Mission Gate and Lunette Archaeology - March 6

March 6, 2023

Ground disturbance occurred throughout the week at the Project Area. There were two main excavation activities this week. The first was the installation of the helical piles. These screw-like piers were installed at the location of the two east-west archaeological trenches that were previously excavated. The trenches were backfilled with spoils, as a result the helical piles were drilled into previously excavated soils. The installation of the helical piles produced a small amount of spoils mounded around the pier (Figures 1 and 2). Once installed, the piers are left in the ground. No artifacts were observed during the helical pile installation.

Dirt section of excavation area zoned off with cones with a truck and workers in the background
Figure 1. Installation of helical piles, facing south.
Man in yellow T-shirt and construction hat squatted in excavation dirt area
Figure 2. Installation of helical piles, facing southeast. Note the low accumulation of matrix around the pile.

The other excavation activity during week 14 was the excavation for the lunette exhibit (Figures 3 and 4). This excavation was located where a live oak tree previously resided. After the tree was relocated, approximately 30 inches of soil was reintroduced to the area, which raised the level to approximately 12 inches above the Alamo Street surface level. Excavation into this raised area occurred for two days and followed the shape of the planned lunette trench exhibit. Depths of excavation were approximately 12 inches below the raised surface. The only cultural material observed was a fragment of PVC pipe and a fragment of concrete.

No other ground disturbance occurred during the week.

Two rows of dirt dug out with construction truck in excavation area
Figure 3. Excavation for the lunette exhibit, facing south.
Two L shaped rows of dug out dirt in construction zone
Figure 4. Completed excavation for lunette exhibit, facing north.