0 Fill: Silty SAND with Gravel
(SM).

3.0 to 20.0 Quaternary Alluvium (Qa);
Silty SAND with Gravel (SM).

B-2
West of
intersection
Tamarisk Ave.
& Cactus Dr.
20 2009 39+75 14.3

0.5 to 3.0 Fill: Well Graded SAND with
Silt (SW-SM).

3.0 to 20.0
Quaternary Alluvium (Qa):

Well Graded SAND with SILT
(SW-SM), Poorly Graded SAND
(SP), Silty SAND (SM), and
Silty SAND with Gravel (SM).

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Field
Exploration
Identification
Approximate
Street
Location
Approximate
Final Drilling
Depth
Below
Existing
Grade, feet
Approximate
Field
Exploration
Surface
Elevation
Approximate
Roadway
Alignment
Station Per
Design
Drawings
Approximate
Depth to Invert
Elevation of
Alignment Near
Boring, feet
Approximate
Elevation Below
Existing Grade
as Encountered
in Field
Exploration, feet
Material Description as
Encountered in Field
Exploration
B-3
West of
intersection
Adobe Rd. and
Old Dale Rd.
20 1993 12+00 16.6

0.4 to 7.0 Fill: Poorly Graded SAND with
Gravel (SP).

7.0 to 20.0
Quaternary Alluvium (Qa) :

Silty SAND (SM), Silty SAND
with Gravel (SM), Poorly
Graded SAND (SP).

B-4
East of
intersection
Old Dale Rd. &
Palo Verde
Ave.
20 1978 58+90 16.2

0.3 to 3.0 Fill: Well Graded SAND (SW).

3.0 to 20.0
Quaternary Alluvium (Qa):

Silty SAND (SM), Silty SAND
with Gravel (SM), Poorly
Graded SAND with Gravel
(SP), and Silty SAND (SM).

B-5
Northwest of
intersection
Inn Ave. and
National Park
Dr.

18.5 1965 10+00 13.1

0.5 to 7.0 Fill: Well Graded SAND (SW).

7.0 to 18.5
Quaternary Alluvium (Qa):

Poorly Graded SAND (SP) and
Poorly Graded SAND with Silt
(SP-SM).

B-6
Desert Knoll
Shoulder and
62 intersection

31.5 1948 30+50 12.0 0.0 to 31.5
Quaternary Alluvium (Qa):

Poorly Graded SAND (SP),
Silty SAND (SM), Silty SAND
with Gravel (SM), Well Graded
SAND with Silt (SW-SM).

B-7
Southbound
edge of Desert
Knoll

31.5 1948 28+50 13.7

0.3 to 3.0 Fill: Silty SAND (SM).

3.0 to 31.5
Quaternary Alluvium (Qa):

Silty SAND (SM), Poorly
Graded SAND with Silt (SPSM), Well Graded SAND (SW).

B-8
East of
intersection
Desert Knoll
Ave. and
Buena Vista
Dr.

31.5 1935 10+10 17.3

0.3 to 3.0 Fill: Well Graded SAND (SW).

3.0 to 31.5
Quaternary Alluvium (Qa):

Well Graded SAND (SW),
Clayey SAND (SC), Poorly
Graded SAND (SP), and Silty
SAND (SM).

B-9
South of
intersection
Joe Davis Dr.
and Desert
Knoll Ave.
20 1934 23+25 10.0

0.8 to 7.0 Fill: Poorly Graded SAND (SP).

7.0 to 20.0 Quaternary Old Alluvium
(Qoa): Silty SAND (SM).

B-10
East of
intersection
Ocotillo Ave.
and S. Slope
Dr.
20 1979 36+60 9.0

0.4 to 5.0 Fill: Poorly Graded SAND with
Silt (SP-SM).

5.0 to 20.0
Quaternary Old Alluvium
(Qoa): Poorly Graded SAND
(SP) and Silty SAND (SM).

B-11
East of Aztec
Ave. and
Buena Vista
Dr.
20 1957 29+75 18.3

0.3 to 4.0 Fill: Poorly Graded SAND (SP).

4.0 to 20.0
Quaternary Old Alluvium
(Qoa): Well Graded SAND with
Silt (SW-SM) and Silty SAND
(SM).

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Field
Exploration
Identification
Approximate
Street
Location
Approximate
Final Drilling
Depth
Below
Existing
Grade, feet
Approximate
Field
Exploration
Surface
Elevation
Approximate
Roadway
Alignment
Station Per
Design
Drawings
Approximate
Depth to Invert
Elevation of
Alignment Near
Boring, feet
Approximate
Elevation Below
Existing Grade
as Encountered
in Field
Exploration, feet
Material Description as
Encountered in Field
Exploration
B-12
North of
intersection
Gorgonio Dr.
and Ocotillo
Ave.
23 1976 10+10 18.1

0.7 to 5.0 Fill: Silty SAND (SM).

5.0 to 23.0 Quaternary Old Alluvium
(Qoa): Silty SAND (SM)
B-13
West of
intersection
Cholla Ave.
and Buena
Vista Dr.
20 1995 52+50 18.3

0.8 to 4.0 Fill: Silty SAND (SM).

4.0 to 20.0 Quaternary Alluvium (Qa):

Silty SAND.

B-14 Northbound
Tamarisk Ave. 31.5 2011 11+40 19.0

0.3 to 6.0 Fill: Silty SAND (SM).

6.0 to 31.5
Quaternary Alluvium (Qa):

Silty SAND (SM) and Poorly
Graded SAND (SP).

B-15
West of
intersection
Adobe Rd. and
Sun Valley Dr.
15 2004 36+10 8.5

0.4 to 4.0 Fill: Silty SAND (SM).

4.0 to 15.0 Quaternary Old Alluvium
(Qoa): Silty SAND (SM).

B-16
West of
intersection
Hillside Ave.
and Sun
Valley Dr.

16.5 2084 61+40 8.8

0.4 to 3.0 Fill: Silty SAND (SM).

3.0 to 16.5 Quaternary Old Alluvium
(Qoa): Silty SAND (SM).

B-17
West of
intersection
Mesquite
Spring Rd.
and Wildcat
Way

16.5 2138 28+00 11.1

0.4 to 4.0 Fill: Poorly Graded SAND with
Gravel (SP).

4.0 to 16.5
Quaternary Old Alluvium
(Qoa): Poorly Graded SAND
with Silt (SP-SM) and Poorly
Graded SAND (SP).

B-18
North of
intersection
Joe Davis Dr.
and Desert
Knoll Ave.
18 1969 33+45 12.0

0.5 to 4.0 Fill: Silty SAND (SM).

4.0 to 18.0
Quaternary Old Alluvium
(Qoa): Poorly Graded SAND
with Silt (SP-SM), Well Graded
SAND (SW), Well Graded
SAND with Silt (SW-SM) and
Silty SAND (SM).

B-19
West of
intersection
Halsey Ave.
and Two Mile
Rd.
15 1902 35+45 8.1

0.7 to 5.0 Fill: Silty SAND.

5.0 to 15.0
Quaternary Old Alluvium
(Qoa): Silty SAND (SM), Sandy
Silt (ML).

B-20 Southbound
Tamarisk Ave. 31.5 2016 13+80 19.1

0.4 to 6.5 Fill: Silty SAND (SM).

6.5 to 31.5
Quaternary Alluvium (Qa):

Silty SAND (SM), Poorly
Graded SAND (SP), Well
Graded SAND with Silt (SWSM), Well Graded SAND (SW).

B-21
Northbound
Bullion Ave.
shoulder

31.5 2080 22+90 19.0

0.0 to 2.0 Fill: Silty SAND (SM).

2.0 to 31.5
Quaternary Alluvium (Qa):

Silty SAND with Gravel (SM),
Silty SAND (SM).

227522-0000190.00 NV5.COM | 11
Field
Exploration
Identification
Approximate
Street
Location
Approximate
Final Drilling
Depth
Below
Existing
Grade, feet
Approximate
Field
Exploration
Surface
Elevation
Approximate
Roadway
Alignment
Station Per
Design
Drawings
Approximate
Depth to Invert
Elevation of
Alignment Near
Boring, feet
Approximate
Elevation Below
Existing Grade
as Encountered
in Field
Exploration, feet
Material Description as
Encountered in Field
Exploration
B-22
South of 29
Palms Hwy.
and Oasis Ave.
18 2022 14+50 12.0

0.0 to 5.0 Fill: Silty SAND (SM).

5.0 to 18.0 Quaternary Alluvium (Qa):

Silty SAND (SM).

B-23
South of
intersection
Joshua Dr.
and Desert
Queen Ave.
20 2017 17+05 13.9

0.5 to 4.0 Fill: Sandy SILT (ML).

4.0 to 20.0
Quaternary Alluvium (Qa):

Poorly Graded SAND with Silt
(SP-SM), Silty SAND (SM),
Poorly Graded SAND (SP).

B-24
South of
intersection
Joshua Dr.
and
Smoketree
Ave.
20 2003 25+05 14.2

0.4 to 4.0 Fill: Poorly Graded SAND (SP).

4.0 to 20.0
Quaternary Alluvium (Qa):

Poorly Graded SAND (SP),
Well Graded SAND (SW), Well
Graded SAND with Silt (SWSM), Poorly Graded SAND
with Silt (SP-SM).

B-25
East of
intersection
Tamarisk Ave.
and Cedar Dr.
20 2009 24+00 9.5

0.0 to 3.5 Fill: Poorly Graded SAND with
Silt (SP-SM).

3.5 to 20.0
Quaternary Alluvium (Qa):

Well Graded SAND with Silt
(SW-SM), Silty SAND (SM)
B-26
South of
intersection
Cactus Dr.
and Palo
Verde Ave.
20 1984 59+25 16.4

0.4 to 3.0 Fill: Well Graded SAND with
Silt (SW-SM).

3.0 to 20.0 Quaternary Alluvium (Qa):

Silty SAND (SM).

B-27
South of
intersection
Verbana Dr.
and Cienega
Dr.

19.5 1964 21+30 8.3

0.3 to 5.0 Fill: Poorly Graded SAND (SP).

5.0 to 19.5
Quaternary Alluvium (Qa):

Well Graded SAND with Silt
(SW-SM).

B-28
East of
intersection
Gorgonio Dr.
and Cienega
Ave.

21.5 1957 21+90 14.0

0.5 to 6.5 Fill: Silty SAND (SM).

6.5 to 21.5 Quaternary Alluvium (Qa):

Silty SAND (SM).

B-29
West of
intersection
Bagley Ave.
and Spit Rock
Ave.

16.5 2036 39+25 8.0

0.3 to 3.0 Fill: Poorly Graded SAND with
Silt (SM).

3.0 to 16.5
Quaternary Alluvium (Qa):

Silty SAND (SM), Poorly
Graded SAND with Silt (SPSM)
B-30
West of
intersection
Yucca Ave.
and El Paseo
Dr.

16.5 2044 38+30 8.3

0.8 to 4.0 Fill: Silty SAND (SM).

4.0 to 16.5 Quaternary Old Alluvium
(Qoa): Silty SAND (SM).

B-31
West of
Sunnyslope
Dr. and Alpine
Ave.
20 2168 157+50 12.2

0.3 to 6.0 Fill: Silty SAND (SM).

6.0 to 20.0
Quaternary Old Alluvium
(Qoa): Silty SAND (SM), Poorly
Graded SAND with Silt (SP).

227522-0000190.00 NV5.COM | 12
Field
Exploration
Identification
Approximate
Street
Location
Approximate
Final Drilling
Depth
Below
Existing
Grade, feet
Approximate
Field
Exploration
Surface
Elevation
Approximate
Roadway
Alignment
Station Per
Design
Drawings
Approximate
Depth to Invert
Elevation of
Alignment Near
Boring, feet
Approximate
Elevation Below
Existing Grade
as Encountered
in Field
Exploration, feet
Material Description as
Encountered in Field
Exploration
B-32
South of
intersection
Granite Ave.
and Juniper
Ave.

18.3 2148 15+20 12.4

0.6 to 3.0 Fill: Silty SAND (SM).

3.0 to 18.3
Quaternary Old Alluvium
(Qoa): Silty SAND (SM), Poorly
Graded SAND with Silt (SPSM).

B-33
Northeast of
intersection
Desert Trail
Dr. and Larrea
Ave.
20 2123 11+00 11.5 0.0 to 20.0
Quaternary Old Alluvium
(Qoa): Silty SAND (SM), Well
Graded SAND with Silt (SWSM).

B-34
Northeast of
intersection
Desert Trail
Dr. and L Luna
Ave.

19.5 2165 115+90 8.0

0.3 to 5.0 Fill: Well Graded SAND with
Silt (SW-SM).

5.0 to 19.5
Quaternary Old Alluvium
(Qoa): Poorly Graded SAND
(SP), Silty SAND (SM)
B-35
East of
intersection
Hillside Ave.
and
Sunnyvale Dr.

16.5 2056 52+90 8.7

0.4 to 4.0 Fill: Silty SAND (SM)

4.0 to 16.5 Quaternary Old Alluvium
(Qoa): Silty SAND (SM).

B-36
East of
intersection
Bagley Ave.
and
Sunnyslope
Dr.
15 2028 38+60 8.0

0.4 to 3.0 Fill: Silty SAND (SM).

3.0 to 15.0 Quaternary Old Alluvium
(Qoa): Silty SAND.

B-37
East of
intersection
Ocotillo Ave.
and Desert
Trail Dr.
15 2010 17+70 8.2

0.3 to 4.0 Fill: Poorly Graded SAND with
Gravel (SP).

4.0 to 15
Quaternary Old Alluvium
(Qoa): Poorly Graded SAND
(SP), Poorly Graded SAND
with Silt (SP-SM).

B-38
South of
Marine Ave.
and Joe Davis
Dr.
20 1916 33+90 17.8 0.0 to 20.0 Quaternary Old Alluvium
(Qoa): Silty SAND (SM).

B-39
North of
intersection
Wainwright
Ave. and Joe
Davis Dr.
20 1898 18+50 16.2

0.0 to 3.0 Fill: Silty SAND (SM).

3.0 to 20.0 Quaternary Old Alluvium
(Qoa): Silty SAND (SM).

B-40
South of
intersection
Utah Trail and
Two Mile Rd.

18.5 1872 18+00 12.0

0.9 to 3.0 Fill: Poorly Graded SAND (SP).

3.0 to 18.5
Quaternary Alluvium (Qa):

Poorly Graded SAND (SP),
Silty SAND (SM), Well Graded
SAND with Silt (SW-SM), Well
Graded SAND (SW).

B-41
East of
intersection
Alpine Ave.
and El Paseo
Dr.
20 2172 78+85 13.4

0.0 to 5.0 Fill: Poorly Graded SAND with
Silt (SP-SM).

5.0 to 20.0
Quaternary Old Alluvium
(Qoa): Poorly Graded SAND
with Silt (SP-SM), Well Graded
SAND with Silt (SW-SM).

227522-0000190.00 NV5.COM | 13
A summary of the laboratory test results completed on soil samples obtained at field exploration locations are presented in Table 3 below. Finding from current lab test results and visual observation suggests the following:
• Natural moisture content test results for seventy-six (76) samples ranged between 0.2 to 8.2 percent and suggest that existing subgrade conditions are generally “dry” to the final depths of exploration explored. However, experience indicates that near-surface groundwater conditions or localized seepage zones can develop in areas where no such groundwater conditions previously existed, especially in areas where a substantial increase in surface water infiltration results from landscape irrigation, agricultural activity, artificial recharge, storage facility leaks, or unusually heavy precipitation.
• In-situ dry density test results for fifty (50) samples ranged between 104.2 to 125.0 pounds per cubic foot (pcf). Six (6) of the samples yielded dry densities less than 110.0 pcf; nineteen (19) of the samples yielded dry densities ranging between 110.0 to 115.0 pcf; nineteen (19) of the samples yielded dry densities ranging between 115.0 to 120.0 pcf; and six (6) of the samples yielded dry densities ranging between 120.0 to 125.0 pcf • Sand equivalent (SE) test results for seventeen (17) samples obtained from field explorations yielded values ranging between 14 to 76. It is our experience that typical specifications for trench bedding have minimum required SE ranging between 20 to 30. Twelve (12) of the test samples yielded SE values of 20 or greater.
• Modified Proctor test results for seven (7) samples obtained from field explorations yielded Maximum Dry Density values ranging between 118.4 to 131.1 pcf; and Optimum Moisture Content test results ranging between 4.3 to 10.5 percent. • R-value test results for seven (7) samples obtained from field explorations yielded values between 64 to 79 suggesting “good” pavement subgrade characteristics. One (1) lower test result (R-value = 22) was encountered.
• Direct shear test results (sample saturated prior to testing) for thirteen (13) samples obtained from field explorations yielded values between 31.5 to 42.3 degrees for “peak friction”; 31.0 to 38.3 degrees for “ultimate friction”/residual friction; 50 to 550 pounds per square foot (psf) for “peak cohesion”; and 50 to 300 pounds per square foot (psf) for “peak cohesion”/residual cohesion.
• Soil corrosivity tests including pH, resistivity, water soluble sulfate and chloride were performed on seven (7) representative soil subgrade samples collected from field exploration locations B-1. Soil corrosivity test results are summarized and discussed in report Section 9.10 below.

