Key Points

📍 Site Overview

• Location: Adjacent to Eagle Lake’s legal elevation (899.26 ft)

• Infrastructure: Sewer lines—including SA 408 (896.66 ft)—are placed within saturated soil zones

• Soils: SW-classified sands with low cohesion and weak filtration

Implication: Infrastructure cannot be safely supported under current subsurface conditions. Standard development methods risk trench collapse, pipe failure, and noncompliance with groundwater protection regulations.

 🧪 Hydrogeological Conditions & Engineering Risks

Findings:

• Borings SB-03 and SB-09 reveal saturation from near-surface to 15 ft

• Loose, non-cohesive sands with no dry zones

• Seasonal groundwater rise and fall amplify stress on buried utilities

Gradient Concern:

• Sewer pipes dip below both Eagle Lake and Pine Island Lake elevations (~4 ft differential)

• May form unintended inter-basin groundwater flow paths

Implication: Persistent high water tables and elevation inversions jeopardize utility alignment and trench integrity. Without specialized mitigation, infrastructure may act as a conduit for contaminant transfer and hydrostatic imbalance.

 ⚠️ Stormwater Management & Compliance Risks

Issues Identified:

• Drainage basins may trigger hydraulic mounding

• Recharge near pipes intensifies saturation and instability

• Shortened Time-of-Travel (TOT) pathways risk violation under Wellhead Protection Ordinance

Implication: Standard infiltration-based drainage is incompatible with the corridor’s subsurface behavior. Without engineered controls, basins could violate aquifer protection thresholds, lead to contaminant migration, and compromise sewer stability.

 🌿 Environmental Impacts

Wetland Sensitivity:

• Sewer breach or misrouted stormwater threatens sensitive habitats

• Nutrient-rich runoff may cause algal blooms and aquatic degradation

  Lake System Vulnerability:

• Eagle Lake’s pumped system risks contaminant recirculation

• Prior flood events necessitated manual forced-main activation

Implication: A single infrastructure failure could have cascading environmental consequences. Contaminants entering wetlands or the lake basin may trigger ecological degradation, enforcement action, and jeopardize regional water quality.

 🧩 Historical Precedent & System Limits

Past Studies (2017 & 2019):

• Infrastructure expansion blocked due to chronic saturation

• Dewatering infeasible without costly or ecologically risky pumping

• SA 408’s elevation remains in conflict with safe trench conditions

Implication: This corridor has a documented history of failed infrastructure planning due to geotechnical limitations. The current proposal replicates prior risk factors without addressing foundational issues, forecasting repeat feasibility failure.

 🛑 Conclusion: Safeguard Aquifer Integrity

Due to persistent saturation, poor soil cohesion, and elevation-driven hydraulic complexity, The Sanctuary poses unacceptable risks to infrastructure integrity, groundwater protection, and environmental health. Texas Township's aquifer management strategy is undermined without sealed utilities, runoff containment, and elevation-adjusted engineering.

Recommendation: Deny final plat approval unless substantially redesigned with ordinance-aligned protections and hydrological resilience measures.

Overview

Hydrogeological Vulnerabilities and Potential Violations Under Texas Township’s Groundwater Protection Act

The proposed plat, The Sanctuary, positioned at or near Eagle Lake’s legal elevation, presents a convergence of hydrological instability, shallow invert depths, and regulatory fragility, particularly under the Wellhead Protection Ordinance. Engineering analyses reveal proximity to fluctuating groundwater and sensitive surface features, reinforcing conditions prone to environmental failure and ordinance breach.

Recent soil borings SB-03 and SB-09 offer direct indicators of subsurface saturation. SB-03 encountered loose sand beneath a thin topsoil layer, with moisture present just below the surface and transitioning to wet within a few feet. SB-09 mirrored these characteristics with medium-to-coarse grains and continuous wet zones extending to termination depths of 10 and 15 feet. The absence of a dry zone in either bore underscores a persistent water table and compromised filtration.

SA 408, with an invert of 896.66 feet, lies nearly two feet below Eagle Lake’s legal level and directly within the saturated zone mapped by both borings. Additional segments also fall beneath Pine Island Lake’s ~902-foot elevation, heightening hydraulic gradients and facilitating subsurface flow between basins.

