CC - Drainage Report B & A Engineers , Inc .
Consulting Engineers & Surveyors
5505 W . Franklin Rd . Boise , ID 83705
Phone . 208 . 343 . 3381 Facsimile 208 . 342 . 5792
Silver S p ri n 9 s Sub ivisio n
Dra i na e Report
November 2O19
0 PROFF
4116
of
Page 1 of 42
Contents
♦ Narrative Overview Page 3
♦ Calculations Page 4
♦ Soils Investigation Report Page 19
♦ Drainage Basin Map Page 41
Page 2 of 42
Narrative Overview
Silver Springs Subdivision is a residential subdivision located on the south side of McMillan Road ,
west of Locust Grove Road and immediately east of Red Horse Way in Meridian , Idaho .
Silver Springs will utilize sub- surface seepage beds to infiltrate storm water generated from public
roadways . Once constructed , the sub - surface seepage beds will be maintained by the Ada County Highway
District . There locations are all in common areas to be owned by the owners ' association of the subdivision .
Included within this report is a Limited Geotechnical Engineering Report dated 27 March 2019 and
prepared by Material Testing and Inspection , Inc . An addendum was created and dated 29 October 2019
that provided enhanced information particularly at the locations of the seepage bed facilities .
This report and addendum has indicated that there are a number of site specific criteria within this
development for developing storm water infiltration facilities . The report has indicated that seasonal high -
groundwater was not encountered during testing , but is anticipated to remain at depths greater than 20 feet
below ground surface . Design infiltration rates are & inches per hour in the soil strata that is approximately
9 feet deep (depending on location on the site) .
During construction , after excavation , the contractor is required to perform an infiltration rate test
at the level of infiltration to confirm or alternatively mediate for the measured infiltration rate .
The report also provided an R value of 6 via testing and recommended pavement cross sections for
the local roadway in the development :
Local Road .
2 . 5Anches asphalt pavement
4- inches compacted 3/4- inch base
14 - inches pit run sub -base
The report did not provide information on collector roads , but we presume the requirement will
be .
Collector Road .
34nches asphalt pavement
44nches compacted base
204nches pit run sub -base
Page 3 of 42
Calculations
Page 4 of 42
AND Calculation Sheet for Finding Peak Discharge/Volume • Rational Method
NOTE. This worbheat Is Intended to be a guideline to stendardlie ACHO chetking of drainage cakulriions and shall not replace the in* eces takutatlon methodology. These
caleulattom shag astabllsh a minlnwm reQuW n+ent The tnglnae/s leetJtodobgy mutt result In facOftles that meet ot eateed these cakulatWs In order to be accepted.
1tttA fW Mat 4M6arp aa11 �trt0ilr ft��llilflugl�-4ttMwt ,
.. .. _. . 1.11�►l+St' ,t1 .�11�t<iBll�.�sh'!�! !lMlii�
User Input Ip yeOoW ceps.
1 Project Name SllverSprintsSubitasin A
2 U area drainage basin map provided? YES
(mop must be inctuded mmh stantevoter colcuJot ms)
3 Enter Design Maim 4100•Year or )$*Year W th IMYear flood Route) 100
4 Enter number of storage Iadaties (I $ maxi
Ctst1 so Show More Subbawx O
Subbasbt Subbatin Subbasln Subbisln Subbasln Subbatln Subbasln Subbatln
1 Subbasln 2 S 4 S Subbath 6 7 8 9 10
S Area of Wainage Subbash ISf or Acres) Ss 10S,602
Acres 242
6 Oetermine the Weighted Runoff Coefflaent (C) 0.60
C•I (CIKA1) s (C2vA2)s(Cn1An)VA Weighted Avq 0,40
7 Calculate Overland Flow Yane of Concanttatlon In Muwtes (Tc) or use default 10 Ur taroara
min Itoµ^ , fAlmatedRunoffCoefficlentsforVoriousSunc�
w -
- -- -- - --- - - TXpe of Surlaoe Runoff Coefficients me
Oetarmine tba avarale ta at tntemlty it) from IOF Curve based on I 3. auaw"
---- - -
y 0.70.O.ei
Cak rate Iry Post areas
0evewpwrnt pack discharge iG►tak) 4.. 3. 7S75 ursu, n.,r po,fgad� 1pp 10 -
10 Calculate lots) runoff W (VI (for siting primary storage) y S,027 h Bata re"°y Ova" so
OWNMuRHamft —__ 940•07S _ -
v • Cr ff( •50)Ax3600 �trsldMnewpr<.g oiso 40
I l Calculate Volume of Runoff Reduction Vrr _Ptwtm.M PwiTM Maas 070
Enter Parcentila Stonnt1951A percenlRe 060 in)
951h 0.60 In tneun" end Commoetteld
aleht araas OJO
Enter Runoff Reductlon Val (9511% Prrcpntilr 0.Wn r Arra a C ) V. Dr142 R M+w�ws e_!0
12 Mention Approved Oluhuge Hale to unlace Waters IN applicable) cis Paltry 23
RadroadT•eratua 010040
ISValumrSummary twttntrerd wat _ 0to-0 !0
--- ---
SuifucStOtsgc With streea
Rasm rorewy 503 I ' Asphalt 0 »
Corvato 035
Privacy lrr,tt -? en:)Storagr Radn N 4324 )t - 01_MAIL — ! -
Sub , urturStOr +gr Rud}. .
L )a 0. 7!
Voiurnu Wdhout Sed mcnt Factor ISea SPA 10 IaD } SA027 Gre"I�I Saner "a So TVP* --
yOP* A e C4 O
rys 0M 00e 0,07 ail O
Aw Islas 24% 00e 0, 13 .as 0
oil ate 0.21 0
1. Wtir"•shamASC
E*\•108flt[\TC04\51orm Oraln\ACHD SD "tCS_112018 rdsm 10/29/2019r 2 24 PM
Version 10.5. November 2018
Paine 5 of 42
ACHD Calculation Sheet for Finding Peak Discharge/Volume • Rational Method
NOTE: This worlatwet is Intended to be a SufdeliFe to Standardize ACHD chaddrts of drs(naje akulallons and Shia not replace the Engineef's ealeutatioo methodowsy. These
calculations sbs(1 establish a mlritinum requhemant. The Engtneces methodolop must result ba fat9Rks that men a exceed that calculations In order to be acceptede
ereies top ftAk oovowspd a 6" Wo faww +n wWftosss. fated tw /OKditei wrns
I4151t>11�1MMg3ilFilsde►11ZittrMlld![l�l��T4 ►-1RS+Mi91.CY�1lL�E �-�lh�+l���lll�l
Cher input in yellow cells
1 fho)ect Name Sliver Springs; Sub Basin W _
2 is area drainage basin map provided? YES
(rrwpmust be utckvdedwith statmvoter cokubnonj)
3 Enter Design Storm ( 100•Year or 2S Year With 100•Year Flood Route ) as-
4 Enter number of stotalle facilities (2S mars)
Cries to Show More Subbaunt ❑
Ubbasin Subbasln Subbastri Subbastn Subbasin Subbasin Subbosin Subbasin
1 Subbesln2 3 4 S Subbasin 7 a 9 f0
S Area of Drainage Subbasin (SF or Acres) $F 1050602
Acres RAI
6 Determine the Weighted Runoff Coetfiuent (C) 060
C• ((C1xA1) o (C2aA2).(CnxAn)(/A Weighted Avle 0.60
7 CaicuUte Overiand Flaw Time of Concentration In Minutes (Tc) or use default 10 tw. c
mfn Cosa» Estimated Runoff Coefficients for Various Surfac
TYO+ aSuffece - RunoffCoeftlents 's
r — - —
Is immrie trte average rainfall Intenslr (I ) from IDF Curve based an Tr 4 its , pvwywn enu aaPO es
akulate the post Oev"merst peat discharge (UFealt) u. 2 f � yorraea o.wo ro
Shiew
10 Calculate iota' runoff vol M (for Siting primary storage) >i 3,613 h +�rast�r o 1y
V a Co (Tc • 60)Ar360D ��aN.r.WI, lnw 14.40 _-
1 t Calcutate Volume of Runoff AFL&Kilon Vrr --
Fnier Percenil'e Storm 1 t95th percentile 0.60 ut) 95th 0 60 In tldtseeees OJ1O
Fntpr Runoff Reducilon Vol (951h Perctanttte 0.64'n a Area rt q Ve 3342 ff Howell am"
12 Detention Approved Discharge Rate to Wflace Waters (if applrcabte) ch _---
eeara4 yera raur oaZoo 40
11 Vuumosummiry � � aria Ol
SuffatcSlorate tlosfn ateeeu
OasrnforebaY b 361 fit I AsphaltM osS
If Consn 0"
onm (y Frealmeat/ totage (isun 3 ,252 t1 9ndsowls
SuhturlareSitxa >;e � - - - �
Volu - P Wit " ji Sedlmef t Facmr Jipp PAP 10 Tab) D,613 1t ' fO"I
fMlis:fyrr0afell e Y1rN
flap. A �/ _ all 0
Itat aatt as om all a
Average' 24% e.oe 0 u a1S 9
u„p .� aas Ole o.as o
i Adapted from ASCe
T \-108FllE\TCo4\Strxm Dfaln\ACHD SD CALCS_112018 xtsm 10/29/2019, 2 24 PM
Version 10 S. November 2018
Pale 6 of 42
ACHO Calculation Sheet for Sizing Seepage Bed With Optional Chambers
NOTE : This worksheat Is Intandad to be a guideline to ctandardga ACHD cheding of drainsp akulatlons and shall not replace the
Engineet's calculation methodology . These calculations shall establish a minimum requirement The Englnaes's methodology must result In
facilities that meet or esceed these calculations In order to be accepted,
Now this spreadsMst pups )nferafadon from the 'isak caw ub
Cakulau Oosc•Development Flews (for pte•devetopment flown, Incifem number d storep facilities to treats new tab)
User input In yellow cells.