227522-0000190.00 NV5.COM | 14
Table 3
Summary of Laboratory Test Results
Field
Exploration
ID

Soil Sample
Depth
(feet)
USCS
Class
Moisture
Content
(%)
Dry Density
(pcf)
% Passing
#4
Sieve
% Passing
#200
Sieve
Maximum
Dry
Density
(pcf)
Optimum
Moisture
Content
(percent)
Expansion
Index
Sand
Equivalent
Corrosion
Tests
R
Value
B-1

11.0 to 11.5
Silty SAND
w/Gravel
(SM)

1.4 115.4 Not
Tested Not Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested

11.5 to 13.0 /

15.0 to 16.5
(combined)
Silty SAND
w/Gravel
(SM)
Not
Tested
Not Tested 80 43.7 Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

19.5 to 20.0
Silty SAND
w/Gravel
(SM)

2.9 112.8 Not
Tested Not Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
B-2

6.0 to 6.5
Poorly
Graded

SAND (SP)

2.9 106.3 Not
Tested Not Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested

6.0 to 8.0
Poorly
Graded

SAND (SP)
Not
Tested Not Tested
Not
Tested
Not Tested Not Tested Not Tested Not
Tested
25 Not
Tested
Not
Tested

12.0 to 14.0 Silty SAND
(SM)

3.8 Not Tested
Not
Tested
Not Tested Not Tested Not Tested Not
Tested
Not
Tested
Not
Tested
Not
Tested

16.0 to 16.5
Silty SAND
w/Gravel
(SM)

1.0 117.7 Not
Tested Not Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
B-3

1.0 to 3.0
Poorly
Graded
SAND
w/Gravel
(SP)

1.2 Not Tested
Not
Tested Not Tested Not Tested Not Tested Not Tested
Not
Tested
See Test
Results
in
Section

9.10 73

1.0 to 3.0 / 5.0
to 6.5
(combined)
Poorly
Graded
SAND
w/Gravel
(SP)
Not
Tested Not Tested Not Tested Not Tested 123.0 4.3 Not Tested 44 Not
Tested
Not
Tested

11.0 to 11.5
Silty SAND
w/Gravel
(SM)

0.9 118.0 Not
Tested Not Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
B-4

1.0 to 3.0
Well
Graded

SAND (SW)
Not
Tested Not Tested 91 4.7 Not Tested Not Tested Not Tested Not
Tested
Not
Tested
Not
Tested

15.0 to 15.5 Silty SAND
(SM)

1.5 114.7 Not
Tested
Not Tested Not Tested Not Tested Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-5

1.0 to 3.0
Well
Graded

SAND (SW)

2.6 Not Tested Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

11.0 to 11.5
Poorly
Graded
SAND
w/Silt (SPSM)

1.1 112.7 Not
Tested Not Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested

12.0 to 14.0
Poorly
Graded
SAND
w/Silt (SPSM)
Not
Tested Not Tested 93 12 Not Tested Not Tested Not Tested Not
Tested
See Test
Results
in
Section

9.10 Not
Tested
B-6

5.0 to 6.5 Silty SAND
(SM)

1.2 Not Tested
Not
Tested Not Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested

15.0 to 16.5
Well
Graded
SAND
w/Silt (SWSM)
Not
Tested Not Tested 98 5.9 Not Tested Not Tested Not Tested Not
Tested
Not
Tested
Not
Tested
20 to 20.5 Silty SAND
(SM)

3.3 Not Tested Not
Tested
Not Tested Not Tested Not Tested Not
Tested
Not
Tested
Not
Tested
Not
Tested

20.5 to 22 Silty SAND
(SM)

1.9 Not Tested
Not
Tested
Not Tested Not Tested Not Tested Not
Tested
Not
Tested
Not
Tested
Not
Tested

227522-0000190.00 NV5.COM | 15
Field
Exploration
ID

Soil Sample
Depth
(feet)
USCS
Class
Moisture
Content
(%)
Dry Density
(pcf)
% Passing
#4
Sieve
% Passing
#200
Sieve
Maximum
Dry
Density
(pcf)
Optimum
Moisture
Content
(percent)
Expansion
Index
Sand
Equivalent
Corrosion
Tests
R
Value
B-7

6.0 to 6.5 Silty SAND
(SM)

4.8 117.9 Not
Tested Not Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested

6.0 to 6.5 / 7.0
to 9.0 / 10.0 to

11.5 (combined)
Silty SAND
(SM)
Not
Tested Not Tested 90 17.4 Not Tested Not Tested Not Tested 20 See Test
Results
in
Section

9.10 Not
Tested

16.0 to 16.5 /

20.0 to 21.5 /

26.0 to 26.5
(combined)
Silty SAND
(SM)
Not
Tested Not Tested 97 7.8 Not Tested Not Tested Not Tested 27 Not
Tested
Not
Tested

26.0 to 26.5 Silty SAND
(SM)

1.7 110.7 Not
Tested Not Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
B-8

5.0 to 6.5
Well
Graded

SAND (SW)

4.3 Not Tested Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

6.0 to 6.5 / 7.0
to 9.0 / 10.0 to

11.5 (combined)
Silty SAND
(SM)
Not
Tested Not Tested 90 17.4 Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

11.0 to 11.5
Poorly
Graded

SAND (SP)

3.0 118.2 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

15.0 to 16.5 /

21.0 to 21.5 /

25.0 to 26.5
(combined)
Silty SAND
(SM)
Not
Tested Not Tested 97 21.9 Not Tested Not Tested
Not
Tested
14 Not
Tested
Not
Tested
B-9

1.0 to 3.0
Poorly
Graded

SAND (SP)
Not
Tested Not Tested Not Tested Not Tested Not Tested Not Tested Not
Tested
Not
Tested
Not
Tested 76

11.0 to 11.5 Silty SAND
(SM)

6.1 108.2 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-10

1.0 to 3.0
Poorly
Graded
SAND
w/Silt (SPSM)
Not
Tested Not Tested Not Tested Not Tested 122.0 8.6 Not Tested 37 Not Tested Not
Tested

6.0 to 6.5
Poorly
Graded

SAND (SP)

1.5 108.2 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

15.0 to 16.5 Silty SAND
(SM)

4.0 119.9 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-11

6.0 to 6.5
Well
Graded
SAND
w/Silt (SWSM)

2.4 114.5 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

7.0 to 9.0 /

10.0 to 11.5 /

11.5 to 13.0
(combined)
Well
Graded
SAND
w/Silt (SWSM)
Not
Tested
Not Tested 97 10.8 Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-12

1.0 to 3.0 Silty SAND
(SM)

8.1 Not Tested 99 21.8 131.1 8.1 Not
Tested
Not
Tested
Not
Tested
Not
Tested

19.5 to 20.0 Silty SAND
(SM)

3.7 113.8 Not
Tested
Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

227522-0000190.00 NV5.COM | 16
Field
Exploration
ID

Soil Sample
Depth
(feet)
USCS
Class
Moisture
Content
(%)
Dry Density
(pcf)
% Passing
#4
Sieve
% Passing
#200
Sieve
Maximum
Dry
Density
(pcf)
Optimum
Moisture
Content
(percent)
Expansion
Index
Sand
Equivalent
Corrosion
Tests
R
Value
B-13

6.0 to 6.5 Silty SAND
(SM)

4.5 115.9 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

6.0 to 6.5 /

10.0 to 11.5 /

16.0 to 16.5
(combined)
Silty SAND
(SM)
Not
Tested Not Tested 98 22.7 Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

16.0 to 16.5 Silty SAND
(SM)

3.7 120.3 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-14

5.0 to 6.5 Silty SAND
(SM)

3.5 Not Tested Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

5.0 to 6.5 /

11.0 to 11.5
(combined)
Silty SAND
(SM)
Not
Tested Not Tested 98 17.5 Not Tested Not Tested
Not
Tested
21 Not
Tested
Not
Tested

5.0 to 6.5 / 6.5
to 8.0 / 11.0 to

11.5 (combined)
Silty SAND
(SM)
Not
Tested Not Tested Not Tested Not Tested Not Tested Not Tested Not
Tested
Not
Tested
See Test
Results
in
Section

9.10 Not
Tested

11.0 to 11.5 Silty SAND
(SM)

5.4 124.7 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

26.0 to 26.5 Silty SAND
(SM)

2.0 107.8 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-15

5.0 to 8.0 /

11.0 to 11.5
(combined)
Silty SAND
(SM)
Not
Tested
Not Tested 98 12.8 Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-16

1.0 to 3.0 Silty SAND
(SM)
Not
Tested
Not Tested Not
Tested Not Tested 131.5 7.1 Not Tested
Not
Tested
Not
Tested
Not
Tested

6.0 to 6.5 Silty SAND
(SM)

5.2 123.6 99 22.8 Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

16.0 to 16.5 Silty SAND
(SM)

1.7 114.1 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-17

1.0 to 3.0
Poorly
Graded
SAND
w/Gravel
(SP)

2.4 Not Tested Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

5.0 to 6.5 /

11.0 to 11.5
(combined)
Poorly
Graded
SAND
w/Silt (SPSM)
Not
Tested Not Tested Not Tested Not Tested Not Tested Not Tested Not
Tested
40 Not
Tested
Not
Tested

11.0 to 11.5
Poorly
Graded
SAND
w/Silt (SPSM)

2.0 115.2 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-18

6.0 to 6.5
Poorly
Graded
SAND
w/Silt (SPSM)

0.2 Not Tested Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

6.5 to 8.0
Poorly
Graded
SAND
w/Silt
Not
Tested Not Tested Not Tested Not Tested Not Tested Not Tested Not
Tested
76 Not
Tested
Not
Tested

11.0 to 11.5
Well
Graded

SAND (SW)

0.6 110.8 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

227522-0000190.00 NV5.COM | 17
Field
Exploration
ID

Soil Sample
Depth
(feet)
USCS
Class
Moisture
Content
(%)
Dry Density
(pcf)
% Passing
#4
Sieve
% Passing
#200
Sieve
Maximum
Dry
Density
(pcf)
Optimum
Moisture
Content
(percent)
Expansion
Index
Sand
Equivalent
Corrosion
Tests
R
Value
B-19

5.0 to 6.5 Silty SAND
(SM)

0.6 Not Tested Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

11.0 to 11.5 Silty SAND
(SM)

3.2 125.0 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-20

5.0 to 6.5 Silty SAND
(SM)

2.7 Not Tested Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

11.0 to 11.5
Poorly
Graded

SAND (SP)

3.1 118.6 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

16.0 to 16.5 /

16.5 to 18.0
(combined)
Silty SAND
(SM)
Not
Tested Not Tested 96 17.5 Not Tested Not Tested
Not
Tested
18 Not
Tested
Not
Tested

21.0 to 21.5
Well
Graded
SAND
w/Silt (SWSM)

2.2 117.0 98 8.1 Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-21

5.0 to 6.5
Silty SAND
w Gravel
(SM)

5.5 Not Tested Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

11.5 to 13.0 Silty SAND
(SM)

2.2 Not Tested Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

26.0 to 26.5 Silty SAND
(SM)

1.3 118.6 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

16.0 to 16.5 /

20.0 to 21.5 /

26.0 to 26.5
(combined
Silty SAND
(SM)
Not
Tested Not Tested 91 17.9 Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-22

1.0 to 3.0 Silty SAND
(SM)

2.8 Not Tested Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

11.0 to 11.5 Silty SAND
(SM)

1.8 117.7 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

15.0 to 16.5 Silty SAND
(SM)
Not
Tested Not Tested Not Tested Not Tested Not Tested Not Tested Not
Tested
24 Not
Tested
Not
Tested
B-23

1.0 to 3.0 Sandy SILT
(ML)
Not
Tested Not Tested Not Tested Not Tested Not Tested Not Tested Not
Tested
Not
Tested
Not
Tested
67 6.0 to 6.5
Poorly
Graded
SAND
w/Silt (SPSM)

3.8 114.2 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

8.0 to 10.0 Silty SAND
(SM)
Not
Tested Not Tested Not Tested Not Tested Not Tested Not Tested Not Tested 27 Not Tested Not
Tested

16.0 to 16.5 Silty SAND
(SM)

0.6 104.2 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-24

1.0 to 3.0
Poorly
Graded

SAND (SP)
Not
Tested
Not Tested Not
Tested
Not Tested 119.3 8.7 Not
Tested
Not
Tested
Not
Tested
Not
Tested

11.0 to 11.5
Well
Graded
SAND
w/Silt (SWSM)

3.1 121.2 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

11.0 to 11.5 /

15.0 to 16.5
(combined)
Well
Graded
SAND
w/Silt
Not
Tested Not Tested 97 10.6 Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

19.0 to 19.5
Poorly
Graded
SAND
w/Silt (SPSM)

1.2 110.7 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

227522-0000190.00 NV5.COM | 18
Field
Exploration
ID

Soil Sample
Depth
(feet)
USCS
Class
Moisture
Content
(%)
Dry Density
(pcf)
% Passing
#4
Sieve
% Passing
#200
Sieve
Maximum
Dry
Density
(pcf)
Optimum
Moisture
Content
(percent)
Expansion
Index
Sand
Equivalent
Corrosion
Tests
R
Value
B-25

10.0 to 11.5 /

11.5 to 13.0
(combined)
Well
Graded
SAND
w/Silty
(SW-SM)
Not
Tested Not Tested 85 10.3 Not Tested Not Tested
Not
Tested
Not
Tested
See Test
Results
in
Section

9.10 Not
Tested

19.5 to 20.0 Silty SAND
(SM)

1.3 115.1 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-26

1.0 to 3.0 Silty SAND
(SM)
Not
Tested
Not Tested 96 8.8 Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
78 5.0 to 6.5 Silty SAND
(SM)

0.6 Not Tested Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

10.0 to 11.5 /

15.0 to 16.5
(combined)
Silty SAND
(SM)
Not
Tested Not Tested 97 17.5 Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

16.0 to 16.5 Silty SAND
(SM)

2.4 112.8 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-27

6.0 to 6.5
Well
Graded
SAND
w/Silt (SWSM)

1.2 115.4 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

6.5 to 8.0
Well
Graded
SAND
w/Silt (SWSM)
Not
Tested Not Tested 96 8.4 Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

11.0 to 11.5
Well
Graded
SAND
w/Silt (SWSM)

1.5 118.1 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-28

6.0 to 6.5 Silty SAND
(SM)

1.6 Not Tested Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

11.0 to 11.5 Silty SAND
(SM)

6.3 110.0 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-29

6.0 to 6.5 Silty SAND
(SM)

5.1 114.8 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

6.0 to 6.5 /

6.5 to 8.0 /

8.0 to 9.5
(combined)
Silty SAND
(SM)
Not
Tested Not Tested 98 19.5 Not Tested Not Tested
Not
Tested 19
See Test
Results
in
Section

9.10 Not
Tested

10.0 to 11.5 Silty SAND
(SM)

1.5 Not Tested Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-30

1.0 to 3.0 Silty SAND
(SM)

5.6 Not Tested 98 25.8 Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
22 6.5 to 8.5 /

11.0 to 11.5
(combined)
Silty SAND
(SM)
Not
Tested Not Tested 96 22.0 Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

11.0 to 11.5 Silty SAND
(SM)

5.2 Not Tested Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

227522-0000190.00 NV5.COM | 19
Field
Exploration
ID

Soil Sample
Depth
(feet)
USCS
Class
Moisture
Content
(%)
Dry Density
(pcf)
% Passing
#4
Sieve
% Passing
#200
Sieve
Maximum
Dry
Density
(pcf)
Optimum
Moisture
Content
(percent)
Expansion
Index
Sand
Equivalent
Corrosion
Tests
R
Value
B-31

6.0 to 6.5 Silty SAND
(SM)

4.2 117.8 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

6.5 to 8.0 /

10.0 to 11.5
(combined)
Silty SAND
(SM)
Not
Tested Not Tested 97 20.2 Not Tested Not Tested
Not
Tested 19 Not Tested
Not
Tested

16.0 to 16.5 Silty SAND
(SM) 4.1 113.9 Not Tested Not Tested Not Tested Not Tested Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-32

6.0 to 6.5
Poorly
Graded
SAND
w/Silt (SPSM)

0.6 Not Tested Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

11.0 to 11.5
Poorly
Graded
SAND
w/Silt (SPSM)

2.5 Not Tested Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-33

8.0 to 9.5 /

10.0 to 11.5
(combined)
Well
Graded
SAND
w/Silt (SWSM)
Not
Tested Not Tested 96 8.5 Not Tested Not Tested Not Tested 29 Not
Tested
Not
Tested

16.0 to 16.5
Well
Graded
SAND
w/Silt (SWSM)

3.8 119.9 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-34

1.0 to 3.0
Well
Graded
SAND
w/Silt (SWSM)
Not
Tested Not Tested 94 10.1 Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
76 5.0 to 6.5
Poorly
Graded

SAND (SP)

1.4 Not Tested Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

6.5 to 8.0
Poorly
Graded

SAND (SP)
Not
Tested
Not Tested 95 4.5 Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

11.0 to 11.5
Poorly
Graded

SAND (SP)

