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154 WEST DAYTON ST.PDF154 W DAYTON ST 0 1- rn f,l In D D y N S D 0 c -1 X f I, _I C27 rn r- r- In c (I, s z C) i 0 z co 0 0 00 r.) 0 (7) J. O 7 ® ® ® ® ® = • FOUNDATION ENGINEERING • EARTHWORK ENGINEERING • GROUI•JDWATER STUDIES • SLOPE STABILITY STUDIES • ROCKERY DESIGN • • SUBSURFACE EXPLORATIONS • CONSTRUCTION INSPECTIONS • DRAINAGE SIUDICS IANDSLIDE INVESTIGATIONS • REIAINING WALL DESIGN • < • SOIL TESTING - LAB a FIELD • WATER RETENTION STUDIES • SITE EVALUATIONS • DAMAGE INVESTIGATIONS • STORMWATER STUDIES • 00 co - 1 m M Z -�-i! m M o -n n (n L 1 VI _ ----�---- ---- 0 � o CD O ? C { `t L�== s c- o D O _ F.(o m r L co �7 'p s - � m •� O Z Z LP L z C7 Z z. rn tv rn - L - I �j AM '\ '(43_..._i TABLE of CONTENTS INTRODUCTION page AUTHORIZATION for GEOTECHNICAL ENGINEERING . 1 DESCRIPTION of PROJECT . . . . . . . 1 LIMITATIONS of INVESTIGATION and REPORT . . . . . . 1 SITE INVESTIGATION EXISTING SURFACE DESCRIPTION . . . . . . . . . . 3 SUBSURFACE INVESTIGATION . . . . . . . . . . . . 3 RATIONALE for INVESTIGATION . . . . . . . . . . 3 METHODS of INVESTIGATION . . . . . . . . . . . 4 VISUAL OBSERVATIONS . . . . . . . . . . . . 4 FIELD TESTS . . . . . . . . . . . . . . . . . 5 GROUNDWATER OBSERVATIONS . . . . . . . . . 5 SITE STABILITY INVESTIGATION. . . . . . . . . . 5 DESCRIPTION of EXISTING SITE SOILS . . . . . . . . . 5 HOW PHYSICAL PROPERTIES of SOILS DETERMINED . . . 5 SUBSURFACE CONCLUSIONS . . . . . . . . . . . . 6 ENGINEERING STUDIES and RECOMMENDATIONS RATIONALE for RECOMMENDATIONS . . . . . . . . . 7 SITE PREPARATION . . . . . . . . . . . . . . . . 8 CLEARING and STRIPPING . . . . . . . . . . . . 8 PROOF ROLLING . . . . . . . . . . . . . . . 8 PLACEMENT of WORKING SURFACE . . . . . . . . 9 GENERAL SITE EXCAVATING . . . . . . . . . . . . 9 GENERAL SITE FILLING . . . . . . . . . . . . . . 9 DESCRIPTION of FILLING . . . . . . . . . . . . 10 DESCRIPTION of STRUCTURAL FILL . . . . . . . . 10 DENSITY REQUIREMENTS of STRUCTURAL FILL. 13 CONTROL of COMPACTION of STRUCTURAL FILL 13 FOOTING DESIGN . . . . . 14 APPROVED BEARING SOILS . . . . . . . . . . .. 15 ALLOWABLE BEARING CAPACITIES . . . . . . . . 15 BEARING CAPACITY of UNDISTURBED SOILS . . . . . 16 BEARING CAPACITY of STRUCTURAL FILL . . . . . . 16 FOOTING SIZES . . . . . . . . . . . . . . . . 16 MAXIMUM SPAN for SOFT SPOTS . . . . . . . . . 17 SPAN for CONTINUOUS FOOTINGS . . . . . . . . 17 SPAN for COLUMN FOOTINGS. . . . . . . . . . 18 MINIMUM WIDTH of FOOTINGS . . . . . . . . . . 18 MINIMUM DEPTH of FOOTINGS . . . . . . . . . . 18 MINIMUM DEPTH for SEARING. . . . . . . . . . 18 MINIMUM DEPTH for FROST PROTECTION . . . . . 19 DRAINAGE of FOOTINGS . . . . . . . . . . . . . . 19 SETTLEMENT ESTIMATIONS. . . . . . . . . . . . SETTLEMENT of UNDISTURBED SOILS . . . . . . SETTLEMENT of STRUCTURAL FILL . . . . . . . DIFFERENTIAL SETTLEMENT . . . . . . . . . . UNEXPECTED or UNUSUAL SETTLEMENT . . . . . EARTHQUAKE . . . . . . . . . . . . . . . . . LATERAL FORCES .. . . . . . . . . . . . . SETTLEMENT . . . . . . . . . . . . . . . LIQUEFACTION. CONCRETE FLOOR SLABS . . . . . . . . . . . . DESCRIPTION of CAPILLARY WATER. . . . . . . PROTECTION of FLOOR SLAB from CAPILLARY WATER DRAINAGE of SLAB BASE COURSE . . . . . . . DRAINAGE . . . . . . . . . SITE SURFACE DRAINAGE . . . . . . . . . . . SITE SUB SURFACE DRAINAGE . . . . . . . . . FUTURE STUDIES and RECOMMENDATIONS DESIGN REVIEW . . . . . . . . . . . . . CONSTRUCTION INSPECTIONS and VERIFICATIONS LIST of FIGURES page 19 19 19 19 20 20 20 20 20 24 24 25 26 27 27 28 29 29 FIGURE TITLE or DESCRIPTION PAGE 1 LOCATION of PROJECT . . . . . . . . 1 2 PLAN of SITE . . . . . . . . . . . . 2 3 PLAN of PROJECT . . . . . . . . . . 3 4 GEOLOGY of SITE . . . . . . . . . . 4 5 TEST PIT LOGS . . . . . . . . . . . 5 6 WORKING SURFACE . . . . . . . . . 9 7 BEARING and SETTLEMENT . . . . . . 15 8 OVER -EXCAVATING FOOTINGS . . . . . 17 9 DRAINAGE . . . . . . . . . . . . . 19 10 LIQUEFACTION . . . . . . . . . . . 23 11 CAPILLARY BREAK . . . . . . . . . 27 FIUUKL I L U ',, iA I I U IN Ul r- 1 VIE -- Project Number 2105 15 July, 1996 ��' page 1 of 30 pages INTRODUCTION AUTHORIZATION for GEOTECHNICAL ENGINEERING On 15 May 1996 WARREN LAFON ARCHITECT, agent for Jack Tawney, owner, authorized HEMPHILL CONSULTING ENGINEERS (HEMPHILL) to conduct geotechnical engineering for the proposed New Tennis Courts for the Harbor Square Athletic Club (PROJECT) to be located at 160 Dayton Street, Edmonds, Washington (SITE) as shown approximately in Figure 1. LIMITATIONS of INVESTIGATION & REPORT This geotechnical report is intended only for the use of the CLIENT as an aid to design and construct the specific structure, and in the specific location, as described in this report. This report may not be used by any other person or firm, or for any other structure, or for any other location on the described property. The recommendations presented in this report are based on the requirement that the presumed subsurface conditions, and the presumptive soil properties, will be verified by HEMPHILL after the true nature of all the soils and the groundwater have been revealed during the excavating process. DESCRIPTION of PROJECT The proposed project will be located adjacent to the existing tennis center as shown in Figure 2 on the next page. The project will be constructed with reinforced concrete tilt up walls supported by shallow continuous and column spread footings. The tilt up walls will support a wood frame roof that will cover 3 tennis courts and offices over a concrete slab floor system. FIGURE 2 PLAN of SITE i 1.1 -i--r 'H4-tttll. L 1 1 1 1 1 Ew5" fEW15 MI R IX IWA5 CMER i � 1 i ----- ----- i . i i J ---------'-''_ 15 July. 1996 page 2 of 30 pages Project Number 2105 FIGURE 3 PLAN OF PROJECT C C,/-:---- 0 Project Number 2105 40 15 July, 1996 Opage 3 of 30 pages SITE INVESTIGATION EXISTING SURFACE DESCRIPTION The existing ground surface is flat with a 2 to 3 foot mound at the rear (south) of the property. The ground surface is gravely sand with sparse vegetation. SUBSURFACE INVESTIGATION RATIONALE for SUBSURFACE INVESTIGATION The request by the CLIENT for HEMPHILL CONSULTING ENGINEERS to conduct geotechnical engineering obligates HEMPHILL to investigate and make recommendations concerning all phases of design and construction that would be affected by soils and foundations, including groundwater and drainage. The extent of the subsurface investigation was based on the cost limitations recommended by HEMPHILL, and approved by the CLIENT, with the requirement that the presumed subsurface conditions would be verified by HEMPHILL after all the true subsurface conditions have been revealed by the excavations, and that any necessary adjustments in foundation design and/or depth of footing placement for bearing and stability will be determined by HEMPHILL at that time. There have been several similar projects constructed in the general vicinity of this proposed project. The subsurface investigations for those projects have revealed conditions similar to the conditions at this site. Therefore, the subsurface investigations, the foundation treatments, and the results of those other projects have been studied in conjunction with this project. rE��' rp rl1Lb -771 �-M. . • _�L•_ , VI At .•\ .. � , � ,-�_�.-'.�. .;:��6, � .�. . � \••_,�:1 �''-.Doi=.-� ..;` :: � 3._.�;_. • .. . . ' C r \` ��•� !(i �t.- ..� ..- '• n_ ":f�: (• ..�. � {l' `'L\_ll_� _ .:�I ` .t_.�_� .`. -� •mil �i L" � • v •:.. F'' °I. ••.,: ;., � �- ;. r::. `,,fir, :�---.:, l� . .� � � i.. ! � �. �,, il.,, � �--,._.,�:' f ��(( vi Ilk a� ,�.'c.. ��'•.U'J�• — �¢� ` i i-.i .� !. �. � '+i : � ltC . . � N7�Vrt'e,./� � .- • J �l;••(` ' • � � ���� �J,'J -Y `� .ft-f Y l�F _,...�+ ..(•,�' i�JG J i t\ `.`"`: � ,' �1`• Yn ') ! \• •� ,, :,•!,'�..�: � 1 •I --- .�.., *:'-�T��- Yam: \ '3� ��l j � •% \ �. I[Al i LL 1lj - U JU T� I.� 1 Project Number 2105 15 July, 1996 page 4 of 30 pages i METHODS of INVESTIGATION HISTORICAL RESEARCH The site and general vicinity is known to have been filled and then covered with mounds of fill prior to the development of Harbor Square, therefore the site has been preloaded. The extent and height of preload fill at the site is not known. The length of time that the fill was stored on the site would have been sufficient to complete any settlement of the original soils .and the overlying existing fill resulting from the weight of the excess fill that has since been removed. GEOLOGIC RESEARCH The surface geology for the vicinity of the project is shown in Figure 4, which is a partial copy of one of the geologic maps of a portion of the Puget Sound area. The geologic map shows that the site has been altered (ml) by removing some of the original soils and/or by filling. That description fits the known history of the site. The geologic maps do not have great accuracy, but they help to show soil types that are probable throughout Puget Sound but are not always obvious, or they help to verify that observed soils are as suspected. The significance of the geologic maps is that they show a general trend of geologic conditions that would appear to be reasonably continuous. VISUAL OBSERVATIONS at the SITE and VICINITY The area adjacent to the south side of the site is a wetland, which is indicative of the conditions that existed at the site prior to filling. FIGUW. TEST PIT LOGS DEPTH TP-1 I TP-2 TP-3 TP-4 DEPTH BROWN GRAVELY SAND 1 BROWN BROWN 1 SANDY SILT GRAVELY SAND GRAVELY SAND 2 2 DARK GRAY MEDIUM DENSE 3 MEDIUM SAND 3 LIGHT GRAY MEDIUM DENSE 4 MEDIUM SAND 4 GRAY MEDIUM GRAY SAND SAND 2000 psf 5 2000 psf 5 GRAY MEDIUM SAND 6 2000 psf GRAY MEDIUM 6 2000 psf 7 7 $ v v v $ PEAT PEAT PEAT 9 9 MEDIUM SILT MEDIUM SILT MEDIUM SILT 10 v 10 PEAT 11 MEDIUM DENSE MEDIUM DENSE 11 FINE SAND FINE SAND MEDIUM DENSE FINE SAND 12 MEDIUM DENSE 12 FINE SAND 13 13 14 14 15 15 LEGEND --------------- ESTIMATED LOCATION of CHANGE of SOILS KNOWN LOCATION of CHANGE of SOILS BOTTOM of TEST PIT 0 TOP of GROUNDWATER Project Number 2105 15 July, 1996 page 5 of 30 pages FIELD TESTS Figure 5 shows the logs of 4 test pits conducted at the site. The test pits were located outside the four corners of the proposed building. The typical soil conditions revealed by the test pits are that the upper 8 feet is composed of sandy soils. The sandy soils below the upper 2 feet can support loads of 2000 psf. At 8 feet below the ground surface is approximately 1 foot of peat that supports groundwater. The peat is underlain by a 1 foot layer of silt, which is then underlain by fine sand. GROUNDWATER OBSERVATIONS The top of the groundwater table was located at a depth of 8 feet below the existing ground surface on 15 May 1996 after a 3 day period that accumulated 1 inch of rainfall. The soils above the water table were damp, the bottom 4 feet from capillary rise, and the top 4 feet from surface water infiltration. SITE STABILITY INVESTIGATION The site is stable because the site is flat except for 2 to 3 foot mounds at the south end of the site. The mounds will be removed during the grading operations. SOIL DESCRIPTIONS HOW PHYSICAL PROPERTIES of SOILS were DETERMINED The physical properties of the soils were determined by visual classification, probing, and penetration tests conducted in the 4 test pits. Project Number 2105 15 July, 1996 page 6 of 30 pages DESCRIPTION of UNDISTURBED NATURAL SOILS The undisturbed natural soils below 8 feet are old beach deposits that then became overlain by vegetation which later became peat. The beach deposits are ; underlain by glacial till (Qvt), shown in Figure 4 on adjacent properties to the south and north, and maybe glacial outwash (Qvr) shown east of the site. DESCRIPTION of EXISTING FILL SOILS. The existing fill soils in the upper 2 feet were probably placed during grading operations when the preload fill was removed. The next 6 feet was fill that was compressed by the preload fill. CONCLUSIONS HEMPHILL concludes that the original glacial till (Qvt) was covered with beach deposits when Puget Sound was at a higher level. The beach deposits were covered with silt that eroded from adjacent slopes after Puget Sound receded. The Peat then accumulated as vegetation grew and died over many years. The peat and marsh plants were then covered with fill that was placed in high mounds that preloaded all the underlying soils, including the peat. The upper preload was removed to a level 2 feet below the existing ground surface. More fill was placed at a later date, probably during the development of Harbor Square. That fill was later graded to the present level, probably during the construction of the existing tennis center. The proposed structure can be placed on the preloaded soils at approximately 2 feet below the existing ground surface. Those soils can support loads of 2000 psf with minimal settlement within the tolerable range of a flexible structure. I I I 1 0 46 Project es Number 2105 15 July, 1996 page 7 of 30 pa . 9 ENGINEERING STUDIES & RECOMMENDATIONS RATIONALE for RECOMMENDATIONS The request by the CLIENT for HEMPHILL CONSULTING ENGINEERS to conduct geotechnical engineering obligates HEMPHILL to investigate and make recommendations concerning all phases of design and construction that would be affected by soils and foundations, including grcundwater and drainage. The subsurface investigation was established in accordance with minimum standards established by HEMPHILL, and also with generally accepted minimum standards determined by other geotechnical engineers. Those standards were derived through experience that has proven reasonably often to reveal the true subsurface conditions throughout the sites of most projects. The geotechnical recommendations presented in this report for the proposed PROJECT are based partially on presumptions by HEMPHILL that all the soils are similar to those observed at the site and on the requirement that HEMPHILL will verify the presumed conditions, and will make final decisions for foundations, structural fill, soil preparation, slabs, paving, and for drainage, at the time that the excavations reveal the true nature of all the subsurface soils and conditions. The following design recommendations are based on the soil conditions that might occur during normally anticipated storm or seismic conditions, and even during some poor construction practices. The worst of any of those conditions would not be normally anticipated, therefore the lower limits of the design parameters and safety factors are based on engineering judgment. rERE , rl; ?) _7TT ,i �I Project Number 2105 15 July, 1996 8 page of 30 pages SITE PREPARATION CLEARING and STRIPPING In those areas where the structure, paving, or special landscaping will be placed, the ground surface should be cleared of any trees and shrubs, high grass and weeds, debris, and trash. The ground surface within fne proposed structure, and under any footings or paving, should be stripped of any sod, organic soils, and roots. NO ORGANIC MATERIALS CAPABLE OF DECOMPOSING SHOULD BE LEFT WITHIN THE PROPOSED STRUCTURE. Decomposing materials are the source of unacceptable odors, and can create methane gas, which can be explosive, and can also be harmful when inhaled. PROOF ROLLING PURPOSE OF PROOF -ROLLING Proof -rolling will densify the upper layer of soil, will compact any soil loosened by excavating operations, and will locate soft spots that should be excavated and replaced with structural fill. If the condition of the underlying soils is questionable, HEMPHILL might require that the soils be proof -rolled. DESCRIPTION OF PROOF -ROLLING Proof -rolling of a soil is accomplished by several passes of a heavy compactor or rubber tired vehicle. At those locations where the condition of the underlying soils is questionable, HEMPHILL might require that the soils be excavated and replaced with structural fill. • FIGURE 6 PROCEDURE for PREPARING and PLACING A WORKING SURFACE OVER SOFT SOILS A•►y�SO%;�.rj��� •e �lop .;'i A B C D A. STRIP TREES, SHRUBS, AND GRASS, INCLUDING ROOTS AND ORGANIC SOILS (IN SOME CASES, WHERE APPROVED AND SUPERVISED BY HEMPHILL, GRASS AND ORGANIC SOILS CAN REMAIN). B. PLACE POORLY GRADED (SINGLE SIZE) COARSE AGGREGATE, COMPOSED OF COARSE GRAVEL OR CRUSHED ROCK, IN THIN LAYERS OVER SOFT SOILS. C. FORCE EACH LAYER OF THE COARSE AGGREGATE INTO THE SOFT SOIL WITH A HEAVY ROLLER, CRAWLER, LOADED RUBBER TIRED VEHICLE, OR VIBRATING COMPACTOR, UNTIL AGGREGATE HAS BEEN FORCED TO THE MORE COMPETENT LAYER OF SOIL, AND AGGREGATE VOID SPACES ARE COMPLETELY FILLED WITH THE SOFT SOIL (PUMPING HAS CEASED AND SOFT SOIL IS NOT SEEPING FROM SURFACE). D. ADD EXTRA LAYER OF AGGREGATE TO ENSURE THAT SOFT SOIL WILL NOT OVERFLOW THE VOID SPACES. • Project Number 2105 15 July, 1996 01page 10 of 30 pages DESCRIPTION of RECOMMENDED STRUCTURAL FILL Structural fill is defined as any soil that can be properly compacted to achieve any or all of the physical properties that are necessary to support foundations, to diminish building and paving loads to softer soils below, to undergo acceptable settlement, to resist attracting capillary water to the underside of the floor slabs and paving, to stand at desired design slopes, to support slopes without blocking groundwater seepage, and to be workable when wet. Many combinations of grain sizes would be satisfactory as a structural fill soil, depending on the intended use of the fill, water content of the soil, and on weather