1 Project Name Sliver Sprinps Sub Dsvn A'
2 Enter number of Seepage Beds 125 max] _ 3 _ _ __ _ __
l)csign Storm 1P O
4 Weighted RunoH Coefficient C 0 k unkto: rw
*2 Area A (Acres) 7 47 aces i 4v rASl
6 Approved d6schargo rate (it appl cable) ""RWO ds l_
7 Is Seepage Bed in Common Lot? No V 6, 284 hr Fst4 C: r!, ,rd ,
I
BletTOla' Ortgr Width ot Ali Drain Nock W 150h
� I
9 Set Total Del gn Depth of A ' Ora n Rock O 6 0 ft i
Roca Onts, Ile Not Include filter Sand Depth or Coos r
10 Void Ratio of Waln Rock Vo ds U 4
OA for 1 S' 2" dire rock and 3/4` Ch ps
I Design Infiltration Rate I81n/hr mea ) Pefc BAO in/hr j
17 Sire of WQ Pert Pipe (Pert 160s) Dla pipe In In l
13 Site of Overflow Pert Pipe (Perts Mon. ROOD If Q10043 Ns in
14 Calculate Total %forage per Foot so 462 hr/ft
1S Calculate Design tangth t 136 h
Overr)cle Value Requtrtd fa Chamfers
16 Variable In( tration Window I SWi 136 ft
17 Variable Infiftrat on Window W SWW ISO tt
18 Time to Drain 4. 2 hours
90% volume In 48 hours minimum —
19 length of WQ b Overflow Prrf Pipes 13a rl
20 Pert Pipe Checks Operf >c Opeak
where Operf• CdxAxVQx0Q
_t �r1M1E10
Note' This assumeschamber; are oirgatfted to a rectangular Ulm
I•Stormlech,
1 Type of Chambea SC74O
2 volume to Store V 0 j4 r
3 Installed Chamber Width Cell 4, 25 h
Insulted Chamber Depth Cd 2h
Installed Chamber Height Ch 742 lit
4 Chamber Void Fsetter �-
5 Chamber Storage Volume, Without Rock Per Manuf 45190 �tsAAnit
B Chamber Storage Volume, With Rock. Per Man kit 74 .90 fts/ynit
7 Total Number of Units Required 0 tea
a Arca of Infiltration Aberc car
9 Volume Infiltration Vperc 0 It'N
10 Time to Drain Noun
90% volume In 48fiours minimum
E \•f08FIt [\TCO4\Storm Orain\ACHD SO CAICS_112018 xism 10/29/20190 2 25 PM
Version 100. May 2010
Page 7 of 42
ACHD Calculation Sheet for Finding peak Discharge/Volume - Rational Method
NOTE Thbs prod ah" t b tritended to be a guWlIne to standatclIm ACHD checldrig of di sbsago Waatatlons and shall not replace the EngInter s calculation methodology. Th"a
calculattons shad? estaWlsh a minimum requIreenent. The tnitieeses methodolon etust result In faculties that meat or exceed these calculallons in order to be ampled.
III C r ' 0
meM -
tak r nfllts �lnFt l!"°!riLl6 etrsfl�" 0 . . W.Wifti
User Input In yellow celh
I project Name Silver Springs Sub Basin At
2 h area drainage bastn map provided? YES
(mop must be inctuded with srormwurter calculatrom)
3 Enter Design Storm (100•Year or 25•Year With IMYear Flood Route) too
A Enter number 04 storage laciites (25 max)
Ck ► to Show Mae Subhas:ro ❑
suhbasln Subbastn Subbastn Subbasln Subbatin Subtion Subbadri Subbasin
I Subbasln 2 S 4 S Subbasdn 6 7 0 9 10
5 Area of Orainage Subtimin (SF or Acres) SF 1sjul
Acre 0.17
6Deteimine the Weighted Runoff CoeHlclent (q 060
C• (IC1xA1)•(C2xA2)4(CnxAn)j/A Weighted Avill 0.40
7CalcutatoOvarlandFlowTimea [ ConcentrationInM,rwlu (Tc) orusedefauhl0 � rnc.►,rw
min IN* MA EsUrnated Runoff CoeMclenm for VarlousSurfac
IT of surface Runoff Coemclents't
941100311 _
Determiner overagera Ionlensny t From Fcurve as on c 2Sy Dowwer+aauen o7oon
YCrtLeate the Post , Oevetpr%" t peas disthharge (QPeak) F3... OS7 . uaers �+�rlreAe 030070aim _,-_ _
. r ---Realdeelsal f —"i
farrgta /aws4r a/SOso
10 Calculate tact runoff vol IV) Iforshing primiey storage) V 760 R I 0{o p n
V a (stTa60)Ax3600 �nre� a!loAo
it Calculate Volume cl Rueoll Reduction Vic r pwaeMe Men _ 0.70 _
Enter Percentle Storm I (95th Percentile • 0.60rnj nth; OAO In r and
! Lot area OJO
Fnvr Runoff Reduction Vol 1951h Pecrnlilr 0 .60 n ■ Arra x C) V. 475
ppr h — INN.
U Deten4un Approved Ulscharge Rate to Surface Waters (if aoc kable) cis �0 °r tP01; TIT
SIR �oaooas _
a►wo_aeyai� are,s 10 ?oor0_
13VolumeSummery �l wrsarwa � O.ttl-0,11 -_ _, -
luilacoSiusage Basin
PatinFoiebay 76
forssveM 0•!S
Pri + pary I fell IM(L Ota,Te 63%ln U 684
SubsarfaceStorage Ra
Volume 1Vo ;-IN tut Sep meni Factnr (See BMP 21) " ab) V 760 drerell - - --- 0711
Flow sertlr sea tea Tyae
SWW C v . 07 Oct, �ss 0
0
rw- o-1% as o
Air areg . 146% 0.0! 0.12 015 0
smP .g% all oil 1021 0
I Ad" Ird t/om MU
E \•IOBFIIE\TC04\Storm Oraln\ACHD 50 CAICS 112018 dun 10/29/2019, 2 25 FM
Version 10 S, November 2018
Page 8 of 42
ACHD Calculation Sheet for Finding Peak Discharge/Volume - Rational Method
NOTE: This wortlhest le rounded to be a atddatlne to standsrdin ACHO chackbt6 of dralAW calculatlans and chap not replan the Eet&eai s akulatlon meithodorogy These
calculations shall establish a mintmurss ncluleemsnt. The Ers2Mates mathodarIM must ►mutt In facilities that meet or exceed these taladatbnt In order to be accepted
lt*►+.fgC$rJA4DMlM wgwbpj ttevORO" aaatwesaaratee4t .aatwutytrant
L �ctN AawaiilKl �1K W. 1�itHiSt t� [till UMt
Wu Input In Ye110 W c4111
I project Nurse Silver SpArip " Dnln A 1
2 Is area dralmle basin map provided? YES
(map must be included "It scotnrwote► cokuld(lons)
1 Enter Des1En Storm 1100 -Yeu or 2S Year With 100 Year flood Route) 1S
4 Enter number of storaile facilities 115 max)
f kk to Show More Sobbatont ❑
Subbasln Subbasln Subbasin Subbasin Subbasln Subbasln Subbatln Subbasin
E Subbasln 2 3 4 S Subbasin 6 7 a 1 10
5 Area of Dra nave Subbasrn (SF or Actes) SF 1S,961
Meet 037
6 Determine the Weighted Runoff Coefficient IC) 060
C• IIC1aAl) t (C2xA2) tlCnxAnl)/A Weighted Avq 040
7 Calculate Overiand Flow Time of Concentration In Minutes (Tc) or use default 10 1 CakuLso
min Estimated Runoff Coefficients for Various Surfac
--- Type of Surface Runoff Coefficients me
Oetetm ate the aveuee Faviall ntemtty III from Its; urve —austriea -
oaanae+m ate" a ►oo to
4 Cak+aate the Post Development peal d stnuEe lOrtaki 4+ 41 Urban ?o a astw rre�crw°°e — --
aesle.nelat
turt4MFaa,tM assaw
Fit
0 Calculate total runoff vol lVl liar siting primary Swale) 546
V a 011caliMU1 Lie
600 aadrlatMW
6dculatPVotumnofRunofflledumorsVrr aA!!p ! #M _ 410
Enter PercentileStgtmt Milt percentile . 0.60in) 95th 0.60 In Yt�rawcooest"
t+VA we" o ao
Enter Runoff Reduction Vol (95th PerconNr 060•in a Area a C' V• 475 it 0" wee" 0.50
12 Oetentlon: Approved 0 schaile Rate to Suuface Waters (tf appicable) ( Is ~t' ref G f60aa
Pteypwtb o7Po_ ik.
I ) Voiumv Summart urimwas _ 010,010
Surface 510 ate Basin servals
Ba .tnFoieWy v 5 , r , ' AspMh oss
tSonereta o SS
Primary Trearmeat/5lotalra Basin V 49P. 1 ' �rMA _ _- q �9
SuhsurlveMoose faMN� _ oaS
Vo umP Withn .,t SMlment Factor (See aMP 20 Tab) V SO h ' —On
bells Tat* Ice! SO Tepo
Nat y� am 0.07 all 141)
Asereee 14% 0.09 012 0-IS O�U"p . GIs O u 0.23 0
� Mtapaa d ham ASa
E \. OBf11E\TC04\Storm Natn\ACHD SO CAICS_ 112018.xism 10/29/20190 2 25 PM
Version 10 5, November 2018
Pane 9 of 42
ACHD Calculation Sheet for Sitting Seepage Bed With Optional Chambers
NOTE: Tfds workslseet b intended to be a guldeline to standardize ACHO chetkli tg of dialnage calculations and dull not replace the
Engineers akulation malhodobgy. Tbese calculations shall establish a minimum requhanent The Engineers malhodology must result In
lacilliles that mat or excited these akulatlons In order to be accepted.
HIM this opreadslism wAlls khrnlatloe from tM "halt Mr tar
Cakulate Post0evelopmM Flows (fa p►e•derMopmeni flows, Increase number of storage far10tles to create new tab)
User triplet In yeltow cells ,
1 Prolect Name Silver Springs Sub Basin "A l'
2 Enter number of $eepjte Beds 125 male 1
Design Storm
4 Weighted Runoff Coefficient C 060 Unkto Qv
b Area A (Attest a•�� acfwk
QV fIIIS
6 Approved discharge rate ( ff applicable) D•oo Cis
7 lit Stepagt• fled n Common tot? No v 683 h ' 2S % Sedvrrnr
8 Set Total Design Width of All Droll, Rock W 5 0 it
9 Set Total Datign Oopth of All Oran Rock D 6 0 it
Rock Only, Do hot Include Frller Sand Depth or Cwer
10 Void Ratio o1 Drain Rock Voids 04
0.4 for 1 .5`- 2' drain rock and 3/4• Chips
11 Design Inflitratipn Rate (8In/hr mar) Perc 8 00 Who
12 Site of WQ Pert Pipe (Pert ISW) Dia pipe 1N In
13 Site of Overflow Petf Pipe Perfs 3 �—( 60°), RFRO II Q10� 3 3 ds in
14 Calculate Total Storage pef Foot Spf 15 S
is Calculate Dalian length 1 44
Override Value Required for Chamfers
16 Variable Infiltration Window l SWL 44 It
17 Variable Infiltration Wutdow W SWW b 0 It
18 Time to Drain 4 2 hours
909wiumr In 48 hours minimum —
19 length of WO A Overflow Pert Pipes 44 ` tit ' !