0.7 112.8 Not
Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-35

6.0 to 6.5 Silty SAND
(SM) 0.8 107.3 Not Tested Not Tested Not Tested Not Tested Not
Tested
Not
Tested
Not
Tested
Not
Tested

8.0 to 9.5 Silty SAND
(SM) 5.2 Not Tested Not Tested Not Tested Not Tested Not Tested Not Tested Not
Tested
Not
Tested
Not
Tested
B-36 1.0 to 3.0 Silty SAND
(SM)
Not
Tested Not Tested Not Tested Not Tested Not Tested Not Tested Not Tested 20 Not
Tested 64
B-37 6.0 to 6.5
Poorly
Graded

SAND (SP)

0.9 108.6 Not
Tested Not Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
B-38

1.0 to 3.0 Silty SAND
(SM)
Not
Tested
Not Tested
Not
Tested Not Tested 126.9 5.3 Not Tested
Not
Tested
Not
Tested
Not
Tested

11.0 to 11.5 Silty SAND
(SM) 5.7 110.6 Not Tested Not Tested Not Tested Not Tested Not
Tested
Not
Tested
Not
Tested
Not
Tested

11.0 to 11.5 /

15.0 to 16.5 /

19.5 to 20.0
(combined)
Silty SAND
(SM)
Not
Tested Not Tested
Not
Tested
Not Tested Not Tested Not Tested
Not
Tested 15 Not Tested
Not
Tested

19.5 to 20.0 Silty SAND
(SM) 1.4 118.7 Not Tested Not Tested Not Tested Not Tested Not
Tested
Not
Tested
Not
Tested
Not
Tested

227522-0000190.00 NV5.COM | 20
Field
Exploration
ID

Soil Sample
Depth
(feet)
USCS
Class
Moisture
Content
(%)
Dry Density
(pcf)
% Passing
#4
Sieve
% Passing
#200
Sieve
Maximum
Dry
Density
(pcf)
Optimum
Moisture
Content
(percent)
Expansion
Index
Sand
Equivalent
Corrosion
Tests
R
Value
B-39

6.0 to 6.5 Silty SAND
(SM) 1.9 112.1 Not Tested Not Tested Not Tested Not Tested Not
Tested
Not
Tested
Not
Tested
Not
Tested

6.0 to 11.5
(combined)
Silty SAND
(SM)
Not
Tested
Not Tested 100 19.0 Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
Not
Tested

16.0 to 16.5 Silty SAND
(SM) 4.5 121.6 Not Tested Not Tested Not Tested Not Tested Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-40

1.0 to 3.0
Poorly
Graded

SAND (SP)

3.0 Not Tested Not
Tested Not Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested

11.0 to 11.5
Well
Graded
SAND
w/Silt (SWSM)

8.2 113.7 Not
Tested Not Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested

11.5 to 16.0
(combined)
Well
Graded
SAND
w/Silt (SWSM)
Not
Tested
Not Tested 88 7.6 Not Tested Not Tested Not
Tested
Not
Tested
Not
Tested
Not
Tested
B-41

1.0 to 3.0
Poorly
Graded
SAND
w/Silt (SPSM)
Not
Tested
Not Tested
Not
Tested Not Tested 118.4 10.5 Not Tested
Not
Tested
Not
Tested
Not
Tested

12.0 to 14.0
Well
Graded
SAND
w/Silt (SWSM)
Not
Tested
Not Tested 98 8.9 Not Tested Not Tested Not
Tested
Not
Tested
See Test
Results
in
Section

9.10 79

16.0 to 16.5
Well
Graded
SAND
w/Silt (SWSM)

2.6 110.3 Not
Tested Not Tested Not Tested Not Tested Not Tested
Not
Tested
Not
Tested
Not
Tested
*Sample saturated prior to direct shear testing

GROUNDWATER
Groundwater in the region is located within the Morongo Basin. The Morongo Basin consists of about 1,000-square miles of alluvium filled valleys surrounded by mountains. In the vicinity of the site, the Morongo Basin is divided into multiple subbasins separated from each other by hydrologic barriers, including bedrock ridges, faults, and folds. The degree of separation and depth to groundwater between the subbasins is dependent upon the character of the aquifer materials and types of barriers separating them. In general, groundwater elevations reportedly range from a high of approximately 2,400 feet above mean sea level (MSL) in the southwest portion of the City limits (Indian Cove Subbasin) to a low of approximately 1,600 feet above MSL near the Mesquite Fault in the Mesquite Lake Subbasin on the eastern portion of the City limits (reference: Groundwater Management Plan – 2014 Update, Prepared for Twentynine Palms Water District by Kennedy/Jenks Consultants, dated May 28. 2014).

In general, experience indicates that near-surface groundwater conditions or localized seepage zones can develop in areas where no such groundwater conditions previously existed, especially in areas where a substantial increase in surface infiltration results from landscape irrigation, agricultural activity, artificial recharge, storage facility leaks, or unusually heavy precipitation. Seasonal variations in the groundwater levels should be anticipated. In addition, it should be understood that groundwater movement near the active fault traces that traverse the site can be complex and difficult to predict and shallow groundwater may be encountered at these locations.

227522-0000190.00 NV5.COM | 21
Indications of a static, near-surface groundwater table were not observed or encountered during the current subsurface exploration to the maximum depth explored (31.5 feet bgs). Groundwater is generally not anticipated to be a constraint during construction along majority of the project alignment.

NV5 previously conducted a screening investigation of potential recharge sites near Twentynine Palms as part of a larger, wastewater-design, feasibility study in 2021. A detailed discussion of depth to groundwater and hydrogeology in the project vicinity was presented in Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California, prepared by NV5, Inc., dated January 26, 2022. A copy of this report is included in Appendix D.

FAULTS
As used in this report, the definitions of fault terms are based on those developed for the Alquist-Priolo Special Studies Zones Act of 1972 (A-P Act) and Special Publication 42 – Earthquake Fault Zones, A Guide for Government Agencies, Property Owner/ Developers, and Geoscience Practitioners for Assessing Fault Rupture Hazards in California, Revised 2018, published by the California Department of Conservation, California Geological Survey (CGS).

For the purposes of the A-P Act, an “active” fault is defined as one which has “had surface displacement within Holocene time (the last 11,700 years). This definition does not mean that faults lacking evidence for surface displacement within Holocene time are necessarily inactive. A fault may only be presumed to be inactive based on satisfactory geologic evidence; however, the evidence necessary to prove inactivity sometimes is difficult to obtain and locally may not exist.” Faults in California that are regulated by the A-P Act are classified into three categories on the basis of the absolute age of their most recent movement and include the following:

1. Holocene-active faults: Faults that have moved during the past 11,700 years.

2. Pre-Holocene faults: Faults that have not moved in the past 11,700 years, thus do not meet the criteria of “Holocene-active fault” as defined in the A-P Act and State Mining and Geology Board (SMGB) regulations. This class of fault may be still capable of surface rupture but is not regulated under the A-P Act.

3. Age-undetermined faults: Faults where the recency of fault movement has not been determined. Within the framework of the A-P Act, age-undetermined faults within regulatory Earthquake Fault Zones are considered Holocene-active until proved otherwise.

The closest known active faults to the site are the Pinto Mountain fault zone that traverses the southern end of the Phase 1 study area and the Pisgah-Bullion Mountain – Mesquite Lake fault that lies approximately 0.5-mile to the east-northeast of the Phase 1 study area. Other important active faults that could affect the Los Angeles County area and their distance to the site are included in the following Table 4. In addition, Figure 5, Site Fault Map and Figure 6, Regional Fault Map depicts the project alignment location in relation to known active faults in the region.

227522-0000190.00 NV5.COM | 22
Table 4 - Distance from the Site to Major Active Faults Fault Distance From the Site
Pinto Mountain 0.0 miles
Pisgah-Bullion Mountain - Mesquite Lake 0.5 miles
Calico-Hidalgo 6 miles
So Emerson-Copper Mountain 7 miles
Eureka Peak 18 miles
Burnt Mountain 20 miles
Landers 21 miles
Johnson Valley 26 miles
San Andreas fault zone 26 miles
North Frontal 29 miles
Lenwood-Lockhart-Old Woman Springs 36 miles
Helendale-So Lockhart 45 miles
San Jacinto 51 miles
Cleghorn 66 miles
Elmore Ranch 67 miles
Gravel Hills-Harper Lake 70 miles
Earthquake Valley 72 miles
Elsinore 74 miles
Superstition Hills 76 miles

8.0 SEISMIC AND GEOTECHNICAL HAZARDS
The principal seismic considerations for most pipelines and water systems in California are damage caused by surface rupturing of fault traces, ground shaking, seismically induced ground settlement and liquefaction. Potential impacts to the project due to faulting, seismicity and other geologic hazards are discussed in the following sections.

FAULT RUPTURE
The site is traversed by the Pinto Mountain fault at the southern end of the Phase 1 study area and the Pisgah-Bullion Mountain – Mesquite Lake fault lie just to the east-northeast of the Phase 1 study area. These two Earthquake Fault Zones (EFZ) are deemed active by the State of California for the hazard of fault surface rupture. As such, the potential for ground-surface rupture and/or shallow ground deformation occurring at the site due to a seismic event are a significant concern for the site development. Special consideration should be taken with respect to any proposed structures and/or facilities within close proximity to these zones, and/or any proposed conduit alignments that may cross these active fault zones.

The planned development of any structures and/or wastewater treatment plant facilities within and/or in close proximity to the two EFZ’s should be avoided. However, should a structure and/or facility be planned within and/or in close proximity to either of the noted EFZ’s, NV5 should be retained to perform a fault hazard study in order to preclude the possibility of an active fault trace underlying the proposed development area.

227522-0000190.00 NV5.COM | 23

SEISMIC SHAKING
The project site is located in an area of California considered a seismically active area, and as such, the seismic hazard most likely to impact the site is ground shaking resulting from an earthquake along one of the known active faults in the region.

Preliminary seismic parameters were developed for the project site based on the 2022 California Building Code (CBC) and ASCE 7-16 guidance document. Using the Structural Engineers Association of California’s U.S. Seismic Design Maps Online Calculator (https://seismicmaps.org/), based on the following site coordinates: Latitude = 34.135567 degrees, and Longitude = -116.054171 degrees.

The earthquake hazard level of the Maximum Considered Earthquake (MCE) is defined in ASCE 7-16 as the ground motion having a probability of exceedance of 2 percent in 50 years. The preliminary seismic design parameters for the project site are presented in Table 5 below.

Table 5 - Summary of Seismic Design Parameters
(Based on 2022 CBC and ASCE 7-16 Standard)
Design Parameter
Recommended
Value
Reference
Site Class D CBC Section 1613.3.2
Mapped Spectral Accelerations for short
periods, SS

1.727g CBC Section 1613.2.1
Mapped Spectral Accelerations for 1-sec
period, S1

0.645g CBC Section 1613.2.1
Short-Period Site Coefficient, Fa 1 CBC Table 1613.3.1
Long-Period Site Coefficient, Fv 1.7 CBC Table 1613.3.1 (1) MCER (5% damped) spectral response
acceleration for short periods adjusted for
site class, SMS

1.727g CBC Section 1613.3.3
(1) MCER (5% damped) spectral response
acceleration at 1-second period adjusted
for site class, SM1

1.096g CBC Section 1613.3.3
Design spectral response acceleration
(5% damped) at short periods, SDS

1.151g CBC Section 1613.3.4
Design spectral response acceleration
(5% damped) at 1-second period, SD1

0.731g CBC Section 1613.3.4
Seismic Design Category D CBC Section 1613.3.5
(2) MCEG Peak Ground Acceleration
adjusted for site class effects, PGAM

0.849g ASCE 7-16 Section 11.8.3
(1) MCER = Risk-adjusted Maximum Considered Earthquake
(2) MCEG = Geometric-mean Maximum Considered Earthquake

227522-0000190.00 NV5.COM | 24

LIQUEFACTION AND SEISMICALLY-INDUCED SETTLEMENT
Liquefaction of soils can be caused by ground shaking during earthquakes. Research and historical data indicate that loose, relatively clean granular soils are susceptible to liquefaction and dynamic settlement, whereas the stability of the majority of clayey silts, silty clays and clays is not adversely affected by ground shaking. Liquefaction is generally known to occur in saturated cohesionless soils at depths shallower than approximately 75 feet. The potential for liquefaction under the same conditions of ground shaking intensity and duration will decrease for sands that are more well-graded, more irregular and gritty, coarser and denser. Also a pronounced decrease in liquefaction potential will occur with the increase in fine-grained (i.e., silt and clay) content. Seed and others have suggested that a non-liquefiable classification be assigned if the clay fraction is 15 percent or greater (Guidelines for Evaluating and Mitigating Seismic Hazards in California, Special Publication 117, CDMG, Ch. 6, 1997). Dynamic settlement due to earthquake shaking can occur in both dry and saturated sands.

The potential consequences of liquefaction to engineered structures inlcude loss of bearing capacity, buoyancy forces on underground structures (including pipelines), increased lateral earth pressures on retaining walls, and lateral spreading. Pipes constructed in soils that become liquefied may become buoyant.

The majority of the project alignment appears to be underlain at depth by medium dense to very dense Quaternary alluvial soils which are not considered to be susceptible to sigificant liquefaction and seismic settlement. The potential for liquefaction induced settlement to be a significant concern for design performance in the area of this study is considered low-to-moderate, due to the the interpreted lack of a shallow groundwater table. However, within and/or along the fault zones and playas outside of the Phase 1 project area, the potential for liquefaction may exist. If structures and/or facilities are planned in these areas, field explorations and soil testing are warranted in order to preclude the possibility of liquefiable subsurface materials in these areas.

The potential for seismically (dry) induced settlement in the limited areas of this study underlain by loose fill and alluvial materials is considered low to moderate due to the proximity to the nearby Pinto Mountain fault zone and Pisgah-Bullion Mountain - Mesquite Lake fault.

Once a specific site for any proposed wastewater treatment plant has been selected, NV5 should be retained to explore the depths and lateral extent of any potentially compressible soils at the selected site.

LANDSLIDES AND SLOPE INSTABILITY
The project alignment is located within the right-of-way along various roads throughout the City of Twentynine Palms with gently sloping valley floor with some moderate to shallow drainage channel incisions. Therefore, the potential for deep-seated landsliding and slope instability within these geologic materials is considered low.

SUBSIDENCE
The site is not located in an area of known ground subsidence due to the withdrawal of subsurface fluids. Based on NV5’s review of the Groundwater Management Plan – 2014 Update, Prepared for Twentynine Palms Water District by Kennedy/Jenks Consultants, dated May 28, 2014, land subsidence has not been identified as an issue within the Twentynine Palms area. However, playa lake

227522-0000190.00 NV5.COM | 25
deposits like those mapped at Mesquite Lake have been known to be a source of land subsidence in Antelope Valley and in other similar areas. Accordingly, the potential for subsidence occurring at the site outside of the playa lake deposits due to the withdrawal of oil, gas, or water is considered to be low.

TSUNAMIS, INUNDATION SEICHE, AND FLOODING
The site is located within the southern region of the Mojave Desert, and at or above an elevation of approximately 1,750 feet above MSL. Also, the site is not located downslope of any large body of water that could affect the site in the event of an earthquake-induced failure or seiche (oscillation in a body of water due to earthquake shaking). Therefore, the potential for damaging tsunamis (seismic sea waves) or seiche is considered remote.

Based on a review of Federal Emergency Management Agency (FEMA) flood insurance rate map (FIRM) and the County of San Bernardino General Planning Map, portions of the project alignment are known to be susceptible to flooding during infrequent but substantial precipitation events. The potential for flooding should be considered during project planning and design. The approximate locations of areas deemed susceptible to flooding are displayed in Figure 7, Flood Hazard Map.

EXPANSIVE SOILS
Soils consisting of clay minerals have the potential to expand when provided a source of water, and can contract upon drying. If not properly accounted for, these swell/shrink mechanisms of clayey soils can cause significant distress to pavements, flatwork, and structures.

Based on NV5’s current field exploration program, the subsurface materials encountered are predominately granular alluvium that is generally considered to have a very low to low expansion potential. However, site soils are variable and soils with higher expansion potential may be encountered. Expansive soils with expansion indices greater than 20 should not be used as compacted fill in structural locations, including underneath the pavements. However, with proper mixing using the “sandier” onsite materials, very low expansion potential subgrade material can likely be achieved during construction.

EROSION
In an effort to evaluate erosion potential for the site vicinity NV5 reviewed available USDA Soil Maps https://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm. Soils are described as having several erosion factors (i.e. Kw, Kf, T) which estimate the soil potential for sheet and rill erosion. The project area generally has erosion factors which indicate a low to moderate potential for surface erosion.

Certain soil deposits in the project area such as young surficial sediments (i.e., alluvium, clay and windblown sand deposits) may be more susceptible to erosion than other soils.

227522-0000190.00 NV5.COM | 26

9.0 CONCLUSIONS AND DESIGN RECOMMENDATIONS

GENERAL
Based on the data obtained from the subsurface exploration, the associated laboratory test results, engineering analyses, and experience with similar site conditions, it is NV5’s opinion that the proposed sewer system improvements project is feasible from a geotechnical standpoint, provided that the recommendations in this report are incorporated into the design plans and implemented during construction. The following sections present recommendations pertaining to the geotechnical engineering design and construction for this project.

