HomeMy WebLinkAboutBLOOM FILING FOUR - FDP240001 - SUBMITTAL DOCUMENTS - ROUND 3 - Geotechnical (Soils) Report• �
SOILS AND FOUNDATION INVESTIGATION
Bloom Filing 4 Apartmen[s', Phase 2
Greenfieltls Dr 8 Intema�ional Blvtl
Porl Collins. Coloratlo
�Bui�dings 1. 4-9, H: antlCWbbouse
Preparetlfor'.
Harifortl Acquisitions
49�8 Gootlman 5l.
Timnath, Colorado 8066�
A[tention:
Dave Derbes
Pmlec� Nn FCO]133.019-020
May 3, 2024
CTLIThomoson Inc.
oe��e�, Fon coums, coio�ado so�mas, cie�wooe so���as, a�emo, s�mmu co�mv—com�aao
C�, Wyoming antl Bozeman. Mon�ana
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Table of Contents
Scope
Summary Of ConcWsions
Site Description
Pmposetl Cons�mc�ion
Previouslnvestigation
Investigation
Subsurtace Conditions
Natural Soils
Gmundwater
Geologic Hazards
Seismicity
Si�e Development
Fill Placement
Excavations
Fountlations
Foo�ings
Reinforced Concrete Ma�
Pos4Tenslonetl Slab-On-Grede (PT)
Floor Systems and Slab-On-Gratle Floors
Slab Pertormance Risk
Simdurally Supporled Floors
Pomhes, Decks and Patios
Ex[erior Flatwork
La�eral Earth Pressure
Backfll Compaction
Subsurface Drains and Sudace Drainage
Concre[e
Pavements
Pavement Design
TraHic Pmlec�ions
Pavemenl Recommentla�ions
Pavement Selection
Subgratle antl Pavement Ma�erials antl Constmction
Main[enance
Surface Drainage
Constmction Observa[ions
Geo�echnical Risk
Limitalions
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FlGURE 1- LOCATIONS OF EXPLORATORV BORINGS
FIGURES 2 THROUGH 6- SUMMARV LOGS OF EXPLORATORV BOR W GS
APPENDIM A- RESULTS OF LABORATORV TESTS
Table A-I - Summary of Labore[ory Tesling
APPENDIM B- SAMPLE SITE GRAD WG SPECIFICATIONS
APPENDI% C- PAVEMENT CONSTRUCTION RECOMMENDATIONS
APPENDI% D - MAINTENANCE PROGRAM
EXHIBIT A- SLAB PERFORMANCE RISK EVALUATION, INSTALLATION AND
MAIMENANCE
EXHIBIT B-SURFACE DRAINAGE, IRRIGATION, AND MAINTENANCE
EXHIBIT C- EXAMPLE BACKFlLL COMPACTION ALTERNATNES
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Scope
This repotl presents the resulis of our Soils antl Pountlation Imes�iga�ion for �he pmposed
multi-famity resitlences (apatlments) antl a clubhouse locatetl in Bloom Filing 4, Phase 2 at
Graenfields �nve and Intema�ional Boulevard in Port Colllns, Coloratlo (Figure 1). Tha purposa
of ourimes�iga�ion was �o evaluate the subsurface contlitions in orderto pmvitle geotechnical
design antl constmction recommentlations for Ihe proposetl resitlences. The scope was
describetl in our Service Agreement (Pmposal Na FG23-0430 CM-1) tla�etl Febmary 22, 2W4.
Thisreport was preparetlfmm tla�a tlevelopetl tluringfield exploration,laboratory�esting,
engineering anatysis. antl experience with similar contlitions. I� inclutles our opinions antl
recommentla�ions for tlesign criteria and wnstmction details for foundations and flwr systems,
slabs-on-gratle, la�eral earth loatls, pavement tlesign. antl tlralnage precautions. The repoh was
preparetl for�he exclusive use of Hatlfortl Acquisitions in the tlesign antl cons�mc�ion of mul�i-
famity residences and clubhouse In �he referenced subdivision. O�her types of cons�mc�ion may
require revision of �his repotl and �he recommendetl tlesign criteria. A brief summary of our
conclusions and recommendations follows. De�ailetl tlesign cri�eria are presen�ed within the
report.
Summary Of Conclusions
1. Soils encountered in our borings generally consis�etl of santly clay, clayey santl.
antl/or clean to slightly dayey, gravelly santl. Betlrock was no� encounteretl in any
of ihe borings to the tlepths explored.
2. Groundwa[er was measuretl at depths ranging from 9 to 14 feet in 15 borinqs
during drilling. When measured several days later. groundwater was encountered
at tlepths of 9Y to 12 feet in 3 borings Existing groundwa�er levels are not
expec�ed [o significantly affec� si�e tlevelopmenL We recommend a minimum 3-
toot separetion between foundation elements and groundwater.
3. The presence of expansive soils cons[iW�es a geologic hazard. There is a risk [ha�
slabs-ongrede and (oundations will heave or settle and be damaged. We judge
�he risk is low. We believe �he recommentlations presentetl in Ihis repotl will help
lo conVol �he risk of damage; �hey will no� eliminate �hat risk. Slabs-on-gratle and,
in some Inslances, (oundations may be damaged.
4 Poo�ing, pos6�ensioned sleb (PT slebJ, or relnforcetl concrete metfountlatlons
placed on naWral, untlisWrbed soil antl/or properly mmpac�ed fll are mnsidered
appmpriate for ihe stmcWres included. Design and consimclion criteria for
fountlations are presen�ed in �he repotl.
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5. The risk of poor slab performance is rated as low for tM1e s�mcWres indutled.
Driveways and other exterior flatwork will be slabs-on-gratle antl may heave or
aettle and crack
B. Surface tlrainaga should be tlasignaQ constmcteQ entl main�ainatl to provitla
rapid removal o! surface runoR away from the pmposetl slmcWres. Conservalive
irrigation practices should be followed to avoid excessive weuing.
1. The design antl mns[mction criteria tor fountlations antl floor sys�em alternatives
in ihls report were compiled with the expectation Ihat all other recommendations
presen[etl rela�etl �o surtace antl subsurtace tlrainage, lantlscaping irrigation,
beckflll compec�lon, etc. wlll be incorpore[etl in�o Ihe proJect and Ihat properly
owners will maintain ihe simcWres. use pmtlent irrigation practices, antl maintain
surface drainage. It is critical �ha� all recommentla�ions in �his repotl are followetl.
8. The pavemenl subgrade soils dassified as A-&6, whlch are considered to exhlblt
good subgrade support.
9. Mi�igalion for swelling or sof[ subgratle soils will no[ be required.
10. Asphal[ic concre�e antl Portlantl cement concre�e are appropriate surtace
pavements. Minimum pavemen� remmmentlations are presen[etl in this report.
Site Description
The shuc[ures are loca�etl a[ Greenfields Drive and Interna[ional Boulevard in Ihe Bloom
Subdlvlslon In Por[ Golllns, Colorado (Figure 1). Outlng �he �me of our Invea�ge�on, overlot
gretling end Installa�lon o( burled u�llltles were comple�e, entl tha slreele were not peved The lote
ere rela[ively flat Leke Wnel rune elong [he soWh slde of �he sl[e. Burling[on Norlhern Rellmatl
tracks are norlheas� of �he si�e.
Proposed Construction
The pmposetl residences are anticipatetl to be wootl or steebframed ihree �o four-story
apatlment builtlings. antl a dubhouse. Asphal� pavetl parking areas antl access tlrives are also
plannetl. No basemen� or crawlspace constmction is plannetl. The four-story uni�s will have
elevator service pi[s �ha� extend 4 �0 5 fee� below gratle. Fountla�ion loatls are expectetl �o vary
be�ween 1,000 antl 3,000 pounds per lineal foo� of fountlation walL. wi�h intlividual column loatls
of 25 klps orless We believa tha� minlmal si�e grading will be naetlatl for this area antl �hat
excavations will �ake place a� or near curren� grade. Final gratling and landscaping will resW� in
slightly grea�er dep�h of backfJl.
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Previous Investigation
CTLIThompson performed several geo�echnical investigations at �his site under CTL�T
Prolect No. FCO]733. �ata fmm previous investigations were considered for this report.
Investigation
The field investiga[ion inclutletl tlrillin9 one to two exploratory borings for each sVuclure
antl two borings for pavemen[s. The borings were drilled to deplhs of approximately 15 leet and
20 feet for ihe stmcWres and 10 feet !or pavements using 4-inch diame[er continuous-fligh[
augers, antl a Vuck-mounted drill. Drillinq was observetl by our field representa[ive who loggetl
the soils antl obtainetl samples for laboramry testing. Summary logs of the borings, inclutling
resul[s of fieltl pene�re[ion resis[ance [es�s, are presen[etl on Figures 2 �hmugh 4.
Soil samples obtainetl during tlrillinq were reWrnetl to our laboratory and visually
examinetl by our geotechnical engineeo Laboratory testin9 was assigned and includetl moisWre
content, tlrytlensity, swell-consolitlation, parlicle-size analysis, AVerberg limits, and wa[er-soluble
sulfa�e [es�s. Swell-consolida�ion �es[ samples were we[tetl a[ a confining pressure which
appmxima[etl [he weigh[ of overlying soils (overburtlen pressures) for [he s�mcWres antl under a
pressure of 150 pountls per square foo[ (psf).. as requiretl by LCUASS for pavemen[s. Resul[s of
lhe labora�ory tesls are presenled in Appentlix A antl summarized in Table A-I.
Subsurtace Conditions
Soils encountered in our borings generelly consisted of sand, clay, antl/or gravelly sand.
Bedmck was not encountered in any of ihe borings lo [he tlepths explored. Grountlwater was
measured at depihs ranqin9 Gom 9 ro 14 feet in 15 borings tluring drillin9. When measured severel
days later, gmundwa[er was encountered at deplhs of 9% to 12 feel in 3 borings. The pertinent
engineering characteristics of the soils encounteretl are describetl in more detail in the followin9
paragraphs. Table A provides a summary of [he swe0 [est resul[s. Fur[her descriptions of ihe
subsurface conditions are presented on our boring loqs antl in our laboratory test resulis.
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TABLE A:
SUMMARV OF SWELL TEST RESULTS
Compression Range of Measured Swell (%)'
Soil Type 0 �o <2 2 �o <4 4 �o <6 >_ 6
Number of Samples antl Percen�
Santl � 6 I 0 I 0 0
14% 08°/ 0% 0% 0%
Clay ,.�, .��,,, ,.�, ,.�, ..�,
Overall Sample Number 1 1] 0 0 0
OverellPercenl 6% 94% 0% 0% 0%
Swell measuretl efler we��ing untler�M1e appmelma�e welgM1� of ��e ovetlNng solls (werouben pressures).
NaWral Soils
The santl was metlium tlense. Samples of the sand con�ainetl 4 to 4� percen� silt antl clay-
size partides (passing the No. 200 sieve). The na[ural santl is consideretl non-expansive or low
swellingbasedon�heresul[soflaboratory�es[ingandourexperience. Theclayencoun�eredwas
stiR antl moist Eleven samples of �he clay exhibitetl swells of 02 �0 1.3 percen�.
Groundwa�er
Gmuntlwa�er was measuretl at dep�hs ranging fmm 9 to 14 (eet in 15 borings tluring
tlnlling_ When measuretl several tlays la�er, gmuntlwa�erwas encounteretl at tlepths of 9hto 12
feet in 3 borings. Gmuntlwater may tlevelop on or near the bedrock surface or o�her low
permeable soil when a source of water no� presen�ly con�ribu�ing becomes available.
Groundwater levels are expedetl to fluduate seasonalty, with precipita�ion, antl with water levels
in �he nearby Lake Canal. Gmuntlwater is no� expec�ed �o aHed below-gratle constmction at �he
site.
Hazards
Coloratlo is a challenging bcation to practiw geotechnlcal engineering. The climate is
relalively dry, and the nearsudace soils are typicalty dry and relativety stiH. These soils and
related sedimentary bedmck formations tend ro react m changes In moisture conditions. Some of
Ihe soils and bedrock swell as ihey'mcrease In moisWre and are called expansive soils. Other
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soils can seltle significan�ly upon wel�ing and are referred �o as collapsing soils. Mos� of �he lantl
available for development east oflhe Fronl Range is underlaln by expansive clay or claystone
bedmck near Ihe eurtece_ The eolls Ihat exhlblt collapse ere more Ilkely west of ihe conllnental
divide; however, bo�h [ypes of soils occur all over Ihe state.
Covering the ground with houses, streets, driveways, patios, etc., coupled wilh lawn
irrigation and changing dreinage pattems, leads to an'mcrease in subsuAace moisW re conditions.
As a result, some soil movemenl Is Inevitable. It is critical that all recommendations in ihls reporl
are (ollowed to increase ihe chances that Ne foundations and slabs-on-grade will perform
satisfaclorily. Afler constmction, pmperty owners must assume responsibllity (or maintaining the
stmcture and use appmpriate practices regarding dreinage and landscaping.
Expansive soils are present a� �his si�e. The presenw of expansive soils. wllec�ivety
referretl �o as expansive or swelling soils, wns�itutes a geologic hazard. TM1ere Is a risk tha�
ground heave or settlement will tlamage slabs-on-grade and foundations. The risks associated
wtih swelling soils can be mitigaled, but not ellminated by careful tlesigq constmcHon, and
ma'mtenance pmcedures.
