Bay Area Vapor Intrusion Mitigation System Design

Terra-Petra Environmental Engineering is providing environmental engineering services for the design of the vapor intrusion mitigation system (VIMS) for a development of affordable Senior Housing in downtown San Rafael, CA. The development consists of the construction of a new six-story building. The building footprint is approximately 14,000 SF.

The site served as a Manufactured Gas Plant prior to the proposed improvements. Site assessment work was completed at the site prior to Terra-Petra’s involvement. A Human Heath Risk Assessment (HHRA) and a Site Conceptual Model (SCM) were carried out to determine the potential risk exposure posed to future construction workers, future commercial occupants and future residential occupants of the building based on VOC’s at the site. It was determined that the calculated risks for all potential receptors were less than the bench marks set forth for the property. The bench marks for this site were HI = 1 and ILCR = 1E-6. Results of the evaluation suggest that soil vapor intrusion mitigation systems may not be required to protect future occupants on this parcel.

The Department of Toxic Substances Control (DTSC) was engaged to serve as the lead regulatory agency at the site. Terra-Petra was directed to design a VIMS system in compliance with DTSC’s published guidelines, which we are in the process of completing.

It will be up to the DTSC to determine if the submitted VIMS design package meets DTSC guidelines and the soil vapor mitigation system provides for adequate human health assurance per the terms of the Land Use Covenant (LUC). If so, the DTSC can formally approve this project. Terra-Petra is confident that our VIMS design will satisfy the mitigation requirements as we have a vast amount of experience designing such systems that have been reviewed/approved by the DTSC.

Aside from the design work, Terra-Petra will be assisting our client in soliciting bids form qualified and experienced vapor intrusion contractors in the Bay Area. We will also be reviewing submittal packages and providing support throughout the Construction Administration Phase of the project. Our inspection crew is slatted to inspect and document the installation of the system using our state of the art field reporting system.

Vapor Intrusion Mitigation System Design & Installation – San Jose, CA

Terra-Petra Environmental Engineering is pleased to provide environmental engineering services for the design of the vapor intrusion mitigation system (VIMS) being proposed for a new affordable housing development in the Diridon Station Area in San Jose, CA.

The project consists of a multi-family residential building having 130 units with 5 stories above grade (no below grade elements). The lowest level will consist of parking with lobby, offices and a community room. The building footprint is approximately 23,400 SF on 1.02 acres.

The site where the proposed building is to be constructed did contain an Underground Storage Tank (UST) potentially containing PCE which was considered to be a Recognized Environmental Condition (REC). As such, soil vapor data was collected from the site during both wet and dry seasons approximately 9 months apart. The data showed that no on-Site sources of PCE have been identified at the Site. Further, no VOCs were detected at concentrations above residential DTSC-AF SLs for future buildings, and no further investigation, evaluation or consideration of exposures associated with VOCs in soil vapor is proposed. Additionally, no residential units were being proposed on the ground floor of the new development. However, the regulatory oversight agency for this site is still requiring that passive Vapor Intrusion Mitigation System (VIMS) be designed and installed at this building.

Terra-Petra was engaged to design a pragmatic code compliant VIMS system that would take into consideration the lack of site-specific risk. As such, we were able to design a creative membrane system that limited the more protective mitigation measures to areas of higher residential occupancy/risk of exposure. These areas included the community room and elevator lobby. While areas of lower risk such as the trash enclosure rooms and parking garage we were able to design a system that would be protective of VI, but also reduce overall cost impacts on the project’s budget.

Terra-Petra will also be providing Construction Administration services and Construction Quality Assurance/Quality Control Services.

Terra-Petra is Proudly Recognized as an SBE – Small Business Enterprise

Terra-Petra is Proudly Recognized as an SBE – Small Business Enterprise

The SBE is a company-level diversity certification. Non-industry specific it is issued by a local or state government. Terra-Petra’s SBE certification is issued by the State of California.

Eligibility for certification as a Small Business Enterprise varies depending on the issuer. Requirements include the number of employees, the length of time the company has been in business and the net worth of the company’s owner.

In order for a small business to be eligible for certification, the small business must meet the following requirements in California:

  • Be independently owned and operated
  • Not dominant in the field of operation
  • The principal office must be located in California
  • Owners (officers, if a corporation) domiciled in California
  • A business with 100 or fewer employees; an average annual gross receipt of $15 million or less, over the last three tax years.
    • A small business will automatically be designated as a microbusiness, if gross annual receipts are less than $3,500,000; or the small business is a manufacturer with 25 or fewer employees.