RIPPABILITY/EXCAVATIBILITY
It is anticipated that excavations for the pipeline alignment will be on the order of 8 to 21 feet below the existing surface grade. It appears that the majority of the alignment, is underlain by old alluvial deposit units at depth, overlain with varying amounts of younger alluvial materials and locally derived fill soils. The fill and alluvial materials consist of Silty SAND (SM), Silty SAND with Gravel (SM), Well Graded SAND (SW), Well Graded SAND with Silt (SW-SM), Poorly Graded SAND (SP), Poorly Graded SAND with Gravel (SP), Poorly Graded SAND with Silt (SP-SM), Clayey SAND (SC), and Sandy SILT (ML).

While not encountered during the current investigation, cobble sized clasts may also be present in the alluvial materials. Based on our NV5’s experience on similar projects in similar subsurface materials, it is anticipated that excavation of the near-surface, weathered materials can be generally accomplished by skilled operators using heavy duty excavators in good operating condition. However, excavations in hard, relatively dense deposits or cobbles may be difficult and may require heavy ripping, hydraulic hammering, blasting, rock drilling, rock-splitting, and/or other methods to facilitate excavation. In addition, excavations of hard rock and cobbles will also likely produce oversize materials that are unsuitable for use in backfill and structural fills.

EARTHWORK
Although major earthwork is not planned for this project, site earthwork should be performed in accordance with the following recommendations and the Typical Earthwork Guidelines provided in Appendix E. In the event of conflict, the recommendations presented herein supersede those of Appendix E.

TEMPORARY EXCAVATIONS AND SHORING
Excavation of the on-site soils may be achieved with conventional heavy-duty grading equipment.

Temporary, unsurcharged, excavation walls may be sloped back at an inclination of 1.5:1(H:V) within fill and alluvial materials. Utility trench excavations should be shored in accordance with guidelines and regulations set forth by Cal-OSHA. For planning purposes, the fill and alluvial deposits may be considered a Type C soil, as defined by the current Cal-OSHA soil classification.

Stockpiled (excavated) materials should be placed no closer to the edge of a trench excavation than a distance defined by a line drawn upward from the bottom of the trench at an inclination of 1:1 (H:V), but no closer than 4 feet. All trench excavations should be made in accordance with Cal-OSHA requirements.

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O.25H

0.25H
H = Height of Shored Wall 0.50H
(feet)
28H
(psf)
Temporary, shallow excavations with vertical side slopes less than 4 feet high will generally be stable, although due to the characteristics of the soil materials, there is a potential for sloughing. In these soil types, vertical excavations greater than 4 feet high should not be attempted without proper shoring to prevent local instabilities. Temporary shoring, if required, may be accomplished by several methods including hydraulic shores and trench plates; trench boxes; and soldier piles and lagging. For vertical excavations less than about 12 feet in height, cantilevered shoring may be used. Cantilevered shoring may also be used for deeper excavations; however, the total deflection at the top of the wall should not exceed half-inch. Therefore, shoring of excavations deeper than about 12 feet may need to be accomplished with the aid of tied back earth anchors. The excavation support system should be designed to resist lateral earth pressures of the soil, surcharge loads, and hydrostatic pressures, as applicable. Preliminary design of cantilevered temporary shoring, a triangular distribution of lateral earth pressure may be used. It may be assumed that the subgrade soils, with a level surface behind the cantilevered shoring, will exert an equivalent fluid pressure of 36 pound per cubic foot (pcf). Tiedback or braced shoring should be designed to resist a trapezoidal distribution of lateral earth pressure.

The recommended pressure distribution, for the case where the grade is level behind the braced shoring, is illustrated in the following diagram with the maximum pressure equal to 28H in psf, where H is the height of the shored wall in feet.

Any surcharge (live, including traffic, or dead load) located within a 1:1 (H:V) plane drawn upward from the base of the shored excavation should be added to the lateral earth pressures. The vertical loads imposed by existing structures, if any, should be determined by the structural engineer. The lateral load contribution of a uniform surcharge load located across the 1:1 (H:V) zone behind the excavation may be calculated in accordance with Figure 8, Lateral Surcharge Loads. As a minimum, a 2-ft equivalent soil surcharge is recommended to account for nominal construction traffic loads.

The actual shoring design should be provided by a registered shoring engineer in the State of California experienced in the design and construction of shoring under similar conditions. Once the final excavation and shoring plans are complete, the plans and the design should be reviewed by NV5 for conformance with the design intent and geotechnical recommendations. The shoring system should further satisfy requirements of Cal-OSHA.

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DEWATERING
As previously mentioned, reported groundwater elevations vary across and within the various subbasins in the site vicinity. Although, groundwater is generally not anticipated to be a constraint along majority of the project alignment, any cases of seepage, perched water, or heavy precipitation should be monitored during construction. The actual means and methods of any dewatering scheme should be established by a contractor with local experience. It is important to note that temporary dewatering, if necessary, will require a permit and plan that complies with RWQCB regulations. If excessive water is encountered, NV5 should contacted to provide additional recommendations for temporary construction dewatering. Based on the NV5’s review of USDA Soil Maps, the onsite nearsurface soils may be considered to be relatively permeable.

Groundwater was not encountered to the maximum final depths explored of approximately 15 to 31.5 feet bgs. The groundwater table is subject to fluctuations in response to several factors. If dewatering is necessary, the actual means and methods of any dewatering scheme should be established by a contractor with local experience. It is important to note that temporary dewatering, if necessary, will require a permit and plan that complies with RWQCB regulations.

TRENCH BOTTOM STABILITY
The bottom of onsite excavations may likely expose fill, alluvium and/or older alluvium. The fill and alluvium is composed primarily of medium dense to very dense granular soils. These soils should provide a suitable base for construction of the pipelines. Oversize cobble-to-boulder size clasts should be overexcavated to allow for appropriate bedding placement for pipe support. For the design of flexible conduits, a modulus of soil reaction (E’) of 600 pounds per square inch (psi) is recommended.

If water is encountered during excavations or if the soils become wet or saturated, they may be prone to settlement due to construction activities such as placement and compaction of backfill soils. Buried improvements underlain by these soils could also be damaged or subjected to unacceptable settlement due to subsidence of these soils. If wet or unusually soft conditions are encountered in the trench bottom, the bottom of the excavations will need to be stabilized. A typical stabilization method includes overexcavation of the soft or saturated soil and replacement with properly compacted fill, gravel or lean concrete to form a "mat" or stable working surface in the bottom of the excavation. There are other acceptable methods that can be implemented to mitigate the presence of compressible soils or unstable trench bottom conditions, and specific recommendations for a particular alternative can be discussed based on the actual construction techniques and conditions encountered.

PIPE ZONE BACKFILL
It is recommended that pipe zone backfill materials be placed in the trench to provide uniform support and protection for the pipe. Pipe zone is defined as that material supporting, surrounding and extending to one foot above the top of the pipe. A cement slurry may not be used as bedding.

The bedding materials should be approved by the geotechnical consultant prior to hauling on site. As noted previously, pipeline installation will be completed in accordance with Pipe Bedding and Trench Backfill Detail included in Phase I Wastewater Collection System Drawings, dated June 16, 2023, prepared by NV5. An excerpt from this Detail is provided below.

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A 6-inch layer of pipe bedding consisting of crushed rock per specifications should be placed beneath the pipe, per the detail shown above. The pipe bedding zone shall be compacted to a minimum of 90 percent relative compaction. If crushed rock is used as bedding, we recommend the crushed rock be wrapped in filter fabric to mitigate the potential for migration of fines into the voids that could result in settlement. Care should be taken by the contractor during placement of the pipe bedding so that uniform contact between the bedding and pipe is attained. The pipe bedding shall be compacted under the haunches and alongside the pipe and care should be taken by the contractor to not damage the pipe. Pipe zone backfill should be placed in loose lift thicknesses not exceeding 8 inches and compacted by mechanical means to attain a relative compaction of 90 percent based on ASTM D1557.

Flooding or jetting should not be allowed. Mechanical compaction and hand tamping should be performed carefully as to not damage the pipe.

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TRENCH BACKFILL PLACEMENT AND COMPACTION
The majority of the on-site granular soils should generally be suitable for use as backfill material.

Screening may be required in some areas where rocks larger than 1 inches in diameter are present.

Backfill should be placed in loose lifts not exceeding 8 inches in thickness and compacted to at least 90 percent of the maximum dry density as evaluated by the latest version of ASTM D1557. Trench backfill should be compacted in uniform lifts (not exceeding 6 inches in compacted thickness) by mechanical means to at least 90 percent relative compaction (ASTM D1557).

Water jetting should not be used for compaction. Trench backfill should consist of granular, nonexpansive soil with an Expansion Index (EI) of 20 or less and should not contain any contaminated soil, debris, organic matter, or other deleterious materials. At least 70% passing by weight of its particles should pass a U.S. Standard ¾ - inch sieve. The sand equivalent (SE) of the trench material to be used for trench backfill shall be 20 or greater. Import material, if needed, should be evaluated for suitability by the geotechnical consultant prior to transporting to the site. For the design of thrust blocks, please refer to Figure 9, Thrust Block Detail.

The upper 12 inches of subgrade soil and all rock base should be compacted to at least 95 percent.

The moisture content of the backfill should be maintained within 2 percent of optimum moisture content during compaction. All backfill should be mechanically compacted. Flooding or jetting is not recommended and should not be allowed.

Trench resurfacing should be constructed in accordance with the Trench Resurfacing Detail included in Phase I Wastewater Collection System Drawings, dated June 16, 2023, prepared by NV5. An excerpt of this Detail is provided below.

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Pavement sections for the trench resurfacing shall be a equal to the existing asphalt concrete (AC) thickness plus 1-inch and shall be minimum of 4 inches thick over 6-inches of class aggregate base (AB).

LIFT STATION RECOMMENDATIONS
Preliminary plans (see excerpt below) indicate construction at the proposed lift station site will consist of the following:
• Above grade construction (structures)
o Concrete masonry unit (CMU) block walls will surround the site with a footprint (rectangular) of 34 feet x 70 feet. The CMU block walls will be founded on shallow continuous footings.
o An eye wash station, odor control tank, removable davit crane, emergency generator and electrical cabinets will be founded on reinforced concrete slabs. o A shade structure (which will cover the electrical cabinets) will be founded on shallow spread footings.
• Below grade construction (structures)
o A proposed duplex lift station, valve vault and meter vault will be founded on reinforced concrete slab.
o The proposed duplex lift station, valve vault and meter vault will be connected via two (2) 4” C900 PVC DR 18 Forcemain pipes.
• Appurtenant construction
o The interior of the proposed lift station will be covered with ¾ inch crushed rock. o Access to the proposed lift station will be provided via a driveway approach constructed in accordance with San Bernardino County Standard Drawing 128. o A 16 feet wide concrete driveway will constructed near the center (east west alignment) of the proposed lift station.

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Foundations for the proposed lift station structures should be bear entirely on compacted fill. General geotechnical recommendations for the design and construction of the lift station are presented below.

9.9.1 Foundation Design for Above Grade Structures - Continuous and Spread Foundations
Prior to shallow foundation (continuous and spread) construction, near-surface material should be removed to a depth of at least 3 feet below the base of proposed foundation elevation. The overexcavation should extend laterally a distance of at least 5 feet outside perimeter footings/foundations unless otherwise directed by the geotechnical engineer. The soils exposed in the bottom of the excavation should be scarified to a minimum depth of 8 inches, moisture conditioned and uniformly recompacted to at least 90 percent of the soil maximum density (based on ASTM D1557) and a moisture content of between 0 and 2 percent above optimum unless otherwise directed by the geotechnical engineer.

Low expansive soils (EI < 50) should be placed back into the overexcavation with a moisture content of 0 to 2 percent over optimum moisture content and be uniformly compacted to at least 90 percent of the soils maximum dry density (based on ASTM D1557) unless otherwise directed by the geotechnical engineer. Backfill should be compacted in uniform lifts (not exceeding 8 inches in loose lift thickness) by mechanical means in accordance with ASTM D1557.

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Import soils should be sampled and tested for suitability by NV5 prior to delivery to the site. Imported fill materials should consist of clean granular soils free from vegetation, debris, or rocks larger than 3 inches in maximum dimension. The Expansion Index value should not exceed a maximum of 20 (i.e., essentially non-expansive), unless otherwise directed by the geotechnical engineer.

Although not anticipated, if wet or unusually soft conditions are encountered in the bottom of the removal excavations, they may need to be stabilized. Typical stabilization methods include overexcavation of the soft or saturated soil and replacement with properly compacted fill, gravel wrapped in geo-fabric or lean concrete to form a “mat” or stable working surface in the bottom of the excavation. There are other acceptable methods that can be implemented to mitigate the presence of compressible soils or unstable trench bottom conditions, and specific recommendations for a particular alternative can be discussed based on the actual construction techniques and conditions encountered.

Based on the overexcavation and recompaction recommendations for subgrade provided above, shallow foundations (continuous and spread) should be designed using the geotechnical design parameters presented in Table 6. Footings should be designed and reinforced in accordance with the recommendations of the structural engineer and should conform to the latest edition of the California Building Code.

Table 6
Geotechnical Design Parameters for Shallow Continuous and Spread Foundations Foundation Dimensions
Continuous or spread foundations at least 12 inches
in width and embedded at least 24 inches below the
lowest adjacent grade.

Allowable Bearing Capacity
(dead-plus-live load)
2,000 pounds per square foot (psf), which may be
increased by 300 psf for each additional foot of depth
and by 100 psf for each additional foot of width to a
maximum of 3,000 psf.

A one-third (1/3) increase is allowed for wind or
seismic loads.

Reinforcement
Reinforce in accordance with requirements as
provided by the project Structural Engineer.

Allowable Coefficient of
Friction

0.35 0.10 in the event a vapor barrier is used.

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Allowable Lateral
Passive Resistance
(Equivalent Fluid Pressure)
250 pounds per cubic foot (pcf) per foot of depth.

A one-third (1/3) increase in passive resistance value
may be used for wind and seismic loads.

The total allowable lateral resistance may be taken as
the sum of the frictional resistance and the passive
resistance, provided that the passive bearing
resistance does not exceed one-half (1/2) of the total
allowable lateral passive resistance.

Note: The above parameters assume level ground or sloping no steeper than 5H:1V.

Where footings are located behind retaining walls or near and parallel to major underground utilities, the footings should be extended below a plane projected at a slope of 1H: 1V upward from the bottom of the retaining wall or the underground utility to avoid surcharging the retaining wall or underground utility with building loads.

If any pipes pass through a footing, a foundation wall, a releieving arch, or a pipe sleeve pipe should be built into the foundation. The sleeve should be at least two pipe sizes greater than the pipe passing through the foudnation.

9.9.2 Foundation Design for Above Grade Structures – Concrete Slab/Mat Foundations
Prior to concrete slab/mat foundation construction, near-surface material should be removed to a depth of at least 3 feet below the base of proposed foundation elevation. The over-excavation should extend laterally a distance of at least 5 feet outside perimeter footings/foundations unless otherwise directed by the geotechnical engineer. The soils exposed in the bottom of the excavation should be scarified to a minimum depth of 8 inches, moisture conditioned and uniformly recompacted to at least 90 percent of the soil maximum density (based on ASTM D1557) and a moisture content of between 0 and 2 percent above optimum unless otherwise directed by the geotechnical engineer.

Low expansive soils (EI < 50) should be placed back into the overexcavation with a moisture content of 0 to 2 percent over optimum moisture content and be uniformly compacted to at least 90 percent of the soils maximum dry density (based on ASTM D1557) unless otherwise directed by the geotechnical engineer. Backfill should be compacted in uniform lifts (not exceeding 8 inches in loose lift thickness) by mechanical means in accordance with ASTM D1557.

Import soils should be sampled and tested for suitability by NV5 prior to delivery to the site. Imported fill materials should consist of clean granular soils free from vegetation, debris, or rocks larger than 3 inches in maximum dimension. The Expansion Index value should not exceed a maximum of 20 (i.e., essentially non-expansive), unless otherwise directed by the geotechnical engineer.

Although not anticipated, if wet or unusually soft conditions are encountered in the bottom of the removal excavations, they may need to be stabilized. Typical stabilization methods include overexcavation of the soft or saturated soil and replacement with properly compacted fill, gravel wrapped in geo-fabric or lean concrete to form a “mat” or stable working surface in the bottom of the excavation. There are other acceptable methods that can be implemented to mitigate the presence of compressible soils or unstable trench bottom conditions, and specific recommendations for a

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particular alternative can be discussed based on the actual construction techniques and conditions encountered.

Based on the overexcavation and recompaction recommendations for subgrade provided above, shallow foundations (continuous and spread) should be designed using the geotechnical design parameters presented in Table 7. Concrete slabs should be supported on at least 4 inches of Class 2 aggregate base compacted to at least 95 percent of the maximum dry density. Concrete slab/mat foundations should be designed and reinforced in accordance with the recommendations of the structural engineer and should conform to the latest edition of the California Building Code.