Wa ba0eve �he recommenda[ions in Ihis repotl wlll help conhol the risk of fountletion
antl/or slab damage; �hey will not elimina�e tha� risk. The builder and pmpetly owners should
untlerstand �hat slabs-on-gratle antl, in some ins�ances, fountlations may be affectetl. Pmperty
owner maintenance will be requiretl �o con�rol risk. We recommend �he builder pmvide a booklet
b �he pmpetly owners that tlescribes swelling soils antl includes recommentlations �or care antl
malntenance of homes consimdetl on expansive soils. Cobratlo Geologlcal Survey Special
Publlca�ion 43' was tlesignetl to pmvitle �his informa�ion.
5¢ISfIIICItY
According to �he USGS, Cobrado s Fmnt Range and eastem plains are consideretl low
seismic hazartl zones. The earthquake hazartl exhibi�s hlgher risk in westem Coloratlo comparetl
b other patls of the state. The Coloratlo Fmnt Range area has experienwtl ear�hquakes wi�hin
�he past 100 years, shown to be rela�ed �o deep drilling,liquld Injection, antl oil/gas ex�rac�lon.
Naturally ocwrring eatlhquakes along faulis tlue to tectonic shifis are rare'm thls area.
1"R Gultle la Swelling Salls b� Colo�atlo Mamebuyers antl Homeowne�s;' Semntl Etllllon Pevlsetl antl Uptla�etl by Davltl
G Nm� Calomtlo GeoloBicalSurveg OeOaM1men� o� NaW�al Resouraq Oenreq Cob�atlo, 200i.
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The soils at this si[e are no� expec[etl lo respontl unusually to seismic ac[ivi�y. The curren�
Intemational Building Code (SecOon 161322) deters [he eatimellon o! Seismic Site
Classificalion to ASCE]-22, a sVucWral engineering publicalion. The lable below summarires
ASCEP22 Sile Qassifca[ion Crileria.
Based on [he resWts of �his inves�igalion antl previous invesli9ations, we judqe a Seismic
Sile Classification o! 0[o DE The feld peneVa�ion test resulls along with Ihe empirical eslima[es
imply that shear-wave velocity seismic tesls lo directly measure v, could result in a belter Seismic
Si�e Classitica�ion. The subsudace contll�ions Intlicate low susceptibility to liquefadion fmm a
materiels entl gmuntlwatar perspec[ive.
Si[e Developmen[
Fill Placement
The existing on-site soils are generally suitable for re-use as new flll from a geotechnical
standpoint, provitled tlebris or deleterious organic materials are removed. In general, Import ftll
should meet or exceetl the engineering quali�ies of �he onsi�e soils. In addi�ion, patlicles larger
�han 3 inches shoultl be bmken tlown or removetl. If impoh ma�erial is useQ i� should be testetl
antl evaluatetl for appmval by CTLIThompson.
Prior�o fill placemen�, tlebns, organlcsNege�afion, and dele�erious ma�erials should be
substantially removed fmm areas to receive fill. The sudace should be scarifled to a deptM1 of at
least 8 inches, moisture condltioned and compacted to tM1e criteria below. Subsequent ftll sM1ould
be placed in ih'm (8'mches or less) loose lifts, moisWre conditloned, and wmpacted_ PJI should
be compacted ro a dry density of at least 95 percent of standard Procror maximum dry density
-_6YN �FiE911 YN CFY.91 tl[N91 [H �[N:! 11 y:i I_-
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(ASTM D 698. AASHTO T 89J. FlII tlep[he grea[er than �5 fael ahould be evaluetetl by CTLIT �o
recommend appropriate compaction speci(iwtions. Sand soils used as (JI should be moislened
lo wifhin 2 percenl of op[imum mois[ure conten[. Clay soils should be moistened belween
op�imum antl 3 percen[ above op�imum moisWre conlent. The fill should be mois[ure-condi�ioned,
placed In �hln, looae Ilfls (8 Inches or leae) and compactetl es descdbed above. FIII placement
and compaction should not be contluc[ed when fill material is Gozen. 5of[ soils were found in one
of our boringe. If e�abillzallon Is necaesery, i� can Ilkely be achleved by crowding 1% �o &Inch
nominal size croshed rock in�o �he subsoils un[il �he base of [he excava[ion does not tleform by
more than about 1-inch when compactive effort is applietl. CTLIThompson should observe
placemenl and compac�ion of fill during consVuctioa Si�e grading in areas of landscaping where
no fu[ure improvemenls are plannetl can be placed a� a dry densi[y of a[leas� 90 percenl of
atandard Proc[or mazlmum tlry tlenelty (ASTM 0 698, AASHTO T 99).
Water antl sewer lines are often cons�mc�ed benea[h areas where improvemen�s are
plennetl. Gompacfian of hench beckilll can have a slgniflcan[ effec[ on �he Ilfe end servlceeblllry
overying sVucWres. We recommentl hench backfill be moisWre mntli�ioned and mmpac�etl as
describetl above. Placement and compac�ion of backfill should be observetl antl [estetl by a
represen[e[ive of om firm tluring cons[mc[ion.
Excavations
We believe ihe soil penehated in our explora�ory borings can generalty be excavatetl
wi�h conven�ional, heavy-tlury excavation equipmenl Excavations shoultl be slopetl or shored �o
mee� local, S�ate, and Fetleral safety regulationa Excavation slopes specifietl by OSHA are
depentlen� upon rypes of soil antl gmuntlwa�er conditions encoun�eretl. The contractors
"competent persort is responsible �o iden�ify �he soils and/or mck encoun�eretl in excavations
antl refer to OSHA stantlards to tletermine appmpriate slopes antl safery measures Based on
our imestiga�ion and OSHA stantlards, we believe [he intetlayeretl santly day antl clayey santl
soils may classify as Type C soils Excava�ions tleeper than 2� fee� should be braced. or a
professional engineer shoultl tlesign �he slopes.
Wind and water emsion is more Ilkely with tlisWrbetl wnditions expected tluring
constmction and may need to be addressed due to municipal regulation. The emsion potential
will decrease after constmction if proper greding prectices, sudace drainage design and re-
vegetation efforis are Implemented.
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Founda[ions
Our inves�iga�ion indica�es low-swelling soils were encoun�ered at dep�hs where they are
Ilkety to aRect foundation performance. Foo�ings, reinforced concre�e ma�, or pos4tensioned (PT)
slab foundations are considered appmpriate for �he proposed wnstmction.
Design on�eria for foo6ngs, aoncre�e ma�, and poshtensionetl (PT) slab founda�ions
developed fmm anatysis of Oeltl antl labora�ory tlata antl our experience are presen�ed below.
The builder and s�mcNral englneer should also wnsider tlesign and cons�mdion de�ails
as�ablished by �he stmcNral warran�or (if any) �hat may Impose adtlitlonal design and installation
requiremen�s.
Foo�
1. ThefootingfountlationshouldbearonnaWral,untlisturbetlsoilsantlloronpmperly
compac�ed fill. Where soils are loosenetl tluring excava[ion or in [he footing
forming process the soils should be removed or compacted to at least 95 percent
of stantlard Proc�or maximum tlry tlensity (ASTM D 698, AASHTO T 99) be�ween
op�imum and 3 percenl above optimum moisWre con�ent, prior �o placing mncrete.
Excavation backfill placed below founda�ions should be compacted using �he same
specifications.
2 Footingsshouldbedesignedforanetallowablesoilpressureof2,000poundsper
square foo� (psf). The soil pressure can be increasetl 33 percen� for Vansient loatls
such as wintl or seismic loatls. We recommentl a minimum 3-foot separa[ion
be�ween foundation elemeNs and groundwa�er.
3. We anticipa[e foo�ings tlesignetl using [he soil pressure recommendetl above
could experience 1-inch of movement Dlfferential movement of'/z-inch should be
considered in �he tlesign.
4. Footings should have a minimum width of 12 'mches. Foundations for isolated
columns shoultl have minimum tlimensions of i6 inches by i6 inches. Larger sizes
may be required depending upon [he loads and sVuc[ural sys�em usetl.
5. Foundalion walls should be well reinforced both top and boHom. We recommend
reinforcemen� suRicient to span an unsupported tlis�ance of a� leas� 10 feet or the
dis[ance be[ween pads, whichever is grea[er. Reinforcemen� shoultl be designetl
by ihe stmcturel englneer considering the eHects oflarge openings and lateral
loatls on wall pertormance.
6- Exteriorfoofings must be pmtected from lrost action, perlocal building codes-
Normalty. 30 inches o( cover over footings is assumed in the area for fmst
pro[ec�ion.
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The comple�ed fountlation excavations shoultl be observetl by a representative of
our firm prior �o placing �he forms to verify subsurface conditions are as anticipated
fmm our borings. Our represen�a�ive shoultl also observe �he placemen� antl �est
compaction of new fill placed for foundation subgratle (if inerited).
Reinforced Concrete Mal
1. Reinforced concre�e ma� fountlations shoultl be constmctetl on naNral,
untlisWrbetl soil antl/or properly compac�ed fll orfill placed for an over-excavalion
as tlescribed in the Site Develoomenl section of this reporL The reinforced
concre�e ma�foundation should be tlesignetl (ora net allowable soil pressure of
2,000 psC The soil pressure can be increased 33 percent for �ransien� loatls such
as wind or seismic loads.
2. Reinforced slabs are typically designetl using a motluWs of subgratle reac�ion. We
recommend using a modulus of �5 pounds per square Inch per inch of deflection
(pai).
3. The soils benealh mat toundations can be assigned an ultimate wefficient of
hiction ot 0 4 to resis� la�eral loads The abillty of founda�lon backfJl �o resist lataral
loatls can be wlcula�ed using a passive equivalent �uid pressure of 250 pcf. This
assumes the back(JI is densety compac[ed and will nol be removed. Backfill should
be placetl and compactetl to �he criteria in �he Fill Placement sec�ion of �he repotl.
A mais� uni[ weight of 120 pcf wn be assumetl for naWral soils antl campac�etl fll.
These values are consideretl ultimate values and appropriate fac[ors ot safety
should be used. Typically, a fac�or of safety of 1.5 is used for sliding and 1 b for
laleral eatlh pressure.
4. Tne edges of tne mats should be thickened or Wmed tlown for s�mcWral streng�h
antl fms� protec�ion.
5. Materials beneath the mat foundation should be pmtected from fmst adioa We
believe 30 inches af fmst cover is appmpriate for lhis si�e.
6. We should be retained to observe �he comple�etl excava�ions to confirm whe�her
�he subsurtace condilions are similar to Ihose fountl in our borings.
Pos4Tensioned Slab-On-Grade (PTl
PT founda�ion tlesign is based on a methotl tleveloped by �he Pos6Tensioning Ins�itute
(PTI) antl is ou�linetl in PTI's thirtl etli�ion of Oesign of PoshTensionetl Slabs-On-Gmund (2004
wi�h 20�8 Supplement). Various clima�e and relevan� soil fac�ors are required �o evalua�e �he PTI
desgn cn�ene. These include Thom�hwaite MolsWre Intlax Qm), sucbon compression intlex (y„),
unsaturatetl diHuslon coeKoien� (a), tlapth o( pmbable moisNre vanetion, Inl�ial and (nal soil
suction pmfiles, antl percen� clay frac�ion antl pretlominanl clay mineral. In the projed area, Im is
about-20.
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The PT founda[ion design methotl is based on [he potential tlifferen�ial movemen[ of [he
slab edges (ym) over a specifietl edge distance (em). Furtheq the PTI desi9n method, evaluates
two mechanlsms of soll movement (edge Ilft and center Ilft) basetl on assumptlons ihat weVing
and drying of [he founda[ion soils are primarily aRected by seasonal clima[e changes. In the 2004
design manual, PTI recommends evaluating movemenls for a minimum tlep[h of wet[ing of 9 fee[
below the grountl surtace. This value can be reasonable for a seasonal moisWre variation;
however, our experience intliw[es [he fountlation soils will normally untlergo an increase in
mois[ure tlue [o covering �he ground surtace wi�h builtlings antl flaWork, coupletl wi�h �he
introtluclion of lantlscape irrigation around lhe builtlings. Basetl on our experience antl �he
subsurtace contli[ions a[ �he si[e, �he tlepth of we[[ing can be abou[ 24 feet or more below �he
ground surtace.
The wefling may not pene�rate this deep', however, we believe i� is a reasonable design
assump�ion when evaluating the etlge lifi for this si�e Por �he deeper dep�hs of wetting, gmuntl
movemen�s can be estima�ed based on swell or sudion profiles or using a compu�er pmgram
(such as "VOLFLO" by Geos�mdural Tool Kit Inc.). The PTI design method does not predict soil
movement caused by site contlitions such as excessive irrigation or poor surface drainage ihat
may lead b dlfferential foundation movement In excess of �he movements estima�ed by the PTI
design method. These conditions may also increase the edge moisNre variation distance above
�he design values provided'm the PTI manual.
Considering the limita�ions of the curren� PTI design me�hod, we believe a conserva�ive
appmach wilh reasonable engineering ludgemen� is meri�ed in PT founda�ion desiga Design
cri�eria for PT founda�ions are presentetl below. Criteria were developed from anatysis o( feld
and laboratory data, ihe PT design method outllned in PTI's third edition of Design and
Constmction o� PosFTensioned Slabs-On-Ground (2004 with 2008 Supplemenq, VOLFLO by
Geostmcturel Tool Kit, Ina, and our experience.