conditions. Durino wet weather or anv wet conditions, soils with areater than 5% passing the no. 50 sieve will be difficult. if not impossible to compact: The recommended structural fill during wet conditions is composed of a well -graded granular soil with a gradation ranging from a fine sand (+50 sieve) to a coarse gravel. With the approval of HEMPHILL, the contractor can choose the structural fill from among those soils available from commercial suppliers, from offsite borrow pits, or from any existing site soils that are determined by HEMPHILL to be satisfactory for structural fill. CONTROL of COMPACTION of STRUCTURAL FILL LABORATORY PROCTOR TESTS A Modified Proctor Test (ASTM D-1557) is conducted on each different soil type to be used for filling to determine the required minimum density of the structural fill to achieve the desired properties, and the optimum water content that will best achieve that density. Project Number 2105 15 July, 1996 page 11 of 30 pages A Modified Proctor Test is conducted in the laboratory by conducting a series of compaction tests, each with a different water content. Each test is conducted by compacting a specific volume of the soil with precise compaction procedures with a controlled or measured water content. A curve is plotted comparing the density achieved for each water content of the soils during the test. The highest point on the curve shows the water content at which the achieved density of the soils is the greatest. The maximum density on the curve is called 100% of the Modified Proctor maximum density, and the water content that achieved that density is the optimum water content at which the soil compacts most easily. At that density the soils are considered to be capable of supporting their maximum loads with minimum compressing, or settlement. Silts and clays will allow the least water to seep through them, sands and gravels can stand at steeper slopes, and generally the desired properties are best achieved at higher densities. Sometimes the desired properties of a structural fill can be less than those achieved at 100% of the Modified Proctor, and the geotechnical engineer can specify a lower value, such as 90% or 95% of the maximum density achieved in the Modified Proctor test. The properties of the structural fill can either be determined by testing in the laboratory, or by comparing with known properties of a similar soil that have been determined by past testing by the geotechnical engineer, or are common values that have been published in engineering journals. The results of Modified Proctor tests are different with different soils. The geotechnical engineer must recognize soils that will have different properties when compacted, or he should conduct periodic classification tests to identify different soils. HEMPHILL should determine when a Proctor Test is required on a different soil. Project Number 2105 July, 1996 page 12 of 30 pages TESTING COARSE GRANULAR SOILS Soils that are coarse granular cannot be tested by the Modified Proctor Test because they shift around too easily when the compacting weight is dropped on them during the test. The weight hits one spot and the adjacent granular soils pop up, therefore no compaction is accomplished. A Relative Density Test is required for the coarse granular soils, which determines the minimum and maximum densities of the soil. The minimum weight is determined by placing the soils loosely into a known volume container and weighing. The maximum density is determined by placing the soil into the container, covering the container with a weight, and then vibrating until the soils have achieved their most compact condition. The relative density of a soil in its compacted field condition in the field is RD = [(max - field) _ (max - min)]. The relative density required to achieve the desired properties is specified by the geotechnical engineer. COMPACTION of STRUCTURAL FILL The procedures to achieve the proper density of a compacted structural fill are dependent on the size and type of compacting equipment, the number of passes to be made over the soils with the compactor, the thickness of the layer to be compacted, and some properties of the soils, including water content. The density of a soil can sometimes be increased by increasing or reducing the water content of the soil, and using the same compactive effort. Water reduces the friction between soil grains and helps the soils to slide into a more compact condition with the same compactive effort. • Project Number 2105 15 July, 1996 page 13 of 30 pages FIELD TESTING for DENSITY Field density tests are conducted by obtaining samples of the field compacted soils, measuring the volume of the sample by measuring the hole from which the sample was obtained, and then weighing the sample in its natural condition, and again after drying, to determine the dry unit weight and the water content. Field densities and water contents can also be determined by nuclear devices, but that equipment is only feasible on very large projects. HEMPHILL recommends that the loose soils be placed in layers that compact not thicker than 8 inches, and the soils. be compacted with several passes of a heavy vibrating type compactor. The soiis should not be too wet or too dry during the compaction process. OPTIONAL TESTING PROCEDURES If HEMPHILL determines that the laboratory and field testing required to control the compaction of the soils is not warranted at this site, then HEMPHILL should observe and approve the compaction procedures, and should verify that the soils have achieved the desired properties. The loose soils should be placed in layers that compact not thicker than 12 inches, and the soils should be compacted with several passes of a heavy vibrating type compactor. The soils should not be too wet or too dry during the compaction process. DENSITY REQUIREMENTS of STRUCTURAL FILL [All densities based on Modified Proctor maximum density (ASTM D-1557)] UNDER STRUCTURES Structural fill that will be located beneath the proposed structure, paving, or areas where settlement would be undesirable, should be compacted to a density equal to or greater than 95% for that particular soil. HrE2MIX (1;!Dm-. TTVI-Tr l Project Number 2105 15 July, 1996 page 14 of 30 pages UNDER FOOTINGS Structural fill to be used for bearing under spread footings should be compacted to a density equal to or greater than 95% to achieve a high bearing capacity soil that would have minimal settling characteristics under normal building loads and anticipated natural disasters. UNDER STEPS, PORCHES, WALKWAYS Structural fill that will be used to backfill foundation wall excavations that will support steps, walks, or driveway paving where settlement would be undesirable, should be compacted to a minimum density equal to or greater than 95%. WHERE SETTLEMENT is NOT CRITICAL Structural fill that will be placed outside the proposed structure, and that will not support loads, can be compacted to a density equal to or greater than 90% to minimize settlement and shifting, and to be fairly stable on slopes less than 1 vertical to 2 horizontal. FOOTING DESIGN RATIONALE for FOOTING DESIGN Footings are designed in a manner to limit any settlement that would distress the structure to a point that it is dangerous to its inhabitants, or is unsightly. How those limits are established is usually dependent on decisions by building departments, by the structural engineer, or by the attitude of the inhabitants. Settlement can occur by either of two ways; by shear failure of the soils when overloaded, and by compressing of the soils. As soils settle they densify and become stronger. If the soils settle uniformly throughout the building, then the settlement might not be noticed, since the structure will not be stressed, but utility connections outside the structure might be damaged, and those utilities that are dependent on gravity might reverse the direction of flow. MINIMUM FOOTING SIZE (feet) 0 m -o 03 m r-- O O O C z 0 c 77 -n D m CD m 0 .D --i co m r- O O O c z D cn C m 'n D C� m CD CD �J W r LEW MINIMUM FOOTING SIZE (feet) N ` :..... ::/...... 0 r O O cn m cn D z 0 m 0 c 0 m z cn m cn D z 0 G) C 70 m y ca m D z G) to Q. cn m r m m z r Project Number 2105 15 July, 1996 page 15 of 30 pages If the general area does not settle uniformly, then differential settlement of the building could cause damage to the structure. Some example tolerable differential settlements are shown in the following table. TOLERABLE DIFFERENTIAL SETTLEMENTS TYPE of STRUCTURE TOLERABLE QUALIFYING DIFFERENTIAL CONDITIONS SETTLEMENT (ft/ft) One or two story steel frame Presence of overhead crane, truss roof, warehouse with 0.006 to 0.008 utility lines, forklifts on flexible siding. warehouse floor, would limit tolerable settlement. One or two story houses Larger vaiue is tolerable if with plain brick bearing walls 0.002 to 0.003 significant portion of and light structural frame. settlement occurs before interior is finished. Structures with sensitive Larger value is tolerable if interior 0.001 to 0.002 significant portion of or exterior finish such as settlement occurs before plaster, ornament stone, or finish is complete. tile facing. Structures with insensitive Damage to structural frame interior or exterior finish such 0.002 to 0.003 might limit tolerable as dry wall, movable panels, settlements. lass panels. HEMPHILL assumes the proposed structure to be very flexible, and can tolerate very large differential settlement, but the tennis floors would have unacceptable differential cracks and sloping; therefore a tolerable differential settlement of 001 (1" per 78') would be acceptable. DESIGN and PLACEMENT of SPREAD FOOTINGS FOOTING SIZING The footing load, which is the load imparted to the footing from the column or wall, is generally established by the architect or the structural engineer. The footing size is determined by dividing the footing load by the allowable bearing pressure. The allowable bearing pressure is determined by dividing the ultimate bearing pressure by the safety factor. HEMPHILL determined that the allowable bearing pressure on the existing medium dense sand is 2000 psf based on Figure 7. Project Number 2105 15 July, 1996 page 16 of 30 pages Minimum allowable footing sizes are given in the UBC. That usually guarantees that a very small footing will not punch into the soil. The minimum footing widths from the UBC are 12" for 1 story, 15" for 2 stories, and 18" for 3 stories. (Don't look for any logical reasoning for anything in the UBC. They just give values with no explanations.) The actual estimated settlement is compared to the tolerable settlement after the footing has been sized and the depth below final grade is known. If the estimated settlement exceeds the tolerable then the footing size is increased until the settlement equals or - is less than the tolerable. Remember that settlement is not directly related to footing size or bearing pressure. The larger the footing the deeper the influence, and therefore the more soils subjected to settlement. CONTINUOUS FOOTINGS To determine the required width of continuous footings, divide the footing load per foot by the allowable soil pressure. The footing loads must be determined by the architect or the structural engineer. Then check to determine that any settlement at that bearing pressure, footing depth, and footing width is tolerable. CAUTION! Typically tilt up walls are placed with temporary shims that exert heavy concentrated loads. The extent of the concentrated loads depends on the size and weight of the wall, and the number of shims used. HEMPHILL recommends that sufficient shims be used to prevent temporary loads in excess of.6000 psf, and that packing be installed as soon as possible. If obvious settlement occurs, then each wall unit must be supported by a crane until the packing is installed. INDIVIDUAL FOOTINGS To determine the required area of an individual footing, divide the total footing load by the allowable bearing pressure. The dimensions of the footing can be any multiple that equals the required area, provided that the minimum dimension is no smaller than the minimum allowable by UBC. Then check settlement to be less than the tolerable, or enlarge the footing until the settlement is tolerable. FIGURE 8 PROCEDURE for OVER -EXCAVATING AND PREPARING a BASE COURSE for FOOTINGS If the allowable bearing soils are located deeper than the minimum depth required for stability or frost protection, and the contractor prefers not to place the footings on the deeper approved soils, then with the approval of the geotechnical engineer (HEMPHILL), the contractor can place the footings on structural fill by the following procedures: a. Excavate D below the proposed final grade as specified for stability, for bearing capacity, or for frost protection. b. HEMPHILL will determine the bearing capacity and potential compressibility of the soils. If the soils are not satisfactory then over -excavate d = B, or as directed by HEMPHILL c. Extend the width of the excavation a distance b = d/2 beyond all edges of the footing to allow the footing loads to dissipate through the structural fill, or if the soils along the sides of the excavation are very compressible and cannot support the column of structural fill, then HEMPHILL will require a higher b/d ratio. d. HEMPHILL should probe the bottom of the excavation to verify that the soils can support the dissipated footing loads. e. Bacicfill to the proposed elevation of the bottom of the footing with soils approved by HEMPHILL, and compact the backfill soils to a minimum density of 95% of the Modified Proctor maximum density in accordance with ASTM D 1557 to achieve a structural fill that is capable of supporting the direct footing loads. f. If the design loads are greater than the capacity of the structural fill, then HEMPHILL will recommend the required footing sizes to achieve the allowable bearing pressure. Project Number 2105 15 July, 1996 page 17 of 30 pages OVER -EXCAVATIONS to BEARING SOILS If the depth to allowable bearing soils is greater than anticipated, the contractor can choose to over -excavate to bearing soils approved by HEMPHILL, and then to backfill with structural fill or lean concrete to the desired grades of the bottoms of the footings. Any over -excavations of footings which will then be backfilled with structural fill should be excavated 1 foot wider than the footing for each 2 feet of over - excavation, as shown in Figure 8 on the opposite page. If allowable bearing soils are not encountered within a reasonable depth, then HEMPHILL can determine the bearing capacity of the encountered soils, and can determine the required thickness of structural fill under the footing to dissipate the footing pressure to the allowable bearing capacity of those soils, provided that the compressibility of those soils is acceptable. If the compressibility is unacceptable, and the depth of the excavation is exceeding the desirable, then another foundation type should be investigated. That should make everyone happy. MAXIMUM SPANS for SOFT SPOTS SPAN for CONTINUOUS FOOTINGS If the bearing soils exceed the minimum required, then HEMPHILL will allow continuous footings to span soft spots. The allowable span can be determined by calculating the necessary footing area to carry the extra pressure exerted on the soils on either side of the soft spot. If the required footing area is less than the design footing width, then the footing can span the soft spot, provided that the footing has the structural integrity to span that distance. Generally the structural engineer should give the allowable distance that a footing can span as a beam. If the soils cannot support the extra loads, or if the footing cannot span the soft spot, then the soft soils must be excavated and replaced with structural fill, or the footing can be stepped to the approved bearing soils. r ��� � Dlejejj - Projctct Number 2105 15 July, 1996 • page 18 of 30 pages SPAN FOR COLUMN FOOTINGS Generally the design of small individual column footings should not include allowances to span soft spots. If soft spots are anticipated on a project, then larger individual column footings can be designed to span soft spots equal to a third of the of the footing width. At the time of construction, if soft spots are encountered, and the good soils exceed the design bearing capacity, then the effective footing size can be adjusted an amount that is in direct proportion with any increased bearing capacity of the good soils, provided that no .eccentricity will be induced into the footings. If the good soils do not exceed the design bearing capacity, then no soft spots will be accepted. MINIMUM WIDTH of FOOTINGS Footings widths can be designed based on the allowable bearing capacity of the soils, with minimum width requirements of the UBC, or the local building code. The UBC minimum widths are based on the number of stories in a structure; 12" for 1 story, 15" for 2 stories, and 18" for 3 stories. MINIMUM DEPTH of FOOTINGS MINIMUM DEPTH for BEARING Footings can be placed directly on the undisturbed soils that have been approved for bearing by HEMPHILL, or they can be placed on structural fill soils that have been properly prepared and approved by HEMPHILL. Sandy soils increase in bearing capacity with confined depth. If additional bearing is required, then HEMPHILL can determine the allowable bearing increase due to depth at the time that the soils are exposed. Hr��.; rPrrl, L FIGURE 9 FOOTING DRAINS 6"min .Q A; r •q•. r GRAVEL COMPLETELY WRAPPED in FILTER FABRIC. PERF PIPE NOT NECESSARY Il NJ � in CASES of LOW SEEPAGE. 