Table 7
Geotechnical Design Parameters for Concrete Slab/Mat Foundations Foundation Dimensions
Concrete slab/mat foundations embedded at least 24
inches below the lowest adjacent grade.

Modulus of Subgrade Reaction
(for a foundation measuring
1 ft x 1 ft)
200 pounds per cubic inch (pci) – Value will need
adjusted to accommodate actual dimensions of
foundation
Reinforcement
Reinforce in accordance with requirements as
provided by the project Structural Engineer.

Allowable Coefficient of
Friction

0.35 0.10 in the event a vapor barrier is used.

Allowable Lateral
Passive Resistance
(Equivalent Fluid Pressure)
250 pounds per cubic foot (pcf) per foot of depth.

A one-third (1/3) increase in passive resistance value
may be used for wind and seismic loads.

The total allowable lateral resistance may be taken as
the sum of the frictional resistance and the passive
resistance, provided that the passive bearing
resistance does not exceed one-half (1/2) of the total
allowable lateral passive resistance.

Note: The above parameters assume level ground or sloping no steeper than 5H:1V.

9.9.3 Foundation Design for Below Grade Structures
Depending on the final design elevation for various below grade structures, we recommend that slab foundations be founded on “dense” soils. If soils encountered at foundation depths are yielding or pliant, we recommend that they be over-excavated and then compacted as structural fill to a depth determined in the field by the geotechnical engineer. For planning purposes, surface material at the base of the foundation elevation should be over-excavated to a depth of at least 2 feet below the base of proposed structure pad. Excavation should extend laterally a distance of at least 3 feet outside foundations unless otherwise directed by the geotechnical engineer. The soils exposed in the bottom

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of the excavation should be scarified to a minimum depth of 8 inches, moisture conditioned and uniformly recompacted to at least 90 percent of the soil maximum density (based on ASTM D1557) and a moisture content of between 0 and 2 percent above optimum unless otherwise directed by the geotechnical engineer.

Low expansive soils (EI < 50) should be placed back into the overexcavation with a moisture content of 0 to 2 percent over optimum moisture content and be uniformly compacted to at least 90 percent of the soils maximum dry density (based on ASTM D1557) unless otherwise directed by the geotechnical engineer. Backfill should be compacted in uniform lifts (not exceeding 8 inches in loose lift thickness) by mechanical means in accordance with ASTM D1557.

Although not anticipated, if wet or unusually soft conditions are encountered in the bottom of the removal excavations, they may need to be stabilized. Typical stabilization methods include overexcavation of the soft or saturated soil and replacement with properly compacted fill, gravel wrapped in geo-fabric or lean concrete to form a “mat” or stable working surface in the bottom of the excavation. There are other acceptable methods that can be implemented to mitigate the presence of compressible soils or unstable trench bottom conditions, and specific recommendations for a particular alternative can be discussed based on the actual construction techniques and conditions encountered.

Based on the overexcavation and recompaction recommendations for subgrade provided above, foundations (underground concrete slab) should be designed using the geotechnical design parameters presented in Table 8. Slab foundations should be designed and reinforced in accordance with the recommendations of the structural engineer and should conform to the latest edition of the California Building Code.

Table 8
Foundation Design Parameters for Below Grade Foundations Unit Weight of Native Soils 115 pounds per cubic foot (pcf) Unit Weight of
Engineered/Structural Fill
130 pounds per cubic foot (pcf)
Modulus of Subgrade Reaction
(for a foundation measuring
1 ft x 1 ft)
200 pounds per cubic inch (pci) – Value will need
adjusted to accommodate actual dimensions of
foundation
Modulus of Elasticity 4,000 pounds per cubic inch (lb/in2) Poisson’s Ratio 0.3
Note: The above parameters assume level ground or sloping no steeper than 5H:1V.

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Uplift resistance can be resisted by the soils above the top of foundation. The uplift pressure can be resisted by widening the bottom of the foundation and calculating the resistiance of the soil above the lip of the foundation in the following manner. The weight of soil resisting uplifting can be taken as that of soils measured within a plane 30 degrees from the vertical from the outer edge of the footing. We would recommend a lip of at least 6 inches be considered to mobiize the weight of the backfill in uplift calculations. If no lip is present, then we recommend only adhesion be considered on the exterior face of the structure wall. An average soil unit weight of 115 pcf can be taken for soil aboev groundwater table and 53 pcf for soil below the groundwater table. An average shearing resistance of 250 can be assumed as acting along this plane. The weight of the structure should also be assumed in calculating the resistance to uplift. If this approach is not feasible and additional recommendations are needed to resist the upift forces, NV5 should be contacted to discuss other alternatives.

Given that the weight of the propsoed below grade structures will probably be less than the weight of the soil removed during excxvation, settlement of these structures from their own weight should be negligible. For design purposes, maximum total and differential foundation settlements of below grade structures should be on the order of ½-inch due to recompressions of the foudnations osils. In order to account for differential settlement between these structurfes and any pipleines, flexible joint connections should be considered.

9.9.4 Lateral Earth Pressure Parameters for Below Grade Structures Below grade structures should be design to resist the earth proessure extered by the retained compacted backfill plus any additional lateral force due to surcharge loading, (e.g, constuction equipment, foundations, roadways, etc.) at or near walls. The following equivalent fluid earth pressures are recommended. For walls below the groundwater table (assuming existing groudnwater table may rise in the future), we recommend that they be moisture proofed. A qualified specialist should be consulted to determine the type of moisture proffing that should be used.

Table 9
Recommended Lateral Earth Pressure for Below Grade Foundations Parameter Level Backfill Case
Static Active Earth Pressure (Pa) 36H
Static At-Rest Earth Pressure (Po) 60H
Seismic Earth Pressure (Pe) 24H
Coefficient of Friction (µ) for
Lateral Resistance of Foundation 0.35
Passive Earth Pressure (Pp) for Lateral
Resistance of Foundation 250H
Notes:

1. All values of height (H) are in feet (ft) and pressure (P) in pounds per square feet (psf).

2. Seismic earth pressure (Pe) is in addition to the static active or at-rest pressure, Pa and Po which should be distributed as an inverted triangle along the wall height and the resultant of this pressure is an increment of force which should be applied to the back of the wall in the upper one-third (1/3) of the wall

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height and may also be applied as a reduction of force to the front of the wall in the upper one-third (1/3) of the footing depth.

3. The above pressure values do not include hydrostatic pressures that might be caused by groundwater or water trapped behind the structure.

4. The pressures listed in the table were based on the assumption that backfill soils will be compacted to 90 percent of maximum dry density (per ASTM D1557).

5. The coefficient of friction (µ) should be applied to dead normal (buoyant) loads when evaluating the sliding frictional resistance.

6. A resistance factor has been applied to the passive earth pressure and may be combined with the sliding frictional resistance using a resistance factor of 0.80. Neglect the upper 6 inches for passive pressure unless the surface is contained by a pavement or a slab. The passive earth pressure should not exceed a maximum value of 3,000 psf.

7. In addition to the above-mentioned pressures, retaining structures must be designed to resist horizontal pressures that may be generated by surcharge loads applied at the ground surface such as from uniform loads or vehicle loads. Figure 8 may be used to evaluate these surcharge loads.

9.9.5 Foundation Observation
To verify the presence of satisfactory materials at design elevations, footing excavations should be observed to be clean of loosened soil and debris before placing steel or concrete and probed for soft areas. If soft or loose soils or unsatisfactory materials are encountered, these materials should be removed and may be replaced with a two-sack, sand-cement slurry or structural concrete. Footing excavations should be deepened as necessary to extend into satisfactory bearing materials; however, NV5 should be notified to approve the proposed change.

9.9.6 Exterior Concrete Driveway
Driveway slab areas and connecting sidewalks should have a minimum concrete thickness of 6 inches.

Driveway concrete slabs should be underlain by at least 6 inches of Class 2 aggregate base compacted to at least 95 percent of the maximum dry density. The upper 12 inches of subgrade soil located below the aggregate base should be overexavated and recompacted to achieve a moisture content of between 0 and 2 percent above optimum unless otherwise directed by the geotechnical engineer, and recompacted to a minimum of 95 percent relative compaction (ASTM D1557).

JACK AND BORE CONSIDERATIONS
NV5 understands that Jack and bore (J&B) construction methods are being considered at up to four (4) potential locations. Three (3) where the alignment crosses the flood control channel (near Tamarisk Avenue, Ocotillo Avenue and Desert Knoll Avenue) and one (1) under Highway 62 at Desert Knoll Avenue. Design plans and profiles for the potential J&B crossings were not available for review as of the date of this report. It is NV5’s opinion that construction using jack and bore construction methods for the proposed crossing is feasible from a geotechnical standpoint. The following paragraphs present geotechnical recommendations pertinent to the proposed J&B crossing.

Based on information obtained from the borings, it is anticipated that the excavation for the sending and receiving pits at the proposed locations will encounter fill, Quaternary-aged alluvium and older

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alluvium deposits consisting of poorly to moderately consolidated, loose to very dense, Silty SAND (SM), Silty SAND with Gravel (SM), Well Graded SAND (SW), Well Graded SAND with Silt (SW-SM), Poorly Graded SAND (SP), Poorly Graded SAND with Gravel (SP), Poorly Graded SAND with Silt (SP-SM), and Clayey SAND (SC), and require shoring. While not encountered during the current investigation, cobbleto-boulder sized clasts may also be present in the alluvial materials. Groundwater was not encountered in any of the exploratory borings to the total depths explored. • Soil Factors – The following soil parameters may be used: moist unit weight of 115 pcf, angle of internal friction of 34 degrees, zero cohesion, and a soil friction coefficient of 0.30 may be used for preliminary J&B design purposes.
• Jacking Forces - Based on past experience, there is no reliable method to calculate anticipated thrust pressures. NV5 is familiar with projects where jacking casings of the same size through the same soil provided different resistance. Factors that impact thrust pressures include soil conditions, moisture content, pipe depth and overall time lapse (start to end of construction affected by inspections, obstructions, holidays, etc.). Casings should be selected by the project mechanical engineer to exceed jacking forces, surface loading requirements and long-term axial loads. Selection of the appropriate jack and bore equipment is ultimately the responsibility of the contractor.
• Other J&B Factors – Other factors for construction include the following:
o Groundwater was not encountered in our test borings. However if groundwater is encountered during construction (see Sections 7.3 and 9.5), then additional measures such as the use grouting or shielding may be required to stabilize against potential “running sand” and development of voids.
o It is recommended that excavation operations be continuous as practical. It is emphasized that the resulting performance of the operations will largely be dependent upon construction procedures and techniques.
o Ground movements associated with the work should be monitored during installation and, if necessary, the construction method should be altered to control the ground movements and minimize disturbance to the overlying improvements. o Underground construction should be in accordance with applicable provisions of CalOSHA and applicable provisions of the State of California labor codes. o Based on the results of the investigation, it is anticipated that the site will be considered “nongassy” as defined by Section 7950-7964 of the State of California Labor Code.

CORROSION POTENTIAL
General recommendations to address the corrosion potential of the on-site soils are provided below.

Any imported soils should be evaluated for corrosion characteristics if they will be in contact with buried or at-grade structures and appropriate mitigation measures should be included in the structure design. It is recommended that a corrosion specialist be contacted to determine if mitigation measures are necessary.

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9.12.1 Caltrans Criteria
The California Department of Transportation (Caltrans) Corrosion Guidelines (Version 3.2, dated March 2021) considers a site to be corrosive to structural elements “if one or more of the following conditions exist for the representative soil and/or water samples taken at the site: Chloride concentration is 500 ppm or greater, sulfate concentration of 1,500 ppm or greater, or the pH of 5.5 or less”. Minimum resistivity in soil or water is considered an indicator parameter and is not used to define a corrosive soil environment. Caltrans’ Guidelines state that a “minimum resistivity value for soil and/or water less than 1,500 Ohm-cm indicates the presence of high quantities of soluble salts and a higher propensity for corrosion”.

Representative samples of the site soils obtained from the borings were tested to evaluate the corrosion potential. The tests include pH, electrical resistivity, and soluble chloride and sulfate concentrations. Results of the corrosivity tests performed are summarized in the table below and presented in Appendix C, Laboratory Test Results.

Table 10 - Corrosivity Test Results
Boring Location
and Sample Depth
Soil Type pH
Minimum
Resistivity
(Ohm-cm)
Water
Soluble
Sulfate
Content
(ppm)
Water
Soluble
Chloride
Content
(ppm)
B-3 @ 1 – 3 ft
Poorly Graded
SAND
w/Gravel (SP)

8.3 9,100 30 32
B-5 @ 12 – 14 ft
Poorly Graded
SAND w/Silt
(SP-SM)

8.2 2,300 81 53
B-7 @ 6 – 11.5 ft Silty SAND
(SM) 8.8 1,600 51 120
B-14 @ 5 – 11.5 ft Silty SAND
(SM) 8.9 2,800 51 53
B-25 @ 10 – 13 ft
(combined sample)
Well Graded
SAND w/Silt
(SW-SM)

8.3 7,200 30 11
B-29 @ 6 – 9.5 ft
(combined sample)
Silty SAND
(SM) 8.8 3,400 45 11
B-41 @ 12 – 14 ft
Well Graded
SAND w/Silt
(SW-SM)

9.1 7,000 30 11
Based on limited laboratory testing, and the Caltrans Corrosion Guidelines, the site soils are not considered to be corrosive to steel based on the water-soluble chloride concentrations. The sulfate test results do not suggest the potential for site soils to be corrosive to steel and concrete foundations.

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9.12.2 ACI Criteria
Based on a review of the American Concrete Institute (ACI) 318, Section 19.3, the following is noted:
• Per Tables 19.3.1.1 and Table 19.3.2.1 - Sulfate Content Test Results • The tested site soils are in a “Class S0” Exposure Category which indicates the potential for a deleterious sulfate attack is not a concern. A minimum concrete compressive strength of 2,500 psi would be required. However, due to the potential for variability of on-site soils, we recommend that Type II/V cement be used for concrete in contact with soil with a watercement ratio no higher than 0.45 by weight for the project. • Per Table 19.3.2.1 – Chloride Content Test Results
• The tested site soils are in a “Class C1” Exposure Category (assuming a potential for encountering water). A minimum concrete compressive strength of 2,500 psi would be required with no specific requirement for cement ratio. The maximum water-soluble chloride ion content in non-prestressed concrete is 0.30 and in prestressed concrete is

0.06 percent by weight of cement.

9.12.3 Ferrous Pipes Criteria
As indicated in the 2006 edition (second edition) of “Corrosion Basics - An Introduction”, a general guideline for soil resistivity and corrosion-severity ratings is presented in the following table:

Table 11 - Soil Resistivity Versus Corrosion Severity
Soil Resistivity Corrosivity
<1,000 ohm-cm Extremely Corrosive
1,000 to 3,000 ohm-cm Highly Corrosive
3,000 to 5,000 ohm-cm Corrosive
5,000 to 10,000 ohm-cm Moderately Corrosive
10,000 to 20,000 ohm-cm Mildly Corrosive
>20,000 ohm-cm Essentially Noncorrosive

Soil resistivity is not the only parameter affecting the risk of corrosion damage; and a high soil resistivity will not guarantee the absence of serious corrosion. For example, the American Water Works Association (AWWA) has developed a numerical soil-corrosivity scale, applicable to cast-iron alloys. The test results do suggest the potential for soils to be moderately to highly corrosive to ferrous metal pipes.

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Any imported soils should be evaluated for corrosion characteristics if they will be in contact with buried or at-grade structures and appropriate mitigation measures should be included in the structure design. It is recommended that a corrosion specialist be contacted to determine if mitigation measures are necessary.

10.0 CONSTRUCTION MONITORING
Observation and testing of the backfill, subgrade and base will be important to the performance of the proposed improvements. Site preparation, removal of unsuitable soils, assessment of imported fill materials, backfill placement, and other earthwork operations should be observed and tested. The substrata exposed during the construction may differ from that encountered in the test explorations.

Continuous observation by a representative of NV5 during construction allows for evaluation of the soil/rock conditions as they are encountered and allows the opportunity to recommend appropriate revisions where necessary.

11.0 LIMITATIONS
The recommendations and opinions expressed in this report are based on NV5’s review of background documents and on information obtained from field explorations. It should be noted that this study did not evaluate the possible presence of hazardous materials on any portion of the site.

Due to the limited nature of the field explorations, conditions not observed and described in this report may be present on the site. Uncertainties relative to subsurface conditions can be reduced through additional subsurface exploration. Additional subsurface evaluation and laboratory testing can be performed upon request. It should be understood that conditions different from those anticipated in this report may be encountered during grading operations, e.g., the extent of removal of unsuitable soil, and that additional effort may be required to mitigate them.

Site conditions, including ground-water level, can change with time as a result of natural processes or the activities of man at the subject site or at nearby sites. Changes to the applicable laws, regulations, codes, and standards of practice may occur as a result of government action or the broadening of knowledge. The findings of this report may, therefore, be invalidated over time, in part or in whole, by changes over which NV5 has no control.

