HomeMy WebLinkAbout1992.11.02 - Wetlands Regulatory Issues for City Water FacilitiesDave Peterson
CH2MHill
c/o Dept. of Public Works
5210 Kuhn St.
Port Townsend, WA 98368
206) 385 -2413
Report File Number: E92 -0059 (EES42323.007)
T
November 2, 1992
Report Subject: Discussion of wetlands regulatory issues on 2
properties being currently evaluated by the City as
sites for City.water facilities. Please refer to
Gregg Miller's Technical Memorandum of October 13,
1992 for additional details.
Location: Site 1: 12 acres in the SE 1/4 of the SE 1/4 of S4,
T30N, R1W -- partially wooded property west of Howard,
and approx. 1/2 mile south of Hastings; also, a
waterline route along the Rainier road easement
heading south from the southeast property corner to
Discovery Road, then along the Howard road easement to
a valve station on Sims.
Client:
Site 2: 10 -12 acres in the S 1/2 of the SW 1/4 of S4,
T29N, R1W -- currently woodland, but slated for
harvest in the next few months, approx. 1 1/2 miles
south of the Four Corners intersection, in the County
southwest of Port Townsend; also a waterline route
heading east approx. along the section line; also an
existing waterline route running along the powerline
easement SIN from the west side of S4 to the east side
of the Four Corners intersection.
Port Townsend Public Works
This letter report is provided, first, to yerify and supp ement the Undinas
of Gregg Miller's field reconnaissance, and -secondly. to provide.regulatory
guidance an t's ic is ds issues .
Both sites were visited by Lisa Palazzi, (ARCPACS certified soil.specialist,
Port Townsend wetlands specialist) on two different occasions to {check for
indications of wetland conditions. Ynitially, SCS soil maps, Port 'Townsend
wetland maps, aerial photos, and -- to a limited degree -- topography maps
were consulted to identify areas of concern on each site. Brief site visits
1
were used to verify, refute, or add to existing information.
No soil pits were evaluated, so soils discussions are based solely on
interpretation of the SCS soil mapping in the areas evaluated.
SOIL SERIES DESCRIPTIONS:
According to the Jefferson County soil survey, only one soil series is mapped
on the 12 acre proposed treatment site (Site 1) and along the entire length of
the proposed waterline route -- the Clallam gravelly sandy loam, -0_15% --slopes
classified as a loamy- skeletal, mixed, mesic Entic Durochrept').
S ITE 2 `
For Site 2, one soil series is mapped in the 12 acre proposed treatment side
Site 2) -- the Tukey gravelly loam, 0 -15% slopes (classified as a loamy -
skeletal, mixed, mesic Entic Durochrept').
Along the proposed E/W waterline, in addition to the Tukey, several other soil
series are mapped:
1) the Alderwood gravelly sandy loam and gravelly loam, 0 -15% and 15 -30%
slopes, (classified as a loamy- skeletal, mixed, mesic Dystric Entic
Durochrept') is mapped over the majority of the upland to the east;
2) the Belfast silty clay loam, wet variant, 0 -3% slopes (classified as
J.
1 Loamy - skeletal, mixed, mesic Entic Durochrept, generally meaning the soil
has minimal horizon development (ept and entic), has a pale- colored, low base
saturation surface horizon (ochr), has an silicate - cemented subsurface layer
dur), has a mesic temperature regime (mean annual temperature ranges from 8° to
15° C (47° - 59° F), has no specific mineralogic source (mixed), texture of the
fine fraction is loam and coarse fragment content is greater than 35% (loamy -
skeletal).
Loamy- skeletal, mixed, mesic Entic Durochrept, generally meaning the soil
has minimal horizon development (ept and entic), has a pale- colored, low base
saturation surface horizon (ochr), has an silicate- cemented subsurface layer
dur), has a mesic temperature regime (mean annual temperature ranges from 8° to
15° C (47° - 59° F), has no specific mineralogic source (mixed), texture of the
fine fraction is loam and coarse fragment content is greater than 35% (loamy -
skeletal).
