HomeMy WebLinkAboutPettygrove's 1st Block 17 & 18 - Geotechnical Engineering Reconnaissance - 1999.07.143 li:-tJ.---
rinx ENcINEERTNc, rNc.BELUNGIIAM r EVEtErr
CIVIL r OFPTECHMCAL oEbMRONMEIIIAL r WET[,A].IDS
July 14, 1999
Williams LLC
P.O. Box 408
PortTo*nscn4 WA 98368
Rc:
ESKENOn|EENINq NC.
2T!'HUVEOI.DT TCREBT
BELUNOHAM. WA 9I12I
360{76-9tt9 .
80G859.559 .
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Rcport - Gcotechnlcd Engincering Reconnakmnce
Portion of Elockr ll & Lt of Pcqgroves Fint Addition
Maplc Strcct
Port Townrond, Washingtou
Ann: Williams' Rcprcecnativc
BEK Engineering, Inc. (BEK) is plcascd to pnxcnt thc rcsults of our gcotcchnical cngineering
rcconnairsancc at thc aforarcntioncd propcrty thal is adjaccnt to Maplo Strcot (Vacatcd) withh tho City of
Port Torvnrcnd, Washington. The site is si.tuat d within Scction 3, Townrhip 30N, Rangc fW of th6
Willamstte Meridien. Thc property is located to the cast and wost of Maple Strect and is situct€d on a
w$tcdy-facing slope. The propcrty consists of cight 50:.foot (N-S) bV 100-fooc (E-!V) lotr tbat arc
bounded on thc north end south by thc easerncntg for L and K Strects, rcspcctirrcly, and includes ths 60-fclot
tvlaplo Strcct casement bewecn thc wert and east halvcs of thc propety (scc Topographic / Vicinity Map,
attachcd).
We un&rstand tho foll,owing:
o ttrouscs with a 450 to 600 square foot fooprint witl bc corutructcd on tome or cll of th€ cight lotr..
Sewage wilt bc transmincd to thc City scwer systcm, probebly by punptng it to a setrrcr mein thst
will bc constructcd along Maple Street.
r Wc undcrstand tlrat gtrect ridc parking will bc utilizcd.
PURPOSE AND SCOPE OF SERVICES
Thc purposc of thir rcconnaissance wts to providc information regerding soil and slope *ability in onder to
derclop thc lots in a manncr that will not indr,rcs soil crosion or cndang* otr- or off'sitc propcttics- Tfc
scopc of this projcct includcd a reconnsirscncc lwcl slopc aomination aIrd rubsurfacc invertigation
Oriugtr hand cxcavation of tcst pitr rnd collcction of soil rampler fium tho fju, Slopot wctlo mcarurcd
using r clinometer et thc propcrty tincr. Thc cublur&ce inrnstigation also includcd thc obgcnation of
cxpJscd roils on thc cssr iiAs roal cut aloog Maple Street. No motorizcd ntbsurfacc invcstigation war
conductcd.
n
8EK VeDOt{llELL SNODaES'!I!{O. INC
zrltcot.aYAVt ruE
BVERSTT.WA 9&IO1EXHIBIT
I A 6)
July l{, 1999
Rcport ' Gcotrthalcil Englnanring Rcconnrhancc (portlon of Blocks 17 and 18, petty$wcc Fi$t Additiou)
SITE OBSERVATIONS
A gcotcchnical
elopes ond test
visit.
Erirting Sloper
The rlopcr along
to scctions with
Iocatiots, Appendix).
the cast onc-half
slope ovcr the 60
Maplc Suect has
Soil Conditions
and tho
enginecr &om 8EK conduacd a sitc visit (Iune 3, 1999) to obsenc and mcasurc thccitcthein-sinr soils for den-sity. A Williams' reprcsentative was prcscnt at the tims of our sitc
propcrty lines vary ghort restions of ls\rcI land along the cast rido of u"o?uo+?'a gradient up to 43 over tho wcstern 50 fect of Iot I (Slopcs and Tcst pir
t lor hEvc lowcr gradieut slopes than tho routherr tob and(east of has lorer gradicnt slopcs than thc west qrtc hatf. Thc-foot wide Mapto Sueet c{Scmcnt is approrimatcly 25 pcrcerlt in sn cast-wcst
a slight slopc to tho north.
Tho- goil-on-thc slopes-is compoeed of a rnoist topsoi.l{uff laycr to a depth of 0.35 !o 0.4j fcct. Estwcan0'35 to 0.45 fcat and 2.35 to 2.5 fct;tthe soil is cornposed of brown silry sand with gravel tlat irmcdiumdetrsc. Thc soil bccomos darker and denscr bctwccn
thc
topsoil snd 2,1i e" bgr il becomer ""
y a"*.and gray in color at ?.7-s foct bgs. Wc interprct tho soif betwcen ttre topeoiftryri *a 2.?5 fcet tobcrreatheredTillandTillthethasbeerdisturbcdandsoftenedbyrmtparotraiionaoatnesoilbelowz.1s fgt
to. bc unn'eathered glacially dcpotitcd Till. Pcnctration resistance if a onc-half inch bar rhat wasdrivcnwithaS-pound hanuncr was used as a surrogatc mcagurc of density.
Vegetation
Thc lbje1 propcrty is vegetated by fir, ccdar, and nra.drone trees with somo red aldcr. The undcrstory
consists of-occan sPEy, rqd eldcrbcrry, sword fcrn, salal, salmonberry', and some Orcgon grape. Some
cxotic rpecies wcrc eslcountercd on ihc site including Himalayan blackberry and holly.
Thc trccr on rhc rhat is indicativc of rlopes with rcit
movement or crcqr.
