REPORT ON ENVIRONMENTAL ASSESSMENT AND REMEDIATION OF THE HAVENS SITE
In California, when school districts receive State funding for acquisition and construction of new schools on new sites, districts are required to complete an environmental review of the site.Although the Havens Elementary School project consists of new construction, the Havens site is not a new school site and is not subject to this requirement.However, when low levels of contamination of soil and ground water were detected during construction of the new building on the current Havens”’ site, the District worked closely with County and State agencies to investigate the extent of the problem to develop and execute an appropriate plan for remediation.The District retained an environmental consultant (Millennium Consultants) a former California Department of Education School Facilities Planning consultant (School Site Solutions) and a peer reviewer (Exponent) to investigate the site, provide an analysis of findings and implement remediation plans.Additionally, the District notified neighbors of the detection of contaminants, its plans to conduct an environmental assessment, and to work with the California Department of Toxic Substances Control (DTSC).
The assessment, analysis, and implementation of the remediation plans have now all been completed.The process included peer review to insure the findings and remediation plans were complete, accurate, and adequate to insure safety for all occupants.Following is a summary of the process and time frame:
Assessment and Remediation
Underground Oil Tank
In July 2009, while installing the new electrical service, PG&E discovered an abandoned and concrete-filled 1500-gallon oil underground storage tank at the Havens site near Bonita Avenue.The Project Team removed the tank according to Alameda County Department of Environmental Health (ACDEH) requirements and a report was submitted to the ACDEH, Hazardous Material Division.A representative of the Alameda County Health Department was on site to observe the removal, as well as a project hygienist to take soil samples from under the tank.All contaminated material from inside the tank was removed to a disposal facility in Kettleman City, California.There was no evidence of soil or ground water contamination outside the tank.The portion of the site where the tank was located has been covered with cement-treated soil, effectively sealing the area from human contact.
Contaminated Ground Water
In August 2009, the Project Team discovered low levels of petroleum hydrocarbons (gasoline and diesel fuel) in ground water at multiple locations on the Havens site.The detected concentrations were not in the area of or down-gradient from the underground storage tank discovered on the site.Subsequent investigation by our consultants suggests that the source of contamination is offsite, coming on to the Havens site from the direction of Highland and Vista Avenues.Nonetheless, the District sought to ensure that ground water flowing under the Havens site is properly filtered to remove contaminants before the water flows offsite into the City”’s storm water system.
In consultation with environmental hygienists and working voluntarily with the DTSC, the Project Team developed and implemented a plan to filter the ground water on site.To contain the water on an interim basis, a 6,000-gallon tank was installed to collect and filter the contaminated groundwater.Filtration removed the hydrocarbons and the filtered water was reused on site for dust control.Permanent filtration boxes which remove contaminants and then release the filtered water into the storm water system have been installed on site.The Project Team also evaluated the potential risk that contamination in ground water (and soils permeated by ground water) might vaporize and percolate upward through building foundations and into the building.Both passive and active soil gas measurements were taken.The potential for health risks from vapor intrusion was evaluated using a DTSC-approved model and incorporating numerous health-protective conservative assumptions, including the assumption that the hypothetical exposed individual is present in the building 350 days per year for 30 years.The District’s peer reviewer, Exponent, also evaluated the risk using site-specific soil data.Based upon the data and modeling, the District”’s environmental consultants (Millenium and Exponent) concur that the presence of contaminants do not present a significant risk to human health and that no further investigation is necessary.The modeling did not include the additional engineering mitigation measures discussed below that were implemented during construction.
Precautionary Engineering Mitigation Measures
To ensure that any health risk would be mitigated, the District incorporated the following engineering mitigation measures into the construction.
“Â¢ Individual building foundation slabs were constructed with concrete additives designed to retard vapor transmission.
“Â¢ Individual building foundation slabs also were constructed with a vapor barrier beneath the slab to prevent vapor intrusion into the buildings.
“Â¢ All buildings include a shallow ground water collection system around the perimeters to intercept shallow ground water and divert potentially contaminated water around the buildings.
These engineering mitigation measures are the measures that would have been taken if any significant health risk had been found and therefore provide additional assurance that the low levels of contamination on the Havens site do not pose a health risk to students and staff.All reports from consultants and State and County agencies are in the process of being finalized.At the August Board meeting, a final report will be presented.The current Havens site has been a school for over 70 years with no previous environmental issues and because mitigations to address any currently known possible risks have already been implemented as part of the construction of the new building, it is anticipated that the recommendation to the Board will be that no further action in this matter is required.
July 14, 2010
from Constance Hubbard, Superintendent
Project Status: Complete.See Division of the State Architect Havens Closeout Letter
Havens Elementary School is a mixture of buildings constructed between 1935 and 1994.Preliminary evaluations indicate that three out of the five buildings need seismic strengthening and accessibility improvements.
|Building||Year||Recommended Improvements||Project Status|
|Main Building – Including West Wings, Administration Office, Library, Faculty Lounge||1954||“Â¢ Add steel bracing along exterior walls
“Â¢ Strengthen interior corridor walls
“Â¢ Infill skylights and selected windows
|3/18/08 Combined Investigation and Concept Design Final Reports (13 mb)|
|Ellen Driscoll Auditorium||1940||“Â¢ Strengthen shear capacity of walls
“Â¢ Modify non-ductile detailing
“Â¢ Preserve historically defined characteristics
|02/07/08 Mark Becker Rebuild Proposal (1mb)|
|Annex||1935||“Â¢ Strengthen portions of building at exterior
“Â¢ Infill selected windows
|01/08/07 Seismic Evaluation Tier 2 (1 mb)|
Havens has significant accessibility issues.By current standards, no compliant path of travel exists to any room in the school.Accessibility improvements will need to be made on doors and hardware, landings, and ramps.In addition, accessibility will need to be improved to bathrooms, drinking fountains, sinks and cabinets, and the school auditorium and stage.
The Havens Playfield
A special meeting of the Board of Education was convened on November 17, 2009. The Board considered the responses of four vendors to a questionnaire about factors such as safety, warranty, and recycling plans, and discussed them with the public.