Geo Mods team installing Single Flo-Vault Heavy Duty modules in Cloverdale

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On-Site Stormwater Detention in Cloverdale, BC

Cloverdale, British Columbia 170 m³ Retention • 3.0m Cover • 500mm Profile

Engineering an ultra-shallow 97-metre underground stormwater detention tank in Cloverdale, BC using Atlantis Single Flo-Vault® Heavy Duty modules. Overcoming shallow depth constraints with only 500mm vault height while enduring up to 3 metres of cover overburden and integrating 375mm pipe boots.

Project Gallery & Construction Progression

Crew interlocking Single Flo-Vault® Heavy Duty modules across the 3.5m wide bed.

97-metre trench excavation and foundation bed leveling in Cloverdale, BC

Trench excavation, subgrade leveling, and compaction (GPS: 49.100108, -122.692978).

Geotextile underlay and Flo-Vault module placement along 97m trench

Geotextile bedding and sequential placement of Flo-Vault modules down the 97m trench.

Close-up assembly of 500mm Single Flo-Vault Heavy Duty modules

Assembly and interlocking of 500mm Single Flo-Vault® modules with >95% void space.

Full view of the 97-metre linear modular chamber profile prior to top encapsulation.

Geo Mods service vehicle on site during geomembrane liner encapsulation

Geo Mods on site providing field support during geomembrane liner encapsulation.

Custom-welded 375mm pipe boot penetration through the detention liner

Engineered 375mm pipe boot welded to the liner for leak-proof pipe penetrations.

Side backfilling and vibratory plate compaction along wrapped tank

Controlled lift backfilling and vibratory plate compaction along vault sidewalls.

Protective nonwoven geotextile armor wrap over sealed detention tank

Protective nonwoven geotextile layer wrapped around the tank before deep burial.

Backfilled detention facility with inspection riser pipes under 3m cover

Backfill completed with inspection risers ready to support up to 3m of cover.

Cloverdale commercial development master site plan

Master commercial site plan utilizing underground OSD to maximize usable land area.

Sustainable stormwater detention infrastructure planning concept

Low-impact civil engineering concept integrating subterranean detention and sustainable drainage.

Project Overview

Project Spotlight: Advanced Underground Stormwater Detention in Cloverdale, BC! 🌧️ 🏗️ When commercial development in Cloverdale, BC required a high-capacity on-site detention (OSD) system within tight vertical depth boundaries, traditional concrete vaults and round CMP culverts were structurally and geometrically unfeasible. Due to shallow discharge inverts and high regional water table conditions in Surrey's lowlands, the system could not exceed an overall profile height of 0.50 metres (500 mm), yet had to provide 170 m³ of critical stormwater surge retention. Geo Mods and Atlantis partnered with the project's engineering team to design, configure, and deliver a custom modular detention system spanning 97 metres in length by 3.5 metres in width using Single Flo-Vault® Heavy Duty modules. Fully encapsulated in an impermeable geomembrane liner and cushioned with puncture-resistant nonwoven geotextile, this system provides massive stormwater detention capacity while engineered to support deep burial conditions with up to 3 metres of cover overburden.

Ultra-shallow 0.50m (500mm) overall profile height across 97m × 3.5m footprint

Single Flo-Vault® Heavy Duty modular engineering (>95% open void space)

Engineered for deep burial withstanding up to 3.0m of cover overburden

Direct 375mm pipe penetrations with custom-welded geomembrane pipe boots

Project-specific shop drawings coordinated with local civil engineering team

Direct on-site technical support and QA/QC verification by Geo Mods

Site & Engineering Challenges

Strict Vertical Height Constraint: Restricted to a maximum 500mm vault height due to shallow discharge inverts and regional groundwater conditions in Cloverdale.

Extreme Overburden & Traffic Loads: System required certification to withstand up to 3.0 metres of heavy granular cover and heavy commercial traffic overhead.

Watertight Detention Imperative: Strict municipal detention criteria mandated 100% containment without unmonitored exfiltration into surrounding soils.

Large Diameter Pipe Integrations: Seamlessly transitioning 375mm diameter stormwater mains into a 500mm shallow chamber without compromising liner watertightness.

97-Metre Linear Alignment: Maintaining laser-level gradient and uniform interlocked placement across an expansive 97-metre trench.

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The Geo Mods & Atlantis Solution

Single Flo-Vault® Heavy Duty Matrix (40+ tonnes/m² load capacity)

Geomembrane & Nonwoven Geotextile Dual-Layer Protection

Sealed 375mm Geomembrane Pipe Boots for Leak-Free Transitions

Collaborative Shop Drawings with Local Engineering Team

On-Site Field Verification & Compaction Monitoring by Geo Mods

Geo Mods supplied and supported the installation of the Atlantis Single Flo-Vault® Heavy Duty modular system, delivering the optimal balance of ultra-shallow clearance and industrial-strength load-bearing capacity. With an ultimate compressive strength of 40 tonnes/m² (56.9 PSI), the Heavy Duty Flo-Vault units easily supported the 3-metre overburden. Atlantis and Geo Mods coordinated detailed shop drawings with the local engineering team, supplied precision-welded pipe boots for the 375mm stormwater lines, and provided active on-site support throughout trench preparation, liner installation, module placement, and multi-lift granular backfill compaction.

Technical Specifications

Cloverdale Detention System Specifications

Project Location Cloverdale, BC (Lot 26-003-000)
Tank Dimensions 97.0 m (L) × 3.5 m (W) × 0.50 m (H)
Retention / Detention Volume 170 m³ (170,000 Litres / 44,900 gal)
Module Model Single Flo-Vault® Heavy Duty
Module Unit Dimensions 575mm (L) × 575mm (W) × 500mm (H)
Internal Void Space >95% Open Storage Ratio
Ultimate Compressive Strength 40 tonnes/m² (56.9 PSI)
Overburden Rating Designed for up to 3.0 metres of cover
Stormwater Pipe Penetrations 375 mm with specialized pipe boots
Liner Configuration Impermeable geomembrane + NW geotextile armor
Completion Date June 2026

Engineering Highlight

Despite extending an impressive 97 metres in length, the underground detention tank was only 500 mm high and was engineered to safely accommodate up to 3 metres of overburden cover above the Single Flo-Vault® Heavy Duty structure.

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