HydrologSr rnd Drainrgc
No rutfacc oxprcssions ofdrainago rrlere obscrvcd on tho depth
indicates that thc drainagc probably docs not penstrats to lorver soil horizons, but trarrcls as shatlow
subsurface flows tlat &llow the topog:raphy of thc site. It is our undcrranding that a drainEge ditch will bo F
con$truccd on the eest sidc of Maplc strcct that will reduce thc potcntial for drainagc impacting thc
propcrty ftom thc prope,rty to thc esst of thc srreet
Thc tributary arca to the subjcct pmpcrtll/ currcntly
100 foot-wide property !o thc cast of thc
crcst of Morgan Hill.
consists of the easernent for Maplc Strcet, $c
cpproximatcly site, and rome subsur&co drainagc &om thc uPp€r
marumum
direction.
t e 2 's'-i
ii
5j-,1.,t"/",
i*'i'.:*:l
Thcrc is a sntall ryrelo that Extends onto drc Fropcrry frotn tlro cast, just to tho oorth of the monumcot
locatcd lt the-ff si& of Lot 6. Tbir svraL bioadcns to a largc io* rfopc "
r""
on o on tho rubjcct
ProP€rty. Thc cwale cxtcnds loss then 100 &st to tho cast of thc subject prop€rtywhcre it flattcu hto a
pen of the rise that makes up thc top of Morgnn Hill. An o(cavetion in thc basc of thc rrvalq rcrrcalcd ng
Tilt. Wc intcrprct thc swalc to bc a rcmnant fcaturc tr-m-ffi;
3BSKENOINEER-6IO. NC.PROfECf,:991d1
July 14, 1.999 !j:. 'r::-1
n.port- Geotcdhnical Engineering Reconnaissance @ortion of Blocls l7 and 18, rettyglov€sFirst Additiol|
Drainage and Erosion Control
Site blearing lhould.be miriiirizd to reduce erosion poteqtiaf anj sil-t 8n9e slrg{a be erected downgradiiat
of all clearing or other land disturbance activities. Straw bale barriirs should be placed and staked in the
bottom of the ditch ilrjt will be consthrcted adjacent to Maple Street. .Erection of silt fencep downgradient
i;;;;;;; trr! prop.rties west of Maple Street, in combinaiion with construction access being
limited to the east side-of the properties;.should eliminate any oFsitg sediment transpod. from Lots I
through 4 during construction.
We recommend that riater from.ail roof and footing'drai* fo, the properties east ofMaple Street should be
transmitted downslope'through appropriate piping to a roadside ditch along Maplg Street. Drainage from
structures to th.e *"it to the .wesi of Maple Streci shoirld be conducted to level spreaders built in a trench -
below at.a distance;f at F*t 25 feetwest of the strirctures. 'The levitspieadgrs should u: I!.1. s!9nes
i. h;n r than 2b; percent if pbsiible. Lbvel sprbaders csnsist of a l.S-foot deep trgnch tharis filled vrith 2' :
inlt grau.t and has. a 4-inch, plrforale{ drainpip.e -
rn
tr" ba;e. the trench should be approxirnaiely one
foot ling for each. i0 square-fe'6t of ioof u..u. .it is our opiniotr that. removal of surface and subsurfrce
drainag water dbove Maplg SriqgJ through the existing_ soil cut, construction of a'roadside ditc! a$
collection of the roof and tr*t drainage to the east of'Maple Street, will more than compensate.for the '
increased impermeability of +SO to 600-rqu"r. .foot rooft to the west of (below) Maple Street.
Altematively, a-irr"g. fto* tool footings, *d othgi imp-ermeable sdrfaces may,be collected.in a drainage
constructed along thi west side of.Lots I through 4 and conducted down the K br L' Street easement to'
appropriate drainage facilities along Fir Street-
Slope Bestoration and Revegetation :
Following construction.at the,it, dirtr.bed areas should be revegetald by glantr|S-T 6rosion control
mixture consisting of native grasses. Additionally, landscaping thortlg
consist
of ptahting deep-rooted
native woody 1r"gltution'such as is found on tha site, Plantings should be installed urs soon as possible
f"[d;tft" "
oii*lncement
of the auumn rains or as early1s posslble in the sprihg
Slope Maintenance
No organic material, bonsisting'of lawn clippings, tree trimmings,.or brush'shouid be placed yar or.oltfre
hill slope. These *"t.riul, *"y tt.tp hold water on the slope face arid may increase.the erosion rale of the
slope. Organic materials. should be properly composted.or disposed of oFsite.
INDEMMFICATION AND LIMITATIONS
This ieport has been'prepared.to aid the development of the site from a geotechnical engineering ,/m
standpoint.i$a geotechnical rep6rt for of the site with
gl@F:&an'4GFeFcent.sloPes.surface conditions at the dates and
indicated. It iis not warranted to assume that they are representative of ionditions at other locations and
times. .The conclusions and recommendations conliined in this rePort are based on surface and subsurface
conditions obseryed ddring our'site visit. We assume that the conditions observed are iepresentative of the
subsurface conditions throughout the property. .If, during furthei site development, different'conditions
from those described in this report are observed or app€ar to be present'in exbavations,' w.e must be'advised
promptly so that we &rn rernglv these conditions and reconsider and/or modi8' our conclusions and
recommendations where necessary.
5BEKENGINEERING.INC.PROJECT:99161
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99061
TlAlflc FIE SIOPN A}TD ,TEST PIT I.OCAI'IONS;
WILLIA!ff! LLC: Plt{ OF BIJCS. 1? & 18
PORT TOITNSEITD, TA.SHINGION
1uN5-23-99 -AEIt =3O'
ECIO st /uln $l
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o"HtfuffiWr**1-<#'m"* mHffi
Site plcn from sketch provided by
Slope Meosurernents by BEK Engin
reet