Historical Constraints in the Sanctuary Plat Corridor

The corridor west of Finnegan along PQ Avenue has historically resisted infrastructure expansion due to chronic groundwater saturation. A 2017 sanitary sewer feasibility study and a 2019 engineering memorandum identified dewatering as impractical without significant pumping efforts. The plan was shelved after evaluations revealed untenable subsurface conditions, particularly near S. 4th Street.

The same groundwater regime persists today. Soil borings show saturation beginning as shallow as 2–3 feet and extending unbroken to depths of 15 feet, confirming that seasonal variation alone cannot explain these conditions. Regional groundwater flow, soil permeability, and elevation differential pose development challenges.

Without substantial shifts in engineering strategy, conventional sewer and utility installations remain unworkable. Elevated corridors, sealed utility designs, or non-traditional wastewater solutions must be prioritized to avoid repeating the infeasibility that defined prior setbacks.

Infrastructure & Environmental Risks

Seasonal hydrological fluctuations pose dynamic threats to sewer systems installed near lake-level elevations. Elevated groundwater increases buoyant forces during summer and jeopardizes pipe alignment, especially between 895 and 900 feet. In winter, declining water tables lead to external support loss, trench instability, and pipe stress. SW-classified soils further exacerbate settlement and filtration concerns, amplifying long-term structural vulnerability.

 Stormwater basins within the plat add a layer of risk. Infiltration may trigger hydraulic mounding in well-drained sandy soils, shortening Time-of-Travel thresholds and increasing direct recharge to underlying aquifers. SA 408 and other low-elevation pipes are especially susceptible, with basin-induced saturation intensifying trench fragility and contaminant migration.

Where pipe segments traverse below Eagle Lake and Pine Island Lake elevations, the sewer may inadvertently form a gradient-driven flow path, accelerating inter-basin groundwater movement. Without engineered interruption—such as trench seals or hydrological breaks—this design could invite instability and elevate pollutant transfer risks.

Potential Risks

The Sanctuary subdivision—positioned near Eagle Lake’s legal elevation of 899.26 feet—poses acute hydrological and infrastructure vulnerabilities. Soil borings SB-03 and SB-09 confirmed persistent saturation within the upper 15 feet, with loose sands and no dry zones encountered, reflecting a chronically high water table. Pipes with invert elevations between 895 and 900 feet, such as SA 408 at 896.66 feet, lie directly within this saturated zone, making them prone to buoyant forces, joint displacement, and trench instability.

SW-classified sandy soils throughout the plat lack sufficient cohesion and filtration capacity. These conditions exacerbate trench erosion, contaminant migration, and maintenance demands. Existing erosion control measures, such as check dams and inlet protection devices, are poorly suited for environments experiencing sustained subsurface saturation, increasing the likelihood of overflow and structural undercutting.

Segments of the proposed sewer system appear to dip below both Eagle Lake and Pine Island Lake elevations, inadvertently forming a gradient that could drive groundwater movement between the two basins. Without engineered barriers, this layout risks contaminant transfer and pressure imbalance. The inclusion of stormwater basins within the plat, though intended for infiltration, may elevate the local water table further and induce hydraulic mounding near critical infrastructure. In this context, shortened Time-of-Travel (TOT) pathways pose additional compliance concerns under the Wellhead Protection Ordinance.

Environmental Impacts

Proximity to wetland areas compounds ecological risk, as sewer system failure or stormwater misdirection could introduce pollutants into sensitive zones. Such disruptions may destabilize wetland hydrodynamics and violate protective thresholds set by township ordinance—even if originating from approved infrastructure. Eagle Lake’s status as a pumped basin further increases vulnerability; contaminants reaching the lake may be circulated through the pump system, diminishing water quality and raising enforcement implications.

Past reliance on manual forced-main activation during flood events reveals the system’s limited resilience. Any added sanitary load from development—especially under saturated conditions—threatens to overload existing capacity. Moreover, stormwater runoff laden with nutrients and thermal discharge could initiate algal blooms and aquatic degradation, particularly during seasonal drawdowns when aquifer pressure and filtration defenses are weakest.

Conclusion: Prioritize Aquifer Integrity

Given this corridor's persistent saturation, low soil cohesion, and elevation-driven hydraulic complexity, conventional development carries significant environmental, structural, and regulatory risks. The plat may compromise the region's aquifer integrity and long-term pumping viability without sealed utilities, runoff containment, and phased construction accounting for seasonal fluctuation. Historical setbacks and current bore data affirm that these risks are endemic—not exceptional—and warrant the denial of final plat approval to safeguard ecological stability and compliance under township ordinance.