20 Pert Pipe Chedu Operf > * Qpeak, - - -
where Qperf•CdxAWj2xga►U
di ,aolao dal I v
lee• This assumes chbrintiM are organized Ina ►Ccta ar layout
1 •Stormlech,
1 Type of Chambers SC740
2 Volume to Store V 0 1r `
3 Installed Chamber Width Cw 4 25, ft
Installed Chamber Depth Cd —��
Installed Chamber Height Ch 7�l'4 ~
4 Chamber Vold Factor
S Chamber Storage Volume, Without Rode, Per Manuf 4590 tir/Unit
6 Chamber Storage Volume, With Rock, Per Manuf 7490 it'/unit
7 Total Nvmber of Units RtQvired 0 as
8 Area of I filuation Aperc All
9 Volume infiltration Vperc Oft `/fw
10 time to Drain hour
9M volume in 484*urs nUrsmum
E :\-10BFItE\TC04\Storm Orom\ACHk SO CAtCS_112018 xlsm 10/29/20190 2 25 PM
Version 100, May 2018
Page 10 of 42
ACHD Calculation Sheet for Finding Peak Discharge/Volume • Rational Method
NOTE : This woctnhett is Intended to boa guldtgne to standardise ACHO checUng of dralnage calculations and shag not replace the U ofe's takulatlon mathodWSY Thew
calculations shall establish a minimum ctquirement The Engtftates methodology must raw% in faclgtles that meet or teceed these cakufations in order to be accepted .
Vatrt tow ►wa tierefrpy Owate aw"t T~' ttllfraras ••eslia e r aat wwl* d fv ifau armlopma nt
�111ti>11f �4�.lZKL•�M .n�rt�sOft� NtiMYalecMillrLO�l� _ _
User input In Yellow COS
1 Project Name SlhrerSpringtSubflae 'V
2 Is area d4na6e basin map piovldtdT YES
(mosi mull be vXwed wfth stamwoter cokulorws)
3 Enter Design Storm ( IMYear (w 25,Year With 100 Year flood Route) 100
4 Enter number of storage fecdltles ()S max)
CbcktoShow More Subbisr s O
Subbasln Subbasln Subbatin Subbsttn Subbasln Subbstin Subbasln Subbstin
1 Subbstin 2 3 4 S Subbstin 6 7 e 9 10
Arta of Drainage Subbstin ISF or Acres) Sf 93,504
Acres 2015
6 Determine the Weighted Runoff CoeHieem (f ) 0.60
CvJ(C1xAI)a(CIeA2)s (CneAn)'/A Weighted A 0.60
7 Calculate Owdand flow Time of Concentration in Minutes (Te or use default 10 lreN+
min trioµ•--J SEstimiated Runoff CoeffklenU for VarlousSurtace
_ _ . _ . TYpe o/ SuAaoe Runoff eoeftklents of
etermrne t arcrage lore ritensty !) tom it)F �urvc can ca so 7 Sbwsieownare" 0.70-093
Y Calculate the Post Deve'oprnent peat discharge IOPeak) < <„ 5. 12 - oAfon awo 70
�erl6eritlel -� - -
10 Cakulate total runoff vol V) (fot slain inv store t V SWf 0 fwhn 0.2" so
1 gPr ry E ) 4,451 0e0,07s
V . Cifi( •60)Aa3600 •ewerwsrLiw 0254040 -
11 (Alculate Volume of Runoff Reduction Vrr Mkt AY MN Owy e 070eeeeeeee
v
Ente: Percenldr Storm I19Sth prrcentite • 0.60on) 9Slh 0.60 In •n�frlYandtwtimerdal
� araea o so
Enter Runoff Rrduolon Vat 1951h PercentNe •0.6(} ws a Area a Q vo 2,762 h How q arm 030
I7 O" enuon : Approved Ulsthafge Rate to Surface Waters (i( applu ab'e) (lb r hr Ctnroaotn - - oa_oo 25
rle�wirroia O2o-035
13 Volume Summa •aLYadeertlanas 020-0AO
— -
rV , U•rrYreradMus � 0100l0
Surface SIOlaee' bas n solve"
Oasfnfoeebd , t 44ri 11 phmk o!S
Centro" Gets
DrimaryTreaiment /Str eRaSrn a 44t)" 1i IMW Z�
Sub %Ufla Cr 5lnraRe L hook _ 0 fS -
Vutuil c Wltfalui Scdimpni Fului ! Sri SNIP 10 Tab) 4 4,451 14 �4Yeoel _ _ 0.73
ndit Saar weirSo I Tv W
Slope A • C D
flat p.� 6044 to all o.
Average 2 .0% oof 0. 17 O.1S 0
u•'P v4% all a1a off O
4 Aderred from A%C(
E \•IOBFtIE\TC04\Storm Dia, n\ACND_SO_CAIIS_11201exl" 10/24/2019$ 9 49 AM
Version 105, November 2018
Page 11 of 42
ACHD Calculation Sheet for Finding Peak Discharge/Volume - Rational Method
NOTE: This worltsheet Is tnta sded to be a guMeNae to aandsrdlte ACHO the kips of d►alnage caltulatlom and shall not replan the [nslneerY tdculatlon lnwtitodotosY. these
callcuUtlons {hail estabflsh a minlinum requirement, The EnSMsees mtthodotosy must result In facgltles that meat or exceed these calnAartlons (A order to Ill accepted
curf+ fmawtotwpwrdeft f■rrfttiw>"aaw. t _
i[tl[iJ� crsi�r�ti�ill�Jiiw�rvwwwr�rrn�tt�,.- �n9i!i21�wr(g _ - i'"1'L_
user Input In Yellow Calls.
1 Istolect Name Sllre► Springs Sub ealln a
2 Is area drainage basin map provided? YES
(mop molt be lncdrded ]vrth srormworer COkulollonf)
3 Enter Design Storm ( IMYear or 254ear With IOD Year flood Route) is
e Enter number of storage fad4lies (2S mas)
CLa to Slaw Mae Subbasms ❑
Subbasin Subbsstn Subbasln Subbasin Subbastn Subbatla Subbasin Subbasin
1 Subbastn 2 3 e S Subbasin 6 7 a 9 10
S Area Of Drainage SYbbasm (Sf or Acres) SS 931Stl9
Acres 2 -iS
6 Oatermnethe Weighted RunofICoefficient (C) 060
C ' ((CIxA1 )+(C2xA2H1CnxAn)3/A We ghted AVC1 0.60
2 Calculate Overtand Flow fir" of Conceni,alfon In Minutes (Tel or use delau(t 10 uvr GrrvtlN
min Do w+�� Estimsted Runoff coefficients for Various Surfac%
Type OI St atin - - — Runoff Coeffidernts "e
tNm rte IM average rrn all tnttmlty r am a Curve rind on It i111SI Oowrrorn Cane► 0loan
9 calevlate the post De .elopment peat discharge (CIPeaA) 4... i » h urlann eda asoo "
aaaaarrsel
n.yte r. � k ass o so
10CakuI etotalvoIM (forllten u
g91n n sioiaye) �' 3199 R
lunoH N„n;aree nio0.7s
V • Co (Ti •6O)Ax360D R_rd_ dr��41bvr1 02" 46
11 Cal -utateVolume of Runoff ReduruonVn mOwa wr. 0.70
Enter pavenlile wit'"Storm I19Sth percentile 0.601n) 911h 0.60 In it'" rW end Co erdel
tJeren 080
Enter Runoff Redaction Vol193th PercenlHe.O 6G4n ■ Area 4 Q u i .7g2 w Cann aso
12 Oelent On Approved Odchit a Rate to Surlace Water] If ►arla. Cer]saterNs aIOQ?�
P s { applxN111:) ck
� RaeroW yar0 anii _ � O. taO e0 _
13 Volumu Summary wWawt 61"30
Surlaee Storaao . OSs n Wesel
a»
Basin Foartraf 32C ft ' Alpha%Conc"te 093
Prrtrart Treatment/Storage Dash N 1979 eAd ass
Suhs .r Ixe Storage ppooll _ _ D.l3
Vniume Wdhnul Sediment factor 15pro eIAP 20lab) v 31199 tr 45541111111 -- 11075 —
rWdz - San*, led Soil type --
Slope A IC0.01 ,
0
flu ORlt► 0.04 007 O
Avereee 14% OJ t 0612 MIS 0
Sit
sale 0. 1a - Ole 013 0
Adaptedfrom ASCI
E \•)00FIIE\TC00\Stoim Orain\ACHD SO_CALCS_ 11201B dun 10124/201919SO AM
Version 10 5, November 2018
Page 12 of 42
ACHD Calculation Sheet for Sand/Grease Traps
NOTE : This worksheet is intended to be a guideline to standardize ACHE checking of drainage calculations and shall not replace the
Engineer's calculation methodology, These calculations shall establish a minimum requirement. The Engineers methodology must
result In facilities that meet or exceed these calculations In order to be accepted,
%lepr for sand/Grease Trap Velocity Calculation
User Input in yellow cells,
i Project Name Silver Springs Sub Basin '8"
2 Enter number of Sand/Grease Tra s 125 max Bedfle i
Number of Peek Flow hrditt ty a the
E1500
S/G Traps Q•cfs king width Area (fly) 0. 5 fps Velocity
c is
1 3 .32 24 615 10625 0 32
Reference for Throat widths (inch)
Eloise ADS
Vaull Lar• ken WQU .
amp 16
1000 G 48.0 5015 n/a
1500 G 60.0 615 n/a
QU1000 n/a n/a 60
QU1500 n/a n/a 60
E :\•108FILE\TC04\Storm Draln\ACHD_SD_CALCS_ 112018. xlsm 10/24/2019, 9 : S5 AM
Version 10 0, May 2018
Page 13 of 42
ACHD Calculation Sheet for Sizing Seepage Bed With Optional Chambers
NOTE: This worksheet Is Intended to be a gutdellne to standardize ACHD checking of drainage calculations and chap not replace the
Enstriser's catculi tlen methodobS. These calculations "I establish a minimum requirement. The Eagineers methodology must result In
facilities that meet or exceed these alculatlons In order to be accepted.
Nate this Mendelian palls IMormatlan from the 'Pak Wr tab
Calculate Postaoawlopment flows (for pre.devdopment flows. Increase number of storage faciBtks to create new tab)
User input In yellow c485.