1. PT foundations should be constmcted on new moisWre-conditioned and
compac�ed fll or tlirectty on native soils. If flVbackfill or soPoloose soils or rela�ivety
dry soils are exposed in foo�ing exwva�ions or are the resW� of [he
excavatioMforming process, these soiis should be removed and rewmpaded.
2. PT fountla�ions shoultl be designetl for a maximum allowable soil pressure of
2,000 psf.
3. For tlesign of uniform ihickness, PT fountlations, or pointloatls, a motlulus of
subgrede reaction (K,) of ]5 pci can be used.
10
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4_ A dlfferential soil movemen� (y,,,) of 1 13'mches for the edge Lft condl6on and -0.05
inches for [he cen�er lifl contlition can be usetl.
5- An edge moisture variatlon tlistance (em) of 4.8 feet for tM1e edge IIH conditlon antl
9 feet forihe center lift contli�ion can be used.
6. The above-grade consimctioq such az lreming, drywall, brick, and stucco should
be consitleretl when determining ihe appmpriate slab stiRness. We are aware of
slWatlona where minor differernlal elab movemen[ has wueetl tlleVesa �o flnleh
materials. One way to enhance pedormance would be lo place reinforcing steel in
�he bo�toms of s[iffening beams. The stmctural enginaer shoultl evelua�e the meri�s
of [his approach, as well as o�her po�ential al[erna[ives �o reduce damage to finish
materials. The slab stiHness shoultl be evaluated per seclion 6.10 of ihe PTI 2008
Supplement as i� relates �o tlifferen� superstmcNre materials.
�. Stiffening beams and edge beams may be poured "neaP' into excavated irenches.
Soil may cave or slough during trench excava�ion for �ha s�iHening baams.
DisWrbed soil should be removed from Vench boVoms prior lo placement of
concrete_ Formwork or other methods may be required (or proper stiffening beam
installefion.
8_ Exterior stl(fening beams should be protected fmm (msl actlon_ Normalty 2'/> feet
of fms� cover is assumetl in ihe area. If ex�erior patios are incorporatetl into the
PT, we believe �he s�iffening beams amund [he pa�ios shoultl be as tleep as �hose
amund the building exterior to Increase the Ilkellhood they will perform similady to
�he rest of the PT.
9. Por slab tensioning design, a coefficient offriction value of �]5 or 1 0 can be
assumed for slabs on potyethylene sheeting or a sand layer, respedively. A
coeRicient of friction of 20 should be usetl for slabs on day soils. We believe Ihe
use of potyethylene Is pre(erable because it serves as a vapor retarder, whlch
helps �o control moisWre migra�ion up �hmugh the slabs.
10. A representative of our frm should observe the completed excavations. A
representative of the s�mcWral engineer or ourfirm shoultl observe the placement
of [he reinforcing tentlons and any miltl reinforcement prior �o pouring the slabs
and beams and observe Ihe tendon shessing.
Floor Svstems and Slab-On-Grede Floors
Slab Performance Risk
Wa conductetl swell-consolide�ion tes�ing �o provide e basis forcalcula�ing potanfiel soil
heave et �his sits. W e es�imate potan�iel heeve of 1-inch or less for the s�mcW res inclutletl. Besed
on our heave calculations, �he subsurtace contli[ions fountl in our borings, and our experience
wi�h resitlen[ial conshuction antl pertormance, we jutlge Iha� �he risk of poor slab-on-gratle
performance at this si�e is low. Our experience intliw[es tha� basemen� slab performance is
11
�
generelty satisfactory on low-risk si[es. Slab heave of 1 to 2 Mches is considered "normaf'for
ihese sites; more or less heave can occur. If floor movements cannot be tolerated, a simcWrelly
supported floor sys�em should be wnsidered. A more de�ailed tliswssion of slab-on-grade
performance risk and consimction recommendations is pmvided in Exhibit A.
If the owner elects to use slab-on-grade cons�mc�ion antl accepts �he risk of movement
antl associatetl tlamage, we recommentl �he following precautions for slab-on-grade cons�mdion
at this si�e. These precaNions can help retluce, but no� elimina�e, damage or distress due �o slab
movemen�.
1. Slabs shoultl be separa�ed from exteriorwalls and in�eriorload bearing members
with a slip joint tha[ allows Gee vetlical movement of ihe slabs. This can retluce
crecking If some movement of ihe slab occurs.
2 We untlerstantl thatthickened.interiorload bearinq slabs may be tlesired forihis
site. We believe thls to be acceptable, (or the units included 'm this investigation,
pmvitletl the risk of movement of up �0 1-inch is acceptable to �he ownec To retluce
the risk of movemen[ we recommend saw cut[ing a� lhe �hickenetl etlge for isolation
(see Image below)_
m.e � ...ua.....wa..m-b
�".n.. a
s � ' � i'_ �e..� ��
�' � SawCut �
�•��u�rc�acnsa�a+a�
Slabs shoultl be placed direc�ly on properly mois[ure contli�ionetl, well-compacled
fill. The 2021 Intemational Building Cotle (IBC) raquires a vapor ratarder between
the base course or subgratle soils antl the concrete slab-on-gratle �oor, inclutling
PT slabs. The merits of ins[alling a vapor retartler below Floor slabs depend on the
sensitivity of Floor coverings and bullding use to moisWre. A pmpedy Installed vapor
rstertler (10 mll minimum) is more bsneflclal below concre�e sleb-onyretle floors
where Floor coverings. painted floor surtaces or produc[s storetl on ihe floor will be
sensitive to moisture. The vapor retarder is most eRective when concrete is placed
direc�ly on lop of i�, rather�han placing a santl or gravel leveling course behveen �he
vapor re�artler antl [he floor slab. The placemen[ of concre[e on the vapor retartler
may increase ihe risk of shrinkage cracking and cuding. The use of wncrete with
retlucetl shrinkage charac�eristics including minimized wa�er content, maximizetl
coarse aggrega�e con[em, antl reasonably low slump will reduce �he risk of
shrinkage cracking and cuding. Considerotions and recommendations for ihe
12
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ine�alla[ion of vepor re[arders below concrete alabs are outllned in Sectlon S2B2 of
tne 2018 report of American Concre�e InsttW�e (ACI) Committee 302,'Guide for
Concrete Roor and Sleb Gonstmction (AGI 302.1 R-� 5)'.
6. The use of slab-bearing partitions shoultl be minimized if used, ihey shoultl be
tlesigned and consimded with a minimum 1% inch space to allow for slab
movemenL Differential slab movemenls may cause crecking of parti[ion walls.
�iiferentlal movement o!'h-inch should be considered 'm the design_ If Ihe void Is
pmvitletl at�he top of patli�ions, the connec�ion between [he slab-suppotled parti�ion
and founda�ion-supporled walls should be tle�ailed to allow for differen�ial
movemenL Doorways. lo-wall uWity connectlons, wall parlltions perpendlcular to Ihe
ex�erior wall or walls supportetl by foundations shoultl be tle�ailed �o allow for vetlical
movemenL Interior perimeter iraming and finishing should not extentl onlo slabs-on-
grade, or if necessary, should be detailed to allow (or movement.
5. Underslab plumbinq should be elimina�ed where feasible. Where such plumbing is
unavoidable it should be ihomughly pressure tested for leaks prior to slab
cons�mc�ion antl be pmvitletl with flexi�le couplings. Pressurizetl wa�er supply lines
shoultl be brought above �he floors as quickly as possible.
6. Plumbing and utilities [ha� pass �hmugh Ihe slabs should be isolatetl hom the slabs
and cons�mc�ed wilh flexible couplings. U�ilities, aswell as elechical antl mechanical
equlpment should be constmcted with sufficient tlexibillty to allow for movement.
1. HVAC or o[her mechenical systems suppotletl by �he slebs (if eny) should be
pmvided with (lexible connecllons wpable o( withstanding at least 3'mches of
movement.
8_ The American Concrete InstiWte (ACI) recommends �requent contml joinis in slabs
to reduca pmblams associatatl with shnnkage cracwng and cutling. To retluce
curling, Ihe concre[e mix shoultl have a high aggregale content and a low slump. If
desired, a shrinkage compensaling admlxture could be added to the concrete lo
raduce �he nsk of shrinkage cracking- We can perform a mix design or assist the
design team in selec[ing a pre-existing mix.
StmcWrallv Supported Floors
SVucWral floors shoultl be used in non-basement, Mished livinq areas. A simcWral Floor
is supported by ihe foundation system. There are design antl consVuction issues associa[etl with
shuc[ural Floors �hat must be considered. such as ventilation and la[eral loads. Where s�mcWrally
supportetl Floors are ins�alletl, �he required air space depends on Ihe ma[erials used to conshuct
lhe floor and [he expansion poten[ial of �he underlying soils. Building codes require a clear space
of 18 inches above exposetl eatlh if unheatetl wood floor components are usetl. Where o�her
floor support materials are usetl, a minimum dear space of 8 inches shoultl be main�ainetl. This
minimum dear space shoultl be maintained between any poin[ on [he untlerside of [he floor
sys[em (including beams antl Floor drain Vaps) and the surtace of [he exposetl earth.
13
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Where sVudurally supported floors are used, utility connections, inclutling wa[er, gas, air
duct, and exhaust s[ack conneclions to floor supportetl appliances shoultl be capable o( absorbing
some tleflection of the floor. Plumbing tha[ passes ihrough [he (loor should ideally be hung from
the underside of the stmcW ral floor and not lain on [he boVom of the excavation. This contiquration
may no[ be achievable for some parts of the installa[ion. It is prudent to main[ain [he minimum
clear space below all plumbing lines. It Venching below the lines is necessary, we recommentl
sloping �hese Venches so [hey discharge m the fountla[ion drains.
ConVol of humitli�y in crawlspaces is impor[an� for indoor air quali�y and pertormance of
wootl Floor sys�ems. We believe �he bes[ current prac�ices [o conVol humitli�y involve �he use of
a vapor re[arder (10-mil minimum), placed on the ezposetl soils below accessible sub-floor areas.
The vapor retartler shoultl be sealetl at joinls antl aVached to concre[e foundation elemenis. If
desired, we can provitle tlesigns for ventilation systems [hat can be ins[alletl in association wi[h
a vapor re[artleq �o improve con[ml of humidity in crawlspace areas. The MoisWre Managemen[
Task Force of Meho Denver� has compiletl adtlitional tliscussion antl recommenda�ions regarding
best prac[ices for �he conVol of humitli�y in below-gratle, under-floor spaces.
Porohes Decks and Patios
Porches or tlecks with overhanging roofs tha[ are integral wilh the s�mcWre such Iha�
excessive fountlalion mavemen� canno� be [olera[eQ shoultl be cons[mctetl with �he same
fountlation type as the builtling. Simple decks,�hat are no�inlegral with �he structure antl can
�olerate fountlation movemen�. can be constmcted with less subslantial (ountla�ions. A short pier
or footing bo�tometl at leas� 3 fee� below gratle can be usetl if movement is accep�able. The use
of 8-foot to 10-foo� piers can reduce po�ential movement Pootings or short piers shoultl no� be
bo�tometl in wall backfill or untlocumentetl fll, tlue �o the risk of setllement The inner etlge of �he
deck may be constmctetl on haunches ors�eel angles boltetl to �he founda�ion walls antl de�ailetl
such tha� movemenl of [he tleck fountlation will no� cause dishess �o [he s[mc[ures. We sugges[
�he use of atllus�able breckebtype connections or o�her de�ails be�ween fountlations antl tleck
posts so the pos[s can be trimmetl or atljustetl if movement occurs.
2"Quitlelines lo� �esign antl Co�S�mqion ol New Hoines wil� Below9atle Untle�flw� 9peces,- MolSW�e ManaBemenl Task
Fo�oe.onooa�aa.wm.
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Porches, patio slabs, antl oNer exterior flatwork shoultl be isola[etl from the simcWres.
Porch slabs can be constmcted ro retluce [he likelihood that seltlemenl or heave will aifect [he
slabs. One approach (for smaller porches located over basement backfll mnes) is to place loose
backfll under a shuc[urally supportetl slab. This fill will more likely seltle than swell antl can [hus
accommodate some heave of the untlerlying soils. A lower risk approach is to consimct [he porch
slab over void-formin9 materials. Conditions shoultl allow ihe voitl-formin9 malerials to soften
quickly after cons�mc�ion �o reduce �he risk of Vansmi�ting grountl heave �o the porch slab. Wax
or plas[ic-coa�etl voitl boxes should not be usetl unless provisions are matle �o allow water�o
penehalein�o[he boxes.
Exterior Flalwork
Ex�erior Flatwork (tlriveways, sidewalks, e[c.) are normalty cons[mcted as slabs-on-grade.
Various properties of [he soils antl emimnmen�al contli�ions influence �he magniWtle of
movemen� antl other pertormance. Increases in Ihe maisWre mn�enl in lhese soils will cause
heaving antl may result in cracking of slabs-on-gratle. Backfill below slabs shoultl be moisWre
conditionetl antl compac�etl �o reduce se�tlemen�, as tliscussetl in Backfill Comoaclioa Ex�erior
slabs fountled on �he backfill may se�tle antl crack if �he backfill is no� pmpetly moisWre �rea�ed
antl compac[etl. Where slabs-on-gratle are usetl, we recommentl atlherence �o the precau[ions
for slab-on-gratle construction lha[ are indudetl in Exhibi[ A.
