HomeMy Public PortalAboutPublic Comment #034 (Jones)Nov. 10, 2014
To: Denyelle Nishimori, Town of Truckee
From: Sara Taddo Jones, SOS Glenshire organizational board member
Canyon Springs Draft EIR and Revised Draft EIR comments prepared for SOSGlenshire.org Board of
Director- Sara Taddo Jones
Noteworthy comments on biological section revisions, as well as in reference to the DEIR hydrology
section (K) from hydrologist David Shaw, Truckee, CA; Pertinent sections of comments in bold by S. T.
Jones:
Section 4.9B.1.a.i. states that "The primary sources of sediment identified in the TMDL are dirt roads,
urban stormwater runoff, legacy erosion sites, and in some watersheds, graded ski runs." The Lahontan
Water Board (Nilson, 2011, Truckee River TMDL Implementation Status Report) has expanded on this to
include other sources: construction, dam releases, population growth, urbanization, highway
operations, and industrial areas. There are a number of legacy erosion sites within the property and
immediately upstream and downstream, but I did not see any information in the project description
or water quality mitigation measures which suggest that legacy erosion sites will be addressed by the
project. For example, headward channel incision downstream of the site has the potential to move
upstream into the project area and compromise trail and road crossings, as well as on site and
downstream wetlands through desiccation and sedimentation, respectively. Existing and abandoned
roads and trails capture runoff and are eroding. If this project will contribute to the factors causing
sedimentation in the Truckee River (i.e. urban stormwater, population growth, urbanization) then the
project must contribute to implementation of the TMDL and the easiest way to do that would be
through addressing these legacy issues. There is an inadequacy in the DEIR addressing how erosion and
legacy sites will be improved and aiding in water quality improvement in the Truckee River. Not
addressing these issues will have a significant negative impact on water quality within the watershed.
Regardless of the TMDL, the DEIR and RDEIR states that 2-foot-wide soft surface trails will be located
primarily on existing trails. This includes a number of very badly eroding trails, some on very steep trails
with slopes up to 15% according a LiDAR-based surface. Without more detailed design information
beyond the statement that they will be replaced with a 2-foot-wide dirt path, we can only assume
that these trails will continue to erode and deliver sediment to receiving waters, significantly
impacting biological resources and water quality. The trails will also continue to be largely inaccessible
due to their steepness and eroded nature.
The floodplain mapping and hydrology appears to be entirely based on Appendix K, a Hydrology and
Hydraulics Report (CFA, 2003, completed for TahoeBoca, LLC- the previous proponent for this site). I
haven't examined the study very closely, but this should provide a reasonable assessment of the existing
conditions and 100-yr floodplain extents for the site. I agree with Jeremy that the 50-foot setback from
the floodplain may not achieve the goal of limited runoff, erosion, and sedimentation on the floodplain,
and they should be looking at hydrologic connectivity from individual lots, rather than a blanket setback.
Figure 3-5 in the DEIR shows a number of grading areas within the 100-ft buffer from the edge of the
drainage way.
The DEIR states that a "Final Hydrology and Hydraulics Report is not planned to be prepared." As
Jeremy has pointed out, this is problematic because a hydrology analysis will be required for them to
appropriately site and size retention basins. Section 4.9F states that "...as illustrated in the drainage
plan, runoff would be captured and detained through the use of vegetated swales and retention
basins..." It is not clear what drainage plan they are referring to, but if it is based on the older hydrology
report, the sizing and siting may be incorrect.
These retention basins are shown in the RDEIR Biological Resources Section and used as part of the basis
for determining impacts (i.e. the basins are treated as impacts). If these are sited or sized incorrectly,
then the basis for determining the associated impacts is incorrect. It is also not clear whether these
are also intended to be outside of the floodplain and drainage way buffers.
The mitigation measures in the hydrology section appear to be exclusively oriented toward controlling
sediment, even though the DEIR points out that urban pollutants such as hydrocarbons and heavy
metals are anticipated to introduce a potentially significant impact. How will this impact be addressed
in the actual project?
Section 4.9C.3.d states that "Pre-cast concrete arch bridges are planned to span the width of the
drainage ways." This is inconsistent with other descriptions of road crossings, which describe clear-
span bridges being used to avoid any impacts to drainages (Bio Res p. 4.4-41). Clear span bridges and
pre-cast concrete arch bridges are different. If arch culverts are used to span the drainage way, fill
may need to be placed within the floodplain, which would likely substantially alter existing drainage
pattern of the site at the 100-year flow. Arch culverts will also likely require placing fill within the
100-year flood hazard area, as mapped in the 2003 study. Also, without detailed bridge design
information, and supporting hydraulic information, it is not clear whether armoring of the channel will
be required to protect these bridges from scour. If it turns out that armoring is necessary, this would
constitute additional wetland and 100-yr floodplain impacts. Finally, it’s important to note that it is
possible to convey the 100-year flood without spanning the 100-year floodplain, so this conveyance
should not be construed as "no impact" on its own.
It is unclear whether wetland plants can survive under either a clear-span bridge or under a wooden
footbridge, so an argument could be made that the impacts to wetlands associated with these
structures is not solely from fill placed in the wetland, but also may be induced by limitations on wetland
functioning due to shading from the structures.
The Biological Resources section describes impacts to wetlands associated with the installation of
wood pilings for the footbridge crossings (p. 4.4-37). This implies that these pilings will also be placed
in the 100-year floodplain. Similarly, there is not discussion of the footbridge structures within the
hydrology section of the EIR, and if or how they will be designed to convey the 100-year flow event, or
otherwise obstruct drainages. How will these wetland impacts be mitigated?
Some smaller but noteworthy items:
1) Section 4.9C.3 incorrectly states that "several ephemeral drainages trend northeasterly through the
northern, central, and southern portions of the site." The drainages found on site have a wide variety of
flow directions, i.e. one flows to the southwest, one flows to the northeast, one to the northwest, etc.
Please correct these descriptions in the Final EIR.
2) Section 4.9C.3 also refers to "Relatively Perennial Waters (RPWs)" but this terminology is not seen
elsewhere in the EIR. It is not clear what this designation signifies or what the implications are.
3) Section 4.9C.3.b says that that surface water was observed in the northwestern portion of the
northernmost drainage, "within the wetlands area." No wetlands, however, are shown in this area on
the wetland delineation. Please correct the wetland identification through a certified wetland
delineation in the Final EIR.
4) The EPA maximum contaminant level for arsenic is incorrectly stated as .05 mg/L. The MCL is .01
mg/L.
5) The Biol. Res. Section (p4.4-26) states that the project site does not contain densely vegetated or
rocky areas that Sierra Nevada red fox typically utilize for cover and denning. Figure 4.6-2 in the DEIR,
however, shows "basalt outcrop" within the project area.
That concludes this comment list and letter.
Regards and signed electronically,
Sara Taddo Jones
Board Member
SOS Glenshire
Resident- Truckee, CA