1 Project Name 511Var Sprirsgs Sub Basin "B"
2 Enter number of See
page8edill5max) 1
IN Design Storm 100
4 Weighted Runoff Coefficient C ice+ cI Unit to: �nu�
S Area A lAcres) �� 15 L#Ms QV IM
6 Approved discharge rate (mf applicable) O. 00 cfs L
7 Is Seepage Bed In Common Lot ? No V S, S64 !t '
8 Set Total DeslAn Width of AO Dra n Rack IN 15 0 it
9 Set Total Design Depth of All Dram Rock O 6 0 it
Rock Only, Do Not Include Filter Sand Depth c( Corer }
10 Void Ratio of Drain Rock Voids 04
OA for 1 S'•2` drain rock and 3/40 Chips
I1 Design Infihratmon Rate (8In/hr max) Perc 8.00 in/hr
12 Site of WQ Poll Pope (Per ( 11109) Du is pit In
13 Site of Overflow Pert Pipe (Perf1360 °). RECTO if QI00*3 3 cis �In
14 Calculate Total Storage per Fool Spi 462 rt
I
IS Calculate Design Length 120 it
Override Value Required for Chambers
16 Variable Infiltration Window L SWL 120 It
17 Variable Infiltration Window W SWW ISO It
18 Time to Drain 4 . 2 hours
90% volume In 484hours min mum —
19 Length of WQ & Overflow Pert Pipes I" It
70 Pert Pipe Checks Qperf > = Qpeak,
where Qpo& CdxAxVJ2,gxN)
- -"lanai �t �` �ftbtn6ae
18` Thb isuurncs chambers are organized in a rectangular layout
1pStormTech,
1 Type of Chambers SC740
2 Volume to Store V 0t
3 Installed Chamber Mhddh Cw 4 2S h
installed Chamber Depth Cd 230 ft
Installed Chamber Height Ch fi
4 Oismber Void Factor
S Chamber storage Volume, Without Rook Per Mwwf 45 .90 r '/unn
6 Chamber Storage Volume. Wlth Rock Per Manut 74 90 „ '/Unit
7 Total Number of Units Required d 4111
8 Area o1 Infiltration Apart �t
r
9 Volume Infiltration Vperc 0 tti/hr
10 nme to Grain tours
SM volume In 48-hours minimum
E:\ JO8ftlt\TC04\Storm DraIn\ACHD SD CALCS_112018.xtsm 10/24/2019, 9:S0 AM
Version 1008 May 2018
Page 14 of 42
ACHD Calculation Sheet for Finding Peak Discharge/Volume • Rational Method
NOTE: This worlisheet Is Intended to be a gutdeUrte to standardhe ACHO shading of drainage calculations and shall oot replace the Engineees calculation m lthodolo=Y Tbete
caltvtations Mefl estsblhh a minimum reputrarnent. The Eegtneerrs rnnetlnodolM must result in facilities that meat or awed three calculations in order to be stapled.
Sis" Vwftals111111VAe1in Now ewsy400 elMH Not 00*1111 - tor 0 wr
Vfer IMput In YelloW calls
1 Project blame Silver Strinr Sub Basin C
7 Is area drainage basin map provided" TES
(mop must beWtuded w1th stormwoler (okutotlons)
3 Enter Design Storm ( 100-Year or 25-Year Wills 100-Year Flood Route) f00
4 Enter number of storage Facilities 425 mace)
Cttk ro Show More Ubbasins ❑
Wbbasln Subbisin Subtasln Subbasan Subbastrt Subbimin Subbssin Subbasln
1 Subbasin 2 3 4 S Subbasln 6 7 a 9 10
S Area of Drainage Sublawn ISF or Acres) SF 1658241
Acre 336
6 Determine the Weighted Runoff Coefficient (C) 0.60
C I(CIrAI ) s(C) sA7Jr(CnxAn)VA WeightedA a60
7 Calculate Overland Flow time of Concentration in Minutes If c) of use default 10 u.rc.snr+se
min [ wMf -1 Estitnatt'_011unoff cat fticients for various suAaK
— — 91lSurfaoe RunoffCoeHfdents 's
Determine the average lad i ; entity 1 from " Me based on Tc 1 taAM" - --
V Calculate the Post Developmenl peals discharge ( OPeak) n O°r "tsee ° cur..' ° so° as
S-9E tartrerr ►rww.aaa _ -_ -_ - - osoo,lo
RetsferMW _ _
ollos
10 Cai% u Aie totalfunoN Vol (V► (for ailing Primary Storage) V 114009 >�tMrerrr+sr 04" 7o
eetdttaw.er o.eoo. »
Va (I ( Tra(iO)NO600 _ a.rte.m�r�n.,ry . - - _ _----- 0.13046
- ---- ---- ----
1l Calculate Volume of Runo" Reduction Vir atx.v.�ns_Or..�.�Areea 070
Ind
Enter Pricenllle Storm t (95th percuntllr ■ 0 60 in) 95th O.GQ In U0KLislerrdCarrtreerl�
Fapq rnrees caw
Fear Runoff Reidunlon Vol 19w Th Pe ru ntlle•0 6D4n aAroa sC) V. S.005 h mom mom Oep
111111111 ra6LOrreaarin -- - O-boas
12 Ottent(on Appr&jed 01Itharge Rate to Surface Waters pf appbsabfeI cgs t aloes as
- — --- -----
13 Volume Summary RerroNyerIweiss Ct0010 � �
Y `IMinMw�N erees __ 0. lOOJ0
SullaCC510ri$ C FlaSln litreeta
Oasm Farrbiy if 801 It Aryhelt 0a3
Concrete O f$
Primary Trrormfni/StrjaFe Ras n V 7, 208 41 ` 4104s.M aI
Subsu • face SlorAEe tbub 0 *5
Volumu Without Sedlmi rh) ti >t,009 4 � -- LrTYa - - - - - -
i lope A C a
Ft* 0i i toe 0.07 jalt 0
Average 34% I O.or o is I at$ o
s
ireep ..cr r 011 I fe air O
ae,nteeaamAseT
E \•J0BFIIE\TC04\Sto1m Oram\ACHD_SO CAECS_112018.r1sm 10/24/201909 Sl AM
Version 10. 5, November 2038
Page 15 of 42
AND Calculation Sheet for Finding Peak Discharge/Volume " Rational Method
NOTE: This worksheet is Intended to be a guldelina to standerdiia ACHD chacWg of drainage calculations and dull not eeplace the Erpht ter's cakulaUrtn methodology. Thew
calculations shall establish a minlntuon requirement. The Engineer's mathodoliM must racult In fwMks that meet a txmd Neu calculadom In order to be accepted .
xM► aa.tx Ot�aptriWoo" + ovol 641041Mlarttwrft$4aa+aae"MW I
k*U thorltr�tg4 R1 i11gl�fFFt _11 T1 i44E�!! 1> _ _ _ _
User Input In Yellow cells,
I "eel Name SUver Springs Sub Basin "C"
2 Is area drainage basin map provided? YES
(map mum be inch,ded wNh storm tvOrer cokuratk3M)
3 Enter Design Storm ( 100-Yeu or 2S•Year With 100•Year Rood Route) 25
4 Enter number of storage facilities (25 mas)
Click to Show More Subbases ❑
Subbasin Subbasln Subbasln Subbstln Subbasin Subbssln Subbasin Subbasin
1 Subbasln3 ! 4 S Subbasin6 7 a 9 10
S Area of Diauuge Subbaiin (SF or Acres) $F 16111241
Acres 36"
6 Otteimrne the Weighttd Runoff Coeflicwnt (C ► 0.60
C ((CIxAI ) r(C ?xA2)s(CnxAn)VA Weighted Avjz 0.60
7 Calculate Overland flow Time of Concentrallon in Minutes ITc) or use dtfauit 10 tftaru
min toss^ 1 Estimated Runoff Coatffdents for Various Surlac
now of surha Runoff Coetricients 'e
OHbn+ete tht aimriaga ra allrntensity (i) frfrom iOl l.urve baled on Ic l +_ doa� 0.700K
9 Calculate the rest Development peak discharge (QPeak) cL . a 2! ud d n 4S" 7o
10 04ulate total wnolf primary storage)lVl lfor slting prima storage) w 5,756 Is �a wp4 ft also $o
anwt4aawtr _!._ _ _ _ _ _ ____ 046o-o75 _.
VAcl (rc• 6OIAx3600 Aftwomwtwin -- ----_ __ 0. 23o.eo __ _- -
11 Catrulatr Volume of Runoff Reduction Vrr Yta .Q+E.rA - 070 -_
nd Coww"1111191111
Enter Percentile Storm I (9Sth percents• 0.60m) 95th 060 it Ught areas O.sO
Enter Runoff Reduction Vol I9Sth Percentile 0.60.1n x Area x q V- 3006 ft s rsas 0.l0 _�
12 Detention . Approved Dluhafge Nate to Sufface Waters lif applicable) (Is
011" as
13 Vo:vmr4ummary ___ ee�Aarp• - -- 0.100J0
Surface StotaRe Resin Sow
Satin Farebay v S76 4 Wash 0 !S
Corsiiv 41s
Primary treatme , :/Sio•age flat n V S,lgl !1 4IA 0 !s
Subtmfaw 5toralc ^_Noahorwres
tiro!ume Without ScJ mart sutni (St: u BtAP 20 fib) V S1756 it 0.1>_"�"
rwta swter cos So Type .
Sa�W A 11 C D
1 S FVA 0,211O4
0.07 011 o.
Avar•ee. 141% 0.01 OLU 015 0
ueepsstt o la o la oil o
t "a dod from Ass[
E \•IOBFIIE\TC0AStorm Dialn\ACHD_SD CALCS_11201b idsm 10/24/20190 9.51 AM
Version IDS. November 2018
Page 16 of 42
AND Calculation Sheet for Sand/Grease Traps
NOTE : This worksheet is intended to be a guideline to standardite AOiD checking of drainage calculations and shall not replace the
Engineer's calculation methodology. These calculations shall establish a minimum requirement. The Engineers methodology must
result In facilities that meet or exceed these calculations in order to be accepted.
Steps iov Sand,/Geesse Trap vetoritx Caicutation
User Input in yellow cells.
1 Project Name Silver Springs Sub Basin "C"
2 Enter number of Sand Grease Traps 25 max 1
Number of Peak Flow Sallie roll 8 e
V
ault Spacing width Area (ftt) 0.5 fps Velocity
3/G Traps Q.cls inch Inch max ok7
8 Sag 24 61 .5 10.25 0.5 4 K
Widths (inch) AD5aut Lar-ken WOU,
BMP 16
1000 G 48.0 503 n/a
15M G 60.0 61 . 5 n/a
QU100D n/a n/a 60
OU150D n/a n/a 60
E :\-JOBFIIE\TC04\Storm Drain\ACHD.SD_CALCS. 112018 . x1sm 10/24/2019, 9 : 52 AM
Version 10. 0. May 2018
Page 17 of 42
ACHD Calculation Sheet for Sizing Seepage Bed With Optional Chambers
NOTE: Thh wotlishest Is Irstended to be a guldeline to stand"ta ACHD cbeclln8 of drainage calculations and stall not replace th►
Engineer's calcu)aUon methodology. These calculations shall establish a minimum requlreftWAL The Ingkl % methodology must mutt In
facilities that meet or exceed time calculations In order to be accepted.
Note this 4woradshaid gluft IefotMNlon Mons the Valais N bb
Gkulate Past-Mvelopment It low (for pmdeval"ment flows, Increase number of storage fadlitlits to create now tab)
Iher Input In yellow cells.