112" min TOP of SEEPAGE OUPERFORA••ED•.•I:: f-Krti E E�rLrnOi� •�:�':•1NITH • T T PIPE-.- ,�Cl�f�IL,LAfjY DRCl,I� ' :`�':`.INITFi••P for LIGHT FLOW ;;'::`:;:: FILL: :`f':..;`:` `::.`::. STRUCTURAL ... .. ..... is l•; •: ': � : •':' :••.. .. TYPICAL POOR PRACTICE of BEDDING PERFORATED PIPE i `f ; �t s r in GRAVEL. PERF PIPE SHOULD be PLACED 0 O_...: O DIRECTLY on FILTER FABRIC ' WATER BUILDS UP to LEVEL of WATER BACKS UP at SOLID PIPE PERFORATIONS BEFORE ENTERING PIPE, UNTIL it RISES and ENTERS the PERFORATIONS, THEN CAN SEEP UNDER FOOTINGS THEREFORE BED PERF PIPE at LEAST to CRAWL SPACE or UNDER FLOOR SLAB to DEPTH so PERFORATIONS are BELOW BASE of CRAWL SPACE and/or CAPILLARY BREAK. If PERF PIPE NOT USED, WATER ENTERS SOLID PIPE at BASE of PIPE. NOTES: 1. GRAVEL SHOULD be COMPLETELY PROTECTED by WRAPPING WITH FILTER FABRIC. GRAVEL is DRAINAGE SYSTEM, NOT PERF PIPE. PERF PIPE is NOT ALWAYS NECESSARY and SOMETIMES CREATES PROBLEMS by MISUSE. 2. BOTTOM of DRAINAGE SYSTEM SHOULD BE LOWER THAN BOTTOM of CAPILLARY BREAK. FATED. PIPE",-.*.-*.'..'-.-*.**.'.,:.-,.'.,-'-.. Y SLOPE PERF l and J SOLID PIPES 01 fUft i v IN w now u 9 9 9 w m IN w u m Project, Number 2105 July, 1996 page 19 of 30 pages MINIMUM DEPTH for FROST PROTECTION In the Puget Sound region frost seldom penetrates to depths in excess of 12 inches, and for an unusually cold spell frost might penetrate 18 inches. Footings to be adjacent to unheated areas should be placed a minimum of 18 inches below the final ground surface to protect against uplift due to frost expansion, or loss of bearing capacity due to softening from thawina conditions. DRAINAGE of FOOTINGS Figure 9 shows general drainage related to footings and floor slabs. Actual drainage requirements should be determined at the time of construction when all conditions are exposed and final elevations are obvious. SETTLEMENT ESTIMATIONS SETTLEMENT of EXISTING FILL SOILS The existing fill soils in their worst condition could settle as much as 1 inch under full design loads. HEMPHILL estimates that a full depth of loose to medium dense existing fill soils will settle less than inch. SETTLEMENT of STRUCTURAL FILL If the existing fill soils are replaced with properly compacted structural fill, the structural fill will not settle under the actual anticipated loads. The settlement of the existing fill soils will then be minimized based on the depth of structural fill, but probably less than %< inch. DIFFERENTIAL SETTLEMENT Differential settlement from building loads will be less than Y4 inch locally. Differential settlement over the length of the building could be inch. 'Project Number 2105 � 15 July, 1996 "Page 20 of 30 pages UNEXPECTED or UNUSUAL SETTLEMENT Any unusual or unexpected settlement will be the result of poor workmanship while preparing the bearing soils. EARTHQUAKE INCREASED LATERAL FORCES Lateral forces from earthquakes are created by the lateral vibrations created by the earthquake. Those lateral vibrations accelerate to a maximum velocity, and then decelerate to zero, then reverse and accelerate to the maximum velocity again. The acceleration and deceleration of the ground around the structure applies a force that drags the structure along with it. Since a force causes a mass to accelerate, that seismic force causes the structure to move laterally, which can damage the structure if the shaking exceeds the resisting strength of the building. The Puget Sound area has been listed by the map of seismic zones as Zone 3, which can have earthquakes with magnitudes of 7 or greater. The average seismic coefficient for a Zone 3 classification is 0.27. According to some.. publications, that number is low for poor soil conditions and high for good soil conditions. Some experts state that the seismic coefficients have no basis from experience, and therefore are arbitrary. HEMPHILL recommends a seismic coefficient of 0.2 (acceleration of 6.4 fps/sec) based on a publication by the University of Washington for the Edmonds vicinity with an intensity of VII occurring every 20 to 40 years. The source and accuracy of the recommendation is not known, but the values have been accepted as standards and are considered acceptable for engineering purposes. A higher value might be appropriate where damage might be life threatening, which is not the case at this site. HrE,�� ��HrIrL L Project Number 2105 15 July, 1996 page 21 of 30 pages The seismic coefficient is a mathematical convenience, which is the lateral acceleration of the soil mass compared to the vertical acceleration of gravity. The true acceleration used to calculate the lateral soil forces is 0.20 x 32 ft/sec/sec = 6.4 ft\sec\sec. The weight of the building can be converted to mass (slugs) by dividing by 32 acceleration of gravity), and then the soil mass can be multiplied by 6.4 to determine the lateral force, but it is mathematically convenient to just multiply the building weight by 0.20. SETTLEMENT from SEISMIC SHAKING Granular soils that are deposited in nature are generally loosely placed either by water or wind. Granular soils are sometimes loosely deposited by man in uncontrolled fills. Such loosely deposited soils have fairly large void spaces, sometimes called pore spaces. As more soils are deposited the loose soils will be pushed closer together until the soil grains contact each other, but not necessarily in the most compact condition. As the weight of overlying soils is increased, the contact force between soil grains increases, and the grains have more difficulty sliding past each other to become more dense. That resistance of the soil grains to sliding into a more dense condition is the frictional resistance of the soils. That frictional resistance is one of the conditions that gives soils their strength. to resist shear failures as heavy building loads are applied. The other condition that gives soils strength is cohesion, which is a sticky condition generally associated with clay and silt, and is nearly non-existent with coarse granular soils. Fine and medium granular soils are held together by dampness between the grains that bonds the grains like a 'weak glue'. That bond between the grains can be lost by drying the soils, or by saturating them. Project Number 2105 15 July, 1996 page 22 of 30 pages That condition is well known by children playing in a sand box, where dry sand cannot be formed or molded, damp sand can be molded, and a molded sand form can be destroyed by pouring water over it. That water 'glue' is called capillary tension, which can only exist in granular soils when they are damp, and cannot exist in dry or saturated granular soils. That capillary tension is also what holds together clay soils and makes them sticky. The smaller the soil grains, the greater effect that a water bond has between the grains. Unless an extremely heavy load is applied to the deeper granular soils, the intergranular friction, and sometimes the capillary tension if the soils are damp, prevents the soil grains from sliding into a more dense condition, and they remain relatively loose. If the soils are suddenly jarred by an earthquake, the friction forces will be temporarily reduced, and the soil grains can be forced into a more compact condition when the weight of the upper soils is reapplied. As the seismic vibrations cause reduction and reapplication of the friction forces, the volume of the existing voids will be reduced, and the soils will settle an amount equal to that reduction in voids. That sometimes causes a large area to settle an equal amount, and differential settlement can be minimal. Differential settlement of a structure can cause structural damage, and differential settlement outside the structure can cause external drainage and sewage lines to reverse flow, or can stress utility lines to the rupture point. LIQUEFACTION Another condition that occurs within loose granular soils during a seismic condition is called liquefaction. Liquefaction occurs two ways; by rising groundwater creating a 'quick' condition, and by trapped porewater reducing the strength of the soils. • FIGURE10 7 10 20 30 DEPTH (ft) 40 50 A 70 NOTES: LIQUEFACTION PROBABILITY I ASSUM ED WATcR TABLE { 0 10 20 30 40 50 60 STANDARD PENETRATION RESISTANCE (blows/ft) THE VALUES SHOWN IN THE CHART ARE CONDITIONS FOR WHICH LIQUEFACTION IS UNLIKELY TO OCCUR (AFTER SE.EED and IDRISS) THE REQUIRED GROUND ACCELERATION TO CAUSE LIQUEFACTION INCREASES WITH DENSITY, AND ALSO WITH DEPTH FOR THE SAME SOIL DENS1 i f, BECAUSE THE WEIGHT OF THE UPPER SOIL INCREASES THE STRESS BETWEEN THE SOIL GRAINS WHICH THEN INCREASES THE RESISTANCE TO MOVEMENT OF THE SOIL GRAINS INTO A MORE DENSE CONDITION. Project Number 2105 15 July, 1996 page 23 of 30 pages When granular soils that are below the groundwater level settle quickly during a seismic vibration, the groundwater that filled the void spaces of the loose granular soils is displaced and forced to rise. If the groundwater rises fast enough in more pervious soils, and can rise to the ground surface, then a 'quick' condition occurs. A quick condition is similar to the cause of quicksand, where the rising water moving past the soil grains reduces the frictional contact between the grains, and therefore causes a reduction of bearing capacity. The rising groundwater also saturates the previously damp granular soils and breaks the capillary tension bond. Therefore the soils have reduced load bearing capacity by losing frictional contact between the grains, and by losing the capillary tension bond. The 'quick' condition is also c-used by increased pore water pressures that prevent the soils from maintaining frictional contact. When the sand grains have reduced friction caused by a vibration, and attempt to move into a smaller space, they are resisted by the porewater that hasn't been able to seep out of the pores as fast as the soils are settling. The soils are then supported by the porewater which acts like small hydraulic systems. Of course, water has no strength to resist shearing, therefore the porewater and reduced soil friction combination will fail under the imposed loads of the upper soils and the structure. Granular soils that have a greater frictional resistance to sliding into a more compact condition, either from being more dense, or that have a greater overlying load that both increases friction and also resists the upward vibration movement of the soils to release the frictional contact, will have a greater resistance to settling and/or liquefying from seismic vibrations. Figure 10 is a graph that shows the probability of liquefaction based on the effect of seismic accelerations on saturated sands at various depths and with various densities. Assuming a density of medium dense", liquefaction could occur at the design acceleration of 0.20 x g in granular saturated soils. Project Number 2105 15 July, 1996 page 24 of 30 pages SEISMIC CONCLUSIONS HEMPHILL concludes that the entire site could settle from seismic vibrations on loose to medium dense sands, but because the conditions are similar throughout the area, any differential settlement will be minimal, and might not be obvious. If a significant earthquake should occur when groundwater is unusually high, then liquefaction could occur at the site. The effects of liquefaction are difficult to predict, but HEMPHILL suspects that any damage will be minor. CONCRETE FLOOR SLABS DESCRIPTION of CAPILLARY WATER If the underside of a concrete slab is in direct contact with groundwater, or is in direct contact with soils that are damp from capillary water, the concrete will also raise the water by capillary action. The water will not flow from the concrete, but will be held like a sponge holds water. The capillary water will evaporate as it contacts the air above the concrete slab. Generally, the vaporized capillary water is insignificant if the upper air can circulate through a heating or cooling system, or with open windows. As the capillary water evaporates at the top of the concrete, more capillary water will rise through the concrete to replace the evaporated water, therefore the flow of capillary water is a continuous process. If there is poor air circulation then the evaporated water will raise the humidity and create foul smells, and will create mildew on wall surfaces. When the humid air contacts an outside wall or window during cold periods, the humid air will condense, and if the condensed vapor contacts wooden structural members then they will begin to decay. The capillary water will also continue to rise if another material contacts the top of the slab, such as certain carpeting materials, cardboard boxes, wood, plasterboard, etc. The water will evaporate from that material, and then more capillary water will be attracted. The continuous dampness will create decay and mildew. Mrs-;- , : r14. �I'3rIrL L Project Number 2105 15 July, 1996 page 25 of 30 pages Any impervious materials such as rubber carpeting, plastic, etc will, stop the evaporation of the capillary water, but if cooler air exists above the impervious surface, such as from air conditioning, then the vaporized capillary water will then condense on the impervious material, and then free water will occur between the floor slab and the impervious material that could seep along the floor, and will then create a wet condition that can create decay, mildew, and bugs. PREPARATION of BASE COURSE for FLOOR SLAB Floor slabs can be placed directly over the undisturbed natural soils with the approval of HEMPHILL. Floor slabs can be placed over any structural fill that has been approved by HEMPHILL, that has been properly placed over undisturbed natural soils, and that has been compacted to a minimum density of 95% of the Modified Proctor maximum density ASTM D-1557). Since it has been determined that there is a source of moisture that could be conducted by capillary action to contact the underside of the floor slab, then the floor slab should be underlain by a capillary break to stop the capillary water. PROTECTION of FLOOR SLAB from CAPILLARY WATER A capillary break is a soil that will not conduct capillary water to ,the underside of the floor slab. The source of the capillary water could be either the groundwater table or exterior infiltration of rainfall or other water sources, such as sprinkling. Different soils have different maximum heights of capillary rise, therefore the effectiveness of a soil as a capillary break depends on the capillarity of the soil and the height from the water source to the floor slab. Project Number 2105 15 July, 1996 • page 26 of 30 pages HEMPHILL has determined that the existing soils are not an effective capillary break, therefore the floor slab should be underlain by a capillary break composed of a 4 inch layer of aggregate with a minimum size equal to approximately 1/4 inch. If the underlying soils are fine enough and become wet they might infiltrate the capillary break aggregate. If HEMPHILL determines that the underlying soils are too fine, then the capillary break aggregate can be underlain by a filter fabric or filter soil to prevent the integration of the underlying soils and the capillary break aggregates. The required. filter soil or material should be determined by HEMPHILL in accordance with the available materials at the time of construction. A plastic vapor barrier can be placed on top of the capillary break aggregate to prevent the condensation of vapor on the underside of the concrete floor slab. The plastic will also prevent the loss of water from the bottom of the slab during the curing process to minimize differential curing, provided that the loss of water is also prevented from the top of the slab. The lower the water/cement ratio of the floor slab concrete, and the longer the concrete is properly cured, the stronger the concrete will be, the more resistant the slab will be to moisture, and the concrete will be more resistant to cracking from both curing shrinkage and temperature changes. Also, a lower water/cement ratio gives the cement finishers less water to work to the surface, which then gives a more wear resistant surface, and allows less differential shrinkage between the top and bottom surfaces of the slab, and therefore less spider web cracks. Figure 11 shows an example of a capillary break, placed beneath a floor slab. FIGURE 11 DESIGN of CAPILLARY BREAK TO PROTECT CONCRETE SLABS FROM CAP I LLARY WATER 1 ' ► :. .: CONCRETE FLOOR SLAB PLASTIC VAPOR BARRIER - 4" CLEAN PEA GRAVEL (1/4- MIN) / FILTER SAND or FABRIC if REQ'D 7— FINE GRAINED CAPILLARY SOIL TOP of GROUNDWATER CAPILLARY WATER CAPILLARY BREAK can be COMPOSED of MANY MATERIALS, the REQUIRED THICKNESS DEPENDING on the HEIGHT of CAPILLARY RISE for the MATERIAL, as SHOWN in the CHART. GENERALLY the COST of TESTING the MATERIAL for HEIGHT of CAPILLARY RISE is NOT JUSTIFIED, and a MINIMUM THICKNESS of 4" of MINIMUM SIZE YA" GRAVEL is CHOSEN. HEIGHT Of CAPILLARY RISE FOR VARIOUS SOIL GRAIN SIZES u. S. STANDARO SIEVE SIZE ]- 1_7' 3/4- 7t2- N•, 4 10 20 JO 10 too 700 100 too V7 0) _ f0 U to L1J (n 20 Q r 10 Q 30 J 40 Q U 70 O 20 (�} t0 u 0 t!7 90 U t0 .-. 