About Ground Penetrating Carbon, Inc.

Ground Penetrating Carbon, Inc. (GPC), a sister company of Holmes and McGrath, Inc. Civil Engineers and Land Surveyors, is an established consulting firm on Cape Cod. The Principals of Ground Penetrating Carbon, Inc. are an experienced team of engineers and wastewater treatment plant operators who have been removing dissolved nitrogen from wastewater for decades. Our engineers were early advocates of RUCK™ denitrifying systems, and early adopters of the Environmental Operating Solutions, Inc. (EOSi) MicroC™ product for use in the denitrification process.

Through our extensive experience in soil based wastewater system construction and operation, we have developed a new process to treat already treated wastewater. This newly patented treatment system is called the GPC Filter Process. Through many years of hard work, experience and study, we have developed the GPC Filter Process which not only significantly reduces low concentrations of Total Nitrogen in wastewater, but substantially reduces certain Pharmaceuticals and Personal Care Products (PPCPs), sometimes called Contaminants of Emerging Concern (CECs), from tertiary wastewater systems. The addition of this GPC Filter Process to a wastewater treatment system can improve the performance of a small scale wastewater system rivaling the performance of large scale wastewater treatment systems.

Ground Penetrating Carbon, Inc. designs and sells the GPC Filter Process that, when added to wastewater treatment systems, consistently reduces BOD5 and TSS to near detection levels, reduces the presence of PPCPs/CECs, and significantly reduces dissolved nitrogen from the effluent. 

The GPC Filter Process can be added to any wastewater treatment technology. While the GPC Filter Process can lower the concentration of dissolved total Nitrogen by half in the first pass of water through the GPC Filter Process, even lower concentrations of dissolved total Nitrogen can be achieved by the installation of two GPC Filter Processes in a series. 

The GPC Filter Process is designed to be installed at existing or proposed tertiary wastewater treatment systems. A GPC Filter Process can be installed as an in-line system at an existing wastewater plant that is not meeting its mandates for TSS, BOD5, or nitrogen reduction. The GPC Filter Process can also be designed and installed as a bottomless filter as a soil absorption system (SAS).

Ground Penetrating Carbon, Inc. is also a distributor of SoilAir™ Systems. SoilAir™ is a simple and effective way to bring failing on-site septic soil absorption systems back to life. The SoilAir™ System has been granted a Revised Remedial Certificate of Approval by the MassDEP, and is approved for use with failed or failing septic soil absorption systems. SoilAir™ has been used as the go-to solution for homeowners and commercial interests to renovate septic systems of all sizes. SoilAir™ has been shown to be extremely effective for clients who are facing challenging Title V compliance issues.


Michael B. McGrath, P.E., P.L.S.

Michael B. McGrath, P.E., P.L.S. has, for over thirty seven years, been the managing principal partner at Holmes and McGrath, Inc., a land surveying and civil engineering firm in Falmouth, MA. Mr. McGrath graduated from Northeastern University in Boston, Massachusetts with a Bachelor of Science in Civil Engineering. He is a Professional Engineer (Civil) and a Professional Land Surveyor. He is a member of the Massachusetts Association of Land Surveyors and Civil Engineers (MALSCE), the American Society of Civil Engineers (ASCE), the American society of Agriculture and Biological Engineers (ASABE), Water Environment and Reuse Federation (WERF) and of the Soil Science Society of America (SSSA).

In 1984, Mr. McGrath and his partners entered into a license agreement with Rein Laak, PhD, P.E. to sell a passive alternative denitrifying septic system known as a RUCK system. Mr. McGrath and his partners designed built and operated the first residential RUCK system in Massachusetts. Today Mr. McGrath and his partners still design and operate the latest "model" of a residential RUCK system through a sister company, Innovative RUCK Systems.

From 2002 to 2004, Mr. McGrath was a founder and part-time employee of Environmental Operating Solutions, Inc. (EOSi). EOSi is the manufacturer of the MicroC™ family of carbon products designed for use in the denitrification process.

Due to his involvement with RUCK sand filters and his ongoing research into septic systems, Mr. McGrath has had a long term interest in soil science, including soil physics and soil microbiology. Mr. McGrath has constantly analyzed the performance of the RUCK sand filters and the movement of dissolved nitrogen and dissolved carbon through those filters. Consequently, he has developed the GPC process which uses the principles of soil physics and soil microbiology to create a process that improves the treatment of wastewater.