I Protect Name Sliver Sptings Sub Basin `C'
2 Enter number of Seepw Beds US max 1
3 Design Storm I00
4 We ghted Runoff Coefficient C 0.60 to QV
S Area A (Acres ; 86 grin QV TaIS
6 Approved dscharge rate (if applicable) 0 00 ds
7 is Seepage Bed In Common tot ? No V Moll F 151E Sedvnrnt
8 Set Total Design Width of All Oran Rock W ISO h
9 Set Total Design Depth of All Drain Rock D 6 0 ft
Rock Only, Do Not Include Filter Sand 0ep1h or Cover
10 Vald Ratio of Drain Rock Voids 04
OA for 1 S' 2' dealn rock and 3/4' Chips
11 Design Infiltrotlo + Rate (e m/hr maa) Perc $ 00 In/hr
12 Site ofWQPertPipe (Pert180a1 Dim pipe Is in
13 Site of Overflow Perf Pipe (Perfs MM, RCQD if (1100* 3. 3 cis In
14 Calculate 70131 j".0rase per Foot Spf 462 h'/e
IS Calculate Design length t 217 {�
Override Value Required for Chambers
16 Variable Infiltration Window L SWt 217 h
17 Variable Infiltration Window W SWW ISO it
IB Time to Drain 4 Z hours
90% volume In 48- hours minimum
i
f
19 Length of WO & Overflow Pert Pipes 217 It
20 Perf Pipe CFmks Ctperl > • Qpeak
where Clperf>CdsAsV(2sgxH)
Note: s assumos chamber am organited In a rectangular layout
I•StormTech,
T Type of Chambers SC740
2 Volume to State V 0 hs
3 installed Chamber Width Cw 4.75
Installed Chamber Depth Cd 125Q ft
Installed Chamber Height Ch 7.12 h
4 Chamber Void factor
t
S Chamber Storage Volume, Without Hock, Per Manuf 4390 ft /fJnit
6 Chamber Storage Volume, %th Rock, Pot Manuf 706 Its/Unit
7 Total Number of Units Required O lea
Are$ of Infiltrallon Aperc )i
9 Volume Infiltration Vpefc 0 fts/M
to Time to Ora in _hours
9Ots volume In 484sours minimum
C:'i, 14BFILE\TC04\Storm Drarn\ACHD SD CAICS 11201tldsrn 10/24/1019, 9 52 AM
Version 10.0, May 2018
Page 18 of 42
Material Testing and Inspection , Inc .
Report and Addendum
Page 19 of 42
MATERIALS 27 March 2019
TESTING 6 Page 8 1 of 14
'� INSPECTION b19t)757g bmnalgw
AN ATLAS COMPANY
O Environmental Services O Geotechn cal Engineering O Construction Materials Testing O Special Inspections
Mr. Dave Yorgason
Tall Timber Consulting
14254 West Battenberg Drive
Boise, ID 93713
2084504070
Re : Limited Geotechnical Engineering Report
Silver Springs Subdivision
905 East McMillian Road
Meridian , ID
Dear Mr. Yorgason :
In compliance with your instructions , MTI has conducted a limited soils exploration for the above referenced
development . Fieldwork for this investigation was conducted on 13 March 2019 . ']' he proposed development
is in the northern portion of the City of Meridian , Ada County, ID , and occupies a portion of the NW 'hNE '/, of
Section 31 , Township 4 North , Range I East , Boise Meridian . This project will consist of construction of a
residential subdivision to be developed on approximately 20 acres .
Authorization
Authorization to perform this exploration and analysis was given in the form of a written authorization to
proceed from Mr. Dave Yorgason of "Fall ' Timber Consulting to Jacob Schlador of Materials Testing and
Inspection ( MTI ), on 28 February 2019 . Said authorization is subject to terms , conditions, and limitations
described in the Professional Services Contract entered into between Tall Timber Consulting and MTI . Our
scope of services for the proposed development has been provided in our proposal dated 27 February 2019 and
repeated below .
Scope of Investigation
The scope of this investigation included review of geologic literature and existing available geotechnical studies
of the area , visual site reconnaissance of the immediate site , subsurface exploration of the site , field and
laboratory testing of materials collected and engineering analysis . Our scope of work did not include
foundation , earthwork , or design recommendations specific to individual residences .
General Site Characteristics
This proposed development consists of approximately 20 acres of relatively flat terrain . The project site includes
four residential properties south of McMillan Road . Each of the four properties consisted of residences and
associated outbuildings in the northern portions of the lots . A landscaping company is present surrounding the
residence on the eastern- most lot . Pasture land or vacant wan was present surrounding the remaining three lots .
Within the single test pit advanced , surficial soils consisted of lean clays . Vegetation primarily consists of
mature trees, bunchgrass , and other native grass varieties typical of arid to semi -arid environments .
2791 S Victory View Way • Boise, ID 83709 • (208) 376 4748 • Fax (208) 322 6515
%wAv. mti d com • nit. inik td,lc.n
Page 20 of 42
MATERIALS 27 March 2019
! ' Page # 2 of 14
d ( TESTING
INSPECTION b19o357s _ brtxtedgeo
AN ATLAS COMPANY
O Environmen�al Services 0 Geotechmcal Engineering O Construction Matetia s Test , ig O Spec a ' Inspections
Regional drainage is north toward the Boise River . Stormwater drainage for the site is achieved by percolation
through surficial soils . The site is situated so that it is unlikely that it will receive any stormwater drainage from
off-site sources . Stormwater drainage collection and retention systems are not in place on the project site and
were not noted within the vicinity of the project site.
Exploration and Sampling Procedures
Field exploration conducted to determine engineering characteristics of subsurface materials included a
reconnaissance of the project site and investigation by test pit . The test pit site was located in the field by means
of a Global Positioning System (GPS) device and is reportedly accurate to within fifteen feet . Upon completion
of investigation , the test pit was backfilled with loose excavated materials . Re-excavation and compaction of
the test pit area is required prior to construction of overlying structures .
In addition , samples were obtained from representative soil strata encountered . Samples obtained have been
visually classified in the field by professional staff, identified according to test pit number and depth, placed in
sealed containers, and transported to our laboratory for additional testing . Subsurface materials have been
described in detail on the log provided in the Enclosures section . Results of field and laboratory tests are also
presented in the Enclosures section . MTI recommends that the log not be used to estimate fill material
quantities .
Laboratory Testing Program
Along with our field investigation , a supplemental laboratory testing program was conducted to determine
additional pertinent engineering characteristics of subsurface materials necessary in an analysis of anticipated
behavior of the proposed structures . Laboratory tests were conducted in accordance with current applicable
American Society for Testing and Materials (ASTM ) specifications , and results of these tests arc to be found
on the accompanying logs located in the Enclosures section . The laboratory testing program f'or this report
included : Atterberg Limits Tcsting ASTM D4318, Grain Size Analysis ASTM Cl 17/C 136, and Resistance
Value ( R -value) and Expansion Pressure of Compacted Soils Idaho T= 8.
Soil and Sediment Profile
The profile below represents a generalized interpretation for the project site . Note that on site soils strata may
vary from the individual soil profile presented in the log, which can be found in the Enel (mures section .
The materials encountered during exploration were quite typical for the geologic area mapped as Gravel of
Whitney Terrace . In the single test pit advanced , surficial soils were lean clays . The lean clays were brown ,
slightly moist , and stiff to very stiff. Underlying the Ivan clays were silt soils . The silt soils were light brown to
pink , dry, hard , and contained fine-grained sand . Strong calcium carbonate cementation was noted in this
horizon . At depth , poorly graded gravel with sand was encountered . These sediments were yellow brown , dry,
medium dense to dense , and contained fine to coarse-grained sand , fine to coarse gravel , and 20Anch -minus
boulders .
2791 S victory View way • Boise ID 83709 • (208) 376.4748 • Fax (208) 322.6515
www mU id com • nu nm! id cc; ,,
Page 21 of 42
MATERIALS 27 March 2019
TESTING & Page tf 3 of 14
INSPECTION WOWSbmncdgco
AN ATLAS COMPANY
U Environmental Services U Geotechmcal Engineer ng U Construction Materais Testing O Special Inspect ons
Competency of test pit walls varied little across the site . In general , fine grained soils remained stable while
more granular sediments readily sloughed . However, moisture contents will also affect wall competency with
saturated soils having a tendency to readily slough when under load and unsupported .
Groundwater
During this field investigation , groundwater was not encountered in the test pit advanced to a maximum depth
of 14 . 8 feet bgs . Soil moistures in the test pit were generally dry to slightly moist throughout . In the vicinity of
the project site , groundwater levels are controlled in large part by residential and commercial irrigation activity
and leakage from nearby canals . Maximum groundwater elevations likely occur during the later portion of the
irrigation season .
r During previous investigations performed in March 2005 , July 2006, June and September 2007 , February 2008 ,
and October and November 2013 within approximately %,- mile to the west and east of the project site, no
evidence of groundwater was noted within numerous borings and test pits advanced to depths as great as 14 . 0
to 21 . 5 feet bgs . Furthermore , according to United States Geological Survey ( USGS) monitoring well data
within approximately �/4- mile of the project site, groundwater was measured at a depth of 20 feet bgs .
For construction purposes , groundwater depth can be assumed to remain greater than 20 feet bgs throughout the
year. Since this is an estimated depth and seasonal groundwater levels fluctuate, actual levels should be
confirmed by periodic groundwater data collected from the piezometer installed in the test pit . if desired , MTI
is available to perform this monitoring .
Soil Infiltration Rates
Soil permeability, which is a measure of the ability of a soil to transmit a fluid , was not tested in the field . Given
the absence of direct measurements, for this report an estimation of infiltration is presented using generally
recognized values for each soil type and gradation . Of soils comprising the generalized soil profile for this
study, lean clay and silt soils generally offer little permeability , with typical hydraulic infiltration rates of less
than 2 inches per hour; though calcium carbonate cementation may reduce this value to near zero . Poorly graded
gravel with sand sediments typically exhibit infiltration values in excess of 12 inches per hour. Infiltration
testing is generally not required within these sediments because of their free-draining nature .
Infiltration Testing
Infiltration testing was conducted in general accordance with the Ada County Highway District ( ACHD) Policy
Manual . The test pit area will need to be re -excavated and compacted prior to construction of structures that
will be sensitive to settlement . The test location was presoaked prior to testing. Pre -soaking increases soil
moistures, which allows the tested soils to reach a saturated condition more readily during testing . Saturation
of the tested soils is desirable in order to isolate the vertical component of infiltration by inhibiting horizontal
seepage during testing .
2791 S Victory Viow Way • Boise ID 83709 • (208) 376- 4748 • Fax (208) 322-6515
worn ml - id com • m AMli- id cam
Page 22 of 42
MATERIALS 27 March 2019
TESTING & Page # 4 of 14
INSPECTION bt `�t ls7g timncai,;e®
AN ATLAS COMPANY
U Environmental Services O Geotechnical Engineering O Construction Materials Testing O Special Inspections
Infiltration testing was conducted within the poorly graded gravel with sand sediments at a depth of 10 . 5 feet
bgs. A stabilized infiltration rate of greater than 12 inches per hour was obtained during testing . Per the ACHD
Policy Manual requirements , the maximum design soil infiltration rate shall not exceed 8 inches per hour.
