Retaining wall and landscaping works, geocomposite supplied and installed, quantity 1,000 SQM

Executive summary

For a medium-scale retaining wall and adjacent landscaping project in Rewari, Ocean Non Wovens supplied and installed 1,000 square metres of geocomposite drainage/reinforcement material. The geocomposite served three simultaneous purposes: filtration, drainage, and partial reinforcement behind the wall face, allowing a slimmer drainage trench, reducing the need for large stone chimney drains, and improving long-term performance under seasonal rainfall. The solution reduced construction complexity on a constrained site while maintaining durability and low maintenance needs.

Project background and challenges

The site in Rewari required a retaining structure to stabilize a landscaped slope adjacent to a newly developed access path. Key constraints were limited site access for heavy plant, the client’s desire for a clean landscaped finish, and seasonal monsoon-driven soil saturation that could generate hydrostatic pressure behind the wall. Conventional approaches using coarse aggregate chimney drains and large drainage pipes would have required significant excavation and imported stone, increasing cost and time.

Our objective was to provide a compact, reliable drainage solution that:

1. Prevented build-up of hydrostatic pressure behind the wall.
2. Minimized excavation and imported aggregate.
3. Preserved a clean, plantable landscaping finish.

Geocomposite products are specifically designed to meet these goals by combining a high-permeability core with filtering geotextiles to both channel water and prevent clogging by fines. This approach replaces, in many cases, the granular chimney drain while occupying much less thickness behind the wall. 

Why geocomposite was selected

Key reasons the project team chose a geocomposite solution:

• Vertical and horizontal drainage efficiency: geocomposites direct water quickly to designated collection points, lowering hydrostatic load on the wall and reducing the need for frequent weep-holes or oversized drains. This is especially valuable where space behind the wall is limited. 
• Filtration and clogging resistance: the geotextile facing allows pore water to pass while retaining soil particles, helping maintain long-term flow capacity compared with some pipe-only systems. Design standards emphasize that geotextiles used for underground drainage must permit filtration while preventing aggregate contamination. 
• Reduced imported aggregate and simpler construction: geocomposite drains often replace layers of stone or gravel, reducing material volume, truck movements, and site handling. This lowers both carbon footprint and cost on constrained sites. 

Design considerations and specification highlights

We collaborated with the client and the design engineer to set material and installation specifications aligned with good practice and local constraints.

Design inputs included:

• Wall height and facing type (low-to-medium height modular facing).
• Backfill type and gradation. Coarser backfills improve drainage, but site fill was variable; therefore filtration selection was critical.
• Expected rainfall intensity and seasonal groundwater table behaviour. For retaining wall performance, drainage that prevents hydrostatic pressure build-up is essential. We referenced mechanistic guidance for geosynthetic-reinforced walls and drainage detailing to set safe factors of safety. 

Material specification (summary):

• Product: geocomposite sheet drain (nonwoven filter bonded to a high-flow core).
• Effective flow capacity: selected to match estimated peak seepage and direct water to the base drain.
• Filtration: nonwoven geotextile with apparent opening size (AOS) chosen based on local soil gradation to minimize clogging risk.
• Durability: polymer selection and thickness chosen to satisfy construction survivability and long-term chemical/biological stability. Design references highlight assessing survivability and degradation when selecting geosynthetics. 

Installation process (what we did on site)

1. Site preparation: excavated to design depth, removed unsuitable organic materials, and compacted bearing areas.
2. Base drain preparation: shallow trench at wall toe with perforated pipe wrapped with aggregate where required; geocomposite tied into the base collection system to ensure continuous flow path.
3. Geocomposite placement: roll lengths cut to suit wall panels and fixed vertically behind the wall face. Overlaps and end-lapping followed supplier guidance, with filter layer oriented toward the soil. Critical vertical seams were sealed or firmly overlapped to avoid short-circuiting.
4. Backfilling: carefully placed free-draining backfill in layers to avoid damaging the composite. We prohibited heavy point-loading directly on the exposed core.
5. Outlet connections and testing: outlets and collection points were checked by controlled water flow tests during installation to confirm unobstructed drainage.
6. Landscaping finish: after structural work, topsoil and planting were reinstated, with the geocomposite remaining concealed and functioning.

Two practical notes from the job:

• Handling and protection: geocomposite cores can be sensitive to puncture during construction; we trained the crew to avoid sharp tools and used protective sacrificial geotextile where mechanical damage risk was higher. Guidance from multiple geosynthetics manuals underscores the importance of construction survivability testing and protective measures. 
• Connection detailing: performance depends on watertight, low-resistance connections from the geocomposite to the base drain. Small errors at junctions negate the benefit of high core permeability.

Performance outcomes and monitoring

Quantitative and qualitative outcomes observed within the first year:

• Zero signs of saturation at the rear face during monsoon events that produced visible ponding elsewhere on site.
• No observable blockages at outlets during scheduled inspections.
• Reduced excavation volumes and eliminated the need for a thick stone chimney drain, which we estimate reduced imported aggregate by approximately 60–70% for the drainage component when compared with a stone-drain design of equivalent capacity, consistent with industry comparisons where geocomposites replace granular layers. 

A longer-term monitored case in India has shown geocomposite drains functioning well even in heavy rainfall when correctly detailed, reinforcing our decision for this site. 

What most companies do not talk about — lessons from the field

1. Small detailing errors matter more than product choice. Even high-capacity geocomposites fail if outlet connections are constricted or overlaps are insufficient. We invested extra time in junction detailing. 
2. Installation survivability trumps nominal capacity. On-site construction damage is common; selecting materials with appropriate protective layers and training installers prevents performance loss. Design guidance emphasizes survivability testing and protective measures. 
3. Lifecycle and maintenance trade-offs. Geocomposites reduce maintenance associated with clogged stone drains or collapse of weep systems, but they can hide issues. Periodic inspection of outlets remains essential. 
4. Compatibility with planting and landscaping. Roots can interact with the filtration layer; specifying appropriate geotextile AOS and installing root barriers where necessary preserves long-term flow. This is often overlooked during tendering.
5. Procuring to performance, not just unit price. Lowest-cost geocomposite options may use thinner cores or inferior filtration that compromise long-term capacity. We recommend suppliers provide index test data (flow capacity, AOS, tensile, and puncture resistance) for design verification. 

Practical recommendations for engineers and clients

• Always match the filter AOS to the retained soil gradation; generic AOS selections are risky. 
• Protect the exposed core during backfill operations using sacrificial geotextiles or plywood where plant access is expected. 
• Design outlet and connection details for easy inspection and maintenance. A small access chamber at the outlet prevents future access headaches.
• Use geocomposites to reduce site vehicle movements and imported stone when access is restricted or sustainability goals matter; lifecycle carbon savings can be significant. 

Conclusion and promotional note

The Rewari retaining wall and landscaping project demonstrated how a carefully specified and installed geocomposite can deliver robust drainage, reduce construction footprint, and support attractive landscaping finishes without sacrificing long-term performance. Ocean Non Wovens supplied 1,000 SQM of geocomposite tailored to the site’s soil conditions, helped with detailing and installation supervision, and validated performance through on-site commissioning.

If you are planning a retaining wall, slope stabilisation, or landscaped earth-retaining feature and want a solution that minimizes excavation, reduces aggregate imports, and lowers long-term maintenance, Ocean Non Wovens can provide specification-grade geocomposites, installation guidance, and site supervision. Contact us for a project review and a performance-based quotation tailored to your site conditions.