Lateral Earth Pressure
All below gratle walls shoultl be tlesignetl �o resis� la[eral earth pressures [ha� ac� upon
lhe wall. The appropriale loatl tlis�ribu[ion �o appty for tlesign tlepentls nol only on the soil rype,
bu� also on �he wall type antl restrainL Por re�aining walls lha[ are in�egral �o adjacen[ shuc[ures
antl resVainetl Gom ro�a[ion, �he walls shoultl be tlesigned lo resis� lhe "a� resC' earth pressure.
For walls, which are free [o rotate to develop [he shear sVengih of the retained soils, such as
walls no[ in[egral [o �he s�mcWre, �he walls should be tlesignetl to resis� �he "ac�ive" eatlh
pressure. Resis[ance ro la[eral loatls can be provitled by fric�ion be[ween concre�e antl soil,
antl/or by "passive" earlh pressure. Passive earlh pressure shoultl be ignoretl for [he top one foo[
of soils agains� �he s�mcWre since it can be removetl easily wi�h [ime. The pmper applica�ion of
lhese loatling condilions is the responsibility of Ihe wall designec Wall backfill shoultl be placetl
acmrding to Ihe Fill Placement sec�ion.
15
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[.nrvn�vev nnuN�T�/Ecarvoiiiorv�
�
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P-Ofi'+�
eanceo oarieeuM �a.vnriory
�:
�;
o-,,..�
BE� LONQqp�EWPLL(AipESTCON01i1pN�
ry i Y� e
I
J_ '- �
P.-I�'fH�}H�
ree �vs�
=acnvE Hvoaosrnrro �Nir w�cHr �cF�
- orvosn.icarvi.weian.�vcn
H� =HFJGHi�OFWALL�Fn
H. -HEIGHiOFSLOGE(F!)
TM1e following �able pmvitles �he necessary equlvalen� fluitl pressure values for �he backfill
wmprised of native soils anticipated a� �his si�e. The pressures glven do not Include allowances
for surcharge loads such as sloping backfill. vehicle traHic. or hydros�a�ic pressure. These values
also tlo not indude a fador of safaty. Nortnally, a faclor of safaty of 1 S is usatl forsliding and 1.8
for lateral aatlh pressura. Por dasign purposaa wmpacled fJl can be consitleretl a� 120 pcf.
Equivalent
Loading Condition Hytlrostatic Fluid
Pressure
Aclive (y�) pcf 45
A�-Rest('yo) pcf 50
aaesi�e (yal v�r zso
Horizontal Friction CoeHlcient (y) 045
i6
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Backfill Compac[ion
Settlemen� o( foundation wall and utillty trench backfill can cause damage to concre�e
Ha�work and/or resul� In pwr tlrainage condl�lons- Compacfion of backfill can reduce se�tlemenL
Attempts to compact backfill near foundatlons to a hlgh tlegree can tlamage fountlatlon walls and
window wells and may increase lateral pressures on ihe foundation walls. The potential for
cracking of a fountla�ion wall can vary witlety basetl on many fadors inclutling the tlegree of
compac�ion achieveQ �he weigM antl type of wmpaction equlpment utillzetl. �he s�mcWral tlesign
of �he wall, the s�reng�h of �he concrete at �he �ime of backftll compaction. and �he presence of
�emporary or permanent bracing.
Pmper moisture condlHoning of backftll Is as Important as compactlon because setllement
commonly ocwrs'm response to wetting. The atldition o( water wmplicates tM1e backftll pmcess,
especially during cold weather. Fmzen soils are not considered suitable for use as backfJl
because excessive settlemenl can result when the frozen materials thaw. Exhibit C describes four
atlemative metM1ods to place, moisNre wndi�ion, and wmpact backfill along wi�h a range of
possible settlemenis, and advantages antl dlsadvantages of each approacM1, all based upon our
experience. These are lust a!ew of the possible tecM1niques and represent a range for your
evaluation. We rewmmend Altematives C or D if you wisM1 to wniml potential settlement.
Precautions should be taken when backflling against a wall. Temporary bracing of
comparetively long, straight sections of toundation walls should be used ro limit damage ro walls
during Ihe compaction process. Walfing at least seven days atter Ne walls are placed to allow ihe
concrete ro galn slrengN can also reduce ihe risk of damage. Compaction of fll placed beneafh
and next to wintlow wells, wuntedorts. and grade beams may be diHlwlt to achleve withwt
damaging these building elemenis Pmper moisWre conditloning of the fill prior to placement in
Ihese areas will help reduce potential settlement.
Ideally, dreinage swalesshould not be located over the backfill zone (Including excavatlon
ramps), as Ihis can Increase Ne amount o( waler infJUallon Into Ne back(JI and cause exczssive
seltlemenL Swales should be designed to be a minimum of al least 5 teet from Ne (oundation ro
help reduce water'mfilVation.lrriga[ed vegetation.. sump pump olscharge pipes, sprinklervalve
boxes, and mof downspout termina[ions should also be at least 5 feet hom the foundalion.
1]
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Subsurtace Drains and Surface Drainage
No below grade areas are planned (or the builtlings- Por thls condl6on, penme�er drains
are no� usually cons�mqed- I( any portion of a floor will be below exterior gratle, or If a crawl space
is planned, we sM1ould be contacted to pmvide rewmmendations for foundation dralns. Pmper
design, consimcllon, antl maintenance oi surface dralnage are crillcal b tM1e satlslactory
performanw of fountlations, slabs-on-gratle. antl o�her impmvemenis Lantlscaping antl Irriga�ion
pratlices will also aHed pedormance. Exhibit B wn�ains our recommentlations for surface
dralnage. irriga�ion, and main�enanw.
Concrete
Concrete In cnntact with soil can be subject lo sW(ate attack We measured watersoluble
sulfate concenVafions In ten samples at less ihan 0.01 pement (below detectable Ilmils) to 0 0]
percent As indlcated In our tests and ACI 33&2q Ne sWfate exposure class is No( Applicable or
RSO. Deviations from the exposure class may occur as a result of additional sampling and testing.
SIILFHTE EXPOSURE CLHSSES PER ACI 33b20
Weterv6oluble 6Whle (60Q
&poaureClassea InSal"
%
Na�Ap lirable RSO �0]0
MOtlBlBI¢ RSt 0.10Ia420
sa�� � asz � ozomzoo
�ms�wT asa >z.oa
� nl ao�omswrem ey mas5 ��� so�i a�i�m�a W ns.m msao
For Nls level of sulfate concentretion, ACI 33&20 Code Requirements fur Residential
Concrete Indlcates there are no cement type requirements for sulfate resislance, as indlcaled in
Ihe lable below.
CONCkETE �ESIGN REQIIIkEMEMS FOk SULFATE EXPOSl1kE PEk AG 53&20
Maeimum Minlmum GemenlAlousMe�erlelTypesa �
E�posure We�etl Compresslve qSTM ASTM ASTM Celcium
Cless Cemanl SVengIM1" C150/ CSBS C115/f CMontle
Ra�b (psp Ci50M G585M G115]M AtlmhWres
PSO NIA 25C0 Na No �o No
TypeR�`s�zlians TypefNSGC�ons Typeft�`sGctons R�`sNc0on5
Rsi oen I zeoo u I Tvnewur,nns, ms I_ mo
asz aas I a000 I v= I ,...__....._. rva
ass oas s000 v.vo��oia�o� I oes�e�a�ro�pi�s Hs.vo��oia� Nm
SlegCemenl° Pounlenor3Yag or5lagCeman�° Pemmlletl
1$
�
Concre�e compresslve slrengN spaci�led sM1ell be basetl on 28-0ay �esls perASTM C39/C39M
Allema�e mmbina�ons o! cemen�i�ious ma�etlels of Nom lis�etl in ACI 332-20 Te�le 54 2 sM1ell �e permlttetl
wM1an �asletl br sWlela resislanw mea�ing IM1a cn�ene In saGion 5 5_
Olhe� aveileble lypes of oemenl sup� es Type III o� Type I are Oe�milletl In �posure Classes R51 0� R92 it
0e C3A con�enLs are less Nen 0 0�5 peaen�, respac�lvely.
ma amo�m or �na spamm so�aa ot pounia� or sae �o oa �ao snau �m oa iass ma� �na amo�m mae nas
been tle�erminetl by seMce remN to impmva sWfa�e resislance wM1en usetl In concre�e con�alning Type V
en�. Al�emetrvaly. �M1e emoun� ol�M1e spacific soume o11M1a posolan orslab lo be usetl sM1ell no� be lass
Ihan �M1e amowt lestetl ln e000�tlanoe wilM1 ASTM C101'LC1012M entl mee�ing �M1a olilelia ln seo�ion SSt o(
HC1332�20.
Wa�er-SoluLle cM1lotlOe lom m��en� Na� Is mnitl�uletl �mm IM1e Ingretllanls Inclutling waler aggrega[az,
men�lllous ma�etlals, ena atlmltlures sM1all be tle�erminetl on �M1e mncrele mlxWre ASTM C12�8/C�218M
ba�wean 29 antl 42 tlays.
Supedlcial tlamage may occur to ihe exposed surfaces of higMy permeable wncrete,
even roough sW(ate levels are relatively low. To wniml this risk antl to resist freeze-ihaw
deterioration. Ihe water-to-cementltious materials ratio should not exceed Ob0 for concrete in
contact with soils that are Ilkety to stay moist due to surface dreinage or high-water tables.
Concrete should have a rotal air content of 6 percent x 15 percent We adwcate damp-proofing
of all (oundation walls and grade beams in contact wiN ihe subsoils (mcluding the Inside and
outside (aces o( garage and crewl space grade beams).
Pavements
The pmlec� will inclutle pavetl parking areas antl access tlrives. The performance of
pavemen[s is dependen� upon �he charac�eris[ics of Ihe subgratle soil, Vaffic loatling antl
frequency, climatic condi�ions. tlrainage, and pavement materials. We usetl samples from our
expbratory borings antl contluctetl labora�ory tests to charac�erize ihe subgrade soils, which
generalty consistetl of sandy clay and clayey santl. The in-situ subgratle soils generalty classifietl
as A-2-6 soils in accordance wi�h AASHTO pmcedures. The subgratle soil will likety pmvitle good
�o fair supPort for new pavemenL If fill is needed we have assumetl it will be soils wi�h similar or
be�tercharacteris�ics.
Raxible ho� mix asphalt (HMA) over ag9regate base course (A8C) is likety plannetl for
in�erior pavemen� areas. Rigid Portlantl cement concrete (PCC) pavemen� should be usetl for
�rash enclosure areas antl where �he pavemen� will be sublec�ed �o frequent tuming of heavy
vehicles. Our tlesigns are basetl on �he AASHTO design methotl antl our experience. Using the
cri�eria tliscussetl above we recommentl the minimum pavement sec�ions provitled in Table B.
19
�
Pavemen[ Design
New cons�mction is planned for Bellamy Lane, access drives, and parking b�s. We
understand Bellamy Lane is a priva�e drive, but for design purposes we have generalty followed
�he regula�ions of the City of Fort Collins and LWASS, which requires �he use of �he AASHTO
and CDOT pavemenl design me�hods for their roadways. These design me�hods require Inpul
parame�ers fir�raffic pmjedions for a spaoified tlesign life, madway classifica6on, chaadens�ios
of �he subgratle materials, type and streng�h charac�eristics of pavement materials, gmuntlwater
wnditions, drainage conditions, minimum pavement sec�ions, and s�atistical data.
Treffic Proiections
The VaRic projections are based on vehicle loatling, [raRic volume, design periotl, and
grow[h factor. TraRic projections are expressed as an 18-kip Equivalenl Daily Load Application
(EDLA)for a single day antl as an 18-klp Equivalent Slnqle lixle Load (ESAL) !or [he tleslgn
periotl, which is typically 20 years. Bellamy Lane is classifietl as a private — resitlen[iaL For our
calcula[ions, we Vea�etl Bellamy Lane as a local — residential roatlway. An ESAL of 36,500 (or
Bellamy Lane was provitled by LCUASS Table 10-1, using a 20-year design life.
Pavemen� Recommendalions
Por our tlesign, we assume �he pavemen� will be constmctetl tluring a single stage. If
multiple-stage cons�mc�ion is tlesired, we should be consWted to revise our recommentlalions.
We have provitled pavemen� tlesign al[erna�ives for new cons�mc�ion inclutling hot mix
esphel[ (HMA) on eggregata bese course (ABG). Rigitl Porllantl cemen� mncrate (PCC)
pavement shoultl be used torVash enclosure areas and where the pavement will be subjec[etl to
trequent Wrning of heavy vehicles. Our pavement ihickness alterna[ives are presen[etl in Table
B. Additional discussion regarding advantages and disadvantages of Ihe pavement altematives
and iheir expecled pertormance is included under [he Pavement Selection section of [his report.
