Gas and Electric Transmission Lines

Our Area of Expertise


Gas and Electric Transmission Lines

In the last 25 years, Dean Chapman & Michelle Patton have appraised over 200 miles of both natural gas and electrical transmission lines. The appraisals included over 150 properties in both urban and rural areas of California and Nevada. Interviews with brokers, agents, planners, owners and developers and civil engineers were necessary to produce a reliable result.


Natural Gas Transmission Lines

The purpose of each natural gas line assignment was two-fold; 1) determine if a high pressure line affected adjacent property value, and 2) if so, under what circumstance did the line affect value?

One of our first assignments related to high pressure gas transmission lines was in 2011 right after the horrific accident in San Bruno, California. PG&E retained Dean Chapman to help understand how the neighborhood and property values where the explosion took place were affected. The assignment included appraising more than a dozen homes in the Crestmoor neighborhood of San Bruno as of 3 valuation dates.The first date was 1 day before the 30” gas line exploded and incinerated 35 houses, killing 8 people. The second date was 1 month after the explosion, and the third date was 1 year later. The experience and knowledge gained in this investigation has proven to be invaluable in later gas line assignments.

Gas Transmission Line Appraisals, Study and article

An assignment involving a new alignment for a 30” gas line through farmland in Northern California prompted Dean and Michelle to question the accuracy of traditional valuation methodology used by appraisers to value temporary construction easements.  Their desire to share this insight resulted in writing an article entitled Transitional Use TCEs. The article was published in the IRWA Magazine in 2019. Chapman & Patton are currently writing yet another article about their experiences appraising a 20 mile long gas transmission line corridor.



Electrical Transmission Lines

Our investigations into electrical transmission lines have involved all types of properties, poles, towers and line sizes that began after the Swedish Study was published in the 1990s. This study concluded that electro-magnetic fields created by high voltage transmission lines caused a cancer cluster in an elementary school in Sweden.  After the results of the Swedish Study were aired on national television in the United States, home values close to electrical transmission lines in California (and elsewhere) suddenly dropped. We were retained to determine how and why this study, which was later determined to be an anomaly, continued to adversely affect property values.    

In 2003, PG&E hired Dean Chapman to study the potential effects posed by a proposed 230kV line route through a modern industrial park in the Silicon Valley area of San Jose. This assignment involved careful investigations and interviews into what effects large lattice towers have on value in a modern master planned industrial development. Mr. Chapman ultimately provided testimony to the California Public Utilities Commission regarding the selected route.

The data collected during that assignment culminated in Mr. Chapman’s award-winning article in the IRWA Magazine entitled “Electrical Transmission Lines and Industrial Property Values”.

As recent as 2018, PG&E retained Chapman & Patton to appraise several houses in an exclusive hilly area with scenic views in the Bay Area to determine if the replacement of 2 lattice towers with 2 tubular steel towers would affect property values. (PHOTO)  By coupling a number of Paired Sales examples with interviews of real estate agents and property owners, a well-supported opinion of compensation helped settle that case.