Loamy - skeletal, mixed, mesic Dystric Entic Durochrept, generally meaning
the soil has minimal horizon development (ept and entic), has a pale - colored, low
base saturation surface horizon (ochr), has an silicate - cemented subsurface layer
dur), has a low sub - surface base saturation, generally indicative of poor
nutrient status ( dystric), has a mesic temperature regime (mean annual
temperature ranges from 8' to 15° C (47° - 59° F), has no specific mineralogic
source (mixed), texture of the fine fraction is loam and coarse fragment content
is greater than 35% (loamy- skeletal).
K
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coarse - loamy, mixed, non -acid, mesic Typic Udifluvent`) is mapped in the
bottom of a north draining channel just outside the eastern boundary of S4; C and _
3) the Cassolary- Everett complex, 15 -30% slopes, ( Cassolary classified as a
fine- loamy, mixed mesic Typic Xerochrept'; the Everett classified as a sandy -
skeletal, mixed, mesic Andic Xerochrept') is mapped on the eastern sideslope
of the drainage channel described above.
For the existing waterline running SIN, in addition to the Tukey, three other
soil series are mapped:
1) the Agnew silt loam, 0 -8X slopes, (classified as a fine - silty, mixed, mesic
Typic Ochraqualf') is mapped for approx. 1/4 mile along the line from Four
Corners south;
coarse - loamy, mixed, non -acid, mesic Typic Udifluvent generally meaning
the soil is very young with minimal horizon development (ent), is-a result of
periodic flooding activity (fluv), has a Udic moisture regime -- in most years
the soil between 4 and 12 inches depth not dry for more than 90 days (udi), has
otherwise average characteristics for these soil types (typic), has a mesic
temperature regime (mean annual temperature ranges from 8° to 15° C (471 - 59° F),
has a pH greater than 5.0 (non - acid), has no specific mineralogical source
mixed), has >15% sand content and <18% clay content by dry weight (coarse -
loamy).
5 Fine- loamy, mixed mesic Typic Xerochrept, generally meaning, soil has
minimal horizon development (ept), the surface epipedon has a pale color and low
base saturation (ochr), the soil has developed under climatic conditions of wet
winters and dry summers (xer), soil properties are otherwise typical of these
soil types (typic), has a mesic temperature regime (mean annual temperature
ranges from 8° to 15° C (47° - 59° F) , has no specific mineralogic source (mixed) ,
and has 15% sand and 18 -34% clay by weight (fine - loamy).
Sandy - skeletal, mixed, mesic Andic Xerochrept, generally meaning, soil
has minimal horizon development (ept), the surface epipedon has a pale color and
low base saturation (ochr), the soil has developed under climatic conditions of
wet winters and dry summers (xer), and the soil properties show influence of
volcanic input (andic), has a mesic temperature regime (mean annual temperature
ranges from 8° to 15° C (471 - 59° F) , has no specific mineralogic source (mixed) ,
has 15 -50% sand by weight and greater than 35% coarse fragments by volume (sandy -
skeletal).
Fine - silty, mixed, mesic Typic Ochraqualf, generally meaning the soil
has an argillic (clay) horizon and greater than 35% base saturation (alf), is
expected to have a seasonal high water table within 18 inches of the soil surface
aqu), has a pale - colored, low base saturation (less than 50%) surface horizon
ochr) , 'is otherwise typical (typic), has a mesic temperature regime (mean annual
temperature ranges from 8° to 15° C (47° - 59° F),.no specific mineralogic source
mixed), and is greater than 18% clay and less than 15% sand or coarser) by
weight (fine - silty).
I
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APPENDIX I lists and briefly describes expected characteristics for each of
the soil series mapped on the two sites.
SITE SPECIFIC CHARACTERISTICS
SITE 1 r
The Clallam soils -- gravelly sandy loam, shallow to glacial till -- are
mapped on the majority of Site 1. Site relief ranges from 290 feet at the
western edge to 260 feet near the northeastern corner. Precise information
about changes in elevation along the proposed waterline route to the south was
not available, but a site evaluation showed that the drop is relatively
gradual and, relative to the distance, the change in elevation appears to be
minimal.