Upon meeting the Small Business Certification eligibility requirements, certified small business (SBs) and microbusinesses (MBs) are entitled to the following benefits:

  • A five percent (5%) bid preference on applicable State solicitations.
  • Certified small business/microbusinesses are eligible for the State’s Small Business Participation Program. This program sets a goal for the use of small businesses in at least 25% of the State’s overall annual contract dollars.
  • Under the Prompt Payment Act, the State must pay a certified SB / MB higher interest penalty for late payment of an undisputed invoice. Prompt payment penalties for construction firms are addressed separately under Public Contract Code, Section 10261.5.
  • State agencies may use a streamlined process, known as the SB/DVBE Option, by contracting directly with a California certified small business/microbusiness for goods, services, information technology and Public Works projects. The solicitation must be valued at more than $5,000 and the State agency must obtain price quotes from at least two California certified small business/microbusiness.
  • The DGS-PD charges state and local agencies an administrative fee, when contracting with a California Multiple Award Schedules (CMAS) vendor. As an incentive, the fee is waived, if the CMAS vendor is a certified small business/microbusiness.

Terra-Petra maintains a working knowledge of numerous environmental and soil gas mitigation matters. Our staff includes Methane Consultants, Radon Mitigation Engineers, Construction Managers, Civil Engineers, Registered Environmental Assessors, Registered Geologist/Certified Engineering Geologist, Petroleum Geologists and Petroleum Engineers. This experience gives Terra-Petra the ability to find compromise solutions for any environmental concern that may arise.

Terra-Petra offers on-call consulting services in the City of Los Angeles. We are available to do the work or make official visits at any time as needed.

Contact us today at 1.888.540.5703 or

The Davis-Bacon Act

The Davis–Bacon Act of 1931 is a United States federal law that establishes the requirement for paying the local prevailing wages on public works projects for laborers and mechanics. It applies to contractors and subcontractors performing on federally funded or assisted contracts in excess of $2,000 for the construction, alteration, or repair (including painting and decorating) of public buildings or public works.

The Davis–Bacon Act is part of the United States Code, codified as 40 U.S.C. 3141-3148.

The Act covers four main areas of construction: residential, heavy, buildings, and highway. Within these areas are further classifications, including craft positions such as plumber, carpenter, cement mason/concrete finisher, electrician, insulator, laborer, lather, painter, power equipment operator, roofer, sheet metal worker, truck driver, and welder.

Terra-Petra performs prevailing wage inspections under the following classification:

Craft: Building/Construction Inspector & Field Soils & Material Tester

Vapor Intrusion Mitigation System – Reno, NV

Terra-Petra is continuing to provide environmental engineering services for the design of the vapor intrusion mitigation system (VIMS) design for the Urology Nevada project located in Reno, NV.

The project will consist of a new slab on grade structure having a footprint of 8,700 SF. Terra-Petra designed the vapor intrusion mitigation system for Phase I of Urology Nevada which consisted of a new slab on grade structure having a footprint of 16,624 SF. The entire site was over-excavated a minimum of 5 feet below finish grade.

Terra-Petra is licensed to perform work in all 50 states!

Although our company started its operations over 20 years ago in Los Angeles to address methane concerns in the region, Terra-Petra has since evolved to become a well-known Environmental Engineering firm throughout the United States, and is certified to work in all 50 states.

No matter where you’re project is located, Terra-Petra’s expertise is available to you.  Learn more about our services, approach and philosophy on our company overview page, or contact us today to get started.

Methane Mitigation Design And Consulting – Los Angeles, CA

Terra-Petra’s Environmental Engineering Division has been engaged by IBI Group to provide methane mitigation design and consulting services for a City of Los Angeles project known as the Hollywood Sanitation Yard in Los Angeles, CA.

The proposed new yard is for the City of Los Angeles Bureau of Sanitation (BOS) Wastewater Conveyance Division. The site area is approximately 38,500 square feet, with about 13,000 square feet of existing one-story garage and office building to be demolished for the new facility. Approximately 8,500 square feet of 2-story new building will house office spaces, locker rooms, restrooms, exercise room, kitchen, assembly room, storage and other support rooms for the building to accommodate the daily yard operation.

Terra-Petra is recognized as an SBE and provides On-Call Consulting Services.

Vapor Intrusion Mitigation System Design And Installation – Santa Fe Springs, CA

Terra-Petra’s Environmental Engineering Division has partnered with a Los Angeles REOC and investment management firm to design a comprehensive Vapor Intrusion Mitigation System (VIMS).

The new development, located in Santa Fe Springs, CA, will consist of a tilt-up industrial warehouse building, on grade, with an approximate building footprint of 150,500 SF. The gas vapor mitigation system shall be designed in accordance with a site specific Phase II Environmental Site Assessment report, and in accordance with the Vapor Intrusion Mitigation Advisory published by the C.A. EPA Department of Toxic Substances Control (DTSC) dated October 2011 (Cal/EPA 2011a, 2011b).

