Abstract. Haddam Meadows State Park in Haddam, Connecticut, serves as a test site for the Branch of Geophysical Support of the USGS in Connecticut. At this site, various geophysical techniques are tested for detection of structures that could influence DNAPL migration. DNAPL's, Dense Non-Aqueous Phase Liquids, sink through the water column until reaching an impermeable boundary. The geology of Haddam Meadows consits of Ordovician metamorphic bedrock, ~43 m deep, overlain by glacio-fluvial and alluvial deposits. If DNAPL's were present at this location, and if no other aquitards exist above bedrock, they should collect in topographic lows in the bedrock. A 3D seismic data set was collected at the site to determine the feasibility of constraining bedrock topography via seismic methods. 120 channels of data were recorded along five parallel receiver lines and recording ground motion from an evenly-spaced shot-point grid. Although acquisition was rapid (2 days), the offset, azimuth, and full-fold range of the data set is restricted, limiting our ability to examine bedrock structure. Data are reduced and interpreted using conventional oil-exploration methods. Two prominent reflections are observed. Both of these tie to a VSP data set collected in the same area. The upper reflector corresponds to the refusal depth of the well from which the VSP was acquired. This reflector can be interpreted as either the top of fractured bedrock or the top of an overlying till layer. On the basis of previous refraction studies, we prefer the former interpretation. The lower reflector shows less topographic relief and is approximately 61 m deep. It is distinguished by larger amplitudes and is spatially more continuous. We interpret this reflection as originating from the top of competent bedrock. Amplitude anomalies along each reflection are examined. We interpret the observed amplitude anomalies as being indicative of mineralogic changes with the bedrock that could be related to remineralization of open fractures, or to the presence of pegmatites. Compared to the cost of drilling shallow test wells or acquiring less costly geophysical data sets, 3D seismic surveys, at this site, have limited economic viability. Investigations that might be deemed suitable for the application of 3D near-surface seismic include those that 1) contain acquicludes of sufficient thickness, lateral extent, and velocity contrast to be resolved by seismic methods, 2) have targets that are relatively deep (>15 m), 3) display significant spatial variability in target depth, target properties, or target continuity, and 4) require the use of noninvasive methods.