FEIS - Tahoe Regional Planning Agency
FEIS - Tahoe Regional Planning Agency
FEIS - Tahoe Regional Planning Agency
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
RESPONSE TO COMMENTS ON THE DEIS<br />
B o u l d e r B a y C o m m u n i t y E n h a n c e m e n t P r o g r a m P r o j e c t E I S<br />
sediment. The total sediment load reduction predicted by the LSCP model is actually<br />
between 97-100% for Alternative C (C100), of which fine sediments are assumed to<br />
comprise between 60-90% of this total.<br />
Comment 335-h: Comment Summary - Baseline water quality studies need to describe how data relate<br />
to 20-, 50, and 100-year events, first flush events, TRPA Surface Water Discharge<br />
Limits, and a discussion of how the small sample size and non-TMDL sampling<br />
methods affect the results and interpretation.<br />
a) The storms sampled in 2008 and 2009 vary between 0.08 and 1.23 inches of total<br />
precipitin (rain, snow and rain on snow events were captured). The 20yr/1hr storm is<br />
reported at 1 inch over a unit area for the duration of one hour, the 50yr/1hr is<br />
reported at 1.25 inches, the 100yr/1hr is reported at 1.55 inches. b) The samples were<br />
taken as close to the peak as possible to correspond to a "first flush". The difficulty<br />
on measuring this first flush using grab sample methods is noted. c) TSS is Total<br />
Suspended Solids, while SSC is Suspended Sediment Concentration. Both provide a<br />
measure of the non-dissolved particles within a unit of water, the difference arises in<br />
the methods of analysis. See http://water.usgs.gov/osw/pubs/ASCEGlysson.pdf for<br />
more information. d) The DEIS was discussing compliance with TRPA discharge<br />
standards and since TSS is not a TRPA standard, concentrations are discussed instead<br />
of compliance. The results are detailed in DEIS Appendix P and are discussed by<br />
storm event. e) Comment does not require a response. f) Automated samplers were<br />
not used in the pre-project monitoring because of site constraints. Automated<br />
samplers have not been installed to date. The commenter states that TMDL methods<br />
were not followed but does not outlined the methods that should have been followed.<br />
The response assumes that the commenter is referring to sediment loading. Loading<br />
calculations are referenced to Appendix AB. g) See Appendix AB, which presents a<br />
supplemental water quality analysis incorporating DRI data collected on<br />
approximately half of the project area. The DRI studies captured complete flow and<br />
concentration measurements for 12 storm events through January 2008. Note that the<br />
JBR event grab sampling data for 2008-2009 was found to be consistent with the<br />
more complete DRI data. Please see response to comment 79-h.<br />
Comment 335-i: Comment Summary - The EIS cannot evaluate impacts if procedures to treat<br />
stormwater in the underground parking garage have not been developed.<br />
The maintenance of the underground parking garage will be determined for<br />
Alternatives C or D, if selected, and included in the Inspection, Maintenance and<br />
Monitoring Plan (SP-10) prepared for TRPA permitting of the selected Alternative.<br />
Based on communications with IVGID, the existing sewer system can adequately<br />
absorb this wash off if necessary.<br />
Comment 335-j: Comment Summary - The EIS should document the efficacy of pervious pavers and<br />
vacuum sweepers.<br />
A number of studies have been completed for LID strategies in cold weather<br />
climates. The DEIS documents the efficiency of pervious pavers and vacuum<br />
sweepers by reference. The TMDL Pollutant Load Reduction Plan included in DEIS<br />
Appendix R provides further documentation. The remaining comments will be<br />
addressed in the Inspection, Maintenance and Monitoring Plan that will be based on<br />
the selected Alternative as a condition of project permitting.<br />
Please see response to comment 137-e.<br />
SEPTEMBER 8 , 2010 HAUGE BRUECK ASSOCIATES PAGE 8- 145