The treatment plant site currently has a water storage tank at the extreme
western edge. The majority of the site to the east is vegetated with upland,
dryer -site types of-vegetation, such as salal, Oregon grape, madrona and
Douglas -fir. However, there are small pockets of wetland vegetation in a
series of low -lying areas along the eastern side of the property. Despite the
appearance that the site drains to the northeast, basin -wide drainage diverts
that water back to a southerly direction across a broad, low - relief area just
east of the site. This broad flat drainage pattern combined with shallow
soils results in there being za jgii aotant -sl— for- saetZandS_rP1 the
area south and east of the sit homes are built, inadvertently
cutting off or diverting historic drainage patterns.
This appears to be the origin of at least two of the four wetlands described
in Gregg Miller's Tech Memo. appear-- to 'be associated `wiith
roa+d buildf76g. It is possible these areas were previously wet, but they
appear to be changing (expanding) as a result of poor culverting and off -road
vehicular traffic disturbing drainage patterns. 'The surface soils in Wetland
3 are sandy for the most part and very disturbed, probably a result of past
forest harvest practices. Drainage appears to move generally to the east.
Any depressions trap water and support wetland vegetation; elevation changes
of only a foot may result in a loss of hydric soil and hydrophytic vegetation.
This makes the wetland a complex of upland and wetland conditions -- very
Sandy - skeletal, mixed, mesic Typic Xerorthent, generally meaning the soil
has minimal horizon development (ent), has no distinguishing characteristics at
the Great Group level (oath— standard), has developed under climatic conditions
of wet winters and dry summers (xer), has a mesic temperature regime (mean annual
temperature ranges from 8° to 15° C (47° - 59° F), has no specific mineralogic
source (mixed), texture of the fine fraction is sand or loamy .gand and coarse
fragment content is greater than 35% (sandy - skeletal). >
4
2) the Cassolary sandy loam, 0 -15% slopes is mapped for approx. 1/4 mile just
r south of the Agnew; and
3) the Hoypus gravelly loamy sand, 0 -15% slopes, (classified as a sandy -
skeletal, mixed, mesic Typic Xerorthent ") is mapped for approx. 1/4 mile on a
side -slope and terrace just south of the Cassolary.
APPENDIX I lists and briefly describes expected characteristics for each of
the soil series mapped on the two sites.
SITE SPECIFIC CHARACTERISTICS
SITE 1 r
The Clallam soils -- gravelly sandy loam, shallow to glacial till -- are
mapped on the majority of Site 1. Site relief ranges from 290 feet at the
western edge to 260 feet near the northeastern corner. Precise information
about changes in elevation along the proposed waterline route to the south was
not available, but a site evaluation showed that the drop is relatively
gradual and, relative to the distance, the change in elevation appears to be
minimal.
The treatment plant site currently has a water storage tank at the extreme
western edge. The majority of the site to the east is vegetated with upland,
dryer -site types of-vegetation, such as salal, Oregon grape, madrona and
Douglas -fir. However, there are small pockets of wetland vegetation in a
series of low -lying areas along the eastern side of the property. Despite the
appearance that the site drains to the northeast, basin -wide drainage diverts
that water back to a southerly direction across a broad, low - relief area just
east of the site. This broad flat drainage pattern combined with shallow
soils results in there being za jgii aotant -sl— for- saetZandS_rP1 the
area south and east of the sit homes are built, inadvertently
cutting off or diverting historic drainage patterns.
This appears to be the origin of at least two of the four wetlands described
in Gregg Miller's Tech Memo. appear-- to 'be associated `wiith
roa+d buildf76g. It is possible these areas were previously wet, but they
appear to be changing (expanding) as a result of poor culverting and off -road
vehicular traffic disturbing drainage patterns. 'The surface soils in Wetland
3 are sandy for the most part and very disturbed, probably a result of past
forest harvest practices. Drainage appears to move generally to the east.
Any depressions trap water and support wetland vegetation; elevation changes
of only a foot may result in a loss of hydric soil and hydrophytic vegetation.
This makes the wetland a complex of upland and wetland conditions -- very
Sandy - skeletal, mixed, mesic Typic Xerorthent, generally meaning the soil
has minimal horizon development (ent), has no distinguishing characteristics at
the Great Group level (oath— standard), has developed under climatic conditions
of wet winters and dry summers (xer), has a mesic temperature regime (mean annual
temperature ranges from 8° to 15° C (47° - 59° F), has no specific mineralogic
source (mixed), texture of the fine fraction is sand or loamy .gand and coarse
fragment content is greater than 35% (sandy - skeletal). >
4
difficult to accomplish a detailed delineation during the dry season.