Therefore, a design infiltration rate of 8 inches per hour should be used for the poorly graded gravel with sand
sediments encountered at depth in the test pit. It should he confirmed that infiltration facilities are constructed
in relatively silt free poorly graded gravel with sand sediments . MTI recommends that all infiltration facilities
be constructed in accordance with the local municipality requirements .
Recommended Pavement Section
As required by Ada County Highway District (ACHD) , MTI has used a traffic index of 6 to determine the
neces%ary pavement cross-section for the site . MTI has made assumptions for traffic loading variables based
on the character of the proposed construction . 'fhe Client should review these assumptions to make sure they
reflect intended use and loading of pavements both now and in the future . MTI collected a sample of near-
surface soils for Resistance Value ( R - value) testing representative of soils to depths of 2 feet below existing
ground surface . This sample, consisting of lean clay collected from test pit 1 , yielded a R- value of 6 . The
following are ,minimum thi& kness requirements for assured pavement function . Depending on site conditions,
additional work , e .g . soil preparation , may be required to support construction equipment . ' I11ese have been
listed within the Soft Subgrade Soils section . Results of the test are graphically depicted as an Enclosure .
Flexible Pavement Section
The Gravel Equivalent Method , as defined in Section 500 of the State of Idaho Department of Transportation
( ITT )) Materials Manual , was used to develop the pavement section . ACI ill ) parameters for traffic index and
substitution ratios, which were obtained from the ACIID Policy Manual , were also used in the design . A
calculation sheet provided as an Enclosure indicates the soils constant , traffic loading , traffic projections , and
material constants used to calculate the pavement section . MTI recommends that materials used in the
construction of asphaltic concrete pavements meet the requirements of the ISPWC Standard Specification for
1lighway Construction . Construction of the pavement section should be in accordance with these specifications
and should adhere to guidelines recommended in the sections on Common Pavement Section Construction
Issues .
Gravel Equivalent Method Flexible Pavement Specifications
Pavement Section Component " Roadway Section
Asphaltic Concrete 2 . 5 Inches
Crushed Aggregate [ lase 4 . 0 Inches
Structural Subbase 14 .0 Inches
Compacted Subgrade Not Required for Native Soils
' it will be rcctuired for MTI personnel to verify subgradc compctcncy at the time of construction
2791 S Victory View Way • Bolse, to 83709 • (200) 3764748 • Fax (208) 322.8515
wvr:, mill ul cam • m 11j'a]ntti id co -
Page 23 of 42
MATERIALS 27 March 2019
TESTING fs Page # 5 of 14
INSPECTION ft1901578 limil<dgco
AN AnA$ COMPANY
U Environmental Services O Geotechn cal Eni ineenni U Construction Mate a Test nq O Special Inspections
Asphaltic Concrete ; Asphalt mix design shall meet the requirements of ISPWC, Section 810 Class Ill plant
mix . Materials shall be placed in accordance with ISPWC Standard Specifications for
Highway Construction .
Aggregate Base : Material complying with ISPWC Standards for Crushed Aggregate Materials .
Structural Subbase . Material complying with requirements for granular structural fill (uncrushed) as
defined in ISPWC .
Common Pavement Section Construction Issues
The subgrade upon which above pavement sections are to be constructed must be properly stripped , inspected ,
and proof- rolled . Proof rolling of subgrade soils should be accomplished using a heavy rubber- tired , fully
loaded , tandem -axle dump truck or equivalent . Verification of subgrade competence by MTI personnel at the
time of construction is required , fill materials on the site must demonstrate the indicated compaction prior to
placing material in support of the pavement section . MTI anticipated that pavement areas will be subjected to
moderate traffic . Sub¢rade clays and silts near and above optimum moisture contents may pump during
compaction , Pumping or soft areas must be removed and replaced with structural fill .
le ill material and aggregates in support of the pavement section must be compacted to no less than 95 percent
of the maximum dry density as determined by ASTM D698 for flexible pavements and by ASTM D1557 for
rigid pavements . If a material placed as a pavement section component cannot be tested by usual compaction
testing methods, then compaction of that material must be approved by observed proof rolling. Minor
deflections from proof rolling for flexible pavements are allowable . Deflections from proof rolling of rigid
pavement support courses should not be visually detectable .
Soft Subgrade Soils
Shallow fine-grained subgrade soils that arc high in moisture content should be expected to pump and rut under
construction traffic . During periods of wet weather, construction may become very difficult if not impossible .
The following recommendations and options have been included for dealing with soft subgrade conditions :
• Track-mounted vehicles should be used to strip the subgrade of root matter and other deleterious debris .
Heavy rubbemired equipment should be prohibited from operating directly on the native subgrade and
areas in which structural fill materials have been placed . Construction traffic should be restricted to
designated roadways that do not cross, or cross on a limited basis, proposed roadway or parking areas .
• Soft areas can be over- excavated and replaced with granular structural fill .
• Construction roadways on soft subgrade soils should consist of a minimum 2400t thickness of large
cobbles of 4 to 6 inches in diameter with sufficient sand and fines to fill voids . Construction entrances
should consist of a 6 - inch thickness of clean , 2 - inch minimum , angular drain-rock and must be a
minimum of 10 feet wide and 30 to 50 feet long . During the construction process, top dressing of the
entrance may be required for maintenance .
• Scarification and aeration of subgrade soils can be employed to reduce the moisture content of wet
subgrade soils . After stripping is complete , the exposed subgrade should be ripped or disked to a depth
of 1 % feet and allowed to air dry for 2 to 4 weeks . further disking should be performed on a weekly
basis to aid the aeration process .
4 2791 S Victory View Way • Dome ID 83709 • (208) 3764748 • Fax 1208) 322 6515
1y&Wn1tPtd n • mti@ tdi- IJ
Page 24 of 42
MATERIALS 27 March 2019
TESTING >Fs Page # 6 of 14
.rye
INSPECTION b11Xi337Ltimncdgeo
AN ATLAS COMPANY
O Env ronmental Services O Geotechnica Engineer ng D Construct on Maier als Testing ® Specuat Inspections
• Alternative soil stabilization methods include use of gcotextiles , lime, and cement stabilization . MTI is
ava ' table to provide recommendations and guidelines at your request .
Warranty and Limiting Conditions
MTI warrants that findings and conclusions contained herein have been formulated in accordance with generally
accepted professional engineering practice in the fields of foundation engineering, soil mechanics , and
engineering geology only for the site and project described in this report . These engineering methods have been
developed to provide the client with information regarding apparent or potential engineering conditions relating
to the site within the scope cited above and are necessarily limited to conditions observed at the time of the site
visit and research . Field observations and research reported herein are considered sufficient in detail and scope
to form a reasonable basis for the purposes cited above .
Exclusive Use
This report was prepared for exclusive use of the property owner(s), at the time of the report , and their
.retained design consultants (" Client" ). Conclusions and recommendations presented in this report are based
on the agreed- upon scope of work outlined in this report together with the Contract for Professional Services
between the Client and Materials Testing and Inspection ("Consultant ") . Use or misuse of this report , or reliance
upon findings hereof, by parties other than the Client is at their own risk . Neither Client nor Consultant make
representation of warranty to such other parties as to accuracy or completeness of this report or suitability of its
use by such other parties for purposes whatsoever, known or unknown , to Client or Consultant . Neither Client
nor Consultant shall have liability to indemnify or hold harmless third parties for losses incurred by actual or
purported use or misuse of this report . No other warranties are implied or expressed .
Report Recommendations are Limited and Subject to Misinterpretation
There is a distinct possibility that conditions may exist that could not be identified within the scope of the
investigation or that were not apparent during our site investigation . Findings of this report are limited to data
collected from noted explorations advanced and do not account for unidentified fill zones , unsuitable soil types
or conditions , and variability in soil moisture and groundwater conditions. To avoid possible misinterpretations
of findings, conclusions, and implications of this report , MTI should be retained to explain the report contents
to other design professionals as well as construction professionals .
Since actual subsurface conditions on the site can only he verified by earthwork , note that construction
recommendations are based on general assumptions from selective observations and selective field exploratory
sampling . Upon commencement of construction , such conditions may be identified that require corrective
actions , and these required corrective actions may impact the project budget . Therefore , construction
recommendations in this report should be considered preliminary , and MTI should be retained to observe actual
subsurface conditions during earthwork construction activities to provide additional construction
recommendations as needed .
2791 S Victory View Way • Bow. ID 83709 • (208) 3764748 • Fax (208) 322.6515
yrd,nv mti id cm • mti (a) mli d coin
Page 25 of 42
MATERIALS 27 March 2019
TESTING & Page # 7 of 14
INSPECTION b190357g l +mitedgco
AN ATLAS COMPANY
O Env ronmental Services O Geolechn cal Fngmeering (] Construction Materials Testing to Special Inspections
Since geotechnical reports are subject to misinterpretation , do not separate the soil logs from the report . Rather,
provide a copy of. or authorize for their use, the complete report to other design professionals or contractors .
Locations of exploratory sites referenced within this report should be considered approximate locations only.
For more accurate locations , services of a professional land surveyor are recommended .
This report is also limited to information available at the time it was prepared . In the event additional
information is provided to MI' l following publication of our report , it will be forwarded to the client for
evaluation in the form received .
Environmental Concerns
Comments in this report concerning either onsite conditions or observations, including soil appearances and
odors , are provided as general information . These comments are not intended to describe, quantify, or evaluate
environmental concerns or situations . Since personnel , skills, procedures , standards, and equipment differ, a
geotechnical investigation report is not intended to substitute for a geoenvironmental investigation or a Phase
I1/III Environmental Site Assessment . If environmental services are needed, MTI can provide, via a separate
contract , those personnel who are trained to investigate and delineate soil and water contamination .
General Comments
Based on the subsurface conditions encountered during this investigation and available information regarding
the proposed development , the site is adequate for the planned construction . When plans and specifications arc
complete , and if significant changes are made in the character or location of the proposed development ,
consultation with MTI must be arranged as supplementary recommendation ", may be required . Often , questions
arise concerning soil conditions because of design and construction details that occur on a project . MTI would
be pleased to continue our role as geotechnical engineers during project implementation . Additionally , M 1' I
can provide materials testing and special inspection services during construction of this project . If you will
advise us of the appropriate time to discuss these engineering services, we will meet with you at your
convenience .
2791 S Victory View Way • Boise. ID 83709 • (208) 3764748 • Fax (208) 322&8515
VA" m1+ - 0 Com • mli[a�mU • +d cam
Page 26 of 42
27 March 2019
MATERWlS TESTING &
Page # 8 of 14
h190337g IimitcJgcv
INSPECTION
AN ARAS COMPANY
O Environmental Services O Geotechnical Engineering O Construction Materials Testing O Special Inspections
MTI appreciates this opportunity to be of service to you and looks forward to working with you in the future .
If you have questions, please call ( 208 ) 3764748 .
Respectfully Submitted ,
Materials Vesting & Inspection
Maren Tanberg , E . IJ . , 0 . 1 . 1 Revieviredb)v Elizabeth Brown. P . E.
