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7540 Main Street
Suite 7
Sykesville, MD 21784
410-795-4626 phone
410-795-4611 fax
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Chronic Wet Basement Evaluation Causal Link to Foundation Fill Compaction Improprieties - Expert Witness Testimony and Litigation Support
Confidential Residential Client
A homeowner experienced chronic wet basement conditions, and neither
sump-pump installation nor a builder-paid treatment of the exterior
foundation wall resolved the problem. We theorized on the probable presence
of some on-site fill materials and that the differential porosity and
permeability between virgin soils and fill could exacerbate seepage
problems. Published information on the local geology and soils supported
these theories, as did a visual reconnaissance of the site setting with
focus on uphill stormwater management measures.
ALWI made soil borings in both the fill proximal to the building, and in the
surrounding undisturbed soil. No evidence of a seasonally high water table
(i.e., standing water in the boring(s), gray color tones in the soil
material, gleying of the soil, low chroma (i.e. muted colors) and mottling)
was observed. We then simulated typical lawn watering and heavy
precipitation events, while using water-soluble fluorescent dye to recreate
a variety of natural conditions and to trace the potential response of
indoor water seepage to outdoor surficial water (and dye) application.
Because the client was contemplating a legal remedy against development
and/or construction interests, careful attention was paid to quality
assurance and control measures. For example, prior to the introduction of
dyed water to the outdoor land surfaces, ALWI first performed a preliminary
visual assessment of both indoor and outdoor areas. The initial indoor
assessment focused on observing the basement floor and walls for signs of
antecedent moisture and ultraviolet fluorescence prior to the test.
Although the indoor basement walls were dry before ALWI began simulating
lawn irrigation and precipitation events, they began to get wet less than
four hours thereafter, but not immediately because of low soil
permeabilities. No other source of water, natural or otherwise, explains
these observations during this short time period. We concluded that
emplacement and/or compaction of fill materials surrounding the residence
increased the local likelihood for the seepage conditions.
We recommended the following remedial measures:
- Excavation of soils adjacent to the foundation to the invert elevation of the basement floor.
- Inspection of the exterior foundation wall and its repair as necessary.
- Application of a waterproof foundation sealer to the exterior and interior walls.
- Installation of a deeply-trenched, sloping french drain system, with appropriately selected and graded backfill materials, to channelize it for safe down-gradient outfall.
- Delay of basement improvement plans (to include vapor barriers, ventilation and inspection access) until the efficacy of remediation was monitored through at least one winter/spring season of normal or high precipitation.
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