Identifying the source(s) and composition of alleged stray gas can be challenging. It may be due to the site operations, a natural condition, or a combination of both. It may be non-threatening. Or it could pose a significant risk.

Biogenic methane is quite common. And it could be the source of your alleged stray gas. But when human health and safety is at risk, you must have the defensible data to know for sure. On the positive side, that knowledge will help you decide when you need to assess or halt operations and when you can proceed safely.

To develop defensible conclusions regarding methane source(s), successful protocols involve:

• Using a variety of methods, including Summa cannisters and laboratory-proprietary apparatus, to collect samples.
• Applying specialized and tiered analytical methane differentiation techniques to test the gas samples.

Carefully interpreting the data using multiple lines of evidence and the principles that include the following:

• Thermogenic methane is produced by thermal cracking of heavier hydrocarbons and some of the more volatile heavier hydrocarbons like butane, pentane and hexane are often present. However, the absence of these heavier hydrocarbons is not proof that the methane is biogenic.
• Biogenic methane (typically almost 100% pure) is produced by low temperature biological processes and butane, pentane and hexane are usually absent from its pure form.
• Hydrocarbon species testing are not 100% conclusive in most cases. To increase certainty, we always also look at the stable isotope ratios for carbon and hydrogen in the methane.
• Individual isotope testing results are cross-plotted and typically fall into one of three methane genesis regions. However, some samples may plot in inconclusive areas between regions. This can occur due to mixing of methane from different sources or other factors and requires expert interpretation.

Differentiating biogenic from thermogenic methane helps you pinpoint the origin/potential source(s) and plan your path forward.

With the right protocol, you can determine your risk(s), define the origin and identify potential sources of stray gas, and delineate the extent of any migration/stray gas plumes. You can then implement measures to ensure public health and safety; evaluate natural background gas concentrations in the area; conduct periodic monitoring to define trends and confirm a remedy; and proactively understand and address any contributing factors that may affect migration pathways; and seal/remediate any root causes, if necessary.

At Apex, we can help. Contact us to learn more.

A ballot Measure W for a special parcel tax within the Los Angeles County Flood Control District was passed by voters on November 6, 2018. You can review a summary of Measure W at safecleanwaterla.org.

This Measure authorizes the Los Angeles County Flood Control District to levy a special tax annually on parcels within the District at a rate of $0.025 (2.5 cents) per square foot of land impermeable to water which includes buildings roofs, driveways, hardscape, and concrete areas but doesn’t include vegetated and other natural permeable areas where water penetrates through the ground. The tax revenue—which property owners have to pay—would enable projects, infrastructure, and programs to capture, treat, and recycle rainwater. The tax, however, is a tough burden to bear. For example, an average sized, big-box retail store can expect a tax bill of $6K-$20K in early October 2019. And that tax is annual, recurring every year thereafter.

Fortunately, there are ways to reduce or eliminate the Measure W Parcel Tax. Here’s how:

Tax Reductions

As a property owner, you lower your tax by reducing the square footage of impervious area on your property. The District has provided two potential offramps: the Appeals Process or the Credit Program. If the District miscalculated your effective impervious area, you can file an appeal. For example, if your impervious parking areas drain stormwater to bioswales or dry wells and the District failed to take them into consideration when calculating parcel tax, you can submit a correction to the County’s record to appeal and reduce your tax.

Under the Credit Program, you can reduce your Parcel Tax for new development projects by constructing rock-lined swales, infiltration structures, or rain barrels to capture and recycle stormwater. For existing parcels, retrofits are also an option. Installing an underground stormwater detention and infiltration-type cistern also qualifies. Removing concrete parking areas and replacing them with something porous, like gravel or paving blocks that water can pass through, will make a significant impact as those portions of your square footage would no longer be subject to the tax.

Information on both the credit program and the appeals process can be found at safecleanwaterla.org.

Timeline: Expect Parcel Tax bills by early October 2019 with a due date of November 1, 2019.

Tax Appeals

• If you believe your tax is wrong, an appeals process is available.
• A web tool has been developed to help expedite appeals process.
• You can appeal if you have a discrepancy of more than 10% error of the Impermeable Area and a $50 difference in the tax amount.
• Approved appeals will typically be credited to subsequent tax bill.

Access the Parcel Tax Calculator Tool the District uses to assess your tax.

Credit Program

• You can qualify for a tax reduction with stormwater improvements (SUSMP, IGP, LID, and equivalent).
• You can qualify for up to 100% credit for additional activities.
• Your stormwater improvement initiatives must have a water quality benefit, additional credit for water supply, community investment, and additional activities.

Ready to reduce your taxes? Apex can help.