Staff Engineer and Geologist Geotechnical Services Mana TONAL Staff ' 14919
Revietied b1 . Monica aculies , N. E . 0X1 11
Senior Geotechnical Frig ee OF �OP �
Enelosures . MCA 8A '
Geotechnical General Notes
Geotechnical Aivectigation Test Pit Log
Gravel Gyuivalent Method Pavement Section
R - Value Lahnratoty Test Data
Vicinity Alap
Site Map
2791 S Victory View Way • Boise. ID 83709 • (208) 37 " 748 • Fax ( 208) 322 6515
YNN 1 ^ t100, c4m • 24am1 1:1 ccrp
Page 27 of 42
j MATERIALS 27 March 2019
` TESTING & Page M 9 of 14
INSPECTION 0191)357g limiredgco
AN ATLAS COMPANY
O Environmental Services U Geotechnical Eny neenr, ;1 0 Construction Materials Testing U Specrai Inspections
GEOTECHNICAL GENERAL NOTES
RELATIVE DENSITY AND CONSISTENCY CLASSIFICATION
Coarse-Grained Soils SP7' Blow Counts N Fine-Grained Soils SPT Blow Counts N
Very Loose : < 4 Very Soft: < 2
Loose : 4- 10 Soft: 24
Medium Dense : l0e30 Medium Stiff.• 4 -8
Dense : 30 .50 Stiff 845
Very Dense : >50 Very Stiff. 15 -30
Hard ; LE�=>30
Moisture Content Cementation
Description Field Test Description Field Test
Dry Absence of moisture , dusty, dry to touch Weakly Crumbles or breaks with handling or
slight ringer pressure
Moist Damp but not visible moisture Moderately Crumbles or beaks with considerable
finger pressure
Visible free water, usually soil is below Will nat crumble or break with finger
Wet water table Strongly pressure
PARTICLE SIZE
Boulders : > 12 in . Coarse•Grained Sand : 5 to 0 .6 mm Silts : 0.075 to 0.005 mm
Cobbles : 12 to 3 in . Medium •Grained Sand : 0. 6 to 0 . 2 mm Clays : <0 .005 mm
Gravel : 3 in. to 5 mm Fine -Grained Sand : 0.2 to 0 .075 mm
UNIFIED SOIL CLASSIFICATION SYSTEM
Major Divisions rGP
Soil Descriptions
Gravel & GravellyWcll -graded gravels; gravcli'sand mixtures with little or no fines
Soils Poorlygraded gravels; graveUsand mixtures with little or no fines
t oarce Grained coarse fractionSilly gravels ; poorly- graded gravelrsand `silt mixtures
Soils passes NoA sieve GC Clayey gravels; poorlygraded gravel sand 'clay mixtures
<50%
passes No . 200 Sand & Sandy SW Well-graded sands ; gravelly sands with little or no fines
sieve Soils SP Poorly- ands wit
Poorly-graded sands ; gravelly sands little or no fines
coarse fraction SM Silly sands ; poorly-graded sand gravel /silt mixtures
passes No .4 sieve SC Clayey sands, poorlygradcd sand 'gravel'clay mixtures
ML Inorganic silts; sandy, gravelly or clayey silts _
Silts & Clays EME 000dw
fine Grained LL 50 CL Lean clays ; inorganic , gravelly , sandy , or silty, law to medium• plaslicity clays
Soils P500oo OL Organic, low•plasticity clays and silts
passes No .200 Mil Inorganic, clastic silts ; sandy, gravelly or clayey elastic silts
sieve Silts & clays C11 fat clays; high-plasticity , inorganic clays
1 1 > 50
Oil Organic , medium to high- plasticity clays and silts
LL
Highly Organic Soils PT Peat , humus, hydric soils with high organic content
2791 S Victory View Way • poise . ID $3709 • (208) 376-4748 • Fax (208) 322 6515
vnvw,mh , id corn • mli@gilil Id con)
Page 28 of 42
MATERIALS 27 March 2019 .
TESTING & Page # 10 of 14
INSPECTION blW15% luniledreo
AN ATLAS COMPANY
O Envi onmenta! Services O Geatechnical Erg • neer, ng U Construct on Malena s Testing U Special Inspections
GEOTECHNICAI . INVFSTICATION TEST PIT LOG
Test Pit Log No TP- I Date Advanced : 13 Mar 2019 Logged by : Maren Tanberg E. I .T. , G . I .T.
Excavated by : Struckman ' s Backhoc Service Location : Sec Site Map Plates
Latitude: 43 .646757 Longitude: - 116 . 382215
Depth to Water Table : Not Encountered Total Depth : 14 . 8 14'
eet bgs
Notes : Water added at 10 . 5 feet bgs and drained in excess of 12 inches per hour.
Plezometer installed to 14 . 8 feet bgs .
Depth Field Description and USCS Soil and Sample Sample Lab
(Feet bgs) Sediment Classification Type Depth QP Test ID
(Feet b
Lean Clay (CL) : Brown, slightly moist, stiff
to very stiffm A
0.0- 3 .2 - - Organic materials primarily noted to 0, 7 Bulk 20-3 . 0 1 . 5 -2 . 5 RZ
foot bgs, tivith minor organic content noted Value
to 2. 0jeet b$s., __
Silt (ML) : Light brown to pink, dry, hard,
! 3 . 2-6 . 6 with fine-grained sand.
Strong calcium carbonate cementation
notedfrom 3. 2 to 5. 2 feet b$s.
Poorly Graded Gravel with Sand (GP):
Yellanv brown, dry, medium dense to dense,
6 .6 - I4 . 8 with fine to coarse-grained sand, fine to
coarse gravel, and 20-inch-minas boulders.
- Minor silt content nosed from 6. 6 to 8. 0
eel q,s,
Lab Test ID M LL PI Sieve Analysis
_%o - - #4 # 10 _#40 1 # 100 1 #200
A 22 .6 33 11 100 100 99 97 94 . 1
2791 S Victory Yew Way • Boise, ID 83709 • (208) 378. 4748 • Fax (208) 32246515
yemv rrii id cam • mh@ml id corr
Page 29 of 42
MATERIALS 27 March 2019
Page # 11 of 14
TESTING &
G' •
INSPECTION 6190357g limaerlyco
AN ATLAS COMPANY
O Cnvironmenta Services O Geotechrncal Engineering O Consbuction Materials Testing a Special Inspections
CiRAVELEQUIVALENT MFTIIOD PAVF: MF. NT TIIICKNFSS OFSIGN PROCEDURES
Pavement Section Design Locallon : Silver Spring Subdimion . Residential Roadways
Average Daily Traffic Count : All l nncc & Nth 1 ) iroctions
Design l ifc : 20 Ycar>
Traffic Index : 600
�71
Climate Factor : I ItNalue of Subgrade : 600
Subgrade CBR Value : 3 Subgrade Mr . 4 , 400
R-Value of Aggregate Base : 80
R-Value of ( Iran uInr Borrow : 60
SuDgraJc R-Value : 6
expansion Pressure ofSuhgradea 0 .93
Unit Weight of Base Materials : 130
total Design Lire 18 kip FNAI :s : 33 . 131
ASPIIA1 . 11 ( CONCHF:IF:
(: ravel equivalent . Calculalcda 0 384
Ihickness : 01969231 Usc 2 . 5 Inchcs
Gravel equivalent . AUIVA1 .: 041
CRUSIM) AGGRFX: A'IFeBASE@
Gravel Fquivalenl ( I{ allast ): 0 . 768
'Ihickness : 0 329 L Use 4 Inc es
Crawl Fgoivalent , AC 'IUA1 .: 0 . 773
SUBBASE:
( : ravel Equivalent ( Ballast ) : 1 805
'Ihickness : L012 Use 14 Inc es
Gravel Fqulvalent , AC '111A1 .: 1 940
'IriTAL Ihickness : L708
Ihickness Required by Esp. Pressure : 1 .030
Design
Depth Substitution
Inches Ratios
Asphaltic Concrete ( at least 2 .5 ) ; 2050 1 . 95
Asphalt IYeatcd Base ( at least 4 .2 ) : 0.00
Cement Ilreated Rase ( al lead 4 .2 ): 0 .00
( ' rushed Aggregate Bnsc (al least 4 .2 ) : 4 .00 1 10
Subbase ( al Mast 4 . 2 ) ; 14 .00 too
2791 S Victory View Way • Boise. ID 83709 • (208) 376.4748 • Fax (208) 322. 6515
www rrtliod corn • rnit.,a)mh- 10 com
Page 30 of 42
MATERIALS 27 March 2019
' TESTING & Pagc # 12 of 14
INSPECTION b190357g limttcdgco
AN ATLAS CONNANY
O Environmental Services _ O Geolechnlcai Engineer ng O Construction Materials Testwg U Spec at Inspections
RNALUE DATA
Source and Description : TP� 1 : 2 .0 ' - 3 .0 % Lean Clay
Date Obtained : 13 March 2019
Sample ID : 194138
Sampling and ASTM n75 : AASHTO T2 : X ASTM AASHTO X
Preparation . D421 : T87 :
'Pest Standard : ASTM AASHTO Idaho ] 8 : X
D2844 : T 190 :
Sample A B C
Dry Density Ib/fl3 101 .E 100. 1 97 . 2
Moisture Content % 21 .0 22 .4 24 . 3
Expansion Pressure ( psi ) 1 .65 0. 93 0. 39
Exudation Pressure (psi ) 1 302 177 127
R- Value 1 7 6 5
WValue t'� 200 psi Exudation Pressure = 6
R-Value @ Exudation Pressure
100
i
80
60
40
400 350 300 250 200 150 100 50
Exudation Pressure ( psi)
27916 Victory View Way • Boise. ID 83709 • (208) 376g4746 • Fax (208) 322.6515
%my' mti id ccm • n�(a'? -Tu i -; cgp. .
Page 31 of 42
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Page 32 of 42
Y
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End �.iYm�
Page 33 of 42
MATERIALS 29 October 2019
G��r
TESTING & Page # 1 of 6
IV INSPECTION b191817g_eddfl
AN ATLAS COMPANY
O Environmental Services O Geotechrnca Enyir een : q ❑ Const uclion Matena s Testing 0 Special Inspect ons
Mr. Dean Waite
Todd Campbell Construction
2650 North Stokesberry Place
Meridian , Idaho 83646
(208) 9414607
Re : Addendum # 1 Infiltration Testing
Silver Springs Subdivision
905 East McMillan Road
Meridian , Idaho
Dear Mr. Waite .
This addendum report presents test results not requested at the time of the previously issued MTI Gcotechnical
Engineering Report ( 13191817g) . Descriptions of general site characteristics and the proposed project are
available in the previous report . Unless otherwise noted in this addendum , all initial recommendations ,
limitations , and warranties expressed in the previous report must be adhered to .