NV5’s recommendations for this site are, to a high degree, dependent upon appropriate quality control of subgrade preparation, fill placement, and foundation construction. Accordingly, the recommendations are made contingent upon the opportunity for NV5 to observe grading operations and foundation excavations for the proposed construction. If parties other than NV5 are engaged to provide such services, such parties must be notified that they will be required to assume complete responsibility as the geotechnical engineer of record for the geotechnical phase of the project by concurring with the recommendations in this report and/or by providing alternative recommendations.

This document is intended to be used only in its entirety. No portion of the document, by itself, is designed to completely represent any aspect of the project described herein. NV5 should be contacted if the reader requires additional information or has questions regarding the content, interpretations presented, or completeness of this document.

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NV5 has endeavored to perform its evaluation using the degree of care and skill ordinarily exercised under similar circumstances by reputable geotechnical professionals with experience in this area in similar soil conditions. No other warranty, either expressed or implied, is made as to the conclusions and recommendations contained in this report.

12.0 SELECTED REFERENCES
American Society of Civil Engineers / Structural Engineering Institute (ASCE/SEI), 2016; Minimum Design Loads for Buildings and Other Structures, ASCE/SEI 7-16.

ASTM, 2001; Soil and Rock: American Society for Testing and Materials: vol. 4.08 for ASTM test methods D-420 to D-4914; and vol. 4.09 for ASTM test methods D-4943 to highest number.

Boulanger, R.W. and Idriss, I.M., 2014; "CPT and SPT Based Liquefaction Triggering Procedures," University of California Davis, Center for Geotechnical Modeling Report No. UCD/CGM-14/01, pp. 1-134
CBC, 2022, California Building Code.

California Department of Transportation (Caltrans), 2021, Corrosion Guidelines (Version 3.2), Division of Engineering and Testing Services, Corrosion Technology Branch: dated May.

California Department of Conservation, Division of Mines and Geology, 1997; Guidelines for Evaluation and Mitigation of Seismic Hazards in California: Special Publication 117, 74 pp.

California Department of Conservation, Division of Mines and Geology, 1998; Maps of Known Active Fault Near-Source Zones in California and Adjacent Portions of Nevada: International Conference of Building Officials, dated February, Scale 1” = 4 km.

California Department of Conservation, Division of Mines and Geology, 1998; State of California Special Studies Zones, Twentynine Palms Quadrangle; dated March.

California Geological Survey, 2008a; Special Publication 117A, Guidelines for Evaluating and Mitigating Seismic Hazards in California
California Geological Survey, 2008ba, “Appendix A: California Fault Parameters for the National Seismic Hazard Maps and Working Group on California Earthquake Probabilities 2007,” Special Report 203A.

California Geological Survey, 2010; Fault Activity Map of California.

Dibblee, T.W.; 1968, Geologic map of the Twentynine Palms quadrangle, San Bernardino and Riverside County, California, U.S. Geological Survey, Miscellaneous Geologic Investigations Map I-561, scale 1:62,500.

FEMA, msc.fema.gov, flood map 06037C0975F
Hart, E.W., and Bryant, W.A., 1997; Fault-Rupture Hazard Zones in California, Alquist-Priolo Earthquake Fault Zoning Act with Index to Earthquake Fault Zone Maps: California Department of Conservation, Division of Mines and Geology Special Publication 42, 38 pp.

Hart, E.W., and Bryant, W.A., 1997; Fault-Rupture Hazard Zones in California, Alquist-Priolo Earthquake Fault Zoning Act with Index to Earthquake Fault Zone Maps: California Department of Conservation, Division of Mines and Geology Special Publication 42, 38 pp.

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Kennedy/Jenks Consultants, 2014; Groundwater Management Plan – 2014 Update, Prepared for Twentynine Palms Water District, dated May 28.

Kennedy/Jenks Consultants, 2014; Final Report, Twentynine Palms Wastewater Master Plan, dated August.

NV5, 2022; Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California, dated January 26.

NV5 2023; City of Twentynine Palms Phase 1 Wastewater Collection System Preliminary Design Report, dated May 09.

NV5, 2023; Phase 1 Wastewater Collection System Drawing, dated June 16.

USGS California Land Subsidence Areas, https://ca.water.usgs.gov/land_subsidence/californiasubsidence-areas.html USGS Seismic Ground Motion Design Parameter Tool, https://seismicmaps.org/

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FIGURES

Project No: 227522-0000190.00
Drafted By: W. Barton
Date: November 2023
15092 Avenue of Science, Suite 200
San Diego, CA
Tel: (858) 385-0500, Fax: (858) 385-0400
FIGURE
1 SITE LOCATION MAP
City of Twentynine Palms
Phase I Wastewater Collection System
Twentynine Palms, CA
N
NOTE: Map Not to Scale. Reference: Google Maps 2023
Approximate
Site Location

15092 Avenue of Science, Suite 200
San Diego, CA
Tel: (858) 385-0500, Fax: (858) 385-0400
FIGURE
2 N
Approximate
Site Location

VICINITY MAP
City of Twentynine Palms
Phase I Wastewater Collection System
Twentynine Palms, CA
NOTE: Map Not to Scale. Reference: Google Maps 2023
Project No: 227522-0000190.00
Drafted By: W. Barton
Date: November 2023 Page 448 of 672
15092 Avenue of Science, Suite 200
San Diego, CA
Tel: (858) 385-0500, Fax: (858) 385-0400
FIGURE
3 EXPLORATION LOCATION MAP
City of Twentynine Palms
Phase I Wastewater Collection System
Twentynine Palms, CA
Project No: 227522-0000190.00
Drafted By: W. Barton
Date: November 2023
LEGEND
B-41 Approximate location of exploratory boring
Approximate limits of Phase I Wastewater Collection Systems 0 0.5 mi 1.0 mi Approximate Scale
B-21
B-22
B-1
B-2
B-25
B-3
B-4
B-26
B-5
B-6
B-7
B-8
B-28
B-11
B-12
B-14
B-20 B-13
B-24
B-23
B-29
B-30
B-35
B-16
B-17
B-36
B-15
B-10
B-37
B-18
B-9
B-39
B-40
B-19
B-33
B-32
B-41
B-31
B-34
B-38
B-27
B-21
B-22
B-1
B-2
B-25
B-3
B-4
B-26
B-5
B-6
B-7
B-8
B-28
B-11
B-12
B-14
B-20 B-13
B-24
B-23
B-29
B-30
B-35
B-16
B-17
B-36
B-15
B-10
B-37
B-18
B-9
B-39
B-40
B-19
B-33
B-32
B-41
B-31
B-34
B-38
B-27

B-1
Description of Map Units
15092 Avenue of Science, Suite 200
San Diego, CA
Tel: (858) 385-0500, Fax: (858) 385-0400
EXCERPT FROM THE “GEOLOGIC MAP OF THE TWENTYNINE PALMS

QUADRANGLE,
SAN BERNARDINO AND RIVERSIDE COUNTIES, CALIFORNIA”
By: T. W. Dibblee, Jr., 1968
FIGURE
4 REGIONAL GEOLOGIC MAP
City of Twentynine Palms
Phase I Wastewater Collection System
Twentynine Palms, CA
N
Project No: 227522-0000190.00
Drafted By: W. Barton
Date: November 2023
Approximate location of
proposed septic to
sewer alignment.

Qa
Qoa
0 0.5 mi 1.0 mi
Approximate Scale
Map Symbols
Quaternary Alluvium
Older Quaternary
Alluvium Deposits

15092 Avenue of Science, Suite 200
San Diego, CA
Tel: (858) 385-0500, Fax: (858) 385-0400
FIGURE
5 N
Approximate
Site Boundary
LEGEND
Approximate locations of California
State designated Earthquake Fault
Zones (EFZ).

Project No: 227522-0000190.00
Drafted By: Sean Roy
Date: November 2023

SITE FAULT MAP
City of Twentynine Palms
Phase I Wastewater Collection System
Twentynine Palms, CA
Reference:

City of Twentynine Palms
Community View: Web Accessible Maps & Planning
http://maps.digitalmapcentral.com/production/vecommunityview/cities/twentyninepalms/index.aspx Approximate Location of City
Limits
Approximate Limits of Phase I
Wastewater Collection System
Area

15092 Avenue of Science, Suite 200
San Diego, CA
Tel: (858) 385-0500, Fax: (858) 385-0400
FIGURE
6 LEGEND
Project No: 227522-0000190.00
Drafted By: Sean Roy
Date: November 2023

REGIONAL FAULT MAP
City of Twentynine Palms
Phase I Wastewater Collection System
Twentynine Palms, CA
N
Approximate City Limits for the City of
Twentynine Palms.

Approximate
City Limits
Reference:

California Department of Conservation / California Geological Survey Fault Activity Map of California (interactive)
https://maps.conservation.ca.gov/cgs/fam/ Page 452 of 672 15092 Avenue of Science, Suite 200
San Diego, CA
Tel: (858) 385-0500, Fax: (858) 385-0400
FIGURE
7 N
LEGEND
Project No: 227522-0000190.00
Drafted By: Sean Roy
Date: November 2023

FLOOD HAZARD MAP
City of Twentynine Palms
Phase I Wastewater Collection System
Twentynine Palms, CA
Approximate location of FEMA/
FIRM delineated special flood
hazard areas.

Reference:

City of Twentynine Palms
Community View: Web Accessible Maps & Planning
http://maps.digitalmapcentral.com/production/vecommunityview/cities/twentyninepalms/index.aspx Approximate limits
of Phase I Wastewater
Collection System area.

15092 Avenue of Science, Suite 200
San Diego, CA
Tel: (858) 385-0500, Fax: (858) 385-0400
FIGURE
8 LATERAL SURCHARGE LOADS
City of Twentynine Palms
Phase I Wastewater Collection System
Twentynine Palms, CA
Project No: 227522-0000190.00
Drafted By: W. Barton
Date: November 2023 Page 454 of 672
15092 Avenue of Science, Suite 200
San Diego, CA
Tel: (858) 385-0500, Fax: (858) 385-0400
FIGURE
9 Project No: 227522-0000190.00
Drafted By: W. Barton
Date: November 2023
Notes:

1. Groundwater Below block:

Pp = 150 (D2-d
2 ) lb/ft

2. Groundwater Above block:

Pp = 1.4 (D-d)[115h + 53(D-d)] lb/ft

3. Assumes Backfill is Granular Material

4. Assumes Thrust Block is adjacent to competent material

5. D, d, and h are in feet

6. Groundwater Table

THRUST BLOCK DETAIL
City of Twentynine Palms
Phase I Wastewater Collection System
Twentynine Palms, CA

227522-0000190.00 NV5.COM |

APPENDIX A
Geotechnical Desktop Study, Prepared by NV5, Dated 2021

Proposed Wastewater Management System
Twentynine Palms, CA 92277
Project No.: 227521-0000132.00
NV5 West, Inc.
15092 Avenue of Science, Suite 200
San Diego, CA 92128

GEOTECHNICAL DESKTOP STUDY
June 2, 2021
Prepared For:

City of Twentynine Palms
6136 Adobe Road
Twentynine Palms, California 92277

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Mr. Farnk Luckino, MPA June 2, 2021
City Manager Project No.: 227521-0000132.00
City of Twentynine Palms
6136 Adobe Road
Twentynine Palms, CA 92277
Subject: Geotechnical Desktop Study
Project: Proposed Wastewater Management System Feasibility Study City of Twentynine Palms
Twentynine Palms, California
Dear Mr. Luckino:

This report presents the results of NV5 West, Inc.’s (NV5) limited desktop geologic reconnaissance for the proposed City of Twentynine Palms wastewater management system feasibility study project, located in the City of Twentynine Palms, County of San Bernardino, California. Based on the information obtained during this desktop study, it is NV5’s opinion that the site is suitable for the proposed development, provided that the pertinent, preliminary recommendations and design parameters contained in this report are incorporated into the design and construction of the project.

NV5 appreciates the opportunity to provide this geotechnical engineering service for this project and looks forward to continuing its role as your geotechnical engineering consultant.

Respectfully submitted,
NV5 West, Inc.

Sean Roy, PG 8765 Madan Chirumalla, PE, GE 3047
Senior Engineering Geologist Manager / Principal Engineer

AH/SB/SR/MC
Distribution: (1) Addressee, via email

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TABLE OF CONTENTS
Page

1.0 Introduction.............................................................................................................................. 1

2.0 Scope of Services.................................................................................................................... 1

3.0 Project and Site Description ................................................................................................. 1

4.0 Geologic and Soil information .............................................................................................. 2

4.1 Regional Geologic Setting............................................................................................................... 2

4.2 Site-Specific Geologic and Soil Information................................................................................. 2

4.3 Groundwater ..................................................................................................................................... 3

4.4 Percolation ........................................................................................................................................ 4

4.5 Faults.................................................................................................................................................. 4

5.0 Seismic and Geotechnical Hazards ..................................................................................... 5

5.1 Fault Rupture .................................................................................................................................... 5

5.2 Seismic Shaking............................................................................................................................... 6

5.3 Liquefaction and Seismically-Induced Settlement ..................................................................... 6

5.4 Landslides and Slope Instability .................................................................................................... 6

5.5 Subsidence........................................................................................................................................ 7

5.6 Tsunamis, Inundation Seiche, and Flooding................................................................................ 7

5.7 Expansive Soils ................................................................................................................................. 7

5.8 Erosion ............................................................................................................................................... 8

6.0 Conclusions and Design Recommendations...................................................................... 8

6.1 General............................................................................................................................................... 8

6.2 Trench Excavations .......................................................................................................................... 8

6.3 Dewatering ........................................................................................................................................ 8

7.0 Design Review and Construction Monitoring ..................................................................... 9

7.1 Plans and Specifications................................................................................................................. 9

7.2 Construction Monitoring.................................................................................................................. 9

8.0 Limitations ............................................................................................................................... 9

9.0 Selected References ............................................................................................................10

227521-0000132.00 NV5.COM | iii

FIGURES
FIGURE 1 – SITE LOCATION MAP
FIGURE 2 – REGIONAL GEOLOGIC MAP
FIGURE 3 – SITE FAULT MAP
FIGURE 4 – REGIONAL FAULT MAP
FIGURE 5 – FLOOD HAZARD MAP

227521-0000132.00 NV5.COM | 1

1.0 INTRODUCTION
This report presents the results of the limited desktop geologic reconnaissance for the proposed City of Twentynine Palms wastewater management system project, located in the City of Twentynine Palms, County of San Bernardino, California. The approximate boundary of the City of Twentynine Palms is shown in Figure 1, Site Location Map.

The purpose of this limited desktop study was to gather readily available published geologic and subsurface soil information at the site in order to recognize and address the presence of geologic hazards, and to provide preliminary recommendations for the anticipated project earthwork. This report summarizes the information collected and presents NV5’s preliminary findings, conclusions and recommendations.

This report has been prepared for the exclusive use of the client and their consultants in the preliminary design of the proposed project. In particular, it should be noted that this report has not been prepared from the perspective of a construction bid preparation instrument and should be considered by prospective construction bidders only as a source of general information subject to interpretation and refinement by their own expertise and experience, particularly with regard to construction feasibility.

Contract requirements as set forth by the project plans and specifications will supersede any general observations and specific recommendations presented in this report. Additionally, the preliminary findings, conclusions, and recommendations presented in this report may be revised in the subsequent report after subsurface investigation is completed.

2.0 SCOPE OF SERVICES
NV5’s scope of services for this project included the following tasks:
• Review of preliminary project information, geologic maps, geologic hazard maps, general planning maps, and geotechnical literature pertaining to the site vicinity. • Performing an assessment of general seismic conditions and geologic hazards affecting the site area and their possible impact on the proposed project. • Geotechnical/Geologic analysis of the accumulated information. • Development of conclusions with respect to the recognized geologic hazards, and their potential impact on the proposed project.
• Preparation of this report, including reference maps and graphics, summarizing the information collected and presenting NV5’s preliminary findings, conclusions, and geotechnical recommendations for the design and construction of the proposed development.

3.0 PROJECT AND SITE DESCRIPTION
Based on preliminary project information provided, NV5 understands that the City of Twentynine Palms (City) is working closely with the Marine Corps Air Ground Combat Center (MCAGCC) exploring the possibility of developing a joint use wastewater treatment plant that will benefit both the MCAGCC and the City. It is understood that budget has been allocated (though not yet part of an approved budget)

227521-0000132.00 NV5.COM | 2
for the construction of a 2.1 million-gallon (MG) treatment plant to be located on the base to replace the current aging treatment plant which only provides Secondary treatment. It is understood that over 170 MG/year of water is lost to evaporation since the effluent from the existing plant is not suitable for use in irrigation. The new treatment plant will be able to provide Tertiary treatment which will be suitable for irrigation purposes and groundwater recharge. NV5 understands that the treatment plant will be constructed using a Design/Build approach and is anticipated to be completed in late 2023.

Early coordination will be required to determine how the City’s collection system could be directed to the wastewater treatment plant which is to be located on the base and how treated effluent can be transported back to the areas and groundwater basins if a joint use treatment plant is an option. It is understood that construction will include significant open trench conduit construction, inspection vaults, accessory structures, and a treatment facility consisting of moderate sized pumping, storage and treatment structures.

The site consists of developed and undeveloped areas of high desert terrain, incised with both minor and major tributary drainages that receive sparse flash flood precipitation events. Other than the incised natural drainages, the site is topographically gentle, and generally slopes and drains to the east and localized playas.