20
�
Table B:
Minimum Pavemen� Thickness Recommentla�ions
C I Hot Miz Asphalt (HMA) t� portlanG Cement
Roatlway Aggrega�e Base Course Full Depth Asphal� ��crete (PCC)
(Aeq
Bellamy Lane 5' HMA+
ESAL = 36,500 6" A8C fi" HMA 6" PCC
ParkingAreas 4 HMA� 6"HMA 5"PCC
6" ABC
Trash Enclosures - - 6" PCC
Pavement Selection
Composite HMA/ABC pavemen� over a compaded subgrade is expectetl to pedorm well
at this site basetl on �he recommendations provided. HMA pmvitles a s�iH, stable pavemen� �o
wi�hstand heavy loading and will provide a good fa�igue resis�ant pavement However, HMA does
no� perform well when subjected �o poin� loatls in areas where heavy tmcks tum antl manewer
at slow speeds. PCC pavemeM is expec�ed �o perform well'm thls area; PCC pavement M1as be�ter
performance In ireeze-thaw condltions and should require less long-term ma'mtenance �han HMA
pavement The PCC pavement fortrash endosures shoub extend out �o areas where trasn tmcks
park to liR antl empty tlumpsters.
and Pavement Materials and Construction
The wnstruction materials are assumed to possess suHlcient quality as reflected by ihe
strengih factors used in our design calculations. Materials and constmction requiremen[s of
LWASS, CDOT-PDM and 2021 CDOT Standard Speci/ica[ions /or Road and Bridge
Cons(ruc(ion should be followed. If the materials cannot meet these requiremenls, our pavement
recommendations should be re-evaluated based upon available ma[erials. The use of recycled
ma[erials, such as recycled asphal[ pavemen[ (RAP) and recycled concrete may be used in place
of aggrega[e base wurse, provitled they meet minimum R-values antl gredations es[ablishetl by
LCUA55 and CDOT. Materials planned for constmction should be submitted antl ihe applicable
laboretory tesis pedormed to verify compliance with [he specifications.
Basetl on ihe resWts of laboratory testing and LCUASS, we believe tha[ mitiga[ion for swell
will no[ be required. Conventional moisWre Ueatmen[ and compaction of the subgretle is
appropriate for these conditions.
21
�
Maintenance
Routine main�enance, such as sealing antl repair of cracks, is necessary to achieve the
long-term life of a pavemen� sys�em. We recommend a preven�ive main�enance pmgram be
developed and followetl for all pavement rys�ems �o assure the tlesign life can be realized.
Choosing to tlefer maintenance usualty resulis in accelera�etl tleteriora�ion leatling to higher fuWre
maintenance cos�s, antl/or repaic A recommendetl main�enance pmgram is ou�linetl in Appentlix
D.
Surtace
A primary cause of premature pavement de[erioration is infiltation of water into [he
pavement sys[em. This'mcrease In moisWre content usually results'm the softening of the base
murse and subgrade soil and evenWal faiWre of Ihe pavemenl. In addilion, par[s of Colorado
experience many freeze-Ihaw cycles each season [hal can resul[ in deterioralion o! [he pavemen�.
We recommend that �he subgrade, pavemenl, antl surrountling grountl surtace be sloped to
cause suRace wa�er lo run off rapidly antl away from pavements. Backs of curbs and gutters
should be backflletl wilh compactetl fill and sloped [o prevent pontling adjacent to backs of curbs
antl to paving. The final grading of the subgrade shoultl be carefully mnVolled so [he pavement
desiqn cross-section can be maintained Low spo[s In Ihe subqrade Ihat can Uap waler should be
eliminated. Seals should be pmvided wi[hin the curb and pavemenl and in all join[s to reduce [he
possibili[y of wa�er infilVa�ion.
Construction Observations
We recommend that CTL�Thompsoq Inc. provide consVuction observation services to
allow us the opporWnity to verify whelher soil condllions are consistent wilh ihose found during
Ihis Investigation. O[her observalions are recommended lo review general conformance with
desiqn plans. I( others peRorm these observalions, Ihey must accepl responsiblllty ro judge
whe�her [he recommenda�ions in [his reporl remain appmpriate.
22
�
Geotechnical Risk
The concep� of nsk is an impoNan� aspec� wi�h any geotechnlcal evaluafion primanly
because tM1e me�hods used �o develop geotechnical recommendations do no� comprise an exact
science. We never M1ave complete knowletlge of subsurface wnditions. Our analysis must be
lempered with englneering judgment and experience. TM1erefore, lhe recommendalions presentetl
in any geo�echnical evalua�ion shoultl no� be wnsitleretl risk-free. Our rewmmentlations
represent our jutlgmen� of those measures �ha� are newssary b Increase �he chances �hat �he
stmcNres will perform satisfatlority. I� Is cri�ical ihat all recommendations 'm �hls report are
followed during wnstmction. Pmpetly owners must assume responsibillty for main�aining �he
stmctures and use appmpria�e praqices regartling drainage and landscaping. Improvemen�s
performetl by pmperty owners a(ter consimction, such as roe wnstmction of retaining walls,
decks, patios,landscaping, antl exterior Flatwork, should be completed In accordance with ihe
recommendations In Ihis repotl.
Limitations
This report has been preparetl for �he excNsive use of HarKortl Acquisitions for �he
purpose ofprovitling geo[echnicaldesign antl constmction criteriaforthe proposed projecL The
informatioq condusions, antl recommentla�ions presen�etl herein are based upon consideration
of many fac[ors inclutling, bul no� limited Iq the rype of s�mcWres proposetl, �he geologic se[ting,
antl [he subsurtace mntli�ions encoun�ered. The conclusions and recommenda�ions con�ained in
Ihe reporl are not valitl tor use by o�hers. 5[antlards of praclice evolve in �he area of geotechnical
engineering. The recommentlations provitletl are appropria�e for abou[ �hree years. If Ihe
proposetl resitlences are not cons[mctetl wi�hin abou� �hree years, we shoultl be contacted �o
de�ermine if we shoultl uptlate �his repotl.
Two borings were drilled for each s�mcWre antl one for each pavemen� sec�ion tluring �his
imestigation to obtain a reasonabty accurate picture of �he subsurtace contlitions. Varia�ions in
Ihe subsurtace condi�ions not indica�ed by our borings are possible. A representative of our firm
should observe fountla[ion excavations �o confirm the exposed materials are as an�icipa[etl fmm
our borings. We shoultl also �es[ compaction of fill if over-excavation is usetl.
23
�
We believe [his investigation was contlucted with ihat level of skill antl care ortlinarily usetl
by geotechnical engineers practicinq in [his area at ihis time. No warrenty, express or implied, is
matle. I( we can be of Nrther service in tliscussing fhe wn[enis ot this report or in [he analysis of
the influence of subsurtace conditions on tlesign of the simcWres, please call.
CTL I THOMPSON, ING
'H -^ ��
O �'
James Pe�Ns, EIT R.B. "Chip" Leadbe��er, III, PE
StaHGeotechnicalEngineer SeniorEngineer
24
�
LEGEND: - �� _ �
THq irvoicaresncvRoxiMnre =
� �ocnnorvoFExP�oRnroav
eoaiNc E.,.��Eaa.,,
APPROXIMATE
scue�. v�=aoo�
o' so' 3ao' VICINRV MAP
� o
International Boulevartl
TH-15 � • TH-24
TH-9
•
TH-14 • TH-23
� � TH-22 �
TH-2� �
� TH-13 �
� � T�19 T:20 �
Q a
TH-�8 °'
. TH-12 ... � -
• �
..- —..TH-17� T�8 �
•
.. ' -,�-::'TH-i6
•
TH-1 �
•
TH-�0
•
Donella Drive
Locations of
Exploratory Borings
FlGl1RE 1
�iiii�
0
2
u 1
6
8
io
TH-8
EI.G93]
914 �
�qn2
TH-9
E1.4941
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6
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LEGEND:
� GLAV. SPN�Y. MOIST. STIFF. BROW N ICL)
� SPNO. GRAVELLY. MOISi iO WET, ME�IUM DENSE, BROWN �SP. SW SN-SG)
� SPNO.GLAYEY,MOIST.ME�IVM DEMSE.BROWN,RED�SG�
� SPNO.GLAYEY,SILT`/,VERYMOISi,LOQSE.BROWN,PED�5GSN1
pok��,AMP�E.�Es.Meo�,z,z��o��.E, ze��soFa 4�o��o�MEk
Fn�uNa �o iNCHEs weae aeooiaeo ro oaiven zsavcH o o. snma�ea iz itiwes.
� ws.ea�eve�mensuaeon..imeoFoai�uNe
z wwreiz�eve�wensuizeoseeeuuonrsnrreizoui�urvo.
y imoicnies oeaiH wHeae Ho�e uveo.
o�sremm- iNoi�nres na�e m� oes.aoveo aeroae sewrvo aaouvownrea �.ou�o ee.nrcei
NOTES:
1 THEOORIN65WERE�RILLEOONMURG129THROUGHAPRIL42@�USING0.INCH
OIAMRER CO�iIN000SFLIGHT Al1GER5AN0 A iROChMO0ME0 DFILL RI6.
2 BORIN6El£VATIONSWERESVRVEYE�BYAREPRESENTA➢VEOFTHECLIEM.
3 iHE9ELOG9ARE5UBJECTTOiHEEXPLANATIDNS,IJMIiATIONSAN�CONQU910N91N
iH15 REPORT.
. WC—INOIC�iE5M013iURECOMEM�B�.
— NOIGHT�SI] fPC��.
3W —INOICPiES BWELLWHEN WEiTEDIINDEROVERBIIRDEN PRESWPE�Gi?
900— INOIGHT�S P0.SSING NO. �00 SN� (yel
LL — INOICPiES LIOUI�IJMIi.
— NOIGHT�S PIAGiIPiVIN!]�%
as -iNoicmessowe�au�Fnrecomreur�ii. $Ufllf118fj� LOgS Of
, Exploratory Borings
�,�� P��,�,o �y�,_,� F��uRe z
�
TH-0O
E1.493fi
1812
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av12
TH-11
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TH-05
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12/12
=2 aa 12
TH-V
10
15
20—�
25
30
35
40
Summary Logs of
Exploratory Borings
FIGl1RE 3
�
TH-08
E1.4938
i�iz
y -."-
_ 39n2 r
TH-09 TH-20 TH-2t TH-22 TH-23
E1.4940 E1.4839 E1.4B4� E1.4841
DESTROYED
2viz zanz
=�oi �' i3nz
15n2 5n2 23h2
y
m=• y .
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]/12
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16tl2
Y --. 1$
20-�
25
30
35
40
Summary Logs of
Exploratory Borings
FicuRE a
�
APPENDIX A
RESULTS OFLABORATORVTESTS
TABLE A-I - SUMMARY OF LABORATORY TESTING
�
E%PANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
Z e
O
6
% �
o -e
N
K �
6
f
O
. . . . ._. �._... . .
. . . . .. _ 1TTTl�T'.. . .
V
�APPLIEOPRESSORE-KSF
Samploor cwr,snmor(c�)
From rH-antaFeeT
orrvurvirweicHr= ia� PCF
moiswvecorviervi= zio 'u
Exanr�sion� uNOER coNsrnr�r
PRESSURE DUE TO WETTING
2
O
a
w
z
o ,
N
C
P �
O
V
I I�:.. .. . .
��APPLIE�PFESSUNE�KSF �"
Sampla o! c�av, samov ic��
FIOm TH-9AT6FEET
�RY ONITWEIGHT- �00
MOISTORECOMENi= 11.5
Swell Consolidation
Test Results
FIGURE H-1
�
O -+
N
Q
X -5
2
O 6
tt
� -i
O
U
E%PANSIONUNDERCONSTANT I
PRESSURE DUE TO WETTING
�APPLIEUPRESSURE-KSF �
Sampleo� ClAV.SANDY(CL)
F10�➢ TH-11ATGFEET
DRYIINITWEIGHi= 12q FCF
MOISTORECOMEM- 8.6 Y
Swell Consolidation
Test Results
FIGUREA2
_ �_
�
o -_
N
Q
X -5
2
O 6
tt
� -i
O
U
nooirioNn� coMaREssioN uNOEa
corvsrnrvr aREssuRE ouE ro wErriNc
�APPLIEUPRESSURE-KSF �
sampieof snrvo�sv7
F10�➢ TH-12AT2FEET
DRYIINITWEIGHi= 126 FCF
MOISNRECOMEM- ],8 %
Swell Consolidation
Test Results
FlGl1RE A3
�
E%PANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
2
O
6
% �
o -e
N
K �
6
f
O
��..... �� . ....
. . . . .. _ 1TTTl�T'.. . .
V
�APPLIEOPRESSORE-KSF
$OrtlplO O( SAND,CIAYEY($C)
F�Om TH-13NT0FEET
2
O
a
w
z
o ,
N
C
P �
O
V
OKYurvITWEIGHT= 118 PCF
MOI61uHeCOMtrvI= 1p0 '�
Exanr�sion� uNOER coNsrnr�r
PRESSURE DUE TO WETTING
. . . .. �:.... . .
��APPLIE�PFESSUNE�KSF �"
Sample o! c�av, samov ic��
FIOT TH-14AT2FEET
�RY uNITWEIGHT- �aa
MOISTORECOMENT= 15]
Swell Consolidation
Tes[ Results
FIGURE H-4
�
E%PANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
Z e
O
6
% �
o -e
N
K �
6
f
O
/ . . . . . �',, . . . . .
"l+�T-... . .
V
�APPLIEOPRESSORE-KSF
$OrtlplO O( SAND,CIAYEY($C)
FIOm TH-15NT0FEET
2
O
a
w
z
o ,
N
C
P �
O
V
OKYurvITWEIGHT= 126 PCF
MOI61uHeCOMtrvI= 9] 'b
NO MOVEMENT �VE TO WETTING
�:.
