EDITOR’S NOTE: In 2020, one of the unique things we found was that not only were older articles performing strongly from both site and Google searches, they were, in many cases, outperforming the newest items. The case studies published by Geosynthetica retain value, precisely because they focus on important issues in infrastructure. As such, we are bringing some “from the vault” back to the front page to celebrate the continued value in revisiting these classic stories–and to introduce new readers to these projects. Today, we look at the May 2018 story on how a CC HydroTM (CCH) Geosynthetic Cementitious Composite Barrier (GCCB) was used to provide secondary containment to a 5000m2 berm face at a petrochemical storage facility in Wales. ***
SemLogistics’ Milford Haven site is one of the largest petroleum products storage facilities in the United Kingdom. It accounts for nearly 25% of the country’s independent multiproduct storage. Located on the local waterway on the west coast of Wales, the facility serves ships transporting in and out of international locations and plays a key part in the region’s economy. The premises were built in the 1960s and are located adjacent to a Site of Special Scientific Interest (SSSI).
As part of ongoing improvements in the oil storage operations, SEM sought to install secondary containment around two of the site’s most critical storage tanks.
SAFE PETROCHEMICAL STORAGE IN WALES
There are 52 tanks of various sizes within the site that are used to store different petrochemical products: gasoline, gasoline blendstocks, naphtha, jet fuel, gas oil and diesel. Crude oil storage is also part of the facility’s stock. Each tank sits within a bunded area formed with granular fill during the original construction of the site.
Mott MacDonald was engaged to design a robust solution which takes into account safety during construction, use, and maintenance. Ease and speed of installation was also a priority to minimize cost and disruption to the site. Following the successful application of an earlier tank (#206) in 2014, and after completing cost comparison analysis considering several design scenarios, CCH was specified as part of Tank 114’s secondary containment.
PRODUCT & PROCESS IMPROVEMENTS
In total, 4000m2 of CCH5TM from Concrete Canvas were installed in less than 5 months, despite very adverse weather conditions. For the Milford Haven petrochemical storage facility, getting the tank back in service on time was of paramount importance.
Of further benefit to the project’s execution, the materials were locally source, enabling the capital expenditure to remain largely within the area.
Concrete Canvas worked closely with the design engineers in the initial, extensive research and preparation phase, developing the standard details for pipe penetrations, corner and valley sections, upstands, interfaces with concrete infrastructure, mating to incumbent liners, and ramp construction details.
That endeavor has helped establish a full portfolio of standard details covering all aspects of secondary containment berm and bund lining for Concrete Canvas.
Similarly, Concrete Canvas Ltd. worked closely with the contractor, Jones Brothers, taking on board feedback during the early sections of work and lessons learned from the lining of the previous tank. That interaction led to significant product improvements over the course of the project, including the introduction of a reinforcement scrim into the material to enable more efficient welding on site.
Another key product improvement was the development of a propriety Triple Tracked Weld, which not only provides the twin track weld required for pressure testing of joint, but incorporates a third weld that secures the overlying CC HydroTM layer to the layer beneath. This provides additional protection to the CC HydroTM membrane from environmental exposure and results in a neater finish.
Following the success of the lining of Tank 114, the system is being proposed for future containment schemes across the site. The Institute of Civil Engineers recognized the work with an Innovation Award in July 2017.
CCH & GENERAL INSTALLATION PROCESS
The secondary containment barrier utilized for the bund lining project was CC HydroTM, which combines Concrete Canvas’s concrete-impregnated fabric technology with a high impermeability, chemically resistant geomembrane backing. The geomembrane provides a high-performance liner with a testable seam for quality assurance. The material incorporates a hi-visibility welding strip, which allows joints to be thermally bonded with a twin-track or triple-track air channel for on-site testing.
CCH is installed in a similar fashion to conventional plastic and geomembrane products, using off the shelf tools and accepted standard design details. The general process for installation for the project referenced here and in general:
Preparation of the substrate: Prior to the installation, the berm faces were graded to the required profile and height for the volume of media being contained in the event of a catastrophic tank failure. Angular rocks, roots, grass, and vegetation were then removed from the base material. In some instances, a compensatory geotextile can be laid first, but here, the surface was made smooth using a fine dust top layer to the soil berm.
Deployment of CCH: Supplied in bulk rolls of up to 150m2, CCH is deployed via spreader beam and plant equipment, before being cut to length using basic hand tools.
Thermal welding and pressure testing of seams: Welded in accordance to Thermal Welding Institute (TWI) guidelines, CCH incorporates a high-visibility welding strip. A twin-track or triple-track air channel bond enabled fast, simple, on-site pressure testing.
Hydration: Following the welding and testing of the joints, CCH was hydrated with local, on-site water mains. CC Hydro cannot be over hydrated, so there was no requirement to measure exactly the water:barrier ratio.
For more petrochemical storage stories and other Concrete Canvas applications, visit www.concretecanvas.com.