FEIS - Tahoe Regional Planning Agency

RESPONSE TO COMMENTS ON THE DEIS
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
See DEIS Appendix R, which outlines the assumptions made for LID performance
strategies (termed TMDL reduction). In all instances, calculations use the most
conservative of values. The following references are incorporated as support of LID
strategy performance and effectiveness:
http://www.unh.edu/erg/cstev/;
http://water.washington.edu/Research/stormwater.html;
http://www.epa.gov/owow/nps/lid/costs07/documents/reducingstormwatercosts.pdf;
http://www.lowimpactdevelopment.org/lidphase2/;
http://www.nrdc.org/water/pollution/storm/chap12.asp;
http://www.nrdc.org/water/pollution/storm/stoinx.asp; and
http://www.dot.ca.gov/dist3/departments/envinternet/deicer/03A1295NEAT_2010Ma
rch.pdf.
a) Pervious pavers were calculated at 50% reductions, which is already conservative
based on reported performance abilities of 70-90%. This conservative approach
accounts for variable performance expected for cold weather climates.
b) Maintenance will be determined by post-project monitoring results and in
accordance with the Inspection, Maintenance and Monitoring Plan (SP-10) developed
for the selected Alternative.
c) Modeled performance for green roofs was calculated at 20% to account for cold
weather climate. Effectiveness of green roofs could be greater, but calculations use a
more conservative assumption. The length of monitoring will be determined during
permitting of the selected Alternative. Snowfall and freeze/thaw cycles will affect
green roofs performance, which is why the conservative 20% was used in the
calculations.
d) See Appendix AB for predicted load reductions. The supplemental water quality
analysis predicts reductions of total sediment of 97-100% for Alternatives C and D.
Tables 2 and 3 present the load reductions by pound for a variety of water year
conditions between 1993 and the present.
Comment 335-af; Comment Summary - Clarify the type of sweeper that will be used: high efficiency,
vacuum, regenerative air, dustless.
The type of sweeper that will be required will be determined by TRPA based on the
selected Alternative. The sweeper will incorporate a vacuum fan design that delivers
superior dry-dust control that meets stringent PM-10 environmental requirements
consistent with the Tennant Sentinel and Tymco DST sweepers. The regenerative air
street sweeper and associated effectiveness for removal of sediment is presented in
DEIS Appendix R as an option for the Project. The frequency of sweeping will be
determined as part of the Operations and Maintenance Plan and amended based on
post-project monitoring results. The TMDL reduction parameters table is a summary
of the strategies proposed.
Comment 335-ag: Comment Summary - The EIS needs to quantify expected population levels and water
supply needs for each Alternative, and compliance with TROA on a project-level and
cumulative level; identify water supply sources and rights.
Population levels per Alternative are discussed in Chapter 4.11-Socioeconomics,
Population, and Housing pages 4.11-10 through 4.11-14. Water supply needs are
provided on page 4.12-13 for Alternatives C, D, and E. Please see responses to
comments 322-br and 332-be regarding water rights purchase and TROA.
SEPTEMBER 8 , 2010 HAUGE BRUECK ASSOCIATES PAGE 8- 151