I-10 Twin Peaks Traffic Interchange, Environmental Assessment

Affected Environment and Environmental Impacts October 2005
approximately 3 feet above the ground at center. The central notch is 5.5 feet wide,
1.5 feet deep, and has a narrow groove that perhaps once held a gate. The second
feature at the site was a shallow swale aligned perpendicularly to the center of the
weir. The swale was approximately 30 feet wide, 2 to 3 feet deep, with low berms
on both sides. The swale could be traced for approximately 150 feet to the northnorthwest
and about 550 feet to the south.
The age of the structure is unknown, but the appearance of the concrete suggested
it dated from the first or second quarter of the twentieth century. The swale was a
silted-in ditch that once carried water, and the weir controlled the flow. The ditch
generally paralleled local contours, but sediment indicated that water flowed to the
north. The North Tucson Basin Survey noted similar ditches to the southeast, and
hypothesized that they were dug to collect rainfall runoff and channel it to bean
fields on the Santa Cruz River floodplain to the west; however, the ditch at this site
does not seem to be oriented to delivering water to the floodplain. The ditch might
have been built to control sheet flow erosion, but the weir does not resemble any
recorded structures built by the Civilian Conservation Corps.
Historic Trash Scatter AZ AA:12:956(ASM)
This site was a sparse scatter of historic cans and broken glass that was recorded
during the field surveys for this project. The irregularly shaped site was
approximately 70 feet wide and 160 feet long. A count of surface artifacts tallied
134 items, but they appear to represent only 30 cans, three glass bottles, and a
crown cap. The artifacts represented food cans, milk containers, key-opened
sardine cans, one tea container, one possible ketchup container, and a patent
medicine bottle. The assemblage is quite small and may have been a secondary
dump of household debris, or possibly the remains of a short-term camp.
The most chronologically diagnostic artifacts were hole-in-top (matchstick filler)
milk cans, which suggested a date in the early 1920s. Although the sale of patent
medicine was outlawed by the Pure Food and Drug Act of 1906, patent medicines
continued to be sold into the 1920s because of loopholes in the law and the
relatively minor fines imposed for violations.
Cortaro-Marana Irrigation District Canal AZ AA:12:957(ASM)
The CMID Canal and two related wells were recorded during the field surveys for
this project. The recorded segment of the irrigation canal site was approximately 3
miles long. The canal was concrete lined and approximately 10 feet wide and 3
feet deep. Thirteen features were recorded along the length of this canal. Seven of
the features were inverted siphons that carried the canal beneath washes. One
siphon was associated with a double culvert. Five of the features were simple slab
bridges that allowed vehicle access from the I-10 westbound frontage road
(Tucson-Casa Grande Highway) across the canal. One feature was a set of gates to
control flow to lateral canals.
Two historic-age wells associated with the CMID also were identified. Well 16
was a fenced well site that may have been drilled as early as 1919 and Well 22 was
Interstate 10 Traffic Interchange at
Twin Peaks/Linda Vista
4-71
Project No.: NH-010-D (AIW)
TRACS No.: 10 PM 236 H5838 01D