Detention and Infiltration Reservoirs

Modular, Efficient Stormwater Storage System for Volume Control Applications

The Jensen Underground Stormwater Detention and Infiltration Reservoirs are precast modular stormwater storage systems that achieve the most economical means to meet small and large scale volume control requirements for both public and private projects. Our underground stormwater detention systems supports project-specific goals including storage volume, runoff flow rates, water quality, and erosion control. Underground stormwater detention systems maximize the land use of the development, especially where space is tight and land costs are significant.

US Patents 10,435,880 B1





Infiltration and Pre-Treatment

Infiltration & Pre-Treatment

Retention with Packaged Pump Station

Rainwater Harvesting Package

Rainwater Harvesting Package

Detention or Infiltration with Advanced Treatment using Coalescing Separators and Filtration Systems

Detention or Infiltration with Advanced Treatment using Coalescing Separators and Filtration Systems

How It Works

  1. Diverted stormwater runoff is captured and pumped into precast concrete detention and infiltration structure.
  2. Stormwater runoff is pretreated for removal of trash and debris through Jensen Deflective Separator.
  3. Coalescing separators and filters perform advanced treatment of stormwater runoff pollutants.
  4. Treated stormwater runoff is stored via rainwater harvesting package for irrigation use or slowly released via infiltration into the ground.



  • Detention
  • Retention
  • Infiltration
  • Release / Discharge Flow Controls


  • Full Capture of Trash and Debris
  • Total Suspended Solids (TSS)
  • Metals
  • Nutrients
  • Total Petroleum Hydrocarbon
  • Physical and Chemical Filtration (Media or Membrane)
  • Water Quality Diversion & High Flow Bypass


  • Biotreatment Soil Media (BSM) for biofiltration
  • Biodetetnion and Bioretention
  • Bioinfiltration
  • Slow Sand Filtration


  • Reuse Flow Diversion
  • Pretreatment
  • Cistern
  • Rainwater Harvesting Pump Station



Project: Culver City, CA

Project: Bell Gardens, CA

Project: Culver City, CA

Project: Anaheim, CA

Project: Lakewood, CA

Case Studies

Documents and Materials

Related Products

Rainwater Harvesting Systems

Rainwater Harvesting

Packaged Pump Stations

Packaged Pump Stations

Hydrodynamic Separators

Hydrodynamic Separators


  • Receive typical and site specific plan and profile drawings for all Jensen Stormwater System Units with engineer’s value estimates.
  • Leverage our readily available tools to support storage and runoff calculations, size our systems, and satisfy stormwater management goals.
  • Take advantage of Jensen Precast’s LID systems to seamlessly integrate our biofiltration and infiltration, and rainwater harvesting designs into areas with limited space.
  • Meet Full Capture requirements with state certified treatment systems.


  • Create competitive bids with quantified, specific information and pricing.
  • Get installation weights and guidance to support estimation of your installation effort.
  • No hidden installation requirements or costs.


  • Complete your projects on time with well constructable plans inherent into all Jensen Precast products for installations that are quick and easy.
  • Secure, safe delivery and timely setting of your stormwater management systems with our expert drivers and delivery personnel.
  • Gain peace of mind with our easy to maintain systems that require minimal upkeep and safe access postinstall.