Expert Advice Series: Subsurface Injection of In Situ Remedial Reagents (ISRRs)

Section 5: This section of the ISRR document focuses on tooling and methods for the successful application of injectable reagents. This section also provides the reader with detailed information on first principles guidance for ISRR installation. This section is somewhat generalized due the highly variable and complex nature of the subsurface. Specifically, this section breaks down reagent delivery methods into three sub-sections that are dedicated to the most common injection methods:  DPI, injection wells, and fracturing.

The first section is dedicated to DPI methods and discusses a few  simple details that will help the user avoid and/or diagnose application problems. One example in this section describes leaks along the drive rod that are associated with worn drive rods. Additional detailed application issues are discussed in two sub-sections dedicated to bottom up and top down application materials and methods.

The second section is dedicated to fracturing methodology.  This section is further sub-divided into two sections on the topic of hydraulic fracturing and pneumatic fracturing injection methods. These discussions are a nice summary of the specific methods and issues associated with each technique and   offer some recommendations on when to consider each method.

The last section is dedicated to injection well installation and application details. This section is one of the more informative sections of the ISRR manual.  A number of the contributing writers have extensive backgrounds in the installation and application of ISRR via injection wells.  This section provides some really usable information and advice on installation details. This includes tidbits on how to test your injection well seal to be sure it’s competent and how to select your well pack and screen size to optimize ISRR application rates. This section also has three sub-sections. Two are dedicated to injection well installation methods (DPI and hollow stem auger), and one is dedicated to injection well development.  These are short sections that nicely summarize the key considerations for each installation method.

On a related matter, I would add that when it comes to application, the reagent you are applying and its characterisitics often play a large role in the overall success of the injection program. We (REGENESIS) have recently released a new activated persulfate material called PersulfOx™. This remediation technology offers the user a safe and easy-to-handle ISCO agent that is an all-in-one material with  built-in activation. This advancement in the science of persulfate activation eliminates the complexity and risk associated with the traditional two-part activation process. PersulfOx provides remediation practitioners with a highly effective, single component product that is easy to ship, store on-site, handle, and inject. More information is available at www.persulfox.com.

In the next review, I will address the topic of measuring and interpreting aquifer injection response.