70 U) 60 Cc SO J �o a Q 10 U O 10 0 T 1000 too 10 1.0 0.1 0.01 0.001 CRAW SIZE I" u11.0-f*ERS Lt av Et i 1—D I LILT Ot CLAT CDt •L!1 .nt[ I NOTES: A. HEIGHT OF CAPILLARY RISE SHOWN IS TO TOP OF SATURATION; CAPILLARY WATER CONTINUES TO RISC AT LESS THAN SATURATION. B. "D10 SIZE" IS GRAIN SIZE OF SOIL `YHERE 10010 OF SOIL IS FINER. Project Number 2105 15 July, 1996 DRAINAGE of SLAB BASE COURSE page 27 of 30 pages Prior to the placement of the filter and/or capillary break aggregate, the natural soils or the structural fill should be sloped a minimum of 1" per 10', or a series of gravel filled trenches can be sloped a minimum of 1" per 10', to allow any trapped water that accumulates io flow out from under the floor slab. Trapped water is not capillary water. Capillary water will not flow out into the drainage system because it is held like a sponge. The trapped water is water that might leak from broken or leaky pipes, or might seep under footings from outside the building. If water fills the voids of the capillary break gravel, then the capillary break will no longer function, and water will be in contact with the underside of the concrete slab. To allow for the escape of any trapped water, the drainage can be openings in the foundation walls that are then connected to an outside drain. The type and number of drains can be determined at the time of construction. DRAINAGE SITE SURFACE DRAINAGE The outside ground surfaces should be graded to conduct surface stormwater away from the building. The water can then enter catch basins, or it can be conducted away from the site in swales. Roof runoff can be conducted to the same system as the catch basins, but should not enter the swale system unless approved by the City of Edmonds. Adjacent paving drainage should not enter the roof system drainage unless an oil/silt separator is included. The adjacent paving can enter the swale system if designed as a biofiltration system with the approval of the City of Edmonds. r Project Number 2105 15 July. 1996 page 28 of 30 pages SITE SUBSURFACE DRAINAGE Most water that infiltrates into the ground will probably seep to the level of the groundwater at 8 feet unless there are less pervious layers that were not encountered in the test pits. If higher water does exist then footing drains can be constructed to intercept water before it seeps under the building Any footing drains should be below the level of the interior floor slab drainage. Any water intercepted by footing drains should be conducted from the site and should not be connected to a storm drainage system, except at a catch basin that has an open grate below the level of the focting drains. The capillary break system under the floor slab can be connected to the footing drain system, assuming that the footing drain system is at a lower level. T�4a T717Q\/rdT-7�4�41T�4J TJ Project Number 2105 15 July, 1996 page 29 of 30 pages FUTURE STUDIES and RECOMMENDATIONS DESIGN REVIEW HEMPHILL has reviewed the final plans and specifications and determined that they are reasonably in accordance with the recommendations presented in the geotechnical report, assuming that HEMPHILL will conduct the recommended geotechnical inspections, and will present any necessary adjustments resulting from differences between presumed site conditions and actual site conditions, along with some options by the contractor, in accordance with actual conditions encountered at the time of construction. HEMPHILL concludes that if the proposed new tennis courts building is constructed in accordance with the plans, and with any recommendations by HEMPHILL at the time of construction, and with the approval of the following inspections, then there should be no risk of damage to the proposed building and/or the adjacent properties. CONSTRUCTION INSPECTIONS and VERIFICATIONS 1. HEMPHILL should inspect the soils that are exposed during excavating for foundations to verify that the allowable bearing soils have been encountered, and that there are no unexpected conditions that would require changes in foundation design. 2. HEMPHILL should inspect, and if necessary conduct tests, to determine that any structural fill is composed of the proper soils, and that the required density has been achieved by the compaction process. 3. HEMPHILL should inspect the excavations to verify any suspected groundwater conditions, or to determine any unexpected groundwater conditions, or to determine any design changes. 4. HEMPHILL should determine that any perforated drain pipes are placed at the proper locations to achieve the required drainage, and that the intercepted groundwater is properly conducted from the site. P_Trv-4M , , ri;9)WM1rITI, Project Number 2105 15 July, 1996 page 30 of 30 pages 5. HEMPHILL should inspect all surface runoff drainage systems to determine that surface water is properly intercepted and conducted from the site, and that the runoff systems are not improperly tied to the subsurface system to cause the runoff system to back up into the subsurface system. 6. HEMPHILL should determine that any drainage backfill has the required permeability, and that properly designed and installed filters will protect the drainage system from clogging by fine grained soils that could be eroded into the drainage system by groundwater seepage. 7. HEMPHILL should determine that the concrete floor slabs are underlain by a proper base course and/or capillary break and drainage to protect against capillary or free water creating dampness or wet conditions. Dale C. Hemphill P.E. Registered Engineer No. 14777 State of Washington o WAS/i q�y 0 r yam o Fcrs�ti° �SI�NAL�'ti EXPIRES 17 FEBRUARY IM 7-rf-FI' ; .? M- Mh Zi ot'. .. .. .-.li ^r,.. ... ...•'i- .w. t,. " w.._. r,r .y: �...F_A•r"'.. i.,,.W >-.v� ••'r""jtivll t-•.i 't"r�.,�.,ar-.�,:t .�'CS-rir•.-,..r . •.�rrS.�].'y1 :4[f lam,!''. �. .•i: �v �_ CITY OF.EDMONDS tSIDE SEWER PERMIT 1890 199° PERMIT 3865 Address of Construction: Property Legal Description (Include all easements): Owner and/or Contractor: State License No. ❑ Single Family ❑ Multi -Family (No. of Units ) Commercial ❑ Public ,E© TREATMENT, PLANT �t t�Llc WORKS DEPi Building Permit No Invasion into City Right -of -Way: K No ❑ Yes RW Construction Permit No. Cross other Private Property: W No ❑ Yes Attach legal description and copy of recorded easement I certify tKat I have read and shall comply with all city requirements as indicAted on the back of the Permit Card. 6143 J Da * CALL DIAL -A -DIG (1-800-424-5555) BEFORE ANY EXCAVATION OFFICE USE ONLY * FOR INSPECTION CALL ".- 4-& , PUBLIC WORKS DEPT. // `77/-oa„3S Permit Fee: (70 • L-Z Issued By Trunk Charge: ' 0 0 Date Issued: Assessment Fee: / Receipt No.: Lid No.: ! 07 Partial Inspection: Date Initial Comments Reason Rejected: Date Initial Final Inspection Approved: Date -W Initial - ** PERMIT MUST BE POSTED ON JOB SITE ** White Copy: File Green Copy: Inspector • Buff Copy: Applicant Revised 3190 Side Sewer Drawing % I The City of Edmonds EASEMENT NO. ........................ ...... ............. NEW CONSTRUCTION REPAIRS F-1 LID NO . ................... ASMT. NO . ................ OWNER......................................................................... ...................... CONTRACTOR ........................................................................ ........... PERMIT NO.6934-t—'7), JOB ADDRESS 15 ..... 4 ----------- V --- d-,.7DA- ........................ LEGAL DESCRIPTION: LOT NO . ...................................... BLOCK NO. .................................... PWW-0001-1 1175 (REV.1 1/78) NAME OF ADDITION. t 3, M/fit} o _.. r Approved: DATE .77�73..-..ff ......... � U' MONDS T,-,,iYTMENT PLANT Be... ......... ----------------------------------------- CA Iwo CrOcal Areas Checklist 3 y .!' ` .FILE Site Information (soils/to o ra h /h drolo /v etation) STREET 1. Site dyes Alhon: 160 W. Dayton �° s c� 4 d� 0D 2. M`dx Nbt Number: •- -" � 3 3. Approximate Site Size (acres or square feet): 28,000 s f 4. Is this site currently developed? yes; x no. JUN:7 - 1 96 If yes; how is site developed? PERMIT".C®UNTER 5. Describe the general site topography. Check all that apply. x , Flat: less than 5-feet elevation change over entire site. - Rolling: slopes on site generally less than 15% (a vertical rise of 10-feet over a horizontal distance of 66-feet). Hilly: slopes present on site of more than 15% and less than 30% ( a vertical rise of 10-feet over a horizontal distance of 33 to 66-feet). Steep: grades of greater than 30% present on site (a vertical rise of 10-feet over a horizontal distance of less than 33-feet). Other (please describe): 6. Site contains areas of year-round standing water: no ; Approx. Depth: 7. Site contains areas of seasonal standing water: no ; Approx. Depth: What season(s) of the year? 8. Site is in the floodway n n floodplain of a water course. 9. Site contains a creek or an area where water flows across the grounds surface? Flows are year- round? no Flows are seasonal? (What time of year? ). 10. Site is primarily: forested ;meadow _;shrubs ;mixed ; urban landscaped (lawn,shrubs etc) Grass 11. Obvious wetland is present on site: no For city Staff Use only . >l. Site is Zoned?f— mapped soil type(s)? # 7 & �y /�A�/ Z,&O ) 1 3.. Wetland inventory or C.A. map indicates wetland present on site? �s5 4:.. Critical Areas inventory or C.A. map indicates Critical Area on site? )If--5 5 Site within designated earth subsidence landslide hazard area? O 6. Site designated on the Environmentally Sensitive Areas Map? 4- DETERMINAT STUDY REQUIRED CONDITIONAL WAIVER WAIVER `J Reviewed by: !1-z-! er Da rcv 01/0"a r4" NRTe . RECEIVED 6190 -199- City of Edmonds Critical Areas- -Checklist The Critical Areas Checklist contained on . this form is to be filled out by any person preparing a Development Permit Application for the City of Edmonds prior to his/her submittal of a development permit to the City. The purpose of the Checklist is to enable City staff to determine whether any potential Critical Areas are or may be present on the subject property. The information needed to complete the - Checklist should be easily available from .- observations of the site or data available at City Hall (Critical Areas inventories, maps, or soil surveys). An applicant, or his/her representative, must fill out the checklist, sign and date it, and submit it to the City. The City will revieww the checklist, make a precursory site visit; and make a determination of the subsequent steps necessary to complete a development permit application. W'ith a signed copy of this form, the applicant should also submit a vicinity map or plot plan for individual lots of the parcel with enough detail that City staff can find and identify the subject parcel(s).., In addition, the applicant shall include other,pertinent information (e.g. site` Plan, topography map, etc -) -or studies in conjunction with this Checklist to assist . . staff in completing their preliminary assessment of the site. I have completed the attached Critical Area Checklist and attest that the answers provided are factual, to the best of my knowledge (fill out the appropriate column below). Owner / Applicant: Name Street Address City, State, ZIP Phone Signature Date Applicant Representative: WARREN LAFON • .. ARCHITECT Name 123 4th Ave. N. Street Address Edmonds, WA 774-0580 Cityfate, ZIP Phone 8-16-95 Signature Date t , . � F • of City of Edmonds Critical Areas Determination Applicant: Warren LaFon Determination #: CA-95-179 Project Name: Permit Number: Site Location: 160 West Dayton Street Property Tax Acct #: 2327-034-088-00 Project Description: non -project specific A site inspection of the property has revealed a flat lot developed with a several multiple story office buildings, a hotel and an athletic club. A large area with standing water and wetland plants was observed directly to the south of the subject property. Research of records in the City of Edmonds Offices revealed that the area to the south of the subject property has been identified as a class 1 saltwater marsh. Based on the above findings, it is determined that there is a wetland critical area adjacent to the site. A Critical Areas Study is required to delineate the boundaries of this potential critical area, the buffers and setbacks. A wetland biologist must locate the wetland and identify the classification of the wetland, then a licensed land surveyor must create a map of the site which indicates the wetland location and the buffer location. The critical area study must be created through a three party contract between the applicant, the City and the consultant(s). If the property owner wishes to apply for a specific development permit which they feel would not impact the Critical Areas located on the site, they may submit their proposal to the Planning Department for review. If the Planning Department finds that the proposed development permit will not adversely impact a Critical Areas or its buffers, a conditional waiver may be issued on a project by project basis. John Bissell September 25, 1995 Name Signature Date • • FA gild au �N i i / i i jig f I i I I I i i i i i i .1 .1 1 .1 .1 .1 .1 1 .1 1� '13 -r _._.J. a a aria V� I o >r W �q V,`t- tEA� X m "W r< is ie�w Darn FMdm yaw �� A -I .nn. HARBOR SQUARE ATHLETIC CLUB arve wnnw. A A O A I T• O T W ILRAY= A ra.�.ar.. �. i.rn.� mgpR f a OR[IR e �a a bw as w� s CITY OF EDMONDS CONSTRUCTION PERMIT APPLICATION _TT )ELEF.Ort rUY9EP L.I r—DMOM.D.5 7ifS'3} AL Z AvE. / . .. ,tLEP„oNE NUMOER ,A.,E VlGCD 5 2cJC•rlal 1, t1I• 1ELEv„ONE NUMBtR EDMdA(DS i7 — 41L5 7­­L1^:vt'NII•ui Gn L. FAIIONDATE I iLGac ¢ i11^' QO 1. - - Do IsG PERMIT 970447 NUMBER ✓ V`�`1 ♦pp RESS i 11 I! Ii- / ILI +/-r Al`. . '.CCPL DLSCI„S'-0'1 C�tC•I,uE:'I..:.. :. .0 .v' U� PUBLIC 116"r/o �A FEn OE rILIPL SiFCEC C+IST,vG �;%IU,. nECUIR[C o[Drf,P•IOr__, rESCv Aoe•o,ea ❑ S:,rrl Urr v.y.,nPmO ❑ p ecG� t o ll i s y��u 00 I%sk d ENwuecnwe GMf UAlep ev¢v:m l,• SIGN AREA ALLOWED vnoeOSED SEnA nE1111 CO7LETE E.EMvt h�/' E,P All NO r ; s.oucL,,.te ARIANC OR CU lA INf. nEvlEw Br 7 ! A}E SETOACKS-FEf.T EIGNT LOT COVERAGE PEMAPI•. 9S- '7 /.�/✓ u�iti fb,�d . -` oo:'Poste CHECKED BY IYFE OF CONSi ugilON CODE -�✓ REEK] lI„SIECrOR REEK] •�EivAT p tS OCCUSP+ PEMARKS PROGRESS INSPECTIONS PER UBC 305 Tzu� ti�bY'C' 9X6 c, A6 e��tL act 6 a e Aletdll ill PE FINAL INSPECTION REOUIRED r 15 O H� z C St?2T UC l7/ES FLAN CHECK FEE BUILDING %3 7Z /SO 30Z0 un �� % �7 FLDMeIND �J�yg7� Ourr Plan Check No. - ' i MECHANICAL SEgq j� */M 1h15 Permit covers work to be done on private property ONLY. GRADINWFILL (, t•.`;E�'sy' i Any construction on the public domain (CUECS, sidewFlks. Cr.v av5, male ee5. Pt C.) wit[ require separate permission. STATE SURC„ARGE 5 4. $Q r O Permit Application: 1BE Days Permit Limit: 1 Year • Provided Work 1, Started Within 130 Day, Aoo( Cant. on behall of his or her Spouse. heirs, assign5 and N SUCL 50'S In interest, agrees to indemnify, defend and hold harn+less !he GIy of Edmonds. Washington, rt9 OIhU01 s, STORY DRAINAGE FEE ENG. INSPECTION FEE .. .. .. y rL P R ;4 j ? employees. and agents from any and all Claims for damages of xhatever nature. arising directly or indirectly from the issuance O! Vus permit. Issuance of this permit shall not be deemed to moody. waive or reduce any requirement of any city ordinance - nor Ilmd in any way the Cily's ability to enforce any ordinance PUN CHECK DEIIEI TOTAL AhIOUNT DUE p, tNt g C07 rSQ 3 IO pravlslon."' 1. APPLICATION APPROVAL This application is not a permit until signed by the Building Otticlal or his/her Deputy; and fees are paid. and receipt is acknowledged in space provided. I hereby acknowledge that I have read this application; that the ATTENTION mfgrmalion given Is correct; and that I am the owner• or the duly O O aulhoC cd agent of the owner. I agree to comply with City and r S Ac.." state laws regulating construction: and in Coing the work aufhoriz• AUT.oncEs ed iherebv. no person will be employed In violation of the Labor oNLr r.E Code of the State of Wasni elating to Workmen's Compensa• WOR, NOTElI Ilon Incur nee and RC`. 8,:1. IVSFECTIpv - r•'E sG,•tD / l0' �' g� of SPEC YCVC CI7Y OF EDMONDS OF LS S' .1EE OPi ATTENTION CALL FOR 66 INSPECTION EL A f IT IS UNLAWFUL TO USE OR O Y A BULD IING OR STRUCTURE UNTIL A FINAL INSPECTION HAS BEEN MADE AND APPROVAL OR A CERTIFICATE OF OCCUPANCY HAS BEEN GRANTED, UBC ��� _Owwo 1` VIGINAL — F,Ie YELL W — Inspector C H APTEP 7. PINK — O'A GOLD — Asses­ E %� lo: er —' O 7 7873 t r. 0. o �•.x.=:. ri: 0 RECORD OF INSPECTIONS iN:PECTOR DATE APPROVED SETBACKS ...... FOUNDATION: Footina ........ ..... . Wall ....................... Pier/Porch ... — ........... Rpiaininq Wall.. . ....... — Slab Insulation............ PLUMBING: Underground ...... Rough -In ......... Cornrne,;al Final .... ... HEATING: 000do Gas Test .............. Gas Piping ........ Equipment.... Commercial Final .... EXTERIORSHEATHING NAILING .............. FRAMING . ............. INSULATION: Fo.rInawation .......... Wall lnsulalion ........... SHEETROCK NAILING...... SPECIAL INSPECTION...... RADON MONITOR AT SITE. FINAL APPROVAL FOR OCCUPANCY.... 