The.sozls in Wetland 1 are finer tex 3
seven _c avev. iii' areas _ -"This ° : MDl'ies 'that '.the'. area : surxoundi
dej'ine the ' "bottom" of °she true' ra na e, since surface run off stormwater
ten s to carry fines from upslope and redepasit them in swales along a
drainage. however, an obvious channel with banks and scoured areas was not
observed. This area does have several trails apparently used by off -road
vehicles. Since a drainage channel may provide the easiest route (fewer
trees), it is possible that the characteristics of th original drainage
channel is obscured by the road. The wet areas observed are on and adjacent
to the existing roads, but the tire tracks tend to cut into the wet soils,
making the roads more likely to conduct and trap stormwater now regardless pf
original site conditions. However, the wetland in this area is less of a
complex than Wetland 3; the soils away from the roads are not as disturbed,
making it slightly easier to delineate. However, the extreme disturbance of
so ve etation i a ire using a
problem areas" delineatio ocedure.
W tland.`2 is located in the southeastern corner of the treatment plant site.
This corner is a low -lying area that collects water naturally from surrounding
uplands. It is small, but probably just large enough to be jurisdictional for
the city. The wetland spans the property line, resulting in there being at
least two and possibly three property owners affected. This wetland appears
to drain to the southeast when the standing water gets high enough in the
winter. It is expected that once the rains stop, the wetland will drain
subsurface relatively fast. There are no indications that water stands on the
surface all winter long.
Wet'Iandi4 was identified by Gregg. I did not observe it, so can only make
limited comments. It appears to be quite small, possibly too small to be
jurisdictional (minimum size for jurisdictional wetlands in Port Townsend is
5000 sgft). Gregg described it as being in a drainage, and on the south side
of Sims. So it appears that the wetland is natural to some degree and
although possibly not jurisdictional, should be noted as an indicator of
stormwater drainage direction.
SITE 2
The Tukey soils are mapped on Site 2's proposed location for the treatment
facility. The proposed site is located on a small plateau at the top of a
hill. Site relief on the facility site is minimal, less then 15 feet, ranging
from around 370 to 360 feet elevation.
E/W PIPM IRE ROUTE
From the facility site to the east, elevation changes from approx. 370 down to
260 in the bottom of the north draining channel just east of the S4 boundary,
then rises again, crossing a ridge (max. elevation 340 feet), finally ending
at an elevation of 280 feet. Soils along the majority of the route are either
Tukey or Alderwood -- both with coarse - textured surface soils over a shallow
glacial till layer at 20 -40 inches. The north draining channel is headwaters
for a wetland receiving area to the north that subsequently drains east to the
valley floor. Soils in the bottom of the channel are hydric -- Belfast
5
1
series. There is a deep drain cut along the western side of the channel that
probably was installed to divert seasonal flow -and allow traffic to travel the
v flat drainage bottom. The SCS maps show a road /trail running up the bottom,
but it is not apparent at this time. This drainage was identified as Wetland
5.in Gregg Miller's Tech Memo.
Although not apparent on the topography maps, the soil maps show another small
drainage running southeast from about the middle of the SE corner of S4,
eventually draining to Anderson Lake. The topography maps, but not the soil
maps, show another drainage running west - southwest from the southern half of
the plateau. We observed two wetland drainages when walking E/W side roads
south of the main road in S4. I assume that the westerly of those two t
observed drainages is the one shown on the topography map, draining west -
southwest. The easterly of the two observed drainages may be a headwater
branch of the western drainage, or may instead be the drainage indicated on
the soils map as being headwaters to Anderson Lake.
Gregg identified 2 wetlands (Wetlands 6 and 7) in the area south of the
proposed treatment plant site. Wetland 6 appears to be located in the western
drainage described above. The location of Wetland 7 suggests that it is
likely to be an upslope headwater area continuation of Wetland 6. But I did
not observe Wetland 7 during my site visit so cannot verify that supposition.
