HomeMy WebLinkAbout1997.10.17 - CT Pipeline Permits and Studies4,J W L
MEMORANDUM
DEPARTMENT OF PUBLIC WORKS o QaaT7 JP
mENGINEERING 'DIVISION A.
5 17 TYLER STREET
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PORTTOWNSEND, WASHINGTON 98.368
360) 385 -241 3 (360) 379-51 77 FAX `a`WA
to: Bob Wheeler, Dave Peterson
from: Paula Mackrow
subject: CT Pipeline Permits and Studies
date: October 17, 1997
cc: J. Surber, B. Freeland, J. Randall; PT BCD
S. Gibboney, D. Mason;• PT Engineering
B. LaCroix; Water Quality
Phil Martinez, Roger Bieiler; CH2M HILL
J. Fleming, M. Szatlocky, D. Llewellin, L. Palazzi, P. Kline
The purpose ofthis memo is to clarify and summarize the findings of the wetland workshop onOctober9, 1997 regarding the permit requirements for the CT Pipeline.
1) Critical areas in Basin 11 associated with the pipeline route include critical drainage
corridors by ESA Ordinance definition, frequently flooded areas by local knowledge
as outlined by John Fleming's April 97 reconnaissance, and wetlands delineated byPalazziandKlinein1993andOctober1997.
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As per ESA Ord. PTMC 19.05.090 (G.) Special reports are require for all development in
frequently flooded areas and critical drainage corridors to establ' that the proposed
development will not create a hazard to the property involved r to other properties in located in
these areas. While a flood plain report would need to demon ate that the project will not reduce
the base flood storage volume, creation of additional impe ions surface in the drainage corridor `a
or potential floodplain is not proposed for the CT pipeline. evelopment of a detailed contour is
map in the flood plain would entail considerable encroachment on the existing,tl ? 'V-
vegetation in both drainage basins. The usefulness of this information combined with a HEC 2
model was considered unnecessary based on the relatively low gradient, headwater osition in
the drainage corridor. The lack of additional impervious surface in the proposal makes analysis
of the pipeline's. probable impact on the drainage basin relatively insignificant to adequately
calculate through modeling.
It was agreed that report requirements for frequently flooded areas and critical drainage corridorsincludingcomplete - Ioodplain analysis, modeling and topographic surveying would not be
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required if enough information was available to determine that the pipeline is consistent with
performance standards and intent of the ESA Ordinance. r%vct S2J2 . ia. os. 0c, 0 --U
Lisa and Pesha worked with John Fleming to reconfirm the 1993 -4 wetland field delineation. The
areas that were flagged are so consistent with the previous study that Lisa has recommended
against the need for an additional survey in the Rainier Street Corridor. Please note that the work
done on the eastern edge near and beyond Howard Street was flagged in 1993 but not surveyed
because the exact boundary was irrelevant to the pipeline proposal. Flags from that delineation
were recorded in the 1995 GPS field work. The letter report does define the area as a probable
class II wetland greater than 5,000 square feet in close association-with the wctlaz d_to_ -the ._north.
This wetland delineation has verified that all of the project impact area is proposed outside of the
delineated wetland area along Rainier Street. BCD has indicated that hydrologic im act anal s* "
is need sr l Patent it can be shown that the wetland hydrology will not be altered —`
through interception of subsIMfIUe flwu. Avoidance of impacts or mitigation proposals may
include measures that effect the design specifications and construction disturbance zone. The
Y? route and construction zone are likely inside the 100 foot wetland buffer as previously1pipeline
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2) Critical areas in Basin 15 associated with the pipeline route also include wetland,
frequently flooded and critical drainage corridor issues as defined in letter reports
from 1994 and delineated in October 1997.
Additional wetland field delineation was completed in the southern wetland at Howard Street and
Sims. This is now delineated as a jurisdictional wetland about 113 acre in size. Lisa noted that
the drainage probably continued across the power line road and contained pockets of wetland
plants. ` - E
The issues of th PYoward Street opening at Sims Way (SR 20) and the placement of the pipeline
in the 11sid asernent or in the drainage corridor/ wetland needs to be resolved. Resolution
shoul e as soon as possible in order to begin the ESA application and evaluation of impacts to
that area related to the pipeline. Avoidance of impacts or subsequent mitigation proposals may
include measures that effect the design specifications and construction disturbance zone in this
section of the pipeline as well as at the north end.,,,,
Additional studies and reports for the ESA permit that have been identified to date are:
1. Survey of wetland delineated and flagged every 25 feet in the Howard Street corridor
south of Sims Wa and east to the power line easement.
2. Survey of the centerline of the watercourse in the same area (PTMC 19.05.090 (C))
3. Geohydraulic analysis of the impact of the trench construction on flows in Basin 11.
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4. Buffer Mitigation Plan including a habitat analysis in accordance with PTMC
19.05.110 (E)2, and (E)5.c
5. Stormwater Control Management Plan including detailed erosion control measures, a
site mitigation plan and monitoring measures.
It is likely that no additional Army Corps of Engineers permitting would be necessary if the
pipeline does not impact the wetland south of SR 20.
Excavation and grading permit is necessary. Street development permitting is not likely. Boring
under SR20 may require a traffic control plan.
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