1 0 STREET FILE MEMORANDUM Date: May 24, 1999 To: File From: FM Westfall Subject: Rea Auction: Public Amusement License Review: 154 W. Dayton St. Harbor Square Athletic Club Mr. Jack Tawney made application for Special Event Application and Public Amusement License on May 17. The event is a charity auction in an approximately 19,000 square feet, type III-1 HR concrete tilt -up building with A3 occupancy. The building is an indoor tennis facility housing three tennis courts. Both Building Department and developer agreed to occupant load limitation of 24 persons. The building is not smoke- or fire -detected and has no fire protection system. I conducted a field inspection of occupancy on May 14. The courts are surrounded with a 8' durable opaque fabric which deadens the deflection of tennis balls. Nets separate the tennis courts. Illuminated emergency lighting and exits are provided, installed above the curtains. Exits to the East provide direct exterior access. NW exit access passes through smoke -detector protected lobby. There are no apparent barrier -free accommodations in the tennis area. Proposed plan is not drawn to scale. Applicant proposes to serve alcohol. Proposed are 24 tables seating 8 persons each (=192), with non -fixed seating in approximately the two courts to the South (12,000 sq. ft.), and accessory use of four rows of silent auction tables with items in approximately the northernmost court (6,000 sq. ft.). The Uniform Building Code (UBC) allows up to 299 for A3 occupancy. The assembly area is calculated for occupant load by a factor of 7 for "assembly: more concentrated use" , per UBC Table 10-A (12,000/7=1714), which is adequate for the proposed occupant load of 200. Required exit width is met for A3 (299 x .2=59.8"). The silent auction accessory area is calculated for occupant load by a factor of 30 for a like use of "stores/retail", per UBC Table 10-A (6,000/30=200), which meets the proposed occupant load of 200. Required exit width is met for A3 (200 x .2=40"). Adequate exits and exit widths are provided, however, I remain concerned regarding the sprinkler requirement for "drinking establishments" greater than 5,000 square feet. Recent construction projects for assembly use "for lease" with incidental alcohol service (in a strict sense) have not been required to be sprinklered. Those occupancies have been typically provided with smoke- and fire -detection as a result of the assembly type occupancy intended. I approve the Public Amusement License for "A Rea of Hope" with the following conditions: City of Edmonds Sb Fire Marshal 1. Occupant load is 200 maximum. 2. Remove curtains obstructing four exits (NW, NE, E & SE) to accommodate temporary increased occupant load. 3. Remove all netting between courts which are obstructing access to exits. 4. Maintain 44" aisles between chairs in seating area, between tables in silent auction areas, and around the perimeter of occupancy. 5. Hours of operation are limited to June 5, 1999 between 6 p.m. and 11:00 p.m. as proposed. 6. Alcohol may be served with respect to existing State and Federal standards, limitations, and guidelines. 7. Provide fire watch as an alternative to a smoke- or fire -detection system. Fire watch will be an uniformed firefighter with the Edmonds Fire Department equipped with a portable radio.. Fire watch will assure that occupant load is maintained; that aisles, exits, and exit access remains free and unobstructed; and that any emergency conditions will be immediately reported for dispatch of nearest available emergency vehicle and crew. The cost incurred for professional firefighter is $40 per hour, which includes employee benefits. PERMIT APPLICATION REQUIREMENTS To: Applicant From: Lyle Chrisman, Engineering liupector owner: H S Oymt f- Address: 15. 4 (D GM tN W STREET FILE Plan Check No: 9 6 - I 1 ? Date: ? Lo y 6 After review of the subject permit application, the following requirements must be met: 1. Construction hours are: WEEKDAYS — 7:00 A.M. ;10:0o PALWEEKENDSIHOLIDAYS —10:00 A.M.-6:00 P.M. Z. A separate RIGHT-OF-WAY CONSTRUCTION PERMIT is required for all work on public property. (ECDC 1&60) 3. Truck haul route plan must be submitted and approved prior to permit' t. Builder/owner is responsible for containing all temporary nmoff and erosion control on site. (ECDC 1830.030d) i. NO WORK SHALL BE DONE WITHIN IS FEET OF STREAMS OR 10 FEET FROM ANY CLOSED DRAINAGE FACHMy- BUILDERIOWNER IS RESPONSIBLE FOR IDENTIFYING CONDITIONS ON THE DRAWING. (ECDC 1830.SOG) i. FILTER FABRIC FENCE SHALL BE INSTALLED AND INSPECTED PRIOR TO CLEARING AND CONSTRUCTION (ECDC 1&30) '• INSPECTIONS ARE REQUIRED ON STORM DRAINAGE SYST INSTALLATION. INSPBCTIONS ARE �� TIG1iTLINES AND CATCH BASIN REQUIRED PRIORTO BACKFIIddNG. (ECDC 1830) Repair or replace aU defective existing auk gutter and sideway adjacent to the property. Van Intersection is involved. a handicap ramp may be 1&required. Contractor shalt meet with the City Engineering stagto determine the extant of repair prior to Issuance of the permit. QXDC DrivcM slope shall not exceed 14% without a waives. Every attempt should be made to keep the slope below 14%. Waiver, granted to (ECDC 1&80.060D) . 0. Driveways must be paved from propertyy line to City RIGHT-OF-WAY. A separate permit is required. (ECDC 18.8o o6oG) 1. INSPECTIONS ARE �• REQUIRED ON DRIVEWAYS AND SIDEWALKS PRIOR TO AND AFTER POURING. (ECDC 1&30) 2. No burning of construction refuse without a permit from die Fire Department. 3. Connection to City water system Is required. Thew Is a separate age for the water meta. (ECDC 7.20) 4. A back water valve is required if downstairs plumbing is below the elevation of tcpstream manhole.. (ECDC 7.20) S. Water and sewer main lines should be separated by 10 feet m (ECDC 1&10) 6. connection to the City sanitary system is required, A b 1s � ._ Far paid: Yeses_ = giarge O OWDC may 1. Undaground wiring is required ou all new. and for additions. alte adons, and repairs that exceed S034 of the total assessed value of the struc wm (ECDC 18,gp) S. A FINAL ENGINEERING VISPEMON IS REQUIRED PRIOR TO TSE BUILDING DIirLSTON GRANTING OCCUPANCY OF THE BUILDING OR STRUCTURE. (ECDC lg 90) o • FOUNDATIO14 ENGINEERING • EARTHWORK ENGINEERING • GROUNDWATER STUDIES • SLOPE STABILITY STUDIES • ROCKERY DESIGN • J- • SUBSURFACE EXPLORATIONS • CONSTRUCTION INSPECTIONS • DRAINAGE STUDIES • LANDSLIDE INVESTIGATIONS • RETAINING WALL DESIGN • -J • SOIL TESTING - LAB d FIELD • WATER RETENTION STUDIES • SITE EVALUATIONS • DAMAGE INVESTIGATIONS • STORMWATER STUDIES • to y T � �- - co y O I 0<0 - -- —I cn rn zL--1. cn , 0 cn L —C 1 0) C Z r— o -- O a: 0 1 4�� uT c- -i - cn D c) m D Z G) L tjj�� co rn rn to > O rn m � C � (� z i t'•'� Z m Cl) m rn m VV -03 77� t-lL n Z r IJ cif? ra - o cr) co r n Y TABLE of CONTENTS INTRODUCTION page AUTHORIZATION for GEOTECHNICAL ENGINEERING . . . . 1 DESCRIPTION of PROJECT . . . . . . . . . . . . . 1 LIMITATIONS of INVESTIGATION and REPORT . . . . . . 1 SITE INVESTIGATION EXISTING SURFACE DESCRIPTION . . . . . . . . . . 3 SUBSURFACE INVESTIGATION . . . . . . . . . . . . 3 RATIONALE for INVESTIGATION . . . . . . . . . . 3 METHODS of INVESTIGATION . . . . . . . . . . . 4 VISUAL OBSERVATIONS . . . . . . . . . . . . 4 FIELD TESTS . . . . . . . . . . . . . . . . . 5 GROUNDWATER OBSERVATIONS . . . . . . . . . 5 SITE STABILITY INVESTIGATION. . . . . . . . . . 5 DESCRIPTION of EXISTING SITE SOILS . . . . . . . 5 HOW PHYSICAL PROPERTIES of SOILS DETERMINED . 5 SUBSURFACE CONCLUSIONS . . . . . . . . . . . . 6 ENGINEERING STUDIES and RECOMMENDATIONS RATIONALE for RECOMMENDATIONS . . . . . . . SITE PREPARATION. CLEARING and STRIPPING . . . . . . . . . . PROOF ROLLING . . . . . . . . . . . . . PLACEMENT of WORKING SURFACE . . . . . . GENERAL SITE EXCAVATING . . . . . . . . . . GENERAL SITE FILLING . . . . . . . . . . . . DESCRIPTION of FILLING . . . . . . . . . . DESCRIPTION of STRUCTURAL FILL DENSITY REQUIREMENTS of STRUCTURAL FILL. CONTROL of COMPACTION of STRUCTURAL FILL FOOTING DESIGN . . . APPROVED BEARING SOILS . . . . . . . . . ALLOWABLE BEARING CAPACITIES . . . . . . BEARING CAPACITY of UNDISTURBED SOILS . . . BEARING CAPACITY of STRUCTURAL FILL . . . . FOOTING SIZES . . . . . . . . . . . . . . MAXIMUM SPAN for SOFT SPOTS . . . . . . . SPAN for CONTINUOUS FOOTINGS . . . . . . SPAN for COLUMN FOOTINGS. . . . . . . . MINIMUM WIDTH of FOOTINGS . . . . . . . . MINIMUM DEPTH of FOOTINGS . . . . . . . . MINIMUM DEPTH for BEARING. . . . . . . . MINIMUM DEPTH for FROST PROTECTION . . . DRAINAGE of FOOTINGS ... . . . . . . . . . . 7 8 8 8 9 9 9 10 10 13 13 14 15 15 16 16 16 17 17 18 18 18 18 19 19 page SETTLEMENT ESTIMATIONS . . . . . . . . . . . . . 19 SETTLEMENT of UNDISTURBED SOILS . . . . . . . 19 SETTLEMENT of STRUCTURAL FILL . . . . . . . . 19 DIFFERENTIAL SETTLEMENT . . . . . . . . . . . 19 UNEXPECTED or UNUSUAL SETTLEMENT . . . . . . 20 EARTHQUAKE . . . . . . . . . . . . . . . . . . 20 LATERAL FORCES .. . . . . . . . . . . . . . 20 SETTLEMENT . . . . . . . . . . . . . . . . 20 LIQUEFACTION . . . . . . . . . . . . . . . . 20 CONCRETE FLOOR SLABS . . . . . . . . . . . . . 24 DESCRIPTION of CAPILLARY WATER. . . . . . . . 24 PROTECTION of FLOOR SLAB from CAPILLARY WATER . 25 DRAINAGE of SLAB BASE COURSE . . . . . . . . 26 DRAINAGE . . . . . . . . . . . . . . . . . . . 27 SITE SURFACE DRAINAGE . . . . . . . . . . . . 27 SITE SUB SURFACE DRAINAGE . . . . . . . . . . 28 FUTURE STUDIES and RECOMMENDATIONS DESIGN REVIEW . . . . . . . . . . . . . . . . . 29 CONSTRUCTION INSPECTIONS and VERIFICATIONS . . . . 29 LIST of FIGURES FIGURE TITLE or DESCRIPTION PAGE 1 LOCATION of PROJECT . . . . . . . . 1 2 PLAN of SITE . . . . . . . . . . . . 2 3 PLAN of PROJECT . . . . . . . . . . 3 4 GEOLOGY of SITE . . . . . . . . . . 4 5 TEST PIT LOGS . . . . . . . . . . . 5 6 WORKING SURFACE . . . . . . . . . 9 7 BEARING and SETTLEMENT . . . . . . 15 8 OVER -EXCAVATING FOOTINGS . . . . . 17 9 DRAINAGE . . . . . . . . . . . 19 10 LIQUEFACTION . . . . . . . . . . . 23 11 CAPILLARY BREAK . . . . . . . . . 27 IE o X 4? -ZZ/ BLAK: 7 7-- .- S-- CHERRi A? W, LN BR66KMERE -F-. r BE:_ STI 'ST Tr-T CEDIL- Lw L PT PC I lfr ,, 0 0 Project Number 2105 15 July, 1996 page 1 of 30 pages INTRODUCTION AUTHORIZATION for GEOTECHNICAL ENGINEERING On 15 May 1996 WARREN LAFON ARCHITECT, agent for Jack Tawney, owner, authorized HEMPHILL CONSULTING ENGINEERS (HEMPHILL) to conduct geotechnical engineering for the proposed New Tennis Courts for the Harbor Square Athletic Club (PROJECT) to be located at 160 Dayton Street, Edmonds, Washington (SITE) as shown approximately in Figure 1. LIMITATIONS of INVESTIGATION & REPORT This geotechnical report is inten�ed only for the use of the CLIENT as an aid to design and construct the specific structure, and in the specific location, as described in this report. This report may not be used by any other person or firm, or for any other structure, or for any other location on the described property. The recommendations presented in this report are based on the requirement that the presumed subsurface conditions, and the presumptive soil properties, will be verified by HEMPHILL after the true nature of all the soils and the groundwater have been revealed during the excavating process. DESCRIPTION of PROJECT The proposed project will be located adjacent to the existing tennis center as shown in Figure 2 on the next page. The project will be constructed with reinforced concrete tilt up walls supported by shallow continuous and column spread footings. The tilt up walls will support a wood frame roof that will cover 3 tennis courts and offices over a concrete slab floor system. a. r ' , r'r FIGURE Z PLAN of SITE - • Project Number 2105 15 July, 1996 page 2 of 30 pages FIGURE 3 PLAN OF PROJECT C bi C�­ 0 HIE-JIMINVEY-11 HiMIL i 0 Project Number 2105 15 July, 1996 10page 3 of 30 pages SITE INVESTIGATION EXISTING SURFACE DESCRIPTION The existing ground surface is flat with a 2 to 3 foot mound at the rear (south) of the property. The ground surface is gravely sand with sparse vegetation. SUBSURFACE INVESTIGATION RATIONALE for SUBSURFACE INVESTIGATION The request by the CLIENT for HEMPHILL CONSULTING ENGINEERS to conduct geotechnical engineering obligates HEMPHILL to investigate and make recommendations concerning all phases of.design and construction that would be affected by soils and foundations, including groundwater and drainage. The extent of the subsurface investigation was based on the cost limitations recommended by HEMPHILL, and approved by the CLIENT, with the requirement that the presumed subsurface conditions would be verified by HEMPHILL after all the true subsurface conditions have been revealed by the excavations, and that any necessary adjustments in foundation design and/or depth of footing placement for bearing and stability will be determined by HEMPHILL at that time. There have been several similar projects constructed in the general vicinity of this proposed project. The subsurface investigations for those projects have revealed conditions similar to the conditions at this site. Therefore, the subsurface investigations, the foundation treatments, and the results of those other projects have been studied in conjunction with this project. rJJ1� �p rlr%L r�•I n► a �:'• __- T - i !O y �i �l-r_r; �.�1:::.—���j � / — _ .ny �-;�' 4�t ;�' f � ,fit; ••<. ,• i > , i E91s f ran - it- -x- _ II _ ` i �' ` III I � I �r. .'' � �� `•. `� .. -1 •lr emu. �� � ;. - 1�y.•..` . � ...✓ • tl+......_ •. .,� F__ _ \ _ �i {- I' I I ` •�� i I`!i 1a'• `�rrf-" cr" .�) 1L � \ _---�\`• . Is H" _ Irv. _ � s� ``_ �� � "_II*_ _tlC._''-„ \• •• �. l_• .i �Z •♦ �. i+ • ii:fb ! 14\ •�� �a) �° .0 u� • • i111•'ri ► 0`°� ° +� •. • \ .. o t �o�, � I i t� '�i d �� ; ,/ � I'% � �l` 1J r it i ..�... 11 � I� //!! _ � • • • /` • FIFT •� • .a�1- - • '��L_— Ilw •� •. I� I� ..... � � Jt." f � r i�' ! il! 1 - ���•1�� . � 1�•....__��_.—'y".� •_� `��� I'- - �'•'�i.� �� �\ `/`'— \_ ;�+-� 1 Project Number 2105 15 July, 1996 page 4 of 30 pages METHODS of INVESTIGATION HISTORICAL RESEARCH The site and general vicinity is known to have been filled and then covered with mounds of fill prior to the development of Harbor Square, therefore the site has been preloaded. The extent and height of preload fill at the site is not known. The length of time that the fill was stored on the site would have been sufficient to complete any settlement of the original soils .and the overlying existing fill resulting from the weight of the excess fill that has since been removed. GEOLOGIC RESEARCH The surface geology for the vicinity of the project is shown in Figure 4, which is a partial copy of one of the geologic maps of a portion of the Puget Sound area. The geologic map shows that the site has been altered (ml) by removing some of the original soils and/or by Tilling. That description fits the known history of the site. The geologic maps do not have great accuracy, but they help to show soil types that are probable throughout Puget Sound but are not always obvious, or they help to verify that observed soils are as suspected. The significance of the geologic maps is that they show a general trend of geologic conditions that would appear to be reasonably continuous. VISUAL OBSERVATIONS at the SITE and VICINITY The area adjacent to the south side of the site is a wetland, which is indicative of the conditions that existed at the site prior to filling. L3'r�"��J�1�T?T:��Tr'T.'