Gregg stated that Wetland 6 and maybe 7 may drain to a large wetland off site
to the southeast, but topography maps indicate otherwise. Gregg does not
comment on the other drainage that I noted farther east.
Portions of the forest on the site and along the proposed waterline to the
east are currently being harvested. Wetlands and riparian areas within the
boundaries of the proposed harvest area are supposed to be marked and
generally avoided when harvesting (Forest Practices rules). These markings
were observed and were approximately correct within a 10 -20 foot margin of
error'. It appears that only vegetation (not soils) was used to identify wet
areas.
In conclusion, it appears that the area south of the proposed facility site
has several riparian wetlands and so should be avoided if possible. Along the
proposed pipeline route to the east, Wetland 5 will be crossed and will be
difficult to avoid without moving the pipeline considerably to the south.
SIN PIPELINE ROUTE
From the proposed plant site to the northern end of the SIN pipeline, relief
ranges from 370 feet at the plant, west, to about 350 feet at the intersection
with the N/S waterline, then north, to about 140 feet near Four Corners
intersection. Soils in the uplands are Tukey series, then progress north
through the Hoypus series and Cassolary series, finally ending in the Agnew
series in the bottom lands near Four Corners. The Agnew is a hydric soil,
indicating that wetland conditions may exist in the flat area at the northerly
extent of the waterline. No wetlands were observed in this area around Four
Corners, but may have been masked by the fact that the area has been cleared,
developed and /or used for agriculture. It may be advisable to revisit the
pipeline route in that area to verify that there are no wet areas
6
Gregg noted a wetland right on the northern boundary of S4 (Wetland 8),
approx. 100 feet west of the existing pipeline. We did observe an area in
y that vicinity where a drainage crossed the access road. It is' possible that
there was wetland vegetation in it downslope, but I did not record an obvious
wetland. However, since this is a sideslope area where the till layer from
above can tend to surface, resulting in seeps, the potential for a wetland is
relatively high.
In conclusion, there is potential for wetlands along the pipeline at slope -
breaks and in the bottoms around Four Corners. Neither Gregg nor I identified
wetlands near Four Corners, but the route along the bottom should be rechecked
as winter progresses.
t
REGUTATORY ISSUES
Federal Requirements
Whenever directly impacting -- i.e. enterin - a wetland, the Army CorDs of
ArE),shguld be notified. Depending on specific criteria defined
for each type of impact, if the area affected is less than the threshold for
that type of impact, the ACE will issue a Nationwide Permit for each specific
action. There are a total of 40 Nationwide Permits covering activities
ranging from maintenance of previously existing structures or fills, to
installation of scientific measurement devices, to road crossings, to mining,
to filling... In addition, some of the permits have regional conditions that
may make the federal rules more restrictive.
Unde -r current rules, the permit must be issued before any activity is
initigted. Issuance of the permit is likely to take more than 30 days since
the ACE must in turn notify several other agencies and give them an
opportunity to comment on the permit. The EPA will review the permit to make
sure it complies with other water - related federal laws.
As part of the Notification procedure, the permittee must contact the U.S.
Fish and Wildlife and the National Marine Fisheries Service regarding the
potential for the existence of any proposed or listed endangered or threatened
species that may be affected by the project. They must also contact the State
Historic Preservation Office regarding any historic properties in the area
that may be affected by the project.
It is assumed that our activities will fall under two different Nationwide
Permit categories, Nationwide Permit 12 for a utility crossing, and possibly
Nationwide 4 for a road crossin .
To qualify for a Nationwide Permit 12 (utility crossing), the area of
disturbance must be the minimum necessary to construct the line; the top 6 -12
inches of backfill in the wetland areas must be the native soil originally
excavated from the wetland; the surface trench width cannot be greater than 2
feet, and'the total lineal distance through the wetland must be less than 500
feet. Furthermore, preconstruction contours must be recreated, and any
sidecast materials must be removed from the wetland. If any of,fthese criteria
are not met, a 404, permit may be required.