��APPLIE�PFESSUNE�KSF �"
Sampleol SAN�,CLHYEY(SG)
from TH-15AT9FEET
�RY ONITWEIGHT- �00
MOISTORECOMENT= 1fi]
Swell Consolidation
Test Results
FlGUREAS
�
O -+
N
Q
X -5
2
O 6
tt
� -i
O
U
NO MOVEMENT OVE TO WETTING
�APPLIEUPRESSURE-KSF �
sampieof snrvo,cuverisci
From TH-�snTiaFeET
oaruuirweicHr= ioz vcF
MOISTORECOMEM- 102 Y
Swell Consolidation
Test Results
FIGURE A-6
�
o -_
N
Q
X -5
2
O 6
tt
� -i
O
U
nooirion�n� connaREssioN uNOEa
. coNsrarvr aaEssuRE ouE ro wErriNc
�APPLIEUPRESSURE-KSF �
Sampleo� SAN�,CLAYEV.SLiY(SCSM)
FIO�YI TH-15AT1BFEET
DRYIINITWEIGHi= 103 FCF
MOISNRECOMEM- 255 Y
Swell Consolidation
Test Results
FIGURE A-]
�
E%PANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
2
N
Q -I
W
O -e
N
K �
6
f
O
. ..� . � .....
. v . . . . .. _. .. .. �- . .
. .. . ��T_... . .
V
�APPLIEOPRESSORE-KSF
Samploor cwr,snmor(c�)
F�Om TH-16NT2FEET
2
O
a
w
z
o ,
N
C
P �
O
V
OKYurvITWEIGHT= 108 PCF
MOI61uHeCOMtrvI= 19] '�
Exanr�sion� uNOER coNsrnr�r
PRESSURE DUE TO WETTING
. . ... �:.. .. . .
��APPLIE�PFESSUNE�KSF �"
Sample o! c�av, samov ic��
FIOT TH-18AT2FEET
�RY uNITWEIGHT- � �aa
MOISTORECOMENi= 11.]
Swell Consolidation
Test Results
FlGURE N 8
�
E%PANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
2
N
Q -I
W
O -e
N
K �
6
f
O
�� . _. �,, . . . . .
. . . . ... �TTTI�T_... . .
V
�APPLIEOPRESSORE-KSF
Samploor cwr,snmor(c�)
F�Om TH-19NT0FEET
orrvurvirweicHr= nz PCF
moiswvecorviervi= ia� 'u
Exanr�sion� uNOER coNsrnr�r
PRESSURE DUE TO WETTING
2
O
a
w
z
o ,
N
C
P �
O
V
..... �:.... . .
��APPLIE�PFESSUNE�KSF �"
Sampla o! c�av, samov ic��
FIOm TH-POAT2FEET
�RY ONITWEIGHT- � �00
MOISTORECOMENi= 11]
Swell Consolidation
Test Results
FIGURE F-9
�
E%PANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
Z e
O
6
% �
o -e
N
K �
6
f
O
/ . . . . . �',, . . . . .
"l+�T-... . .
V
�APPLIEOPRESSORE-KSF
Samploof snrvo,cuvev(sc)
From rH-2iaT2Feet
orrvurvirweicHr= i2z PCF
moiswvecorviervi= iaz 'u
Exanr�sion� uNOER coNsrnr�r
PRESSURE DUE TO WETTING
2
O
a
w
z
o ,
N
C
P �
O
V
. . ... �:.. .. . .
��APPLIE�PFESSUNE�KSF �"
Sampla o! c�av, samov ic��
FIOT TH-P2AT4FEET
�RY ONITWEIGHT- � �00
MOISTOREWMENT= 19D
Swell Consolidation
Test Resul[s
FicuREn-io
�
E%PANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
2
N
6
W
O -e
N
K �
6
f
O
. .. � . .._ �- . . . ..
� '�'. .'�'. �.
. .. . . . _..���_... . .
V
�APPLIEOPRESSORE-KSF
Samploor cwr,snmor(c�)
F�Om TH-23NT0FEET
orrvurvirweicHr= ias PCF
moiswvecorviervi= z2.o 'u
Exanr�sion� uNOER coNsrnr�r
PRESSURE DUE TO WETTING
2
O
a
w
z
o ,
N
C
P �
O
V
'. '.. I I�:.. .. . .
��APPLIE�PFESSUNE�KSF �"
Sample o! c�av, samov ic��
FIOT TH-P4AT2FEET
�RY uNITWEIGHT— �aa
MOISTOREWMENT= 9.8
Swell Consolidation
Test Results
FIGUREA- 1
�
;o � ' '
flOrt
GMVEL 21 °6 BAND ]p °/n
SILTBCLhY 5% LI�UI�IIMIi
PVSTICITYINDE%
2 co . . . . . . . '.. . �.
$OmpIEO� 9HN�.SLIGHTLYCLAYEY(9WSC) GRnvP 2396 Survo �0%
ROm TH-i6ATBFEET BiLT&Cuv ]°5 uquioumrt k
RASTICIiV INDE% %
Gradation
Test Results
c*i r aRaem rvo rcwrn ois �vo FIGURE A-12
�
;o � ' '
fmm
GMVE� 10 °6 BAND ]B %
SILTBCLhY 4% LI�UI�IIMIi
PVSTICITYINDE%
2 co �. . �. �. �.
$OmpIE01 SHN�.SLIGHTLYCLAYEY(9WSC) GRnvP 2696 Survo 64%
ROm TH-20AT8FEET BiLT&Cuv 10°5 uquioumrt k
RASTICIiV INDE% %
Gradation
Test Results
FIGURE A-13
�
vua��,ei
SUMMNRY OF LABORATORY TESTING
Page 1 ot 1
"NEGATNE VA W E IN�ICATES COMPRESSION.
�
APPENDIX B
SAMPLE SITE GRADING SPECIRCATIONS
iW�i
SAMPLE SITE GRADING SPECIFICATIONS
1. DESCRIPTION
Thls i�em shall consis� of �he excavation, Uansporla�ioq placemen�, and wmpac�ion of
materials from loca�ions intlicatetl an [he plans, or staked by Ihe Engineer, as necessary
to achieve site eleva[ions.
2. GENERAL
The Soils Engineer shall be the Owners representafrve- The Soils Engineer shall
appmve fill ma�arials, methotl of plecemen�, moisWre con�ents, and percant compacbon,
entl shall give wri�[en approval of �ha comple�ed fill.
3. QEARINGJOBSITE
The Con[ractor shall remove all trees, brush, and mbblsh before excavatlon or fill
placemenl is begun. The Contractor shall dispose of �he clearetl material �o pmvitle the
Owner with a clean, nea[ appearing lob site. Clearetl material shall not be placetl in
areas to receive flll or where Ihe material will supporl stmcWres of any klnd.
4. SCARIFVINGAREATOBERLLED
All �opsoil antl vegetable matler shall be removetl fmm the gmund sudace upon which
flll is to be plecetl. The surtece shell [hen be plowetl or scerifietl �o e tlepth o( 8 Inches
until Ne surface Is free from mts, hummocks, or olher uneven feaWres, which would
preven� unlform compaction by the equipment �o be usetl.
5. COMPACTING AREA TO BE FlLLEO
Afler �he founde�ion for �he fill has been Gseretl entl scerifieQ i� shell be disketl or
blatled until il is free hom large clods, brouqM to the proper moisWre conten� and
compaded b not less than 95 percent of maximum tlensity as determinetl in accortlance
wi�h ASTM � 698.
6. FlLL MATERIALS
Materials classifying as CL, Sq SM, SW, SP, GP, GC. and GM are acceplable. Fill
soils sM1all be free from organlc ma¢er, debris, or o�her tleletenous substances, and shall
no� con�ain rocks or lumps having a diame�er grea�er �han three (3) inches.
]. MOISTURECONTENT
Fill ma[erials shall be moisWre Irealed. Qay soils should be moisWre-hea[etl to
be�ween op�imum and 3 percent above op�imum moisWre conten� as determinetl fmm
Stantlard Pmctor compaction �esis. Santl soils shoultl be mois�enetl to within 2 percent
op�imum moisWre contenL SURicien[ labore[ory compaction tes[s shall be matle lo
determine ihe optlmum moisture content for roe various soils encountered In bormw
areas.
aco�isp Ns B_�
�
The ConUactor may be required to add moisWre lo the excavation materials in the
borrow area It, In �M1e opinion ot tM1e Soils Engineer, It Is no� possible �o obtaln uniform
moleture conlent by etlding we�er on �he fill surtace. The ConVactor may be requiretl to
rake or dlsk the (JI soils to provide uniform moisWre mnlent through the soils.
The applice[ion o{ �(er �o embenkmen[ meteriels shall be metle wi�h eny type of
watering equipment approved by Ihe Soils Engineer. which will give the desired results.
Water jets fmm the spreatler shall not be tlireded at �he embankmen� wi�h such force
�hBl�l�l RIBIEII9I5 d�B WB6hEd OUI.
Should �oo much wa�er be added �o any part of �he flll, such tM1at �he ma�erial is �oo wet
b pertni� the tlesirad compecfion from being obteineQ mlling, entl ell work on ihat
secfion o! ihe (ill shall be delayed unfil ihe malerial has been allowed to unitormly dry to
ihe requiretl moisture content The ConUacbr will be permitled to rework wet ma�erial in
an approved manner �o hasten i5 drying.
8. COMPACTION OF RLLAREAS
Selacted flll materlal shall be placetl and mlzed In evenly spread layers. Afler each fll
layer has been placed, It shall be uniformly compaded to no� less �han �he specifled
percentaga of ineximum tlensiry. Fill me�erials shall be placetl such �hat �ha thickness of
loose malerial does nol exceed 8 inches and the compacled IiR thickness does not
exceed 6inches.
Compac�ion, as specifietl above, shall be obtained by the use of sheepsfool rollers.
multiple-wheel pneumatiatired mllers, or other equlpment appmved by ihe Engineer.
Gompec�ion shell be eccomplishetl whila the fill me�eriel is et �ha specifed maisNra
content Compaclion of each layer shall be con�inuous over �he en�ire area.
Compaction equipment shall make sufflcient Vips to ensure ihat the required density is
obtainetl.
Fill slopes shell be compec�ed by meens of sheepsfaot mllers or o[her sui�eble
equipmenL Compactlon operations shall be cnnfinued until slopes are stable, but not
�oo tlense for plan�ing. and there is no appreciable amoun� of loose soil on the slopes.
Gompectlon af alapee mey be done progresslvely ln Incremen[e of thrae to flve feet (3' �o
6')'m height or after Ihe fill Is brought to Ils total helghL PermaneN (ill slopes shall not
exceed 3 1(honzon�al �o vetllcal)_
1�. DENSITV TESTS
Fieltl densiry tes5 shall be metle by �he Soils Engineer et loce�ions antl tlep�hs of his
choosing. Where sheepsfoot rollers are used. the soil may be disWrbed to a depth of
several inchas. Density tes�s shall ba �aken in compactetl ma�erial below �ha disNrbed
60IfdCB. WhBfl dBfI61IY �B6IS IfIdICB�E �hB� �hE dEfl61�Y OI RIOIS�OfB COfIIBf1I O� BfIY �BYBf Of
(ill or portion thereo( Is below Ihat required, the parlicular layer or portion shall be
reworked until the requiretl density or moisNre con�en� has been achieved.
acowsi.��oxs B_p
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11. COMPLETED PRELIMINARV GRADES
All ereas, both cW end flll, ehell be flnlehed to e lavel surtace, antl shell meet [he
(ollowing Ilmlis of consVuctio¢
e. Ovetlot cut orfill aress shell be within pWs or minus D10 of one foo�.
b. Street grading shall be wi�hin plus or minus 1I10 of one foot.
The civil englneer, or duly aulhorized representative, shall check all cut and flll areas to
observe tM1a� �he work is In accordance witM1 �he above limi�s.
12. SUPERVISION AND CONSTRUCTION STAKING
Observetion by [he Soils Engineer shell be con[inuous during the placemen� o( fill entl
compacllon operetions ao Ihat he can declare Ihat the flll wae placed In general
wnformance wi�h specificafions All spe visits necessary to tes� the placemen� of fill antl
observe compac�ion opere�ions will be at �he expense of �he Ownec All cons�mc�ion
s[aking will be provltled by [he Qvll Englnaer or hls tluly eu[hotlzed reprasentetive.
Ini�ial antl final gratling staking shall be a� the expense of �M1e owner. The replacemen� of
gratle stekes �hmugh constmction shell be e� the expense of ihe contrector.
13. SEASONAL LIMITS
No fill material shall be placed, spreatl, or rolletl while it is Gozeq thawing, or during
unfavoable weather condltions. When work Is 'mterrupted by heavy precipitatloq fill
opera�ions shall not be resumetl un�il the Soils Engineer indicates �hat ihe moisWre
content end densiry of prevlously placed me�erlals are ae epeclfled.
14. NOTICE REGARDING START OF GRA�ING
The contractor shall submit nofifcafion to tM1e Soils Englneer ana Owner advising ihem
of�ha s�atl ofgratling opera�ions atleast�hrea (3) tlays in ativance of�ha statling date.
Notifice�ion shall elso be submit�etl a[ leas� 3 tleys in etivence of eny resump�ion detes
when grading operations have been stopped tor any reason other than adverse wealher
wndi�ions.
15. REPORTWG OF FIELD DENSITV TESTS
Denel�y teste made by [he Sails Englnear, es epeclfled untler "Denslry Tesls" above.
shall be submltled progressively to the Owner. Dry density, moisWre content, of each
�est �aken, and percentage compadion shall be reportetl for each �est taken.