�T� Ta FIGU 5 TEST PIT LOGS DEPTH TP-1 TIP-2 TIP-3 TIP-4 DEPTH BROWN 1 GRAVELY SAND BROWN BROWN 1 SANDY SILT GRAVELY SAND GRAVELY SAND 2 2 DARK GRAY MEDIUM DENSE 3 MEDIUM SAND 3 LIGHT GRAY MEDIUM DENSE 4 MEDIUM SAND 4 GRAY MEDIUM GRAY SAND 5 SAND 2000 psf 2000 psf 5 GRAY MEDIUM SAND 6 2000 psf GRAY MEDIUM 6 2000 psf 7 7 8 v v v 8 PEAT PEAT PEAT 9 9 MEDIUM SILT MEDIUM SILT MEDIUM SILT 10 v 10 PEAT 11 MEDIUM DENSE MEDIUM DENSE 11 FINE SAND FINE SAND MEDIUM DENSE FINE SAND 12 MEDIUM DENSE 12 FINE SAND 13 13 14 14 15 15 LEGEND --------------- ESTIMATED LOCATION of CHANGE of SOILS KNOWN LOCATION of CHANGE of SOILS BOTTOM of TEST PIT 0 TOP of GROUNDWATER n Project Number 2105 15 July, 1996 page 5 of 30 pages FIELD TESTS Figure 5 shows the logs of 4 test pits conducted at the site. The test pits were located outside the four corners of the proposed building. The typical soil conditions revealed by the test pits are that the upper 8 feet is composed of sandy soils. The sandy soils below the upper 2 feet can support loads of 2000 psf. At 8 feet below the ground surface is approximately 1 foot of peat that supports groundwater. The peat is underlain by a 1 foot layer of silt, which is then underlain by fine sand. GROUNDWATER OBSERVATIONS The top of the groundwater table was located at a depth of 8 feet below the existing ground surface on 1 May 1996 after a 3 day period that accumulated 1 inch of rainfall. The soils above the water table were damp, the bottom 4 feet from capillary rise, and the top 4 feet from surface water infiltration. SITE STABILITY INVESTIGATION The site is stable because the site is flat except for 2 to 3 foot mounds at the south end of the site. The mounds will be removed during the grading operations. SOIL DESCRIPTIONS HOW PHYSICAL PROPERTIES of SOILS were DETERMINED The physical properties of the soils were determined by visual classification, probing, and penetration tests conducted in the 4 test pits. j �Y Project Number 2105 15 July, 1996 page 6 of 30 pages DESCRIPTION of UNDISTURBED NATURAL SOILS The undisturbed natural soils below 8 feet are old beach deposits that then became overlain by vegetation which later became peat. The beach deposits are underlain by glacial till (Qvt), shown in Figure 4 on adjacent properties to the south and north, and maybe glacial outwash (Qvr) shown east of the site. DESCRIPTION of EXISTING FILL SOILS. The existing fill soils in the upper 2 feet were probably placed during grading operations when the preload fill was removed. The rnext 6 feet was fill that was compressed by the preload fill. CONCLUSIONS HEMPHILL concludes that the original glacial till (Qvt) was covered with beach deposits when Puget Sound was at a higher level. The beach deposits were covered with silt that eroded from adjacent slopes after Puget Sound receded. The Peat then accumulated as vegetation grew and died over many years. The peat and marsh plants were then covered with fill that was placed in high mounds that preloaded all the underlying soils, including the peat. The upper preload was removed to a level 2 feet below the existing ground surface. More fill was placed at a later date, probably during the development of Harbor Square. That fill was later graded to the present level, probably during the construction of the existing tennis center. The proposed structure can be placed on the preloaded soils at approximately 2 feet below the existing ground surface. Those soils can support loads of 2000 psf with minimal settlement within the tolerable range of a flexible structure. Project Number 2105 15 July, 1996 page 7 of 30 pages ENGINEERING STUDIES & RECOMMENDATIONS RATIONALE for RECOMMENDATIONS The request by the CLIENT for HEMPHILL CONSULTING ENGINEERS to conduct geotechnical engineering obligates HEMPHILL to investigate and make recommendations concerning all phases of design and construction that would be affected by soils and foundations, including grcundwater and drainage. The subsurface investigation was established in accordance with minimum standards established by HEMPHILL, and also with generally accepted minimum standards determined by other geotechnical engineers. Those standards were derived through experience that has proven reasonably often to reveal the true subsurface conditions throughout the sites of most projects. The geotechnical recommendations presented in this report for the proposed PROJECT are based partially on presumptions by HEMPHILL that all the soils are similar to those observed at the site and on the requirement that HEMPHILL will verify the presumed conditions, and will make final decisions for foundations, structural fill, soil preparation, slabs, paving, and for drainage, at the time that the excavations reveal the true nature of all the subsurface soils and conditions. The following design recommendations are based on the soil conditions that might occur during normally anticipated storm or seismic conditions, and even during some poor construction practices. The worst of any of those conditions would not be normally anticipated, therefore the lower limits of the design parameters and safety factors are based on engineering judgment. aERE w� FTF T-rle ,i � I Project Number 2105 15 July, 1996 page 8 of 30 pages SITE PREPARATION CLEARING and STRIPPING In those areas where the structure, paving, or special landscaping will be placed, the ground surface should be cleared of any trees and shrubs, high grass and weeds, debris, and trash. The ground surface within fne proposed structure, and under any footings or paving, should be stripped of any sod, organic soils, and roots. NO ORGANIC MATERIALS CAPABLE OF DECOMPOSING SHOULD BE LEFT WITHIN THE PROPOSED STRUCTURE. Decomposing materials are the source of unacceptable odors, and can create methane gas, which can be explosive, and can also be harmful when inhaled. PROOF ROLLING PURPOSE OF PROOF -ROLLING Proof -rolling will densify the upper layer of soil, will compact any soil loosened by excavating operations, and will locate soft spots that should be excavated and replaced with structural fill. If the condition of the underlying soils is questionable, HEMPHILL might require that the soils be proof -rolled. DESCRIPTION OF PROOF -ROLLING Proof -rolling of a soil is accomplished by several passes of a heavy compactor or rubber tired vehicle. At those locations where the condition of the underlying soils is questionable, HEMPHILL might require that the soils be excavated and replaced with structural fill. itT�J rP �_J_T2 1eTe ,Te,► FIGURE 6 PROCEDURE for PREPARING and PLACING A WORKING SURFACE OVER SOFT SOILS A C 101 A. STRIP TREES, SHRUBS, AND GRASS, INCLUDING ROOTS AND ORGANIC SOILS (IN SOME CASES, WHERE APPROVED AND SUPERVISED BY HEMPHILL, GRASS AND ORGANIC SOILS CAN REMAIN). B. PLACE POORLY GRADED (SINGLE SIZE) COARSE AGGREGATE, COMPOSED OF COARSE GRAVEL OR CRUSHED ROCK, IN THIN LAYERS OVER SOFT SOILS. C. FORCE EACH LAYER OF THE COARSE AGGREGATE INTO THE SOFT SOIL WITH A HEAVY ROLLER, CRAWLER, LOADED RUBBER TIRED VEHICLE, OR VIBRATING COMPACTOR, UNTIL AGGREGATE HAS BEEN FORCED TO THE MORE COMPETENT LAYER OF SOIL, AND AGGREGATE VOID SPACES ARE COMPLETELY FILLED WITH THE SOFT SOIL (PUMPING HAS CEASED AND SOFT SOIL IS NOT SEEPING FROM SURFACE). D. ADD EXTRA LAYER OF AGGREGATE TO ENSURE THAT SOFT SOIL WILL NOT OVERFLOW THE VOID SPACES. Project Number 2105 15 July, 1996 page 9 of 30 pages PLACEMENT of WORKING SURFACE on SOFT SOILS During wet periods construction activities on the soils might be difficult. The construction activities will cause any disturbed soils to become less dense, and to lose strength. If construction is scheduled during wet periods or while the soils are wet, and the soils become soft and difficult to support construction activities, then a working surface composed of coarse crushed rock can be forced into the soft soils that will then support the construction equipment, will protect the underlying soils from disturbance, and might be a satisfactory base for the driveway and portions of the garage. To place a working surface, the site should be stripped of the upper vegetation and organic soils. Poorly graded crushed rock should be placed over the existing soft site soils and then forced into the softer soils by a heavy vibrating compactor, as shown in Figure 6. This procedure requires close supervision to ensure that the crushed rock is forced to the more competent layers below, and rises above the soft and wet soils, and that the soft soils do not support the rock, but fill the void spaces between the crushed rock. GENERAL SITE EXCAVATING Very little excavating will be accomplished except for the removal of the mound at the rear of the site, and foundation excavating. GENERAL SITE FILLING The need for any significant amount of structural fill on this project is not anticipated. If the depth to subgrade and/or allowable bearing soils is greater than anticipated, the contractor can choose to over -excavate to soils approved by HEMPHILL, and then to backfill to the required grades with structural fill approved by HEMPHILL. 'ram �rPTrYT-elT-eiI Project Number 2105 15 July, 1996 page 10 of 30 pages DESCRIPTION of RECOMMENDED STRUCTURAL FILL Structural fill is defined as any soil that can be properly compacted to achieve any or all of the physical properties that are necessary to support foundations, to diminish building and paving loads to softer soils below, to undergo acceptable settlement, to resist attracting capillary water to the underside of the floor slabs and paving, to stand at desired design slopes, to support slopes without blocking groundwater seepage, and to be workable when wet. Many combinations of grain sizes would be satisfactory as a structural fill soil, depending on the intended use of the fill, water content of the soil, and on weather conditions. Durina wet weather or anv wet conditions. soils with areater than 5% oassin the no. 50 sieve will be difficult. if not impossible, to compact: The recommended structural fill during wet conditions is composed of a well -graded granular soil with a gradation ranging from a fine sand (+50 sieve) to a coarse gravel. With the approval of HEMPHILL, the contractor can choose the structural fill from among those soils available from commercial suppliers, from offsite borrow pits, or from any existing site soils that are determined by HEMPHILL to be satisfactory for structural fill. CONTROL of COMPACTION of STRUCTURAL FILL LABORATORY PROCTOR TESTS A Modified Proctor Test (ASTM D-1557) is conducted on each different soil type to be used for filling to determine the required minimum density of the structural fill to achieve the desired properties, and the optimum water content that will best achieve that density. Project Number 2105 15 July, 1996 page 11 of 30 pages A Modified Proctor Test is conducted in the laboratory by conducting a series of compaction tests, each with a different water content. Each test is conducted by compacting a specific volume of the soil with precise compaction procedures with a controlled or measured water content. A curve is plotted comparing the density achieved for each water content of the soils during the test. The highest point on the curve shows the water content at which the achieved density of the soils is the greatest. The maximum density on the curve is called 100% of the Modified Proctor maximum density, and the water content that achieved that density is the optimum water content at which the soil compacts most easily. At that density the soils are considered to be capable of supporting their maximum loads with minimum compressing, or settlement. Silts and clays will allow the least water to seep through them, sands and gravels can stand at steeper slopes, and generally the desired properties are best achieved at higher densities. Sometimes the desired properties of a structural fill can be less than those achieved at 100% of the Modified Proctor, and the geotechnical engineer can specify a lower value, such as 90% or 95% of the maximum density achieved in the Modified Proctor test. The properties of the structural fill can either be determined by testing in the laboratory, or by comparing with known properties of a similar soil that have been determined by past testing by the geotechnical engineer, or are common values that have been published in engineering journals. The results of Modified Proctor tests are different with different soils. The geotechnical engineer must recognize soils that will have different properties when compacted, or he should conduct periodic classification tests to identify different soils. HEMPHILL should determine when a Proctor Test is required on a different soil. IrET, VFP— HeI1,Li Project Number 2105 July, 1996 page 12 of 30 pages TESTING COARSE GRANULAR SOILS Soils that are coarse granular cannot be tested by the Modified Proctor Test because they shift around too e—asily when the compacting weight is dropped on them during the test. The weight hits one spot and the adjacent granular soils pop up, therefore no compaction is accomplished. A Relative Density Test is required for the coarse granular soils, which determines the minimum and maximum densities of the soil. The minimum weight is determined by placing the soils loosely into a known volume container and weighing. The maximum density is determined by placing the soil into the container, covering the container with a weight, and then vibrating until the soils have achieved their most compact condition. The relative density of a soil in its compacted field condition in the field- is RD = [(max - field) = (max - min)). The relative density required to achieve the desired properties is specified by the geotechnical engineer. - COMPACTION of STRUCTURAL FILL The procedures to achieve the proper density of a compacted structural fill are dependent on the size and type of compacting equipment, the number of passes to be made over the soils with the compactor, the thickness of the layer to be compacted, and some properties of the soils, including water content. The density of a soil can sometimes be increased by increasing or reducing the water content of the soil, and using the same compactive effort. Water reduces the friction between soil grains and helps the soils to slide into a more compact condition with the same compactive effort. I . 0 9 Project Number 2105 15 July, 1996 page 13 of 30 pages FIELD TESTING for DENSITY Field density tests are conducted by obtaining samples of the field compacted soils, measuring the volume of the sample by measuring the hole from which the sample was obtained, and then weighing the sample in its natural condition, and again after drying, to determine the dry unit weight and the water content. Field densities and water contents can also be determined by nuclear devices, but that equipment is only feasible on very large projects. HEMPHILL recommends that the loose soils be placed in layers that compact not thicker than 8 inches, and the soils. be compacted with several passes of a heavy vibrating type compactor. The soiis should not be too wet or too dry during the compaction process. OPTIONAL TESTING PROCEDURES If HEMPHILL determines that the laboratory and field testing required to control the compaction of the soils is not warranted at this site, then HEMPHILL should observe and approve the compaction procedures, and should verify that the soils have achieved the desired properties. The loose soils should be placed in layers that compact not thicker than 12 inches, and the soils should be compacted with several passes of a heavy vibrating type compactor. The soils should not be too wet or.too dry during the compaction process. DENSITY REQUIREMENTS of STRUCTURAL FILL [All densities based on Modified Proctor maximum density (ASTM D-1557)] UNDER STRUCTURES Structural fill that will be located beneath the proposed structure, paving, or areas where settlement would be undesirable, should be compacted to a density equal to or greater than 95% for that particular soil. rEID , ,g? MT71,hr Project Number 2105 15 July, 1996 page 14 of 30 pages UNDER FOOTINGS Structural fill to be used for bearing under spread footings should be compacted to a density equal to or greater than 95% to achieve a high bearing capacity soil that would have minimal settling characteristics under normal building loads and anticipated natural disasters. UNDER STEPS, PORCHES, WALKWAYS Structural fill that will be used to backfill foundation wall excavations that will support steps, walks, or driveway paving where settlement would be undesirable, should be compacted to a minimum density equal to or greater than 95%. WHERE SETTLEMENT is NOT CRITICAL Structural fill that will be placed outside the proposed structure, and that will not support loads, can be compacted to a density equal to or greater than 90% to minimize settlement and shifting, and to be fairly stable on slopes less than 1 vertical to 2 horizontal. FOOTING DESIGN RATIONALE for FOOTING DESIGN Footings are designed in a manner to limit any settlement that would distress the structure to a point that it is dangerous to its in or is unsightly. How those limits are established is usually dependent on decisions by building departments, by the structural engineer, or by the attitude of the inhabitants. Settlement can occur by either of two ways; by shear failure of the soils when overloaded, and by compressing of the soils. As soils settle they densify and become stronger. If the soils settle uniformly throughout the building, then the settlement might not be noticed, since the structure will not be stressed, but utility connections outside the structure might be damaged, and those utilities that are dependent on gravity might reverse the direction of flow. MINIMUM FOOTING SIZE (feet) 0 m ..e 0 m r- O O O C z v c M n D m c� cD MINIMUM FOOTING SIZE (feet) 0 m co m r O O O C z 0 cn C m -n D C� m CD cD r O O ch m cn D z a F. m 0 c v m z cn m cn D z 0 -11 G C m y co m D z G) Q. cn m r rn ig m z -i Project Number 2105 15 July, 1996 page 15 of 30 pages If the general area does not settle uniformly, then differential settlement of the building could cause damage to the structure. Some example tolerable differential settlements are shown in the following table. TOLERABLE DIFFERENTIAL SETTLEMENTS TYPE of STRUCTURE TOLERABLE QUALIFYING DIFFERENTIAL CONDITIONS SETTLEMENT (ft/ft) One or two story steel frame Presence of overhead crane, truss roof, warehouse with 0.006 to 0.008 utility lines, forklifts on flexible siding. warehouse floor, would limit tolerable settlement. One or two story houses Larger value is tolerable if with plain brick bearing walls 0.002 to 0.003 I significant portion of and light structural frame. settlement occurs before I interior is finished. Structures with sensitive Larger value is tolerable if interior 0.001 to 0.002 significant portion of or exterior finish such as settlement occurs before plaster, ornament stone, or finish is complete. the facing. Structures with insensitive Damage to structural frame interior or exterior finish such 0.002 to 0.003 might limit tolerable as dry wall, movable panels, settlements. lass panels. HEMPHILL assumes the proposed structure to be very flexible, and can tolerate very large differential settlement, but the tennis floors would have unacceptable differential cracks and sloping; therefore a tolerable differential settlement of 001 (1" per 78') would be acceptable. DESIGN and PLACEMENT of SPREAD FOOTINGS FOOTING SIZING The footing load, which is the load imparted to the footing from the column or wall, is generally established by the architect or the structural engineer. The footing size is determined by dividing the footing load by the allowable bearing pressure. The allowable bearing pressure is determined by dividing the ultimate bearing pressure by the safety factor. HEMPHILL