Project No. VV4271 8 May 2017

Mr. Anthony Arger Soda Canyon Group 3030 Soda Canyon Road Napa, CA 94558

Subject: Proposed Mountain Peak Winery 3265 Soda Canyon Road Napa County, California GEOTECHNICAL ROAD IMPACT REVIEW & RECONNAISSANCE

References: 1) Use Permit Drawings – Mountain Peak Winery By Bartelt Engineering, dated March 2016

2) Traffic Impact ReportBy Crane Transportation Group, dated 3/16/15

3) Soda Canyon Road Study – Mountain Peak WineryBy Bartelt Engineering, dated May 2016

4) Peer Review Letter of Crane Transportation Group– Mountain Peak WineryBy Smith Engineering & Management, dated 7/18/16

Dear Mr. Arger:

INTRODUCTION At your request, KC ENGINEERING COMPANY has reviewed specific sections of the referenced drawings and road/traffic impact reports and letters relating to the proposed Mountain Peak Winery to determine whether Soda Canyon Road was adequately evaluated with respect to the proposed effects of heavy construction equipment traffic and future vineyard operations truck and auto traffic. Our review summary, comments and recommendations are presented herein.

In addition, we performed a geotechnical reconnaissance on 4/12/17 of the 6-mile long Soda Canyon Road surface located in Napa County, California. The purpose of our services was to evaluate the current road and pavement surface conditions, as well as the potential impact from heavy construction equipment and truck/auto traffic related to the proposed Mountain Peak Winery operations.

865 Cotting Lane, Suite A Vacaville, California 95688 (707) 447-4025, fax 447-4143

8798 Airport Road Redding, California 96002 (530) 222-0832, fax 222-1611

KC ENGINEERING COMPANYA SUBSIDIARY OF MATERIALS TESTING, INC.

Geotechnical Review Soda Canyon Road, Napa County 8 May 2017 ________________________________________________________________________________________________________

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DOCUMENT REVIEW The Reference #1 Use Permit civil demolition and grading drawings by Bartelt Engineering show the proposed Mountain Peak Winery (MPW) improvements to be constructed at 3265 Soda Canyon Road. Various improvements are proposed such as a new office and tasting room structure, an extensive network of wine caves, roadways, parking lots, an underground cistern, a wastewater treatment system and dispersal field, as well as various vineyard improvements. Significant earthwork and wine cave tunneling operations will be required and result in the use of heavy construction equipment to be transported over Soda Canyon Road. Construction of the proposed building structures, wine caves and new roads and parking lots will also require numerous ready-mix concrete trucks, lumber delivery trucks, concrete pump trucks, asphalt paving equipment, and contractor trucks that will have to travel on Soda Canyon Road. The Reference #2 report by Crane Transportation Group (CTG) provides detailed traffic study information regarding existing and proposed traffic volumes related to the Mountain Peak Winery (MPW) project. The report clearly indicates an increase of winery operations truck traffic and employee/visitor auto traffic on Soda Canyon Road related to the proposed MPW operations. However, the CTG does not provide an assessment of the existing asphalt pavement road surface condition, nor the impact to the road surface related to heavy construction equipment loading during construction of the MPW facility and/or future operations and visitor traffic. In addition, specific geotechnical and pavement investigations were not performed by CTG or other consultants for any portion of Soda Canyon Road that are proposed to be impacted by use of the road. Typically, a pavement surface and structural section analysis would be performed, including asphalt and aggregate base coring and soil R-Value testing, to perform pavement section calculations based on Average Daily Traffic volume projections and a calculated Traffic Index per the 2016 Napa County Road & Street Standards. The Reference #3 Soda Canyon Road Study drawings by Bartelt Engineering show the existing road profile along with numerous photographs of the road. No statements, conclusions or recommendations are provided. It is pointed out that the small size of the photographs do not clearly show the existing extensive pavement distress cracking and potholes. Some of the photos do show cracking, but not the extensive alligator cracks and other pavement distress that currently exists. The Reference #4 report by Smith Engineering provides a peer review of the CTG Traffic Impact Report. Various concerns and non-compliant concerns were addressed relating to traffic safety and traffic volume. Their report recommends that an Environmental Impact Report focusing on traffic safety be prepared. Based on our review of the submitted documents and plans, Soda Canyon Road has not been assessed by an independent geotechnical or pavement consultant. In our opinion, References

Geotechnical Review Soda Canyon Road, Napa County 8 May 2017 ________________________________________________________________________________________________________

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#2 and #3 are inadequate and incomplete because they did not perform an assessment, nor subsurface investigation and analysis of the significant impact to Soda Canyon Road, and they did not propose adequate mitigation measures. The report and drawings failed to divulge the MPW vineyard operation impacts to roads and subsurface infrastructure. In addition, the traffic impact report failed to address and provide mitigation measures for impacts to the road and subsurface infrastructure due to construction traffic and future operations of the vineyard project. SITE RECONNAISSANCE Our reconnaissance of the approximate 6-mile stretch of Soda Canyon Road was performed on 4/12/17. The purpose of our reconnaissance to observe and photo document the existing typical conditions of the pavement surface, as well as to consider the impact to the road surface relating to the proposed heavy construction equipment traffic and increased traffic loading due to winery operations. In general, Soda Canyon Road consist of a two-lane road surface with asphalt concrete (AC) that was constructed more than 50 years ago. Our observations revealed that the existing AC is highly distressed in the form of alligator cracking, longitudinal and transverse cracking, and numerous potholes. Drainage ditches on the uphill sides of the road were either not present nor had the appearance of adequate maintenance. This allows water from the uphill slopes to sheet over the road and saturate the downhill fill slope embankment. In addition, the numerous open cracks and potholes allow the infiltration of water into the subgrade soil and the underlying road fills. Experience on similar roads has shown that fill embankments of this type with lack of adequate drainage can fail suddenly as a result of heavy rain and the infiltration of water into road cracks and on the downhill fills. The result can be failure of the fill embankment and loss of the road, as well as underground utilities. A few photographs were taken along the road alignment to document the typical condition of the highly distressed road condition. The photographs with annotated notes are attached herein. CONCLUSIONS & RECOMMENDATIONS Based on our review and site reconnaissance, it is our opinion that the addition of heavy truck traffic from the proposed Mountain Peak Winery operations to the roadway would substantially increase hazards due to incompatible uses and will significantly exacerbate the existing road damage and increase the design Traffic Index. It is assumed that all winery/vineyard construction and future operations traffic would be on Soda Canyon Road. The referenced traffic impact report and road study failed to perform an adequate analysis of current and future road stability of Soda Canyon Road, and failed to divulge the impacts to the road surface and subsurface infrastructure. In addition, the report and plans failed to address and provide mitigation measures for impacts to the road and subsurface infrastructure due to future operations of the vineyard project. Due to the existing distress and considering that the road was constructed more than 50 years ago, the asphalt concrete pavement surface has essentially reached the end of its useful life and

Project No. VV4271 Soda Canyon Road, Napa County Photos of Typical Pavement Conditions

KC ENGINEERING COMPANY 865 Cotting Lane, Suite A Vacaville, CA 95688 707-447-4025

Project No. VV4271 Soda Canyon Road, Napa County Photos of Typical Pavement Conditions

KC ENGINEERING COMPANY 865 Cotting Lane, Suite A Vacaville, CA 95688 707-447-4025

Project No. VV4271 Soda Canyon Road, Napa County Photos of Typical Pavement Conditions

KC ENGINEERING COMPANY 865 Cotting Lane, Suite A Vacaville, CA 95688 707-447-4025