Hemme Station Park Project, Alamo

Coming soon…. A new park for Alamo residents and travellers along the Iron Horse Trail to open later this summer!
boy on bike
PARK FEATURES
This new park, located at Hemme Avenue and Danville Boulevard and accessible from the Iron Horse Trail, will provide a respite park for travellers on the Iron Horse Trail and for the local community. It includes restrooms, drinking fountains and water station, bike racks, benches, shade structure with picnic tables, trash and recycling cans, “Mutt Mitt” station, decomposed granite walking path, a central turf area, and associated landscaping. A train themed tot lot play area and interpretive elements with historical and park environment information are also included. The park will be fenced with semi-solid fencing adjacent to the roadways and Iron Horse Trail, and solid fencing adjacent private property. The facilities will be accessible, per American with Disabilities Act guidelines. Access for park users will be via a paved connector to the Iron Horse Trail.
train
BACKGROUND
This property was identified as a future park site by the Alamo community as early as 2008. The County acquired the property in 2014. A public meeting held in September 2014, a Community Survey, and subsequent meetings of the Alamo Municipal Advisory Council (MAC) through 2014 and 2015, gathered public input and led to the completion of a conceptual design by the County’s landscape architect consultant (Stantec).

Environmental testing has been conducted to ensure that the park soils are safe for park users. With the exception of two locations along Danville Boulevard, the soils at the park site were found to contain no lead, arsenic, pesticides or hydrocarbons above background and/or residential screening levels (the most stringent requirements). The two exceptions had surficial soils containing slightly elevated lead levels; these soils are being removed and replaced with clean soil, in accordance with a Remedial Workplan prepared by the County’s environmental consultant, ENGEO. Elevated lead levels are not unusual close to the roadway due to the use of leaded gas in the past and the fact that Danville Boulevard used to be the main route thru the San Ramon Valley.

ENVIRONMENTAL TESTING DETAILS
At the time of purchase by the County In 2014, a Modified Phase I Environmental Site Assessment was completed by ENGEO. They followed standard ASTM E1527 guidelines, and reviewed numerous historical records and standard databases for historical uses, presence of storage tanks, and other environmental concerns. These records reflected former agricultural use of the site and the nearby railroad, so four soil samples were taken and tested for pesticides and metals. None were found exceeding applicable residential and recreational screening levels or, in the case of arsenic, exceeding naturally occurring background levels. Unfortunately, the prior use of the site for gas pumps was not revealed during any of this research; this was, however, addressed in subsequent testing, described below.

In 2016, additional testing was performed in areas where soils would be excavated during park construction. Samples were taken at the park site and also in the location of the park access trail/connector to the Iron Horse Trail. The samples from the park property were analyzed for lead, arsenic, and pesticides, all of which were below residential screening levels. The samples from the access trail contained arsenic and polycyclic aromatic hydrocarbons (PAHs) above residential screening levels, thus a Soil Management Plan was prepared for the construction of the connector trail, to protect workers and passersby from exposure to these contaminants when soils are disturbed during construction activities. Once the connector trail is constructed, public access to the park will be on the paved connector trail and through an opening in the fence, thus precluding park and trail users from exposure to contaminated soils.

In Spring of 2017, some residents of the area expressed concern that the park site had not been tested for contaminants associated with a gas station and garage, which had existed at the site for part of the Shady Way Inn’s existence. Following additional research to establish the former location of the Shady Way Inn and its facilities, additional soil sampling was conducted where the former gas pumps and garage are believed to have been located.

The Shady Way Inn was located at the eastern end of the park parcel, with gas pumps right along Danville Boulevard and a garage at the corner of Danville Boulevard and Hemme Avenue. It is not known whether the gas pumps utilized an above- or below-ground storage tank, and it is also not known if automotive servicing was conducted at the garage. Soil samples taken from these locations were collected at depths of 0-6 inches and 12-18 inches and were tested for petroleum hydrocarbons, metals, and other volatile organic compounds. Levels of all contaminants of potential concern were found below residential screening levels, with the exception of lead in the shallow soils at two locations. Since lead levels on the rest of the park property are all significantly lower, it is likely that the lead detected was aerially deposited from the days when automobiles using leaded gasoline traveled along Danville Boulevard. A Remedial Workplan has been prepared for removal of the lead impacted soils and replacement with clean soil.

ADDITIONAL INFORMATION
The reports for the ENGEO studies of 2014, 2016 and 2017, and the 2017 Remediation Workplan, are available here:

Modified Phase I Environmental Site Assessment, 2014, by ENGEO
Remedial Investigation Report, 2016, by ENGEO
Supplemental Characterization Report, 2017, by ENGEO
2017 Remediation Workplan, by ENGEO

Questions regarding the project may be addressed to: Adele Ho, Construction Project Manager, at (510) 815-4043, adele.ho@pw.cccounty.us
Soil Sampling, April 2017