Vapor Intrusion Consulting, Testing And Monitoring – San Diego

Terra-Petra has been performing continuous inspections in San Diego at the Witt Mission Valley Apartments project since early this year. Terra-Petra observed the installation of a VI-20 geo-membrane and Liquid Boot Vapor Barrier application with smoke and thickness testing most recently.

Terra-Petra is one of the foremost experts on Vapor Intrusion consulting, inspecting, testing, monitoring and mitigation design in Southern California.  We are conversant with the many laws, codes and regulations at the city, state, county and national level. We understand the testing, design, monitoring and reporting procedures for many different regulatory agencies.

#vaporinstrution #inspection  #CETCOliquidboot #CETCOVI-20 #smoketest

Photo Gallery From Project

Vapor Intrusion Mitigation System Design – San Francisco

Terra-Petra’s Environmental Engineering Division has partnered with a leading environmental consulting firm in the Bay Area to design a comprehensive Vapor Intrusion Mitigation System (VIMS) for a new high-rise residential-rental mixed-use building located in San Francisco, CA.

We will be following the Department of Toxic Substances Control (DTSC) Vapor Intrusion Mitigation Advisory to design a combination passive venting and sub-slab membrane VIMS system as a means of mitigating human health risks associated with PCE in subsurface soil vapor. Our services will also include providing the necessary Quality Assurance/Quality Control Oversight during the installation of the system. This is a process and a role that we feel very comfortable carrying out.

Regardless of the reason, Terra-Petra can design a vapor intrusion mitigation system for you. We routinely design these passive and active Building Protection Systems across numerous cities and counties governed by many different agencies.

A typical Building Protection Systems consists of an impermeable soil vapor membrane and a pressure relief system. Where deemed appropriate, Terra-Petra can design mechanical vapor extraction systems, electronic gas detection and alarm systems; employing the latest technologies.

Among our many capabilities, Terra-Petra offers:

  • A Civil Engineer, Registered Environmental Assessor, Registered Geologist and Certified Engineering Geologist on staff.
  • Years of experience designing code compliant Building Protection Systems for numerous governing agencies.
  • Easy to read comprehensive plans including project specific details and specifications.
  • Passive and Active Design Capabilities.
  • Plan coordination with project Architect, Civil, Structural, Plumbing, HVAC as well as the Landscape Architect.
  • CAD Draftsmen on staff carry an Associates of Science Degree in Computer Aided Drafting Technology and Certificates in Architecture and Design for Drafting.

Terra-Petra Providing Waterproofing Services For New High-End Project in West Hollywood

Terra-Petra is thrilled to have been a part of this fabulous project being finished off in West Hollywood, The Pendry Hotel. Terra-Petra served as the Quality Assurance/Quality Control Waterproofing Inspectors throughout the entire construction process. We are also in the process of completing the QA/QC Fenestration Testing at the Residence in compliance with the project’s performance specifications.

Our field-testing crew has been ramping up over the last week to ensure we have the necessary labor and material to meet the demand of the water testing schedule. We are currently in production mode as we are testing the exterior fenestrations of the building with 3 crews working simultaneously.

Re-Post From

The Britely, a New Member’s Club in Los Angeles, Is Feather-Filled and Fabulous

There’s this famous Oscar Wilde quote: “Everything in moderation, including moderation.” That very well could be plastered on the gilded door of The Britely, a new member’s only club in Los Angeles where maximalism is the modus operandi. There’s not one, but two Wolfgang Puck restaurants—one of which is painted a flamingo pink. Their rooftop bar, with sweeping views of L.A.’s urban sprawl, is adorned in jade palmeral-tiger print. Then there’s the hangout de resistance: an underground lounge with turquoise banquettes, gold lamé pillows, Hollywood Regency feather lamps, and a bowling alley. Simply put: it’s a place where you can have some serious fun. (Or as Estelle Lacroix, The Britely’s managing director puts it, “a little self-indulgence.”)


Re-Post from

First Look Inside Wolfgang Puck’s Pair of New Restaurants at Pendry West Hollywood

Wolfgang Puck is making a pizza. The 71-year-old chef, who has become a household name from his airport eateries, grocery line, and upscale establishments, has been making pizza for a very long time. Best known for creating the smoked salmon pizza at Spago, which was one of the city’s first restaurants to have a wood-fired oven, Puck is contemplating the signature pizza at his new daytime hotel cafe Ospero.

He stretches the dough while posing for the camera, as if this was a shoot for a glossy fashion magazine. Puck is always posing, holding a dish out for maximum exposure. He, and the team at Ospero and the penthouse restaurant Merois, will likely need it as the ongoing pandemic continues to hamper an ideal opening scenario at the massive new Pendry West Hollywood.


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