4.0 GEOLOGIC AND SOIL INFORMATION

4.1 REGIONAL GEOLOGIC SETTING
The project site is located in southern San Bernardino County traversing the Mojave Desert Geomorphic Province at the northern end of the site and the Transverse Ranges Geomorphic Province at the southern end of the site. The Mojave Desert province is characterized by isolated mountain ranges separated by expanses of desert plains. The province is known for its interior drainage systems and many playas. There are two important fault trends that control topography, a prominent NW-SE trend and a secondary east-west trend (apparent alignment with Transverse Ranges is significant).

The province is topographically controlled by the two major active fault zones known as the Garlock (to the north) and the Southern San Andreas (to the south). As such, many major secondary faults and fault zones traverse the interior of the province, and at a transverse manner to the previously mentioned fault zones.

The Transverse Ranges province are characterized by east-west trending mountain ranges bordered by relatively straight-sided, sediment-floored valleys. The western limit of the province is the offshore island group of San Miguel, Santa Rosa and Santa Cruz. The eastern limit extends into the Mojave Desert and includes the San Bernardino Mountains on the east side of the San Andreas Fault.

4.2 SITE-SPECIFIC GEOLOGIC AND SOIL INFORMATION
Typical geologic stratigraphy in the site vicinity include erratic outcrops of Precambrian-age igneous and metamorphic rocks and Mesozoic-age granitic and metamorphic rocks that make up the underlying “basement” bedrock, with vast and massive bedded Cenozoic-age and Quaternary-age sedimentary deposits covering the desert valley floors. The general geologic conditions in the project vicinity are displayed in Figure 2, Regional Geologic Map.

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Reference to the regional geologic map Geologic Map of the Twentynine Palms Quadrangle, San Bernardino and Riverside Counties, California, by T.W. Dibblee, Jr., 1968, indicates that the site vicinity is predominantly underlain by Quaternary-age relatively younger surficial sediments and older surficial sediments.

These relatively younger surficial sediments derived from the adjacent highlands are described as unconsolidated and undissected fill found in the valley areas and flood plains of stream channels, and are mapped as windblown sand (Qs), younger alluvium (Qa), and micaceous clay and silt (Qc). The older alluvial surficial sediments (Qoa) are described as older valley fill materials derived from mountains to the west and south. These materials are found at slightly elevated positions and are much more dissected and lie unconformably on pre-Tertiary aged rocks. Anticipated soil conditions in the site vicinity are discussed in detail below.
• Windblown Sand (Qs): These materials are described as loose, fine sands that are deposited by the prevailing westerly winds as dunes or thin cover over alluvial materials. • Micaceous Clay and Silt (Qc): These materials are generally alkaline clay and some micaceous silt of playa lakes.
• Younger Alluvium (Qa): These younger alluvial deposits are described as ranging from subangular boulders and cobbles in small alluvial fans adjacent to mountains, through pebbly sands down slope, to sand and silt in valleys; includes sand and gravel of stream washes. • Older Alluvium (Qoa): These older alluvial deposits are described as poorly bedded to nonbedded, fine-to-coarse sand with some pebble-cobble gravel and little micaceous silt or clay.

4.3 GROUNDWATER
Groundwater in the region is located within the Morongo Basin. The Morongo Basin consists of about 1,000-square miles of alluvium filled valleys surrounded by mountains. In the vicinity of the site, the Morongo Basin is divided into multiple subbasins separated from each other by hydrologic barriers, including bedrock ridges, faults, and folds. The degree of separation and depth to groundwater between the subbasins is dependent upon the character of the aquifer materials and types of barriers separating them. In general, groundwater elevations reportedly range from a high of approximately 2,400 feet above mean sea level (MSL) in the southwest portion of the City limits (Indian Cove Subbasin) to a low of approximately 1,600 feet above MSL near the Mesquite Fault in the Mesquite Lake Subbasin on the eastern portion of the City limits (reference: Groundwater Management Plan – 2014 Update, Prepared for Twentynine Palms Water District by Kennedy/Jenks Consultants, dated May 28, 2014).

Groundwater is generally not anticipated to be a constraint during construction along majority of the project alignment, however, field explorations would be needed to preclude any such groundwater conditions that may or may not exist.

In general, experience indicates that near-surface groundwater conditions or localized seepage zones can develop in areas where no such groundwater conditions previously existed, especially in areas where a substantial increase in surface water infiltration results from landscape irrigation, agricultural activity, artificial recharge, storage facility leaks, or unusually heavy precipitation. Seasonal variations

227521-0000132.00 NV5.COM | 4
in the groundwater levels should be anticipated. In addition, it should be understood that groundwater movement near the active fault traces that traverse the site can be complex and difficult to predict and shallow groundwater may be encountered at these locations.

For a more detailed discussion on hydrogeological conditions in the site vicinity see NV5’s Preliminary Hydrogeological Conditions Study that will be presented under a separate cover as part of this Project.

4.4 PERCOLATION
In an effort to evaluate percolation rates for the site vicinity NV5 reviewed available USDA Soil Maps https://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm. USDA defines four distinct hydrologic soil groups: A, B, C and D. These groups correspond to distinct infiltration rates [i.e. A = high infiltration rate (low runoff potential) when thoroughly wet, B = moderate infiltration rate when thoroughly wet, C = slow infiltration rate when thoroughly wet, and D = very slow infiltration rate (high runoff potential) when thoroughly wet]. The vast majority of the site vicinity has no mapped soil group data available.

Based on NV5’s review of the geologic map for the project area the majority of the site vicinity is underline by alluvial soils, with portions along the perimeter composed of near-surface bedrock units.

The granular alluvial materials are interpreted as having High to Moderate infiltration rates, with hydrologic soil groups of A and B, with the exception of the playa lake deposits that are higher in silt and clay content with a hydrologic soil group of D. The bedrock materials are described as having a Very Slow infiltration rate with a hydrologic group of D. In general, the site vicinity should be considered to have favorable infiltration conditions with the exception of the playa lake deposits. Site conditions may vary from data obtained from the USDA soil maps. Prior to final design or construction activities, NV5 should be retained to evaluate the percolation and infiltration characteristics of the site’s soils.

For a more detailed discussion on percolation and infiltration in the site vicinity see NV5’s Preliminary Hydrogeological Conditions Study that will be presented under a separate cover as part of this Project.

4.5 FAULTS
The numerous faults in southern California include active, potentially active, and inactive faults. As used in this report, the definitions of fault terms are based on those developed for the Alquist-Priolo Special Studies Zones Act of 1972 and published by the California Division of Mines and Geology (Hart and Bryant, 1997).

Active faults are defined as those that have experienced surface displacement within Holocene time (approximately the last 11,000 years) and/or have been included within any of the state-designated Earthquake Fault Zones (previously known as Alquist-Priolo Special Studies Zones). Faults are considered potentially active if they exhibit evidence of surface displacement since the beginning of Quaternary time (approximately two million years ago) but not since the beginning of Holocene time.

Inactive faults are those that have not had surface movement since the beginning of Quaternary time.

Reference to the State of California Earthquake Hazards Zone searchable map web application indicates that the site is traversed by two separate State-designated Earthquake Fault Zones. They are the Pinto Mountain Fault zone and the Mesquite Lake Fault zone. The Pinto Mountain Fault zone is located at the southern end of the site and trends in an east-west manner, and the Mesquite Lake Fault zone is located at the northeastern end of the site and trends in a southeast-northwest manner.

The approximate locations of these fault zones are displayed in Figure 3, Site Fault Map. These faults are considered active, and as such, special consideration should be taken with respect to any

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proposed structures and/or facilities within close proximity to these zones, and/or any proposed conduit alignments that may cross these active fault zones.

Other important active faults that could affect the project area and their distance to the site are included in the following Table 1. In addition, Figure 4, Regional Fault Map depicts the site location in relation to known active faults in the region.

Table 1 - Distance From the Site to Major Active Faults Fault Distance From the Site
Pinto Mountain 0.0 miles
Mesquite Lake 0.0 miles
Calico-Hidalgo 5.7 miles
So Emerson-Copper Mountain 7.0 miles
Eureka Peak 19 miles
Burnt Mountain 21 miles
Landers 21 miles
Johnson Valley 26 miles
South San Andreas 27 miles
North Frontal 29 miles
Lenwood-Lockhart-Old Woman Springs 36 miles
Helendale-So Lockhart 45 miles
San Jacinto 52 miles
Cleghorn 66 miles
Elmore Ranch 67 miles
Gravel Hills-Harper Lake 70 miles
Earthquake Valley 74 miles
Elsinore 75 miles
Superstition Hills 78 miles

5.0 SEISMIC AND GEOTECHNICAL HAZARDS
NV5 performed a review of state and municipal geologic hazard maps. The findings of NV5’s seismic and geotechnical hazards evaluation for the proposed project are summarized in the following sections.

5.1 FAULT RUPTURE
As previously mentioned in Section 4.4, the site is traversed by two Earthquake Fault Zones (EFZ) that are deemed active by the State of California. As such, the potential for ground-surface rupture and/or shallow ground deformation occurring at the site due to a seismic event are a significant concern for the site development. Special consideration should be taken with respect to any proposed structures and/or facilities within close proximity to these zones, and/or any proposed conduit alignments that may cross these active fault zones.

227521-0000132.00 NV5.COM | 6
The planned development of any structures and/or facilities within and/or in close proximity to the two EFZ’s should be avoided. However, should a structure and/or facility be planned within and/or in close proximity to either of the noted EFZ’s, NV5 should be retained to perform a fault hazard study in order to preclude the possibility of an active fault trace underlying the proposed development area.

5.2 SEISMIC SHAKING
The project site is located in an area of California considered a seismically active area, and as such, the seismic hazard most likely to impact the site is ground shaking resulting from an earthquake along one of the known active faults in the region.

For preliminary seismic design criteria, the site may be considered as a Site Class D. Once locations for proposed structures are developed, NV5 can provide seismic design parameters for specific sites.

5.3 LIQUEFACTION AND SEISMICALLY-INDUCED SETTLEMENT
Liquefaction of soils can be caused by ground shaking during earthquakes. Research and historical data indicate that loose, relatively clean granular soils are susceptible to liquefaction and dynamic settlement, whereas the stability of the majority of clayey silts, silty clays and clays is not adversely affected by ground shaking. Liquefaction is generally known to occur in saturated cohesionless soils at depths shallower than approximately 50 feet. Dynamic settlement due to earthquake shaking can occur in both dry and saturated sands.

Reference to published geologic and geotechnical maps and documents indicates that the site is generally underlain at depth (greater than 10 feet bgs) by medium dense to dense alluvium. Within these areas, the potential for liquefaction and associated ground deformation occurring beneath the structural site areas during a seismic event is considered low. However, within and/or along the fault zones and playas to the south and southeast of the site, the potential for liquefaction may exist. If structures and/or facilities are planned in these areas, field explorations and soil testing are warranted in order to preclude the possibility of liquefiable subsurface materials in these areas.

Seismic settlement is often caused when loose to medium-dense granular soils are densified during ground shaking.

Near-surface (shallower than 10 feet bgs) alluvium in the site area is typically considered to be in a relatively compressible state. Mitigative efforts such as removal and recompaction of the near-surface soils would reduce potential damage to future structures due to seismic settlement. However, within and/or along the fault zones and playas to the south and southeast of the site, the presence of “deep” compressible soils may or may not exist. Once specific sites for proposed structures and/or facilities have been selected, NV5 should be retained to explore the depths and lateral extent of any potentially compressible soils at each site.

5.4 LANDSLIDES AND SLOPE INSTABILITY
The site is predominantly underlain at depth by medium dense to dense granular alluvium. In addition, the sites mapped topography generally displays a gently sloping valley floor with some moderate to shallow drainage channel incisions. Therefore, the potential for deep-seated landsliding and slope instability within these geologic materials is considered low. There are two types of slope instabilities

227521-0000132.00 NV5.COM | 7
that are more likely to affect the alluvial hills and crystalline mountains surrounding the desert floor, being shallow soil slip and rock falls.

Shallow soil slips may occur in steeper alluvial hills should near-surface poorly consolidated cohesionless materials become saturated for longstanding periods of time. Engineered fill slopes and adequate hillside drainage design would greatly reduce the potential for shallow soil slips.

Rock falls may occur along the “walls” of the crystalline basement rocks that surround the valley floors.

Gravity, heavy precipitation, and seismic events are the major catalysts for rock fall events in these desert regions. Other factors affecting potential for rock falls are steepness of slopes and degree of weathering/fracturing of crystalline rock. Engineered structures such as debris barrier walls and rock fall catch fencing/netting would greatly reduce the chance of a rock fall event damaging any proposed structures.

5.5 SUBSIDENCE
The site is not located in an area of known ground subsidence due to the withdrawal of subsurface fluids. Based on NV5’s review of the Groundwater Management Plan – 2014 Update, Prepared for Twentynine Palms Water District by Kennedy/Jenks Consultants, dated May 28, 2014, land subsidence has not been identified as an issue within the Twentynine Palms area. However, playa lake deposits like those mapped at Mesquite Lake have been known to be a source of land subsidence in Antelope Valley and in other similar areas. Accordingly, the potential for subsidence occurring at the site outside of the playa lake deposits due to the withdrawal of oil, gas, or water is considered to be low.

5.6 TSUNAMIS, INUNDATION SEICHE, AND FLOODING
The site is located within the southern region of the Mojave Desert, and at or above an elevation of approximately 1750 feet above MSL. Also, the site is not located downslope of any large body of water that could affect the site in the event of an earthquake-induced failure or seiche (oscillation in a body of water due to earthquake shaking). Therefore, the potential for damaging tsunamis (seismic sea waves) or seiche is considered remote.

Based on a review of Federal Emergency Management Agency (FEMA) flood insurance rate map (FIRM) and the County of San Bernardino General Planning Map, portions of the site are known to be susceptible to flooding during infrequent but substantial precipitation events. The potential for flooding should be considered during project planning and design. The approximate locations of areas deemed susceptible to flooding are displayed in Figure 5, Flood Hazard Map.

5.7 EXPANSIVE SOILS
NV5’s research and review of geologic and geotechnical documents in the site vicinity, indicate that the site is predominantly underlain by granular alluvium that is generally considered to have a low expansion potential. However, the lower elevation playa lake deposits may or may not contain significant clay content. Should proposed structures and/or facilities be planned in these playa areas, NV5 should be retained to evaluate the expansion potential characteristics of the site’s soils.

227521-0000132.00 NV5.COM | 8

5.8 EROSION
In an effort to evaluate erosion potential for the site vicinity NV5 reviewed available USDA Soil Maps https://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm. Soils are described as having several erosion factors (i.e. Kw, Kf, T) which estimate the soil potential for sheet and rill erosion. The project area generally has erosion factors which indicate a low to moderate potential for surface erosion.

Certain soil deposits in the project area such as young surficial sediments (i.e., alluvium, clay and windblown sand deposits) may be more susceptible to erosion than other soils.

6.0 CONCLUSIONS AND DESIGN RECOMMENDATIONS

6.1 GENERAL
Based on the results of our background review, the proposed project is considered geotechnically feasible. The most significant geotechnical concerns for the project are the presence the two mapped active fault zones, and the presence of potentially compressible near-surface soils.

When preliminary or conceptual plans are completed, NV5 should be retained for review. Planning of any proposed structures and/or facilities will warrant the need for field explorations and appropriate soil testing.

Paleontological resources will be evaluated by the City separately as part of the California Environmental Quality Act (CEQA) process for the project.

6.2 TRENCH EXCAVATIONS
All trench excavations and access pits should be shored in accordance with Cal-OSHA regulations. For planning purposes, the native soil materials may be considered as Type C, as defined in the current Cal-OSHA soil classification.

Stockpiled (excavated) materials should be placed no closer to the edge of a trench excavation than a distance defined by a line drawn upward from the bottom of the trench at an inclination of 1(H):1(V), but no closer than 4 feet. All trench excavations should be made in accordance with Cal-OSHA requirements.

6.3 DEWATERING
As previously mentioned, reported groundwater elevations vary across and within the various subbasins in the site vicinity. Although, groundwater is generally not anticipated to be a constraint along majority of the project alignment, any cases of seepage, perched water, or heavy precipitation should be monitored during construction. The actual means and methods of any dewatering scheme should be established by a contractor with local experience. It is important to note that temporary dewatering, if necessary, will require a permit and plan that complies with RWQCB regulations. If excessive water is encountered, NV5 should be contacted to provide additional recommendations for temporary construction dewatering. Based on the NV5’s review of USDA Soil Maps, the onsite nearsurface soils may be considered to be relatively permeable.

227521-0000132.00 NV5.COM | 9

7.0 DESIGN REVIEW AND CONSTRUCTION MONITORING
Geotechnical review of plans and specifications is of paramount importance in engineering practice.

The poor performance of many structures has been attributed to inadequate geotechnical review of construction documents. Additionally, observation and testing of the subgrade will be important to the performance of the proposed improvements. The following sections present recommendations relative to the review of construction documents and the monitoring of construction activities.