7
To qualify for a Nationwide Permit 14 (road crossing), in the event that a
maintenance road is desired, the width of the road is limited to the minimum
necessary for the actual crossing; total fill placed in the wetland must be
less than 1/10 acre; the total lineal feet must be less than 200 feet;. the
crossing must be culverted, and the wetlands must be delineated using the ACE
1987 Manual in the affected areas.. A mitigation plan may be required as part
of the notification prior to permitting. Native vegetation is to be used for
restoration to the greatest extent possible. Hydroseeding may be used for
to o erosion control. If any of these criteria are not met, a 404 permit
may be required.
State Requiremgnts f
The ACE will notify several State agencies for review of 'the permit. The
Dept. of Ecology will review the permit to see whether it complies with State
water quality standards (401 certification) as well as any other laws that
control activities in a Water of-the State. On the basis of water quality
ws and other rules governin activit' s in wetlands, the State can deny the
Nationwide permit, a conditions to the Nationwide permit, or request that a
404 permit procedure a initiated instead.
In general, water quality standards will require that best management
practices be used during and after construction to assure that minimal
sedimentation and erosion will result from the activity. This will be
scrutinized more in areas around salmon bearing streams or shellfish beds.
For projects in coastal counties, an individual Coastal Zone Management
consistency determination will also be required, which will be based primarily
on a potential effect of the activity on shellfish beds and other coastal zone
ecosystems of importance.
County Requirements
The County will review the SEPA checklist for Site 2. The Dept. of Ecology
and any other agencies with jurisdiction also will review the SEPA checklist.
The County may request additional information and reports to accompany the
SEPA. Finally, the County may grant a Determination of Non - Significance
DNS), may add conditions to the DNS based upon comments received from other
jurisdictional agencies, may instead require an EIS, or may deny the project
altogether.
At this time, Jefferson County has no Environmentally Sensitive Areas
Ordinance, but are projecting to have an Interim Ordinance adopted by January
1, 1993.
City Requirements
Jefferson County and Port Townsend share the same NAgter ,Shorelands•Program at
this time. But the City is in the process of updating their program, so
provisions are expected to change very soon. These provisions will primarily
affect development directly along the marine waters, or around Kah Tai Lagoon,
or the Ghinese Gardens. It does not aRpear likely. but depending on the
than es a Gi ds ermit for Site 0221
because of proximity to marine waters at Sims WaX. The permit wirll be
reviewed by the State Dept. of.Ecology and other jurisdictional agencies.
8
Dave Robison is the permitting officer; the City Council is responsible for
the final permitting. _
The City will review the SEPA - checklist for Site 1. The Dept, of Ecology and
any other agencies with jurisdiction also will review the SEPA checklist. The
City may request additional information and reports to accompany the SEPA.
Finally, the City may grant a Determination of Non - Significance (DNS), may add
conditions to the DNS based upon comments received from other jurisdictional
a.g, or project altogether. encLes,. may instead .require an EIS, may deny the . ... ,
Y n ..:. ........... >..,.....:.`- y.:..,. -
The Port Townsend Ez_v_jronmentally Sensitive AXeag Ordin =re was adopted on
October 14, 1992., For Site 1, the sections describing wetlands issues and
critical drains a cor o s will a Activities in a'wetland are to be
avoided if possible and minimized if not. Certain activities are allowed, but
may still require mitigation and delineation of the impacted area.
Section 19.05.040(8.10) Exemptions: says that "relocation of ...lines, pipes,
mains, equipment..." is exempt from the ESA provisions "when undertaken
pursuant to best management practices—and no practicable alternatives exists
which will reduce impacts _on Environmentally Sensitive Areas." This implies
that the water line will be cellod,...but only after evaluating alternatives .
rand providing plans that describe the best management practices that will be
used to minimize and compensate for the impact.
The City will be responsible for working with the ACE on the Nationwide
Permits that are likely to be needed for Site 2 (since Wetland 5 will be
almost impossible to avoid) and may be needed for Site 1 if the waterline runs
through Wetland 3.
If you have any questions, please feel free to call.
Thank You,
Lisa Palazzi
Port Townsend Wetlands Specialist
ARCPACS certified soil specialist
Certification #3313.