16. DECLARATION REGARDING COMPLETE� FlLL
The Soils Engineer shell pmvide e writtan tleclare�ion s�e�ing [he� �he site was filletl wi�h
acceplable materials or was placed in generel acmrdance with Ihe speci(ma0ons_
am�isip Ns 83
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APPENDIX C
PAVEMENT CONSTRUCTION RECOMMENDATIONS
�
SUBGRADEPREPARATION
MoiSNre Treated Subarade (MTSI
1. The subgrade shoultl be shipped of organic mat[eq scarifetl, mois[ure Vea[ed
and compacted �o �he specifications stated below In Item 2. The compacted
subgratle shoultl extentl at leas� 3 fee� beyontl Ihe etlge of the pavement where
no edqe support, such as curb and gutler, are lo be cons�mc[etl.
2. Sandy antl gravelly soils (A-1-a, A-0-b, A3. A-2-4, A-&5, A-2-6, A-2-1) should be
molsWre contllboned near optlmum moleWre con�ent end compactetl [o e[ leas[
95 percent of standard Pmctor maximum dry density (ASTM D 698, AASHTO T
99). Clayey soils (A-6, A-]-5, A-]-6) shoultl be moisWre contli�ionetl between
op�imum and 3 percent above op[imum moisWre con[en� antl compac�ed �o a[
leasl 95 percenl o! standard Proctor maximum dry density (ASTM D 698,
AASHTO T 99).
3. Utillty Venches and all subsequenlly placed fill should be pmperly compacted and
�estetl prior to paving. As a minimum, fill shoultl be compactetl �0 95 percen[ of
standartl Proc�or maximum tlry tlensi�y.
4 Final gratling of the subgrade should be carefulty conVolled so the design cross-
slope is mein�ainetl antl low spo[s in [he subgretle �he� could Vep we�er ere
eliminated.
5. Once final subgratle elevation has besn compac[etl end tes�ed to complience
and shaped ro ihe required cross-sectioq ihe area should be proobrolled using a
minimum axle loatl ot 18 kips per axle. The proobmll shoultl be performetl wMle
molsWre conten�s of �he subgrede are etlll wl�hln �he recommentled Ilmlts. Drying
of Ihe subgrede pdor lo proof-roll or paving should be avoided_
6. Areas [ha� are observetl by the Engineer Iha� have soft spo[s in the subgratle, or
where tleflec�on Is not uniform of soft or we[ subgrede shall be rlpped. ecatlfied,
dried or we��ed as necessary antl recompaded �o the requirements for Ihe
tlensity antl moisture. As an al�ema�ive. those areas may be sub-excavated antl
replaced with properly compacted slmcWral backfill. Where exlensively sofl,
yielding subgrade is encountere4 we rewmmend a represen�ative of our oHice
observe [he excavation.
G1
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PAVEMENT MATERIALS AND CONSTRUCTION
Aaareaa�e Base CourselABCI
1. A Claes 5 or 6 Colorado Deperlment of Transporlallon (CDOT) epeci(ied ABC
should be used Redaimetl aspM1alt pavement (RAP) or reclaimetl concrete
pevemen[ (RCPJ eltema�ive which mee�s �he Qess 5 or 6 tlesignetian entl
design R-value/eVen9th coefflcient Is also acceplable.
2. Beses should heve e minimum Hvsem s�ebilometer value of ]8, or gree�er. ABC.
RAP, and RCP musl be moisWre stable. The chanqe in Rvalue from 300-psi lo
100-psi exudation pressure shoultl be 12 poin�s or less.
3. ABq RAP, or RCP bases shoultl be placetl in thin lifls no[ �o exceetl 6 inches
antl moisWre ireated to near optimum moisWre content and wmpacted �o at
leas� 95 percent of stantlard Pmctor maximum dry tlensity (ASTM D 698.
AASHTO T 99).
4. Placemen� and compaction of ABC, RAP, or RCP shoultl be observed and �estetl
by a repreaen�a�lve of om flrm. Placement ehould not commence untll [he
undertying subgrade Is properly prepared and tested_
Ho[ Mix Asohalt (HMAI
1. HMA shoultl be composetl of a mixture of aggregate, filler, hytlra�etl lime, antl
asphal� cemenL Some mixes may require potymer motlifetl asphalt cement or
make uae of up �0 20 percent reclalmed aephal[ pevemen[ (RAP). A ob mlx
desion is recommended antl ceriodic checks on tM1e iob si�e sM1ould be made �o
V¢flfY COIIIpIIBfICB Wl(h SpBCIfICd�lOf15.
2 HMA sM1ould be relatively Impermeable to moisWre and should be designed with
croshetl aggregates �hat have a minimum of 80 percen� of [he aggregate re�ainetl
on the No. 4 sieve with Iwo mechanically fracWretl faces.
3. Gretle�ions �het approach �he meximum tlensiry line (wi�hin 5 percant behveen
the No. 4 antl 50 sieves) should be avoided. A gradation wi�h a nominal
maximum size of 1 or 2 inches developetl on tM1e fne sitle of �he maximum
tlensity lina should be usetl.
4_ Total void content, voids In ihe mineral aggregate (VMA) and voids filled sM1ould
be consitlered in the selection of the op�imum asphalt cemen� con�ent The
opllmum aaphalt content ehould be aelecled at a �olal alr vold conten� of
approximately 4 percent The mixWre should have a minimum VMA ot 14 percent
and be�ween 65 percen� and 80 percen� of voitls filletl.
5. Asphalt cement should meel the requiremenls of ihe Superpave Pedormance
Gratled (PGJ Bintlars. Tha minimum performing esphal� ceman� should conform
to �he requiremenls oi [he goveming agency.
acn�isi.ioNs G2
�
6. Hydrated Ilme should be added at the rete o! 1 percent by dry weighl o! ihe
aggrega�e antl shoultl be Inclutletl In �he amoun� passing tM1e Na 200 sieve.
Hytlrated lime for aggrega�e preVea�men[ shoultl conform to the requiremen[s of
ASTM C 20], Type N.
1. Paving shoultl be pertormetl on propetly prepareQ unfrozen surtaces �ha[ are
hee of water, snow, and ice. Pavinq should only be performed when bolh air and
suAace �emperaNres equal, or exceetl. �he �emperaNres specifietl in Table 401-
3 of the 2023 Colorado Depahment of Transportation Stantlartl Specifcations for
Road and Bridge Constmction.
8. HMA shoultl not be placed a� a temperaNre lower than 245°F for mixes
contalninq PG 6422 asphalt, and 290'F for mixes containing potymer-modi(ied
asphalL The breakdown compaction should be wmpleted before the HMA
temperaWre tlmps 20`F.
9- Wearing surtace course shall be Gratling S or SX for resitlen�ial matlway
classifice0ons end Gretling 5 for collecror, atlenel, intlusViel, antl commamial
roatlway classifca[ions.
10. The minimum/meximum lifl thicknesses (or Gretle SX shell be �% inches/2%
Inches. The minimuMmazlmum II(t ihlckneases tor Grade S ahall be 2lnches/3%
inches. The minimum/maximum lift ihicknesses for Grade SG shall be 3 Inches/5
inches.
11. Joinls should be staggered. No joints should be placed withln wheel palhs.
12 HMA should be compac�ed [o between 92 antl 96 percent of Maximum
Theoretical Density. The sudace shall be sealed with a flnish roller priorto ihe
mix cooling �0 185°F.
13. Placement antl compaction o( HMA shoultl be observed and tested by a
representative of our firm. Placement shoultl not commence until appmval of �he
proof rolling as tliscussetl in �he Subgrade Preparation section of this report. Sub-
base, base course or initial pavement course shall be placed withln 48 hours of
approval of the pmof rolling. If ihe Con�rador fails to place �he sub-base, base
course, or ini[ial pavemen� course within 48 hours or the condi[ion of �he
subgrede changes due to wealher or olher conditions, pmof mlling and correction
shall be performed aga'm.
G3
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APPENDIX D
MAINTENANCE PROGRAM
iWli
MAINTENANCE RECOMMENDATIONS FOR FLEXIBLE PAVEMENTS
A pnmary cause for tle�eriora6on of pavemen�s is oxida6ve aging resul6ng In bri��le
pavementa. Tlre loade hom Vafflc are necassary �o "work" or knead �he asphal� concrete lo
keep It flexible and rejuvenated_ Preventive main�enance treatmenis will typically preserve ihe
original orexisting pavemen� by pmvitling a protec�ive sealor rejwenating [he asphal� bintler�o
extend pavemen[life.
Annual Praventive Main�enance
a- Vlsual pavement evaluatlons shoultl be peAormed eacM1 spring or falL
b. Reports documenting �he pmgress of tlis�ress should be kep� curren� to
provide informa�ion on effective �imes to apply preven[ive main[enance
treatmenis.
a Crack sealing shoultl be pertormed annually as new cracks appear.
2 3 to 6 Vear PrevenOve Malntenance
e. The owner shoultl budgel for a preven�lve [reatmen� at approxima�a Intervals
ot 3to 6 yearsto reduce oxidative embrittlementproblems.
b. Typical preven�ive maintenance �rea�ments include chip seals, fog seals,
slurty seals end creck seeling.
3. S to 10 Vear Corrective Main�enance
a_ Correcfrve maintenance may be necessary, as dlctated by Ihe pavement
condtioq b correct m�6ng, cracking, antl s�mcWrally failetl areas
b. Corrective maintenance may include full dep[h patching, milling and ovetlays.
a In order for ihe pavement ro provide a 20.year service Ilte, at least one major
corrective oveday should be expectetl.
a�a��s�.�atis ai
�
EXHIg�T A
SLAB PERFORMANCE RISK EVALUATION,
INSTALLATION AN� MAINTENANCE
As patl of our evaluation of �he subsoils antl betlmck, samples were �estetl in [he
labore�ory using a swell �esL In Ihe �est procedure, a relatively untlisWrbed sample oblainetl
during dnlling Is flrst loatled and �hen flooded wi�h wa�er and allowetl �o swelL The pressure
applietl prior �o we��ing can appmximate the weigh� of soil above �he sample tlep�h or be some
s[andard loatl. The measured percent swell is no� Ihe sole criteria in assessing poten[ial
movement of slabs-on-grade and roe risk o( poor slab pedormance. TM1e results of a swell test on
an intltvidual lo� are �emperetl wph data fmm surmunding b�s, dep�h of �ests, depih of excava6on,
soil profile, and other tes�s. This judgmen� has been tlescribed by Ihe Colorado Associa�ion of
Geotechnical Engineers (CAGE, 1996) as it relates to basement slab-on-grade floors- It can also
be usetl �o halp judge pertormance nsk for other slebsbn-gratle such as gerage floors, tlriveways,
and sitlewalks. CTLIThompson also performs po[enlial heave calculations lo aitl in ourjutlgmen[.
The risk evaluation Is considered when we evaluate appropriate foundation systems tor a given
site. In general, more conservative fountlation tlesigns are usetl for higher risk si�es to coMml �he
likelihootl oi excessive fountlation movemen�.
As a resW� of ihe Slab Pertormance Risk Evalua�ion, si�es are ca�egorizetl as low.
motlerale, high, or very high risk. This is a lutlgmen� of [he swelling charec�eristics of �he soils
and betlmck likely to iniluence slab pedormance.
REPRESENTATIVE MEASURED SW ELL AN� CORRESPONDING SLAB
PERFORMANCE RISK CATEGORIES
Slab PeKo�mance Represen�ative Percent Swell' Represen�ative Percent Swell'
Risk Ca�egory (500 psf SumM1arga) (1000 psf SurcM1arge)
Low O�a<3 O�oQ
Motlea�e 3 �o �5 2 �o �4
HIgM1 Slo<8 010<6
VeryHIgM1 >8 >6
•NOR'. TM1erepresentaweperteniswellvaluespresenteoar notnecessadrym ureovalues:raNeqlM1eyare
�
e ludgmanto� Ne swelling cM1aretlens�ius o(IM1a soil entl betlmck likely �o InAuence slab pe�ortnence.
The rating of slab performance risk on a site as low or hlgh Is not absolute. Rather, thls
rating represents ajudgment Movement of slabs may occurwith time in low, moderate, high, antl
very hiqh risk areas as the expansive soils respontl [o increases in moisWre contenL Overall, �he
severity and (requency of slab damage usually Is greater in high and very hlgh rated areas. Heave
of slabs-on-grade of 3 �0 5 inches is not uncommon in areas ratetl as high or very high risk. On
low and modare[e rlak sl�ee, slab heeve of 1[0 2 inches Is coneldered normal and we belleve In
Ihe majority of Instances, movemenis of thls magnllude cons[itute reasonable slab performance�,
more heave can occur. Slabs can be affec[etl on all sites. On lo[s ratetl as high or very high risk,
Ihere is more likelihootl of need �o repaio. maintain, or replace basemen[ and garage Floors and
extenor(latwork_
EXHIBIT A-0
�
CTLIThompson, Inc. recommends use of s�mcWrally supportetl basement floors. known
as "stmcNral floors," for lots rated as high and very higM1 risk. We also recommend use of stmcNral
basementfloors on walkou� antl garden levello�s ra�ed as motlera�e, high, or very high risk.lf
homebuyers cannot tolerate movemenl of a slab-on-grade basemen[ floor. they should select a
lot where a stmcturalty supported floor will be wnstmctetl or request that a simdurally supportetl
floor be installed.