determined that the allowable bearing pressure on the existing medium dense sand is 2000 psf based on Figure 7. i 0 Project Number 2105 15 July, 1996 page 16 of 30 pages Minimum allowable footing sizes are given in the UBC. That usually guarantees that a very small footing will not punch into the soil. The minimum footing widths from the UBC are 12" for 1 story, 15" for 2 stories, and 18" for 3 stories. (Don't look for any logical reasoning for anything in the UBC. They just give values with no explanations.) The actual estimated settlement is compared to the tolerable settlement after the footing has been sized and the depth below final grade is known. If the estimated settlement exceeds the tolerable then the footing size is increased until the settlement equals or - is less than the tolerable. Remember that settlement is not directly related to footing size or bearing pressure. The larger the footing the deeper the influence, and therefore the more soils subjected to settlement. CONTINUOUS FOOTINGS To determine the required width of continuous footings, divide the footing load per foot by the allowable soil pressure. The footing loads must be determined by the architect or the structural engineer. Then check to determine that any settlement at that bearing pressure, footing depth, and footing width is tolerable. CAUTION! Typically tilt up walls are placed with temporary shims that exert heavy concentrated loads. The extent of the concentrated loads depends on the size and weight of the wall, and the number of shims used. HEMPHILL recommends that sufficient shims be used to prevent temporary loads in excess of.6000 psf, and that packing be installed as soon as possible. If obvious settlement occurs, then each wall unit must be supported by a crane until the packing is installed. INDIVIDUAL FOOTINGS To determine the required area of an individual footing, divide the total footing load by the allowable bearing pressure. The dimensions of the footing can be any multiple that equals the required area, provided that the minimum dimension is no smaller than the minimum allowable by UBC. Then check settlement to be less than the tolerable, or enlarge the footing until the settlement is tolerable. FIGURE 8 PROCEDURE for OVER -EXCAVATING AND PREPARING a BASE COURSE for FOOTINGS If the allowable bearing soils are located deeper than the minimum depth required for stability or frost protection, and the contractor prefers not to place the footings on the deeper approved soils, then with the approval of the geotechnical engineer (HEMPHILL), the contractor can place the footings on structural fill by the following procedures: a. Excavate D below the proposed final grade as specified for stability, for bearing capacity, or for frost protection. b. HEMPHILL will determine the bearing capacity and potential compressibility of the soils. If the soils are not satisfactory then over -excavate d = B, or as directed by HEMPHILL c. Extend the width of the excavation a distance b = d/2 beyond all edges of the footing to allow the footing loads to dissipate through the structural fill, or if the soils along the sides of the excavation are very compressible and cannot support the column of structural fill, then HEMPHILL will require a higher b/d ratio. d. HEMPHILL should probe the bottom of the excavation to verify that the soils can support the dissipated footing loads. e. Backfill to the proposed elevation of the bottom of the footing with soils approved by HEMPHILL, and compact the backfill soils to a minimum density of 95% of the Modified Proctor maximum density in accordance with ASTM D 1557 to achieve a structural fill that is capable of supporting the direct footing loads. f. if the design loads are greater than the capacity of the structural fill, then HEMPHILL will recommend the required footing sizes to achieve the allowable bearing pressure. Project Number 2105 15 July, 1996 page 17 of 30 pages OVER -EXCAVATIONS to BEARING SOILS If the depth to allowable bearing soils is greater than anticipated, the contractor can choose to over -excavate to bearing soils approved by HEMPHILL, and then to backfill with structural fill or lean concrete to the desired grades of the bottoms of the footings. Any over -excavations of footings which will then be backfilled with structural fill should be excavated 1 foot wider than the footing for each 2 feet of over - excavation, as shown in Figure 8 on the opposite page. If allowable bearing soils are not encountered within a reasonable depth, then HEMPHILL can determine the bearing capacity of the encountered soils, and can determine the required thickness of structural fill under the footing to dissipate the footing pressure to the allowable bearing capacity of those soils, provided that the compressibility of those soils is acceptable. If the compressibility is unacceptable, and the depth of the excavation is exceeding the desirable, then another foundation type should be investigated. That should make everyone happy. MAXIMUM SPANS for SOFT SPOTS SPAN for CONTINUOUS FOOTINGS If the bearing soils exceed the minimum required, then HEMPHILL will allow continuous footings to span soft spots. The allowable span can be determined by calculating the necessary footing area to carry the extra pressure exerted on the soils on either side of the soft spot. If the required footing area is less than the design footing width, then the footing can span the soft spot, provided that the footing has the structural integrity to span that distance. Generally the structural engineer should give the allowable distance that a footing can span as a beam. If the soils cannot support the extra loads, or if the footing cannot span the soft spot, then the soft soils must be excavated and replaced with structural fill, or the footing can be stepped to the approved bearing soils. Project Number 2105 15 July, 1996 page 18 of 30 pages SPAN FOR COLUMN FOOTINGS Generally the design of small individual column footings should not include allowances to span soft spots. If soft spots are anticipated on a project, then larger individual column footings can be designed to span soft spots equal to a third of the of the footing width. At the time of construction, if soft spots are encountered, and the good soils exceed the design bearing capacity, then the effective footing size can be adjusted an amount that is in direct proportion with any increased bearing capacity of the good soils, provided that no .eccentricity will be induced into the footings. If the good soils do not exceed the design bearing capacity, then no soft spots will be accepted. MINIMUM WIDTH of FOOTINGS Footings widths can be designed based on the allowable bearing capacity of the soils, with minimum width requirements of the UBC, or the local building code. The UBC minimum widths are based on the number of stories in a structure; 12" for 1 story, 15" for 2 stories, and 18" for 3 stories. MINIMUM DEPTH of FOOTINGS MINIMUM DEPTH for BEARING Footings can be placed directly on the undisturbed soils that have been approved for bearing by HEMPHILL, or they can be placed on structural fill soils that have been properly prepared and approved by HEMPHILL. Sandy soils increase in bearing capacity with confined depth. If additional bearing is required, then HEMPHILL can determine the allowable bearing increase due to depth at the time that the soils are exposed. FIGURE 9 FOOTING DRAINS o:...: s�" min :Q ' A' 112" min TOP of SEEPAGE 4: r1,41 , GRAVEL COMPLETELY WRAPPED in FILTER FABRIC. i• PERF PIPE NOT NECESSARY in CASES of LOW SEEPAGE. C C EFL O R /7'TC77liJ ii i 1 i r VR n i ' 1NITH0 T RF RAPED PIPE / , CAPILLARY BRE I ...:.................. TH LIGHT FLOW ;';;';;:: _ STRUCTURAL• f ILL: :: ::::::,; C. :.:::;:for HEAVY FLOW':.:'.i;;' i,.. .... ....... .. .... ... .........: _ :�; :J. TYPICAL POOR PRACTICE of BEDDING PERFORATED PIPE Vr}�a::::.`:.':'•:`:' ' ':::;...:;`.:::::`:::;::: ::•;:.:;..:•.:: .::::..:.:.:.•.;::.;:,;.,..-:.:;::::::.::::>:: in GRAVEL. V"s:v ,' d3c�/its_•_._::;.; • SLOPE PERF PERF PIPE SHOULD be PLACED -- . .. - - O O O Q_.,,:, 77.7 Q an SOLID .... S S DIRECTLY on FILTER FABRIC �,:. ..:.::.... :::s ::.; :::::>:,: ::::::::::: ::::::.: .01 It/it WATER BUILDS UP to LEVEL of WATER BACKS UP at SOLID PIPE PERFORATIONS BEFORE ENTERING PIPE, UNTIL it RISES and ENTERS the PERFORATIONS, THEN CAN SEEP UNDER FOOTINGS THEREFORE BED PERF PIPE at LEAST to CRAWL SPACE or UNDER FLOOR SLAB to DEPTH so PERFORATIONS are BELOW BASE . of CRAWL SPACE and/or CAPILLARY BREAK. If PERF PIPE NOT USED, WATER ENTERS SOLID PIPE at BASE of PIPE. NOTES: 1. GRAVEL SHOULD be COMPLETELY PROTECTED by WRAPPING WITH FILTER FABRIC. GRAVEL is DRAINAGE SYSTEM, NOT PERF PIPE. PERF PIPE is NOT ALWAYS NECESSARY and SOMETIMES CREATES PROBLEMS by MISUSE. 2. BOTTOM of DRAINAGE SYSTEM SHOULD BE LOWER THAN BOTTOM of CAPILLARY BREAK. W WIN Nun mum NUNN 9 Nun um P. 0 9 Project Number 2105 1 - July, 1996 page 19 of 30 pages MINIMUM DEPTH for FROST PROTECTION In the Puget Sound region frost seldom penetrates to depths in excess of 12 inches, and for an unusually cold spell frost might penetrate 18 inches. Footings to be adjacent to unheated areas should be placed a minimum of 18 inches below the final ground surface to protect against uplift due to frost expansion, or loss of bearing capacity due to softening from thawino conditions. DRAINAGE of FOOTINGS Figure 9 shows general drainage related to footings and floor slabs. Actual drainage requirements should be determined at the time of construction when all conditions are exposed and final elevations are obvious. SETTLEMENT ESTIMATIONS SETTLEMENT of EXISTING FILL SOILS The existing fill soils in their worst condition could settle as much as 1 inch under full design loads. HEMPHILL estimates that a full depth of loose to medium dense existing fill soils will settle less than'/z inch. SETTLEMENT of STRUCTURAL FILL If the existing fill soils are replaced with properly compacted structural fill, the structural fill will not settle under the actual anticipated loads. The settlement of the existing fill soils will then be minimized based on the depth of structural fill, but probably less than %< inch. DIFFERENTIAL SETTLEMENT Differential settlement from building loads will be less than Y4 inch locally. Differential settlement over the length of the building could be'/z inch. W- e7r?- , , r7;�)WI TeTe.,71., • f • Project Number 2105 15 July, 1996 *e 20 of 30 pages UNEXPECTED or UNUSUAL SETTLEMENT Any unusual or unexpected settlement will be the result of poor workmanship while preparing the bearing soils. EARTHQUAKE INCREASED LATERAL FORCES Lateral forces from earthquakes are created by the lateral vibrations created by the earthquake. Those lateral vibrations accelerate to a maximum velocity, and then decelerate to zero, then reverse and accelerate to the maximum velocity again. The acceleration and deceleration of the ground around the structure applies a force that drags the structure along with it. Since a force causes a mass to accelerate, that seismic force causes the structure to move laterally, which can damage the structure if the shaking exceeds the resisting strength of the building. The Puget Sound area has been listed by the map of seismic zones as Zone 3, which can have earthquakes with magnitudes of 7 or greater. The average seismic coefficient for a Zone 3 classification is 0.27. According to some. publications, that number is low for poor soil conditions and high for good soil conditions. Some experts state that the seismic coefficients have no basis from experience, and therefore are arbitrary. HEMPHILL recommends a seismic coefficient of 0.2 (acceleration of 6.4 fps/sec) based on a publication by the University of Washington for the Edmonds vicinity with an intensity of VII occurring every 20 to 40 years. The source and accuracy of the recommendation is not known, but the values have been accepted as standards and are considered acceptable for engineering purposes. A higher value might be appropriate where damage might be life threatening, which is not the case at this site. I' E- I ��Hr]CrL L 0 Project Number 2105 15 July, 1996 page 21 of 30 pages The seismic coefficient is a mathematical convenience, which is the lateral acceleration of the soil mass compared to the veriical acceleration of gravity. The true acceleration used to calculate the lateral soil forces is 0.20 x 32 ft/sec/sec = 6.4 ft\sec\sec. The weight of the building can be converted to mass (slugs) by dividing by 32 acceleration of gravity), and then the soil mass can be multiplied by 6.4 to determine the lateral force, but it is mathematically convenient to just multiply the building weight by 0.20. SETTLEMENT from SEISMIC SHAKING Granular soils that are deposited in nature are generally loosely placed either by water or wind. Granular soils are sometimes loosely deposited by man in uncontrolled fills. Such loosely deposited soils have fairly large void spaces, sometimes called pore spaces. As more soils are deposited the loose soils will be pushed closer together until the soil grains contact each other, but not necessarily in the most compact condition. As the weight of overlying soils is increased, the contact force between soil grains increases, and the grains have more difficulty sliding past each other to become more dense. That resistance of the soil grains to sliding into a more dense condition is the frictional resistance of the soils. That frictional resistance is one of the conditions that gives soils their strength_ to resist shear failures as heavy building loads are applied. The other condition that gives soils strength is cohesion, which is a sticky condition generally associated with clay and silt, and is nearly non-existent with coarse granular soils. Fine and medium granular soils are held together by dampness between the grains that bonds the grains like a 'weak glue'. That bond between the grains can be lost by drying the soils, or by saturating them. UE-:1�1' rNr il -A 0 • Project Number 2105 15 July, 1996 page 22 of 30 pages That condition is well known by children playing in a sand box, where dry sand cannot be formed or molded, damp sand can be molded, and a molded sand form can be destroyed by pouring water over it. That water 'glue' is called capillary tension, which can only exist in granular soils when they are damp, and cannot exist in dry or saturated granular soils. That capillary tension is also what holds together clay soils and makes them sticky. The smaller the soil grains, the greater effect that a water bond has between the grains. Unless an extremely heavy load is applied to the deeper granular soils, the intergranular friction, and sometimes the capillary tension if the soils are damp, prevents the soil grains from sliding into a more dense condition, and they remain relatively loose. If the soils are suddenly jarred by an earthquake, the friction forces will be temporarily reduced, and the soil grains can be forced into a more compact condition when the weight of the upper soils is reapplied. As the seismic vibrations cause reduction and reapplication of the friction forces, the volume of the existing voids will be reduced, and the soils will settle an amount equal to that reduction in voids. That sometimes causes a large area to settle an equal amount, and differential settlement can be minimal. Differential settlement of a structure can cause structural damage, and differential settlement outside the structure can cause external drainage and sewage lines to reverse flow, or can stress utility lines to the rupture point. LIQUEFACTION Another condition that occurs within loose granular soils during a seismic condition is called liquefaction. Liquefaction occurs two ways; by rising groundwater creating a 'quick' condition, and by trapped porewater reducing the strength of the soils. r-'r?r]C�`L L • C 10 20 30 DEPTH (fit) 40 50 .9 70 FIGURE 10 LIQUEFACTION PROBABILITY i ASSUMED WATER TABLE I I — I � I MAXIMUM GROUND ACCELERATION 0.1 g 0.15g 0.2g 0.25g LOOSE i MEDIUM I DENSE VERY DENSE 0 10 20 30 40 50 60 STANDARD PENETRATION RESISTANCE (blows/ft) NOTES: THE VALUES SHOWN IN THE CHART ARE CONDITIONS FOR WHICH LIQUEFACTION IS UNLIKELY TO OCCUR (AFTER SEED and IDRISS) THE REQUIRED GROUND ACCELERATION TO CAUSE LIQUEFACTION INCREASES WITH DENSITY, AND ALSO WITH DEPTH FOR THE SAME SOIL DENS1 —if, BECAUSE THE WEIGHT OF THE UPPER SOIL INCREASES THE STRESS BETWEEN THE SOIL GRAINS WHICH THEN INCREASES THE RESISTANCE TO MOVEMENT OF THE SOIL GRAINS INTO A MORE DENSE CONDITION. Project Number 2105 15 July, 1996 page 23 of 30 pages When granular soils that are below the groundwater level settle quickly during a seismic vibration, the groundwater that filled the void spaces of the loose granular soils is displaced and forced to rise. If the groundwater rises fast enough in more pervious soils, and can rise to the ground surface, then a 'quick' condition occurs. A quick condition is similar to the cause of quicksand, where the rising water moving past the soil grains reduces the frictional contact between the grains, and therefore causes a reduction of bearing capacity. The rising groundwater also saturates the previously damp granular soils and breaks the capillary tension bond. Therefore the soils have reduced load bearing capacity by losing frictional contact between the grains, and by losing the capillary tension bond. The 