9
rr
7)
I
APPENDIX I
EXPECTED CHARACTERISTICS OF MAPPED SOIL SERIES
AGNEW SERIES
The Agnew silt loams are moderately deep, somewhat poorly- drained soils formed
in shallow glaciolacustrine sediments overlying laminated glacial till. These
soils are often associated with wetlands. Generally, the upper soils are silt
loams grading to silty clay loams with depth. Mottling is expected at 3
inches depth and gleying at 9 inches depth -- evidence of seasonal water
almost to the surface for extended periods. Below approx. 30 inches (in the C
horizon), gravel content increases abruptly from C5% in the surface soils to
between 10 and 50% in the subsoils. The lower horizons are highly laminated
and very hard glacial till.
Average soil percolation rates in the upper 9 inches are expected to be
moderate (0.6 -2 inches per hour), decreasing to moderately slow (0.2 -0.6
inches per hour) below 9 inches depth.
The Agnew soils are generally suitable for some crops and pasture with the
main limitation being seasonal wetness (a perched water table) at 12 to 24
inches depth.
The main limitations for onsite septic and stormwater treatment are related to
both the minimal depth to the hardpan and seasonal wetness. Soil water
percolating through these soils will move laterally in the soil rather than
down. The seasonal high water table and /or the shallow till layer limits the
amount' of soil available to effectively treat stormwater or septic effluent.
ALDERWOOD SERIES
The Alderwood gravelly sandy foams are.moderately deep, moderately well -
drained soils formed in ablation till overlying basal till. Generally, the
upper soils are gravelly or very gravelly sandy loams. A weakly cemented
hardpan is usually found at around 30 inches depth, and a strongly cemented
duripan is found underlying the hardpan at 20 to 40 inches depth.
Average soil percolation rates in the upper horizons are expected to be
moderately rapid (2 -6 inches per hour) above the pan and very slow (less than
0.06 inches per hour) in the pan -- effectively impermeable.
The Alderwood soils are generally suitable for woodland and homesites with the
main limitation being seasonal wetness (a perched water table) at 18 to 36
inches depth.
The main limitations for onsite septic and stormwater treatment are related to
both the minimal depth to the hardpan and seasonal wetness. Soil water
percolating through these soils will move laterally in the soil rather than
down. The seasonal high water table and /or the shallow till layer limits the
amount of soil available to effectively treat stormwater or septic effluent.
BELFAST SERIES f
The Belfast silty clay loams, wet variant, are very deep, poorly drained soils
formed on alluvial flood plains originally under forests. Typically, the
10
upper 20 inches is a grayish brown silty clay loam or sandy clay loam.
Subsoils to a depth of 60+ inches are dark grey or olive grey stratified fine
sandy loam, silt loam, and clay loam.
Permeability is moderately slow (0.2 -0.6 inches per hour). A seasonal high
water table is expected at 6 to 12 inches depth.
The Belfast silty clay loam, wet variant soils are used primarily for pasture.
Its main limitation is the seasonal wetness at 6 to 12 inches depth and very
poor trafficability when wet. These soils are easily compacted when wet,
greatly affecting surface infiltration rates and subsurface flow patterns.
CASSQIARY '
The Cassolary series is a deep, well- drained soil found on upland terraces in
reworked glacial and marine sediments. The Cassolary is a series of coarse
and fine - textured layers, The upper horizons tend to be sandy loam. Horizons
from 27 to 40 inches is silt loam and silty clay loam. Below that, soil
texture becomes sandy again, composed of stratified layers of fine Sandy loam
and sandy loam down to 60 inches.
Soil permeability is moderately slow (0.2 -0.6 inches per hour).
These soils are used primarily as pasture or woodland. They can be used for
homesites, but have severe restrictions for septic design. The slow
permeability increases chances of on site drainfield failure. Furthermore,
the textural layering typical of the Cassolary can result in temporary perched
water tables above the finer textured soils. The sandy soils below the silt
loam and silty clay loam layers have rapid permeability, i.e. poor filtering
capacity. It is suggested that community sewage systems be used to avoid
contamination of water supplies. Grass -lined swales or sand -lined ponds may
be encouraged for pretreatment of stormwater prior to infiltration in
subsoils.