The homebuyer should be advised ihe (loor slab'm the basement may move and creck
due to heave or setllement and �hat ihere may be maintenance cos�s associatetl tluring antl after
Ihe builder warranry periotl. A buyer who chooses to finish a basemen[ area mus� accepl the risk
of slab heave, cracking, and consequential damages. Heave or seltlemenl may requlre
maintenance of fnish tle�ails �o control tlamage. Our experience suggesis �hat soil moisWre
increases below residence si�es due [o covering the grountl with Ihe house and ex�erior fla[work,
coupletl wtih ihe'mhoducHon of landscape Irrigafion. In most cases, slab movemenis Qf any)
resulting fmm [his change occur within �hree to five years. We suggest delaying finish in
basements wi[h slab-on-grade (loors until at least three years after slart of irriqation. II is possible
basement floor slab and (inlsh work pedormance will be safisfactory i( a basemenl Is ilnished
aatlie5 particularly on low risk si�es.
For portions of the houses where comentional slabs-on-grede are used, we recommend
�he following precau�ions. These measures will not keep slabs-on-gratle fmm heaving; �hey tentl
lo mi[iga[e damages due �o slab heave.
1. Slab-on-grade floor cons�mc�ion shoultl be limitetl to areas such as garages and
basemen[s where slab movemen� and cracking are accep[able �o �he builder antl
homebuyer.
2 The 2021 Interna�ional Resitlen�ial Cotle (IRC R506) states �ha[ a 4-inch base
course layer consisting of clean greded sand, gravel, croshed smne, or croshed
blas� fumace slag shall be placetl benea�h below gratle floors (unless the
untlerlying soils are free-draining).. along with a vapor retartler. Ins�allation of �he
base course and vapor retarder is not common M thls area. Hlsrorically, ihere has
been some concem tha� Ins�alla�lon of dean base course could allow we�tlng of
expansive soils �o spread fmm an isola�etl source.
IRC statas tha� the vapor ratarder can be omitlatl whara appmvetl by the builtling
officiel. The meri�s ofins�ellation ofe vepor retartler belowfloorslebs tlepend on
Ihe sensi[ivity of floor coverings and buildinq use lo moisNre. A properly ins[alled
vapor retartler is more beneficial below concrete slab-on-gratle floors where floor
coverings, pain�etl Floor surtaces, or protluc�s stored on �he floor will be sensitive
lo moisture. The vapor retarder Is most effective when concrete Is placed dlrectly
on �op of it, ra�her �han placing a santl or gravel leveling wurse between the vapor
retartler antl Ihe floor slab. Placement oi concre�e on the vapor retarder may
increase ihe risk of shrinkage cracking and cuding. llse ot concrele wilh reduced
shrinkage charac�eristics induding m mized wa�er wn�ent maximlzed coarse
aggrega�e con�en[, antl reasonably low slump will retluce the risk of shrinkage
crackinq and curling. Considerations and recommendalions for lhe installalion o!
vapor re�artlers below concre�e slabs are oNlinetl in Section 32.3 of the 2015
American Concrete Insti�u�e (ACI) Commi�tee 302,'Guide for Concrete Floor and
Sleb Conehmtlon (ACI 302 R-96)".
EXHIBIT A2
�
3. Conven�ional slabs should be separa�ed from ex�erior walls antl interior bearing
members wi�h a slip join� tha� allows free vetlical movemen� o( �he slabs. These
joints mus� be main�ained by �he homebuyer to avoid �ransfer of movemen�.
4. Untlerslab plumbing should be tM1omughly pressure tested during wnstmction for
leaks and be pmvldetl with flexible couplings. Gas end wa�etllnas leading to sle�
suppor[ed appliances should be conslmcled with Flexibili�y. The homebuyer must
ma'mtain these connections.
5. Use of slab bearing parti[ions shoultl be minimized. Where such par[i�ions are
necessary, a sllp joint (or floal) allowing at least 2'mches of free vertical slab
movemen� should be usetl. Doorways shoultl also be designetl �o allow vetlical
movemen� of slabs. To limi� tlamage in [he even[ of movemen�, shee�rock shoultl
not extend to ihe floor. The homebuyer should monitor partition voids and other
connections antl re-establish the voitls before �hey close to less than V2-inch.
6. Plumbing and utilities ihal pass ihmugh slabs should be isolated from ihe slabs.
Hea�ing antl air contlitioning sys�ems constmctetl on slabs shoultl be pmvitletl wi�h
flexible mnnections capable of a[ leas� 2inches of vertical movemen[ so slab
movement is not Vansmltled to the duciwork. These connections must be
maintained by the homebuyer.
]. Roofs tha[ overhang a patio or porch should be conslmcted on the same
fountlation as �he resitlence. Isolatetl piers or patls may be installed benea�h a mof
overhang provitletl the slab is intlependen[ of �he founda�ion elements. Patio or
poah mof columns may be positioned on ihe slab, direclly above the foundation
system. provitled the slab is stmcWral and suppotled by the fountla�ion system.
StmcWral porch or patio slabs shoultl be cons[mcted [o retluce [he likelihootl Iha�
settlement or heave will affect the slab by placing loose backflll under the
stmcNralty supportetl slab or cons�mding �he slab over void-forming materials.
8. Patio and porch slabs without roofs and other exterior flatwork should be isolated
fmm �he founda�ion. Movements of slabs shoultl no� be �ransmi�ted b the
tountla[ion. Decks are more Flexible antl more easily atljusted in [he even[ of
movemenl.
9. Requen� contml join�s shoultl be pmvidetl in conven[ional slabs-on-gratle to
reduce problems associated wi[h shrinkaqe crecking antl curlinq. Panels tha�are
appmximately square generalty perform betlerihan rec�angular areas. We suggest
en etldifionel loint ebou� 3 feet ewey hom antl perellel to founde�ion wells.
EXHIBIT A-3
�
EXHIBIT B
SURFACE DRAINAGE,
IRRIGATION AND MAINTENANCE
Pertormance of fountla[ions antl concrete fla�work is influencetl by lhe moisW re contli�ions
existing within the fountlation soils. Surface tlreinage should be designed m provide repitl runoff
of surface water away (rom pmposetl resitlences. Pmper suAace tlrainage and irriga�ion pradices
can help con�rol �he amounl o( surtace wa�er �hat pene�rates to fountlation levels antl con�ribu[es
lo settlement or heave of soils and bedrock that support foundations and slabs-on-grade. Positive
drainage away fmm the founda�ion antl avoidance of irriga�ion near �he fountla�ion also help to
avoitl excessive we�ting of backfill soils, which can leatl �o increasetl backfill setllement antl
possibly ro hiqherlaleral earth pressures, due toincreasetl weight and retluced strengih ofthe
backflL CTLIThompson, Inc. recommends �he Pollowing precau�ions. The homebuver should
main[ain surface tlrainaqe antl if an irriqa�ion sys�em is installetl. i� shoultl substan[iallv conform
to ihese recommendations.
1. Wetling or tlrying of [he open fountla�ion excava�ions should be avoitletl.
2. Excessive wetling o( founda�ion soils bePore, tluring and aker constmction can
cause heave or softening of fountla�ion soils antl result in fountla�ion antl slab
movemenis. Proper surtace drainage around ihe resitlence antl between lots is
cri�ical to wn�ml we�ting.
3. The qround suRace surrountling ihe exterior of each residence should be sloped
to drain away fmm ihe building in all directions. We recommend a minimum
constmc�etl slope of et lees� 12inches ln �ha Orst 10feet (10 percent) In
lantlscapetl areas around each resitlence, where prectical. The recommended
slope is for �he soil surface slope, no� surface of landscaping rock.
4. We do not view ihe recommentlalion to provide a 10 percent slope away fmm ihe
foundation as an absolute. It is desirable to create this slope where prectical
because we know �ha� backfll will likely setlle �o some tlegree. By starting with
suffcien� slope, posi[ive tlrainage wn be main�ainetl for mos[ set�lemen[
conditions. There are many siWations around a residence where a 10 percent
slope cannot be achieved practicalty, such as arountl pa�ios, at insitle founda�ion
mrners, antl between a house and nearby sidewalk. In these areas, we believe it
is desirable to establlsh as much slope as practical and to avoid Irrigation. We
believe it is acceptable to use a slope on �he ortler of 5 percent perpendicular �o
the toundation in these limiled areas.
5. Por lots gradetl to tlirec� tlrainage fmm lhe rear yartl to �he fmn[ it is tlifficW� �o
achieve 10 percent slope at ihe high poin[ behintl [he house. We believe it is
acceptable to use a slope of about 6lnches In Ihe flrst 10 feet (5 percent) at thls
loca�ion.
6. Between houses ihat are separated by a distance of less tnan 20 feet ihe
constmc�etl slope shoultl generalty be a� least 10 percent to the swale usetl �o
convey water ou� of [his area Porlots �hal are gratletl [o tlrain [o �he Gon[ antl
back, we belleve it is acceptable ro Install a slope of 5 to 8 percent at the high point
(eka "break poinP') be�ween houses.
acnwpqnorvs EXHIBIT &1
�
]. Conshuc[ionofretainingwallsanddecksatljacenitotheresitlenceshoultlnotal[er
�he recommended slopes and sudace drainage amund �he residence. The gmund
surface untler tlecks shoultl be compactetl antl slope away from the resitlence. 10-
mil plas[ic sheeting and lantlscaping mck may be placetl untler decks to soil
erosion andlor forma�ion of depressions under ihe tleck. The plas�ic shee�ing
should tlirec[ water away fmm �he resitlence. Retaining walls shoultl wt flatten �he
surtace drainage around ihe residence or impede surface runoR.
8. Swalesusetltocomeywa�eracrossyardsantlbe�weenhousesshoultlbeslopetl
so tha[ wa�er moves quickly antl tloes not pond for eztentled periods of time. We
suggest minimum slopes of aboN 2 m 25 percent in grassed areas and about 2
percent where lantlscaping rock or o�her materials are presenL If slopes less than
abou[2 percentare necessary, mncrete-lined channels orplas�ic pipe shoultl be
used. Fence posts, irees, and retaining walls should not impede mnoff in the
swales.
9. Backfll around �he foundation walls should be moistened and compac�ed.
10. Roof downspou[s antl drains shoultl discharge well beyond ihe limi[s of all backfll.
Splash blocks and/orextensions should be provided a� all downspouts so water
discharges onto �he gmuntl beyontl the bac�ll. We generalty recommend against
burial of tlownspoul tlischarge. Where i� is necessary to bury tlownspou[ tlischarge,
solid, rigid pipe should be used and it should slope m an open greviry outlet.
Downspout ex�ensions, splash blocks and burietl ou�lets must be maintainetl by
lhe hameowner.
it The impotlance of pmper irriga�ion antl drainage pradices and main�enance
canno� be over-emphasizetl. Irriga[ion should be limi�etl to �he minimum amount
suffcient to ma'mtain vegetation; application of more water will increase Ilkelihood
of slab antl foundation movements. Landscaping should be carefulty designed and
main[ained lo minimize irriga�ion. Planls placed close �o founda�ions, parlicularly
within 5 feet of the (oundation, should be limited to those wilh low moisWre
requiremen�s and utillze onty sub-surface Irrigation such as s�andard low volume
tlrip emi[lers or in-line tlrip irriga�ion. Irriga�ed gress, irrigation mainlines, above-
surtace sprey heads, mtors, and other above-suRace irrigation sprey tlevices
should no� be loca�ed or discharge above the gmund surface within 5(ee� o( �he
fountla[ion.
12 Plas�ic sheeting should no� be placed beneath lantlscapetl areas atljacen� �o
fountlation walls or grade beams. Geo�eatile fabric will inhibit weetl gmwth yet still
allow naturel evaporotion ro ocwr.
acnwpqnoxs
EXHIBIT B-2
�
EXHIBIT C
EXAMPLE BACKRLL COMPACTION ALTERNATIVES
ALL Descriplion I Settlemenl I P� (�) � Cons (-)
Place In 18 to 24-'mch II(is, wilhout 5 to 15 + Fas�
moisWre contlitioning. Compact Percen[of + Wa�erno�requiretl
A lif[ surtace �o about 85 percen� of depth - Excessive Seltlemenl
maximum standard Proctor (�or 8 fee� of - Highest water pene�ration
(ASTM D698) tlry tlensity. backfill, 5[o - Highest probabiliry of
15'mches) warrentyrepalr
MoisWre contli�ion wi�hin 2 + Relatively Fast
percen� of oplimum, place in 12 to 5 to 10 _ Motlerale water penelre[ion
B 18-inch lifts. Compact li(t surface PetleP�h°f - Excessive seltlement
to about 85 to 90 percent - Need forwa�er
- Warranty repairs probable
MoisWre condl[ion lo wilhin 2 pto5
percen� of op�imum and place In 8
� to �2-inch lifts. Compac� IIft Percento(
sudace to 90 to 95 percent. depth
+ Reducetlwarranly
+ Reduwtlwa�er'mfiltra�ion
+ Reducetlsetllement
- Possible hlgher lateral pressure
Slower
- Needforwa�er
- Potenlial damage ro walls
MoisWre condition antl place es in � to 2
� G Compact Ilft sudace to at least percent of
95 percen� tleptn
nenwsinoxs
+ Reducedwarranly
+ Reducetl water infiltration
+ Lowest compara�ive settlement
- Possible hlgher lateral pressure
Slower
- Needforwa�er
- Potenlial damage ro walls
E%HIBIT C-0