Infiltration Testing
Infiltration testing was conducted in general accordance with the Ada County Highway District (ACHD) Policy
Manual . Test pit areas will need to be re -excavated and compacted prior to construction of structures that will
be sensitive to settlement . Test locations were presoaked prior to testing . Pre-soaking increases soil moistures,
which allows the tested soils to reach a saturated condition more readily during testing . Saturation of the tested
soils is desirable in order to isolate the vertical component of infiltration by inhibiting horizontal seepage during
testing.
Testing was conducted on 23 October 2019 . Details and results of testing are as follows :
Infiltration Testinlo, Results
Test Test Stabilized Design
Location Depth Soil Type Infiltration Rate Infiltration Rate
feet s inches/hour inches/hour
Poorly G
TP- I 809 Graded Gravel >24 8 0 '
with Sand
TP-2 9 . 8 Poorly Graded Gravel >24 8 0 "
with Sand
TP-3 860 Poorly Graded Gravel >24 8. 0 *
with Sand
* Per the ACHD Policy Manual , the maximum design infiltration rate is 8 inches per hour.
In accordance with the ACHD Policy Manual , a factor of safety of 2 has been applied to the stabilized infiltration
rates achieved during testing . M7' I recommends that all infiltration facilities be constructed in accordance with
the local municipality requirements .
2791 S Victory View Way • Boise, 10 83709 • (208) 376.4740 • Fax (208) 322 .6515
%vww mli id cOm • tn ( Ca inli • id cQm
Page 34 of 42
MATERIALS 29 October 2019
TESTING & Page # 2 of 6
INSPECTION b191817�oddMl
AN ATLAS COMPANY
0 Environmental Services 0 Geotechnical Engineeong 0 Construction Maser als Testing 0 Special Inspections
IVITI appreciates this opportunity to be of service to you and looks forward to working with you in the future.
If you have questions, please call (208) 376 .4748 .
Respectfully Submitted , �pNAL
Materials Testing �c Inspection �`'S�CENSfoy%y
18300
Hunter Hayes, E . I . Reviewed by. Jacob Schlador, P . G . 10-29.19
Staff Engineer Geotechnical Enginec ✓,qA OF %k1QRX `
Enclosures: fie SC"V
Geotechnical General Notes
Geotechnical Investigation Test Pit Logs
Site Map
2791 S Vietory View Way • Boise, ID 83709 • (208) 3764748 • Fax (208) 322.8516
%"wi. n II id ,cori • mtina mil id cr , y, : � � •" •�'
Irua:v4 uit Ric
Page 35 of 42
MATERIALS 29 October 2019
Page �! 3 of 6
TESTING &
INSPECTION b191817& cQddpl
AN ATLAS COMPANY
O Environmental Semces O Geotechnical Engineering O Construction Materials Test• ng O Special Inspections
GEOTECHNICAL GENERAL NOTFS
RELATIVE DENSITY AND CONSISTENCY CLASSIFICATION
Coarse-Grained Soils SPT Blow Counts Rine-Grained Soils SPT Blow Counts N
Very Loose : < 4 Very Soft . < 2
Loose: 440 Soft : 2A
Medium Dense: 10.30 Medium Stiff: 4 -8
Dense: 30-50 Stiff: 8 • I5
Very Dense: > 50 Very Stiff: 1 S •30
Hard : >30
Moisture Content Cementation
Description Field Test Description Field Test
Dry Absence of moisture, dusty, dry to touch Weakly Crumbles or breaks with handling or
slight fin er pressure
Moist Damp but not visible moisture Moderately Crumbles or beaks with considerable
finger pressure
Wet Visible free water, usually soil is below Strongly Will not crumble or break with finger
water table g pressure
PARTICLE SIZE
Boulders: > 121n . Coarse-Grained Sand : 5 to 0.6 mm Silts: 0 .075 to 0.005 mm
Cobbles: 12 to 3 in . Medium-Grained Sand 0.6 to 0 .2 mm Clays : <0 .005 mm
Gravel . 3 in. to 5 mm Fine-Grained Sand : 0 .2 to 0 .075 mm
UMF1ED SOIL CLASSIFICATION SYSTEM
Major Divisions Symbol Soil Descriptions
Gravel & Gravelly GW Well -graded gravels ; gravel/sand mixtures with little or no fines
Soils GP Poorly-graded gravels , gravel/sand mixtures with little or no fines
<50%
GM Silty gravels ; poorly-graded gravel/sand/sih mixtures
Coarse Grained coarse fraction
Soils passes NoA sieve GC Clayey gravels; poorly -graded gravellsand/clay mixtures
< 50%
passes No. 200 Sand & Sandy SW Well -graded sands ; gravelly sands with little or no fines
sieve Soils SI' Poorly-graded sands; gravelly sands with little or no fines
> 50 r5
coarse fraction SM Silty sands; poorly-graded sand/gravel %silt mixtures
passes No .4 sieve SC Clayey sands; poorly -graded sandfgravel /clay mixtures
ML Inorganic silts ; sandy, gravelly or clayey silts
Silts & Clays CL Lean clays ;
Fine Grained I . I. < 50 inorganic , gravelly, sandy, or silty, low tomedium -plasticity clays
Soils > 50% OL Organic, low-plasticity clays and silts
passes No . 200 MH Inorganic, elastic silts ; sandy, gravelly or clayey elastic silts
sieve Silts & Clays CH Fat clays ; high-plasticity, inorganic clays
LL > 50
LOH Organic, medium to high- plasticity clays and silts
Highly Organic Soils PT Peat , humus , hydric soils with high organic content
2791 S Victory View Way • Boise, ID 83709 • (208) 37&4748 • Fax (208) 322-8515
yyww mind cont • Q.-1tioini , - 1d Co «l
Page 36 of 42
MATERIALS 29 October 2019
TESTING & Page # 4 of 6
INSPECTION b 19 i 917g`adddl
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GEOTECHNICAL INVESTIGATION TEST PIT LOG
Test Pit Log # : TP= I Date Advanced : 22 Oct 2019 Logged by : Hunter Hayes, E . I .
Excavated by : Just Dig It Excavation Location : See Site Map Plates
Latitude: 43 .648211 Longitude : el 16 . 382783
Depth to Water Table: Not Encountcred Total Depth : 12 . 3 Feet bgs
Notes : Piezometer installed to 12 . 3 feet bgs .
Infiltration testing conducted at 8 .9 feet bgs.
Depth Field DSediment Classification
and ST ple Sample Depth Lob
Qp_ Test ID
Lean Clay with Sand (CL) : Light brown to
brown, dry, hard, with fine to medium-
0 .0-2 .4 grained sand. 4 . 5 +
--Organics noted to a depth of 0. 8 foot with
sparse tree roots to a depth of 3. 0 eet. _
Sandy Silt (ML) : Light brown to red-brown,
dry, very stiff to hard, with fine to coarse-
2 .4 -6 . 5 grained sand,
-- Weak calcium carbonate cementation noted
from 3. 9 to S. 1 eet bgs,
Poorly Graded Gravel with Sand (GP): Tan
to light brown, dry to slightly moist, medium
6 . 5 - 12 . 3 dense to dense, with fine to coarse -grained
sand, fine to coarse gravel, and S-inch minus
cobbles.
- Silt content noted in upper 1 . 5 eel.
2791 S Victory View Way • Boise. ID 83709 • (208) 376.4748 • Fax (208) 322.6515
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Page 37 of 42
MATERIALS 29 October 2019
� s TESTING fs Page # 5 of 6
a
INSPECTION nrelai7g rtaaal
AN ATLAS COMPANY
0 Enwronmen ! al Services 0 Geotechn cal Engineering 0 Construction Materials 'Testrrg O Special Inspection s
GEOTECHNICAL INVESTIGATION TEST PIT LOG
Test Pit Log # : TP-2 Date Advanced : 22 Oct 2019 Logged by : Hunter Hayes, E . I .
Excavated by : Just Dig It Excavation Location : See Site Map Plates
Latitude : 43 .647291 Longitude: - 116 . 382022
Depth to Water Table : Not Encountered Total Depth : 12 . 0 Feet bgs
Notes : Piezometer installed to 12 . 0 feet bgs.
Infiltration testing conducted at 9 . 8 feet bgs .
Depth Field Description and USCS Soil and Sample Sample Depth Lab
et bgs _ Sediment Classification Type �Fcet b 8 _ Qp Test ID
Lean Clay with Sand (CL): Brown, dry, hard,
0 .0 -2 . 2 with fine to medium-grained ,sand. 4 . 5 ►
wamOr anics noted to a depth Of 0. 7 oot .
Sandy Silt (ML) : Light brown, dry, very stiff
2 2 - G 2 to hard, with fine to coarse-grained sand.
- - Weak to moderate calcium carbonate
cementation noted throughout. _
Poorly Graded Gravel with Sand (GP) : Tan
to light brown, dry to .slightly moist, medium �
Unit 12 .0 dense, with fine to coarse -grained sand, fine r
to coarse gravel, and 6 - inch minus cobbles.
- -Silt content noted to u r2. 01
eet.
2791 Victory View Way • Boise ID 83709 - (208) 3764748 • Fax (208) 322*6515
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Page 38 of 42
MATERIALS 29 October 2019
TESTING fs Page # 6 of 6
INSPECTION b191817g addNl
AN ATLAS COMPANY
O Environmental Services O Geotechrrcal Ergineennd O Construction Materials Testing D Special Inspections
GEOTECHNICAL INVESTIGATION TEST PIT LOG
Test Pit Log M TP•3 Date Advanced : 22 Oct 2019 Logged by : Hunter Hayes , E . I .
Excavated by : Just Dig It Excavation Location : See Site Map Plates
Latitude: 43 .647399 Longitude : - 116. 384026
Depth to Water Table: Not Encountercd Total Depth : 13 . 3 Feet bgs
Notes • Plezometer installed to 13 . 3 feet bgs .
Infiltration testing conducted at 8 .0 feet bgs .
Deft b s th Field
SeaimDescription
ent ClassifwcactionSoil and Sample Samp Type �li bDepth Lab
ffeQp Test ID
0.0-2 . 3 Lean Clay (CL) : Brown, dry, hard. 4 . 5+
--Organics noted to a depth of 0. 9 oot.
Sandy Silt (ML) ; Light brown to brown, dry,
very stiff to hard, with fine to coarse-grained
sand.
2 . 3 -6 . 0 - -Intermittent weak calcium carbonate
cementation noted from 2. 3 to 4. 9 feet.
--Moderate to strong calcium carbonate
cementation noted om 4. 9 to 6. 0 eel.
Poorly Graded Gravel with Sand (GP) : Tan
to orangish-brown, dry to slightly moist,
6.0 - 13 . 3 medium dense to dense, with fine to coarse-
grained sand, fine to coarse gravel, and 6-
inch minus cobbles.
--Silt content noted in upper !. S eel.
2791 S Victory View Way • 8013e. ID 63709 • (M) 3764746 • Fax(208) 322.6515
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Page 39 of 42
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Drainage Basin Map
Page 41 of 42
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