7.1 PLANS AND SPECIFICATIONS
The design plans and specifications should be reviewed by NV5 prior to bidding and construction, as the geotechnical recommendations may need to be reevaluated in consideration of the actual design configuration. This review is necessary to evaluate whether the recommendations contained in this report and future reports have been properly incorporated into the project plans and specifications.

7.2 CONSTRUCTION MONITORING
Site preparation, removal of unsuitable soils, assessment of imported fill materials, fill placement, and other earthwork operations should be observed and tested. The substrata exposed during the construction may differ from that encountered in the test borings. Continuous observation by a representative of NV5 during construction allows for evaluation of the soil/bedrock conditions as they are encountered, and allows the opportunity to recommend appropriate revisions where necessary.

8.0 LIMITATIONS
The recommendations and opinions expressed in this report are based on NV5’s review of background documents. It should be noted that this study did not evaluate the possible presence of hazardous materials on any portion of the site.

Due to the limited nature of this desktop study, conditions not described in this report may be present on the site. Uncertainties relative to subsurface conditions can be reduced through additional subsurface exploration. Additional subsurface evaluation and laboratory testing can be performed upon request. It should be understood that conditions different from those anticipated in this report may be encountered during grading operations, e.g., the extent of removal of unsuitable soil, and that additional effort may be required to mitigate them.

Site conditions, including ground-water level, can change with time as a result of natural processes or the activities of man at the subject site or at nearby sites. Changes to the applicable laws, regulations, codes, and standards of practice may occur as a result of government action or the broadening of knowledge. The findings of this report may, therefore, be invalidated over time, in part or in whole, by changes over which NV5 has no control.

NV5’s recommendations for this site are, to a high degree, dependent upon appropriate quality control of subgrade preparation, fill placement, and foundation construction. Accordingly, the recommendations are made contingent upon the opportunity for NV5 to observe grading operations and foundation excavations for the proposed construction. If parties other than NV5 are engaged to provide such services, such parties must be notified that they will be required to assume complete

227521-0000132.00 NV5.COM | 10
responsibility as the geotechnical engineer of record for the geotechnical phase of the project by concurring with the recommendations in this report and/or by providing alternative recommendations.

This document is intended to be used only in its entirety. No portion of the document, by itself, is designed to completely represent any aspect of the project described herein. NV5 should be contacted if the reader requires additional information or has questions regarding the content, interpretations presented, or completeness of this document.

NV5 has endeavored to perform its evaluation using the degree of care and skill ordinarily exercised under similar circumstances by reputable geotechnical professionals with experience in this area in similar soil conditions. No other warranty, either expressed or implied, is made as to the conclusions and recommendations contained in this report.

9.0 SELECTED REFERENCES
American Society of Civil Engineers / Structural Engineering Institute (ASCE/SEI), 2016; Minimum Design Loads for Buildings and Other Structures, ASCE/SEI 7-16.

ASTM, 2001; Soil and Rock: American Society for Testing and Materials: vol. 4.08 for ASTM test methods D-420 to D-4914; and vol. 4.09 for ASTM test methods D-4943 to highest number.

Boulanger, R.W. and Idriss, I.M., 2014; "CPT and SPT Based Liquefaction Triggering Procedures," University of California Davis, Center for Geotechnical Modeling Report No. UCD/CGM-14/01, pp. 1-134
Bowles, J.E.; 1997; Foundation Analysis and Design, 5th Edition.

CBC, 2019, California Building Code.

California Department of Transportation (Caltrans), 2018; Corrosion Guidelines, Version 3.0, Division of Engineering Services, Materials Engineering and Testing Services, Corrosion and Structural Concrete Field Investigation Branch, March.

California Department of Conservation, Division of Mines and Geology, 1997; Guidelines for Evaluation and Mitigation of Seismic Hazards in California: Special Publication 117, 74 pp.

California Department of Conservation, Division of Mines and Geology, 1998; Maps of Known Active Fault Near-Source Zones in California and Adjacent Portions of Nevada: International Conference of Building Officials, dated February, Scale 1” = 4 km.

California Environmental Protection Agency, 2020, (waterboards.ca.gov ) GeoTracker California Geological Survey, 2008a; Special Publication 117A, Guidelines for Evaluating and Mitigating Seismic Hazards in California
California Geological Survey, 2008b, “Appendix A: California Fault Parameters for the National Seismic Hazard Maps and Working Group on California Earthquake Probabilities 2007,” Special Report 203A.

California Geological Survey, 2010; Fault Activity Map of California.

Dibblee, T.W. Jr., 1968, Geologic Map of the Twentynine Palms Quadrangle, San Bernardino and Riverside Counties, California, Scale 1:62,500.

227521-0000132.00 NV5.COM | 11
Hart, E.W., and Bryant, W.A., 1997; Fault-Rupture Hazard Zones in California, Alquist-Priolo Earthquake Fault Zoning Act with Index to Earthquake Fault Zone Maps: California Department of Conservation, Division of Mines and Geology Special Publication 42, 38 pp.

Kennedy/Jenks Consultants, 2014; Groundwater Management Plan – 2014 Update, Prepared for Twentynine Palms Water District, dated May 28.

Southern California Earthquake Center, 2002; Recommended Procedures for Implementation of DMG Special Publication 117 Guidelines for Analyzing and Mitigating Landslide Hazards in California: dated March, 127 pp.

USGS Seismic Ground Motion Design Parameter Tool, https://seismicmaps.org/ USGS Probabilistic Seismic Hazards Deaggregation Tool,
http://geohazards.usgs.gov/deaggint/2008/.

Project No: 227521-0000132.00
Drafted By: A. Hespeler
Date: May 2021
15092 Avenue of Science, Suite 200
San Diego, CA
Tel: (858) 385-0500, Fax: (858) 385-0400
FIGURE
1 SITE LOCATION MAP
Proposed Feasibility Study for Future Waste
Water Management System
Twentynine Palms, CA
N
NOTE: Map Not to Scale. Reference: Google Earth 2021
Approximate
Site Area

B-1
Description of Map Units
15092 Avenue of Science, Suite 200
San Diego, CA
Tel: (858) 385-0500, Fax: (858) 385-0400
EXCERPT FROM THE “GEOLOGIC MAP OF THE TWENTYNINE PALMS QUADRANGLE, SAN BERNARDINO AND RIVERSIDE COUNTIES, CALIFORNIA”
By: T. W. Dibblee, Jr., 1968
FIGURE
2 Approximate
Site Boundary

REGIONAL GEOLOGIC MAP
Proposed Feasibility Study for Future Waste Water
Management System
Twentynine Palms, CA
N
Project No: 227521-0000132.00
Drafted By: A. Hespeler
Date: May 2021
Approximate location of proposed
waste water alignment.

15092 Avenue of Science, Suite 200
San Diego, CA
Tel: (858) 385-0500, Fax: (858) 385-0400
FIGURE
3 N
Approximate
Site Boundary
LEGEND
Approximate locations of California State
designated Earthquake Fault Zones (EFZ).

Project No: 227521-0000132.00
Drafted By: A. Hespeler
Date: May 2021

SITE FAULT MAP
Proposed Feasibility Study for Future Waste Water
Management System
Twentynine Palms, CA
Reference:

City of Twentynine Palms
Community View: Web Accessible Maps & Planning
http://maps.digitalmapcentral.com/production/vecommunityview/cities/twentyninepalms/index.aspx Approximate location of proposed
waste water alignment.

15092 Avenue of Science, Suite 200
San Diego, CA
Tel: (858) 385-0500, Fax: (858) 385-0400
FIGURE
4 LEGEND
Project No: 227521-0000132.00
Drafted By: A. Hespeler
Date: May 2021

REGIONAL FAULT MAP
Proposed Feasibility Study for Future Waste Water
Management System
Twentynine Palms, CA
N
Approximate site boundary.

Approximate
Site Boundary
Reference:

California Department of Conservation / California Geological Survey Fault Activity Map of California (interactive)
https://maps.conservation.ca.gov/cgs/fam/ Page 475 of 672 15092 Avenue of Science, Suite 200
San Diego, CA
Tel: (858) 385-0500, Fax: (858) 385-0400
FIGURE
5 N
LEGEND
Project No: 227521-0000132.00
Drafted By: A. Hespeler
Date: May 2021

FLOOD HAZARD MAP
Proposed Feasibility Study for Future Waste Water
Management System
Twentynine Palms, CA
Approximate location of FEMA/FIRM
delineated special flood hazard areas.

Reference:

City of Twentynine Palms
Community View: Web Accessible Maps & Planning
http://maps.digitalmapcentral.com/production/vecommunityview/cities/twentyninepalms/index.aspx Approximate location of proposed
waste water alignment.

227522-0000190.00 NV5.COM |

APPENDIX B
Field Exploration Logs

227522-0000190.00 NV5.COM |
Sampling Methods
Representative bulk-disturbed and relatively undisturbed drive samples were retrieved during exploratory drilling at selected depths appropriate to our investigation. The samples were labeled in the field and transported to our laboratory for observation, evaluation, and testing. The drive samples were obtained using the California Modified Split Spoon (CAL) and Standard Penetration Test (SPT) samplers, as described below.

California Modified Split Spoon (CAL) Sampler

A split-barrel drive sampler was driven with a 140-pound hammer allowed to drop freely 30 inches in general accordance with ASTM D1587. The sampler has external and internal diameters of approximately 3.0 and 2.4 inches, respectively, and the inside of the sampler is lined with 1-inch-long brass rings. The drive sampler was driven a maximum of 18 inches (or to refusal) and the number of blows per 6-inch interval, or any portion thereof, were recorded during sampling and are presented on the logs of the borings. The relatively undisturbed soil samples within the rings were removed, sealed, and transported to the laboratory for observation and testing.

Standard Penetration Test (SPT) Sampler

A split-barrel SPT sampler was driven with a 140-pound hammer (using a 30-inches drop) in general accordance with ASTM D1586. The sampler has external and internal diameters of 2.0 and 1.4 inches, respectively. The SPT sampler was driven 18 inches (or to refusal) and the number of blows per 6-inch interval was recorded on the field boring logs. The uncorrected N-value (numbers of blows for the last two 6-inch intervals or any portion thereof) is presented on the borings logs. The soil samples retrieved from the STP sampler were logged and transported to the laboratory for classification and testing.

Note: The penetration resistance (blows/foot) shown on the logs of the exploratory borings represents field penetration that has not been corrected for overburden pressure, sampler size, hammer type, borehole diameter, rod length, sampling method or any other correction factor.

Logging Methods
Earth materials encountered during the field investigation were classified in accordance with the Unified Soil Classification System (USCS) and augmented with ASTM Standard Testing for Soil (see Appendix B). The apparent density of materials was derived from blow counts (ASTM D1586). The number of blows recorded for the last twelve inches of the drive sampler was used to determine the uncorrected “N-value” in accordance with ASTM D1586. The corrected “N-value” for hammer efficiency (N60) was used to determine consistency of cohesive soils (clays and silts) and apparent density of granular soils (sands and gravels) using the following charts (Chart 1 and Chart 2).

CHART
1 15092 Avenue of Science, Suite 200
San Diego, CA 92128
Tel: (858) 385-0500, Fax: (858) 385-0400

BORING LOG LEGEND

CHART
2 15092 Avenue of Science, Suite 200
San Diego, CA 92128
Tel: (858) 385-0500, Fax: (858) 385-0400

SOIL CLASSIFICATION

SM
SM
115.4
112.8
El. 2017.7'
El. 2015.0'
El. 1998.0'
*Sieve
*Combined Sample

11.5' - 13' / 15' - 16.5'

1.4 2.9

0.3'

3.0'

20.0'
Approximately 4 inches thick AC
Fill: Silty SAND with Gravel (SM); light brown, dry, fine grained sand with some coarse, weakly to moderately
cemented, subangular gravel.

Quaternary Alluvium (Qa):Silty SAND with Gravel (SM);
light brown, dry, fine grained sand with some coarse,
moderately cemented, subangular gravel.

Very dense
Weakly cemented
Medium dense
Dense
Fine subangular gravel
Very dense
Dense
G- 1
SPT- 1
CAL- 1
SPT- 2
SPT- 3
CAL- 2
Notes: Hollow-Stem Auger. Boring terminated at approximately 20' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings. Patched with Aquapahlt.
20 24
15 10
10 15
9 10
20 10
20 25
15 20
24 Boring No.

Depth (ft.)
Project Number
Completed: 6/5/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: South of intersection Split Rock Ave & Cactus Dr.

Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.132897
Sheet 1 of 1
Started: 6/5/2023 Graphical Log
Longitude: -116.060205 Moisture Content (%)
2018'
Boring Log
B-01
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

SW-SM
SW-SM
SP
SM
SM
106.3
117.7
El. 2008.5'
El. 2006.0'
El. 2004.0'
El. 1999.0'
El. 1993.0'
El. 1989.0'
*Sand Equivalent
*Combined Sample

6.0' - 6.5' / 6.5' - 8'
Direct Shear

2.9 3.8

1.0 0.5'

3.0'

5.0'

10.0'

16.0'

20.0'
Approximately 6 inches thick AC
Fill:Well Graded SAND with Silt (SW-SM); light brown to brown, dry, coarse grained sand with fines, subangular
gravel.

Quaternary Alluvium (Qa):Well Graded SAND with Silt
(SW-SM); brown, moist, fine grained sand with coarse,
trace subangular gravel.

Poorly Graded SAND (SP); light brown, moist, trace
subangular gravel
Medium dense
Dense
Silty SAND (SM); light brown, moist, dense, fine grained sand with coarse, trace fine gravel
Silty SAND with Gravel (SM); light brown with orange
oxidation, moist, fine to coarse grained sand, fine
subangular gravel with some coarse
Dense
G- 1
CAL- 1
SPT- 1
SPT- 2
G- 2
CAL- 2
SPT- 3
Notes: Hollow-Stem Auger. Boring terminated at approximately 20' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings. Patched with Aquaphalt.
9 7
8 9
10 16
12 15
18 15
25 26
13 16
17 Boring No.

Depth (ft.)
Project Number
Completed: 6/5/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: West of intersection Tamarisk Ave & Cactus Dr.

Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.133566
Sheet 1 of 1
Started: 6/5/2023 Graphical Log
Longitude: -116.058647 Moisture Content (%)
2009'
Boring Log
B-02
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

SP
SM
SM
SP
118.0
El. 1992.6'
El. 1986.0'
El. 1982.0'
El. 1975.0'
El. 1973.0'
*Proctor
*Corrosion
*R Value
*Sand Equivalent
*Combined Sample

1.0' - 3.0' / 5.0' - 6.5'

1.2 0.9

0.4'

7.0'

11.0'

18.0'

20.0'
Approximately 5 inches thick AC
Fill:Poorly Graded SAND with Gravel (SP); brown, moist, coarse grained sand with fines, fine gravel.

Medium dense
Quaternary Alluvium (Qa):Silty SAND (SM); brown,
moist, very dense, fine to coarse grained sand, trace
gravel.

Silty SAND with Gravel (SM); brown, moist, medium dense, fine to coarse grained sand with gravel
Poorly Graded SAND (SP); light brown, moist, very dense G- 1
SPT- 1
SPT- 2
CAL- 1
SPT- 3
CAL- 2
Notes: Hollow-Stem Auger. Boring terminated at approximately 20' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings. Patched with Aquaphalt.
4 5
11 19
21 23
7 8
21 10
11 11
10 25
40 Boring No.

Depth (ft.)
Project Number
Completed: 6/5/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: West of intersection Adobe Rd & Old Dale Rd
Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.132042
Sheet 1 of 1
Started: 6/5/2023 Graphical Log
Longitude: -116.055052 Moisture Content (%)
1993'
Boring Log
B-03
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

SW
SM
SM
SP
SM
114.7
El. 1977.7'
El. 1975.0'
El. 1969.0'
El. 1966.0'
El. 1964.0'
El. 1958.0'
Sieve
Direct Shear1.5

0.3'

3.0'

9.0'

12.0'

14.0'

20.0'
Approximately 4 inches thick AC
Fill:Well Graded SAND (SW); light brown, moist, fine to coarse grained sand, trace gravel.

Quaternary Alluvium (Qa):Silty SAND (SM); light brown,
moist, medium dense, fine to coarse grained sand, trace gravel.

Silty SAND with Gravel (SM); light brown, moist, dense, fine to coarse grained sand, fine subangular gravel
Poorly Graded SAND with Gravel (SP); light brown, moist, coarse grained sand, fine gravel
Silty SAND (SM); light brown to light grey, moist, very dense, fine to coarse grained sand, moderately cemented, small caliche
G- 1
CAL- 1
SPT- 1
SPT- 2
SPT- 3
G- 2
CAL- 2
SPT- 4
Notes: Hollow-Stem Auger. Boring terminated at approximately 20' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings. Patched with Aquaphalt.
10 5
7 5
7 3
5 6
7 10
11 11
24 34
35 15
22 22
Boring No.

Depth (ft.)
Project Number
Completed: 6/5/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: East of intersection Old Dale Rd & Palo Verde Ave Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.131727
Sheet 1 of 1
Started: 6/5/2023 Graphical Log
Longitude: -116.051862 Moisture Content (%)
1978'
Boring Log
B-04
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