Resolving Municipal Stormwater Issues with GEPS®

5 days ago
4 min read

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Every spring, the calls start coming in. A resident's yard holds water for days after a storm. A basement floods for the third year running. A low-lying neighborhood turns into a temporary pond after a moderate rain event. The homeowners do what any reasonable person would do: they call their municipality and ask for help.

And here is where things get complicated. The municipality wants to help, but often cannot offer the one solution the resident expects: a new connection to, or increased discharge into, the existing storm sewer system. The pipes are already at capacity. The infrastructure is aging. Regulators are watching. The system simply cannot absorb more stormwater.

Both parties end up in a frustrating impasse. The resident has a real, legitimate problem. The municipality has real, legitimate constraints. And the gap between those two realities has historically been filled with expensive workarounds, or nothing at all.

Exlterra's GEPS® (Groundwater Energy Passive System) technology was built precisely for this gap.

The Municipal Stormwater Dilemma

Most stormwater infrastructure in American cities and towns was designed decades ago, sized for a landscape that no longer exists. Suburban sprawl has replaced permeable fields and forests with rooftops, parking lots, and compacted lawns, surfaces that shed water rapidly instead of absorbing it. The result is that storm sewers, designed for pre-development hydrology, now receive far more water than they were engineered to handle.

When a resident's property has a drainage problem, the instinctive fix is to route that water somewhere else: a catch basin, a street drain, a tie-in to the municipal system. But municipalities operating under MS4 permits, combined sewer overflow control programs, or simply capacity constraints cannot legally or practically accept additional stormwater inputs. Doing so shifts the flooding problem downstream, increases treatment costs, and puts the municipality out of compliance with state and federal regulators.

The options historically available to residents are almost universally problematic. Expensive underground drainage systems require major excavation. French drains may simply move water to a neighbor's property. Detention cisterns need to be manually emptied or pumped. Regrading is disruptive and often short-lived. Draining stormwater onto a neighbor's yard is a potential nuisance liability. And sump pumps typically discharge to the storm system anyway, which circles right back to the original constraint.

What neither the resident nor the municipality had, until recently, was a tool that removes water from the problem entirely by returning it to where it naturally belongs: the ground.

What GEPS® Actually Does

GEPS® works by fundamentally improving the soil's own capacity to accept and distribute moisture, operating in harmony with the natural hydrological cycle rather than circumventing it. There are no pumps, no electrical requirements, and no connections to the storm sewer.

There is no trenching, no major excavation, and no removal of material, so lawns and landscaping remain intact. The top of each unit sits roughly two feet below grade, capped to prevent direct surface channeling.

Over an acclimation period of several months, the GEPS® units allow water to move more freely through the vertical and horizontal soil matrix, turning the soil itself into a more effective sponge.

The outcome is a lasting transformation in how that ground responds to precipitation. Water that would have pooled, run off, or overwhelmed drainage infrastructure instead percolates into the soil.

No connection to the municipal system is required, and no new volume is added to already-stressed infrastructure.

Why This Is the Tool Municipalities Have Been Waiting For

GEPS® reframes the entire relationship between a resident's stormwater complaint and what a municipality can offer in response. Instead of telling a homeowner that the system cannot accept their water, municipalities can point to a solution that resolves the problem on-site, without adding a single gallon to the storm sewer system.

This has meaningful implications across several areas:

Regulatory Compliance
- Municipalities operating under MS4 stormwater permits or combined sewer overflow control programs face strict limits on total system inputs. Facilitating GEPS® installations in residential neighborhoods actively reduces the volume entering the municipal system, supporting compliance rather than threatening it. Every acre of residential property that infiltrates more effectively is one less acre sending runoff downstream.
Infrastructure Longevity
- Reducing inflow and infiltration at the source, in residential soils, helps extend the useful life of existing pipe networks and defer costly capital replacement projects. Prior studies also found that GEPS® reduced groundwater infiltration into old, porous storm sewer pipes, further lightening the load on aging infrastructure.
Equitable Service
- Without an on-site solution, lower- and middle-income residents facing drainage problems are often left with no good options. Engineered French drain systems, underground dry wells, and professional regrading are simply out of reach for many households. GEPS® offers a scalable, comparatively accessible technology that municipalities can explore supporting, subsidizing, or recommending as part of their stormwater assistance programs.
Neighbor Relations and Nuisance Avoidance
- When residents cannot get municipal help, some take matters into their own hands, regrading their yards to push water toward a neighbor or installing pipes that discharge onto adjacent property. These situations generate complaints, sometimes litigation, and always headaches for municipal staff. GEPS® addresses water where it falls, on the property where the problem exists, without displacing it elsewhere.

A New Conversation Between Cities and Their Residents

The stormwater challenge facing municipalities is not going to get easier. Changing precipitation patterns, more intense storms and longer dry spells followed by heavy rainfall events, are placing increasing demands on infrastructure that was never designed for today's conditions. Meanwhile, the cost of leaving residents with flooded yards, wet basements, and no path forward is real and growing.

GEPS® fills a specific, critically underserved gap: the residential stormwater challenges that cannot be solved by connecting to the storm sewer. For municipalities, it offers something rare: a way to say yes. A genuine, validated, minimally invasive solution that works on the property where the problem exists, without adding burden to a system already under strain.

That is the answer residents have been waiting for. And it is the answer municipalities can now actually offer.