CLALLAM SEP
The Clallam gravelly sandy loams are moderately deep, well- drained soils
formed in glacial till.. They are usually found on uplands, slopes ranging
from 0 -30x. The surface soils are generally grayish -brown to dark grayish -
brown gravelly sandy foams. They have a weakly cemented glacial till layer at
20 -40 inches depth that will restrict vertical soil percolation to some
degree.
Average soil permeability is expected to be moderate (0.6 -2 inches per hour)
above the cemented till and very slow (less than 0.06 inches per hour) in the
till layer. A seasonal perched water table is not expected; the till in these
areas must be more fractured. However, the soil is expected to be saturated
periodically during the rainy season and the majority of soil water will
percolate laterally.
The Clallam soils originally developed under a forest, but more than half of
the mapped acreage has been cleared and is now used for pasture,;kardens,
orchards and homesites. The primary limitations are related to shallow soil
depths. Stormwater will percolate into the soil readily in undisturbed areas,
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but will move laterally across the till layer,
and low -lying areas. Septic system design will
depths and fluctuating seasonal high water.
surfacing in adjacent drainages
be limited by minimal soil
EVERM SERIES
The Everett series is a very deep,.somewhat excessively drained soil found on
terraces and glacial outwash plains. Generally, the texture becomes coarser
and more gravelly with depth, ranging from very gravelly (35 -65% gravel) sandy
foams near the surface, extremely gravelly sandy loam or loamy sand down to
approximately 30 inches, and extremely gravelly ( >65% gravel) sand at depths
greater than 30 inches.
Soil permeability is rapid (6 -20 inches per hour) to very rapid ( >20 inchest
per hour) below 3 inches depth.
These soils are suitable for homesites with a few restrictions. Cutbanks will
slough severely and should be avoided to control erosion. Septic absorption
field and stormwater facility design is limited by poor filtering capacity --
i.e. these soils drain too rapidly to provide adequate treatment. It is
suggested that community sewage systems be used to avoid contamination of
water supplies. Grass -lined swales or sand -lined ponds may be encouraged for
pretreatment of stormwater prior to infiltration.
HOYPUS SERIES
The Hoypus gravelly loamy sands are deep, somewhat excessively drained
gravelly soils formed in glacial outwash on terraces. They are usually found
on uplands, slopes ranging from 0 -30 %. The surface soils are generally dark
gray to dark brown gravelly loamy sands. Subsoils are dark yellowish -brown
gravelly loamy sands overlying dark grayish brown gravelly loamy sands grading
to very gravelly sands with depth. These horizons with varying colors and
textures are a result of different depositional events.
Average soil permeability is expected to be rapid (6 -20 inches per hour).
Most of the Hoypus soils were originally wooded, but a great deal of the
mapped acreage has been cleared and is now used for limited pasture, gardens,
and homesites. The primary limitations are related to rapid percolation rates
and slope. Stormwater will percolate into the soil readily in undisturbed
areas, but will receive relatively little treatment in the soil due to rapid
percolation. Septic system design will be limited also by rapid percolation,
poor treatment of effluent, and steep slopes making design difficult.
TUK6Y SERIES
The Tukey gravelly foams are moderately deep, moderately well - drained soils
formed on terraces in glacial till. The surface soils are generally grayish -
brown to brown gravelly loams. The subsoils are grayish -brown gravelly clay
foams. They have a cemented gravelly clay loam glacial till layer at 20 -40
inches depth that will restrict vertical soil percolation.
Average soil permeability is expected to be moderately slow (0.2 -0.6 inches
per hour) above the cemented till and very slow (less than 0.06 inches per
hour) in the till layer. A seasonal perched water table is expected at 1.5-
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0
2.5 feet during the rainy season. Soil water will percolate laterally across
the surface of the till, surfacing in low -lying areas and drainages.
i.
The Tukey soils were originally - woodland, but the majority of mapped acreage
has been cleared and is now used for pasture, and homesites. There are
inclusions of soils with enough cobbles and stones to hinder cultivation. The
primary limitations are related to shallow soil depths and slow percolation
rates. Stormwater will percolate into the soil slowly, increasing the chance
of surface run -off and erosion. Once in the soil, water will move laterally
across the till layer, surfacing in adjacent drainages and low -lying areas.
Septic system design will be limited by minimal soil depths, slow percolation
rates, and seasonal high water.
t
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