'quick' condition is also caused by increased pore water pressures that prevent the soils from maintaining frictional contact. When the sand grains have reduced friction caused by a vibration, and attempt to move into a smaller space, they are resisted by the porewater that hasn't been able to seep out of the pores as fast as the soils are settling. The soils are then supported by the porewater which acts like small hydraulic systems. Of course, water has no strength to resist shearing, therefore the porewater and reduced soil friction combination will fail under the imposed loads of the upper soils and the structure. Granular soils that have a greater frictional resistance to sliding into a more compact condition, either from being more dense, or that have a greater overlying load that both increases friction and also resists the upward vibration movement of the soils to release the frictional contact, will have a greater resistance to settling and/or liquefying from seismic vibrations. Figure 10 is a graph that shows the probability of liquefaction based on the effect of seismic accelerations on saturated sands at various depths and with various densities. Assuming a density of medium dense", liquefaction could occur at the design acceleration of 0.20 x g in granular saturated soils. �rEJ, ? rIle,l • • Project Number 2105 15 July, 1996 page 24 of 30 pages SEISMIC CONCLUSIONS HEMPHILL concludes that the entire site could settle from seismic vibrations on loose to medium dense sands, but because the conditions are similar throughout the area, any differential settlement will be minimal, and might not be obvious. If a significant earthquake should occur when groundwater is unusually high, then liquefaction could occur at the site. The effects of liquefaction are difficult to predict, but HEMPHILL suspects that any damage will be minor. CONCRETE FLOOR SLABS DESCRIPTION of CAPILLARY WATER If the underside of a concrete slab is in direct contact with groundwater, or is in direct contact with soils that are damp from capillary water, the concrete will also raise the water by capillary action. The water will not flow from the concrete, but will be held like a sponge holds water. The capillary water will evaporate as it contacts the air above the concrete slab. Generally, the vaporized capillary water is insignificant if the upper air can circulate through a heating or cooling system, or with open windows. As the capillary water evaporates at the top of the concrete, more capillary water will rise through the concrete to replace the evaporated water, therefore the flow of capillary water is a continuous process. If there is poor air circulation then the evaporated water will raise the humidity and create foul smells, and will create mildew on wall surfaces. When the humid air contacts an outside wall or window during cold periods, the humid air will condense, and if the condensed vapor contacts wooden structural members then they will begin to decay. The capillary water will also continue to rise if another material contacts the top of the slab, such as certain carpeting materials, cardboard boxes, wood, plasterboard, etc. The water will evaporate from that material, and then more capillary water will be attracted. The continuous dampness will create decay and mildew. M-11 U;M. TL I, Project Number 2105 15 July, 1996 page 25 of 30 pages Any impervious materials such as rubber carpeting, plastic, etc will stop the evaporation of the capillary water, but if cooler air exists above the impervious surface, such as from air conditioning, then the vaporized capillary water will then condense on the impervious material, and then free water will occur between the floor slab and the impervious material that could seep along the floor, and will then create a wet condition that can create decay, mildew, and bugs. PREPARATION of BASE COURSE for FLOOR SLAB Floor slabs can be placed directly over the undisturbed natural soils with the approval of HEMPHILL. Floor slabs can be placed over any structural fill that has been approved by HEMPHILL, that has been properly placed over undisturbed natural soils, and that has been compacted to a minimum density of 95% of the Modified Proctor maximum density ASTM D-1557). Since it has been determined that there is a source of moisture that could be conducted by capillary action to contact the underside of the floor slab, then the floor slab should be underlain by a capillary break to stop the capillary water. PROTECTION of FLOOR SLAB from CAPILLARY WATER A capillary break is a soil that will not conduct capillary water to'the underside of the floor slab. The source of the capillary water could be either the groundwater table or exterior infiltration of rainfall or other water sources, such as sprinkling. Different soils have different maximum heights of capillary rise, therefore the effectiveness of a soil as a capillary break depends on the capillarity of the soil and the height from the water source to the floor slab. r Project Number 2105 15 July, 1996 40ge 26 of 30 pages HEMPHILL has determined that the existing soils are not an effective capillary break, therefore the floor slab should be underlain by a capillary break composed of a 4 inch layer of aggregate with a minimum size equal to approximately 1 /4 inch. If the underlying soils are fine enough and become wet they might infiltrate the capillary break aggregate. If HEMPHILL determines that the underlying soils are too fine, then the capillary break aggregate can be underlain by a filter fabric or filter soil to prevent the integration of the underlying soils and the capillary break aggregates. The required filter soil or material should be determined by HEMPHILL in accordance with the available materials at the time of construction. A plastic vapor barrier can be placed on top of the capillary break aggregate to prevent the condensation of vapor on the underside of the concrete floor slab. The plastic will also prevent the loss of water from the bottom of the slab during the curing process to minimize differential curing, provided that the loss of water, is also prevented from the top of the slab. The lower the water/cement ratio of the floor slab concrete, and the longer the concrete is properly cured, the stronger the concrete will be, the more resistant the slab will be to moisture, and the concrete will be more resistant to cracking from both curing shrinkage and temperature changes. Also, a lower water/cement ratio gives the cement finishers less water to work to the surface, which then gives a more wear resistant surface, and allows less differential shrinkage between the top and bottom surfaces of the slab, and therefore less spider web cracks. Figure 11 shows an example of a capillary break placed beneath a floor slab. FIGURE 11 DESIGN of CAPILLARY BREAK TO PROTECT CONCRETE SLABS FROM CAPILLARY WATER FLOORCONCRETE SLAB PLASTIC VAPOR BARRIER yM •ty .�•�.t..��wiar�,,. V 1- �Ii�� •.•N•�.•�Mw'�sw,5 f4' CLEAN PEA GRAVEL (1/4 FILTER SAND � —.�� •:4Rjj��� i►�N-��J or - • FINE GRAINED CAPILLARY SOIL •' of -• CAPILLARY BREAK can be COMPOSED of MANY MATERIALS, the REQUIRED THICKNESS DEPENDING on the HEIGHT of CAPILLARY RISE for the MATERIAL, as SHOWN in the CHART. GENERALLY the COST of TESTING the MATERIAL for HEIGHT of CAPILLARY RISE is NOT JUSTIFIED, and a MINIMUM THICKNESS of 4" of MINIMUM SIZE Y." GRAVEL is CHOSEN. HEIGHT of CAPILLARY RISE FOR VARIOUS SOIL GRAIN SIZES U. S. STANDARO SIEVE SIZE 100 7' 1.7' 7/1- 7A' H.. J 10 70 J0 to 100 700 100 N d _ 90 U W in 70 40 Q 30 J G 10 a U 70 O 70 T C7 10 w 0 y 90 U t0 70 N 40 } SO �{ J 40 a a 30 U O 70 � 10 V' LS1 0 T 1000 100 10 1.0 0.1 0.01 0.001 C11•IM SIZE I" YILLIY!TERS I 0••TEL I 1•"0 SILT 02 CL•T C 0•.1t0 .nf[ 1 NOTES: A. HEIGHT OF CAPILLARY RISE SHOWN IS TO TOP OF SATURATION; CAPILLARY WATER CONTINUES TO RISE AT LESS THAN SATURATION. B. "Di 0 SIZE" IS GRAIN SIZE OF SOIL 17HERE 10010 OF SOIL IS FINER. • 0 Project Number 2105 15 July, 1996 page 27 of 30 pages DRAINAGE of SLAB BASE COURSE Prior to the placement of the filter and/or capillary break aggregate, the natural soils or the structural fill should be sloped a minimum of 1" per 10', or a series of gravel filled trenches can be sloped a minimum of 1" per 10', to allow any trapped water that accumulates io flow out from under the floor slab. Trapped water is not capillary water. Capillary water will not flow out into the drainage system because it is held like a sponge. The trapped water is water that might leak from broken or leaky pipes, or might seep under footings from outside the building. If water fills the voids of the capillary break gravel, then the capillary break will no longer function, and water will be in contact with the underside of the concrete slab. To allow for the escape of any trapped water, the drainage can be openings in the foundation walls that are then connected to an outside drain. The type and number of drains can be determined at the time of construction. DRAINAGE SITE SURFACE DRAINAGE The outside ground surfaces should be graded to conduct surface stormwater away from the building. The water can then enter catch basins, or it can be conducted away from the site in swales. Roof runoff can be conducted to the same system as the catch basins, but should not enter the swale system unless approved by the City of Edmonds. Adjacent paving drainage should not enter the roof system drainage unless an oil/silt separator is included. The adjacent paving can enter the swale system if designed as a biofiltration system with the approval of the City of Edmonds. T-W VF . rf—� WeTeTe.,Te.I 0' Y 0 • Project Number 2105 15 July, 1996 page 28 of 30 pages SITE SUBSURFACE DRAINAGE Most water that infiltrates into the ground will probably seep to the level of the groundwater at 8 feet unless there are less pervious layers that were not encountered in the test pits. If higher water does exist then footing drains can be constructed to intercept water before it seeps under the building Any footing drains should be below the level of the interior floor slab drainage. Any water intercepted by footing drains should be conducted from the site and should not be connected io a storm drainage system, except at a catch basin that has an open grate below the level of the footing drains. The capillary break system under the floor slab can be connected to the footing drain system, assuming that the footing drain system is at a lower level. '$�5.���717QV%�T-7��'J41TJ 4J TJ Project Number 2105 15 July, 1996 page 29 of 30 pages FUTURE STUDIES and RECOMMENDATIONS DESIGN REVIEW HEMPHILL has reviewed the final plans and specifications and determined that they are reasonably in accordance with the recommendations presented in the geotechnical report, assuming that HEMPHILL will conduct the recommended geotechnical inspections, and willi.present any necessary adjustments resulting from differences between presumed site conditions and actual site conditions, along with some options by the contractor, in accordance with actual conditions encountered at the time of construction. HEMPHILL concludes that if the proposed new tennis courts building is constructed in accordance with the plans, and with any recommendations by HEMPHILL at the time of construction, and with the approval of the following inspections, then there should be no risk of damage to the proposed building and/or the adjacent properties. CONSTRUCTION INSPECTIONS and VERIFICATIONS 1. HEMPHILL should inspect the soils that are exposed during excavating for foundations to verify that the allowable bearing soils have been encountered, and that there are no unexpected conditions that would require changes in foundation design. 2. HEMPHILL should inspect, and if necessary conduct tests, to determine that any structural fill is composed of the proper soils, and that the required density has been achieved by the compaction process. 3. HEMPHILL should inspect the excavations to verify any suspected groundwater conditions, or to determine any unexpected groundwater conditions, or to determine any design changes. 4. HEMPHILL should determine that any perforated drain pipes are placed at the proper locations to achieve the required drainage, and that the intercepted groundwater is properly conducted from the site. Project Number 2105 15 July, 1996 0 page 30 of 30 pages 5. HEMPHILL should inspect all surface runoff drainage systems to determine that surface water is properly intercepted and conducted from the site, and that the runoff systems are not improperly tied to the subsurface system to cause the runoff system to back up into the subsurface system. 6. HEMPHILL should determine that any drainage backfill has the required permeability, and that properly designed and installed filters will protect the drainage system from clogging by fine grained soils that could be eroded into the drainage system by groundwater seepage. 7. HEMPHILL should determine that the concrete floor slabs are underlain by a proper base course and/or capillary break and drainage to protect against capillary or free water creating dampness or wet conditions. Dale C. Hemphill P.E. Registered Engineer No. 14777 State of Washington y�U C. WASH, r$ij 4 y 0t•' �r7 14777 O �FCISitiit� SfONAL'� EXPIRES 17 FEBRUARY 1998 �F2. W 1�NeFLeile i �Cik M5CMPTION LANn5CAM NOT�5 IRK PMON Of GMKWNt LOr 5, 5eC11ON 25, tOWN5HP 21 N", Ma 5 Wt, W.M. 11 CONT KfR SWELL M 95PON51tte i'M PAMILIAPIZING HIM5fLP W fH ALL OTMP 51T IMPPMACNT5 PPIOP t0 StWNG L*V5CAM WORK, PLAN' 5CHNU 5YM5OL 50T'ANICAL / COMMON NW 5IZe COMWWT5 M5MP A5 POLLOW5: COMMNClNG'At TIC INiPSCTION C Tl 5OU1N LIM OF SPMV 25, � ff eA501Y 2; CONT%' fR 5ftL Use COON W U UCAVAIING TO AVOID 1215fLOINCt ANY eX1511NG U11L T51 IF ANY AM eNCOLWITR CONT?KTM 15 fO PIGHt Of- WAY WW OF 11f BL�:LWON NOMRN PAI�.POW; fOMP1LY AI�VISP TIC APCH11�Ct, 0 r ruses 'coul a 9r car a-itzc-x . 1c>-1a'r.MAIM ,� wt+r TI�Na ALONL`i 5N eA PLY 1"-OF--WAY LINe N42 54'54'T 616.W W, 31 CONif?ACt01� 51KL MAIWAIN ANSI WA11;t` PLANT MAT KK WL OWNW 5 FINK. ACC�Pf*a. 11• Ka N1f 00' "T 401.09 ftf; 4. (.OL�it7 COVPP SHALL M PLN4W IN AN eQU1LA1'eF;AL• TPW�GLLAP 5PACI N(A PAflfRN At ft OW aNMR SPACING SHOWN ON ff PI,ANt 5CI•�RLE. 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CON- 11ON; L i I aN p CONTWO: SHALL VERIFY ALL 51T COM9111ON5 WOI ANI212 INC CONMIC110N ANn 9i&L INFOPM THE r111ECf OE VAPLAJ1ON5 MMN CONTMf 120CUMEW5 AN2 EXI%W CON12111ON51 PUILI2 G WAP1"WW MWOVE1219P.AWNG5 SMALL CAE ON 1"HE J01351TE Af ALL TW5 r2WIN6 CON51WON. 5: 1NSPEC110 5E 1NEP.AL 5fU AL NM5 POP ITOUIM19 IN59C11ON51 MOM COPIE5 9E IN5PEC110N MPOPIfo HPM9a4 CITY R9MONn5131,11WINC I M,, WN', A CH11"ECf ANn 5VUCUA MAIMM 511E WM:. W511 IrOPXCAVA110N5, LOCATE U11LIir1E5, PMOVE ANY SIC�EWALKS, C1.5, ASPHALT", NnCP �AM�' LIG r�OLE5, M. A5 PEQUIWt9. ,Z lW-51PI.ICUM NO1E5 FM MQUIMP 5HOP nEAWINGSM 5WMlff&5. f.plCONTIZATR SHALL EMIT, tO" AP\CHlfECf, CATALOG CLO ON WATEP CL05M, 51NK5, Cr\Al3 DAPS, /pTAk-_ CAOftf, MIPP6P5 AN2 OV "A1 `OOP5. CONCTE. %E5fhERM MAWNC45 AN12 SUTI AL 6MM N0 5 POP ITINI'MCIN64ANP ALL Off P WQUIMWNt5 PEKA=lN6f0C0NCMS OPC TE P 1NC,T 5H .L 9 V&L- FOW12 WI1'I I.#1" POMt5 M 12EfECf5. MPAR ALL 5UCH Mffc "5 fO fit• 5A` 15FAC11ON OF 1 -ARCHISCT. PAINIIN6 ALL 00M WALL 5ML PECEIVE TWO (2) COAf5 OF ACMIC LATEX, FLAT. ALl. 19OM5 PAINTER; COLOP A5 5ELECTE 2, VIM.5H&L K NAR . CON TE 111 1' PANELS (EXTEPIOK) q4Al L r E 19AIK11P PPEPAPE 51 ACE fO PE(T-IVE PAINT" I'OOPINC: OMN COPNINC C MULIM S aNPLY 5Y5TEM, M WLK TNN15 COLA' ' 5EMI- If SPACE 1 rr / I E. P COLT �,;*\l NCA SHALL V1, LIMITER I L/ VEI VVLEN V I U( H 1 1'1� ) 10 U M U C H 1 I 1' OILING SHALL P-19 PAtt IN51LA11ON 0rma & LOCmI;. q4A L 1 W rik� MACE IN51MON: WA15 (OFFICE SPACE) `1--19 PO01= (OP M P- 8 POOP (TENNIS) P- 5LA13- OW GM P-10 \ 1 CAJ% OF tIV- IF CONCPETE CONS WN CONNeC110N5 P-10 061P IN51, KION 15 IN5MLEI2 H(XI &LY1 VENTIWON: ,\ Al I ATINC ANI2 VENMAT1N6 5YSTEM5 5HALL At1' 1994 VW COM 1 \, PPOJ Cf NM5 . CONSIPLICt10N T1 : ,UN15 - M III - I W. \ OFFICE - IM V- N •,�. OCCIP*a M: TENN15 - A-•5 •``, PING: W4'n - 4r COW - 12 %1OWN - 15 TNN15: 125 x 160. 20,000 5P I" 15,500 5f ALLOWW INC A% (2 511 5) 50% - 6150 ALLOi1VMLW AMA - 20,250 SP ``•. . 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A MTTI b* N St mu St cr''( Meln tic t, 60 2 O 1 t 08 n *Li rary St at c" n \ 10-0 1-- VARp�v p� EEDMO DS EM�MY �IIOX WALL Mr . �i�'� walnut � st \a 104 Rn tn Ceder st ow /4p Oa AR.GN. FX DETAIL) 0 2kD 00 a W J b E, " 41,g ��� YD I (YARD DRAIN-TYP) ----� °O'�o„4 RE 14.0 SPEGIFIG TI © 2 t8th St Pine St 216rh St SWit mu SW h c� t Fir St 2 t8th St �OP� / 50, •• ' ALL WORK SHALL i =ORM TO THE' LATEST EDITION OF THE alle C Rd Elm St 220th St s� a h���A`� Mf�'M��r • WASHINGTON DOT S T':', �RD SPECIFICATIONS FOR ROAD, BRIDGE, AND q MUNICIPAL CONSTRU" i , b �N/ ' UG 2 51992 1' 4p�w"" II0.00' ALL CB'S SHALL BE TYPt_- UNLESS OTHERWISE NOTED. �7.fj 1c , . -,) 0 0 � m 88.30'00111.1 48-INCH DIAMETER CPI S` 1_L BE TYPE 2. .�. ti. 7'P 6ALI Ay1-WAyN. yt. 9Ta. yPEGy PVC PIPE SHAL BE AST f,'. 3034, SDR 35. S ,� b , STREET FIL � ,too '^ m SEG. q-03 `I(U l a� Oc 22eth 5t KcvlIlED a N peer w tio` CMP SHALL BE SPIRAL-("' ALUMINUM CMP, 16 GAUGE. E C IE I'4 I [peer p�sa` �, 230th + CPEP SMOOTH PIPS. !ALL BE CORRUGATED HIGH ED 2Stsr sr MINIMUM (SMOOTH) H G DENSITY POLY- 1WCi I�WAY` Gobi tio_ sty` $��' ETHYLENE PIPE WITH S OTH INTERIOR AND SHALL COMPLY WITH TYPE AUG 2 5 1992 GZAM 600%U(TION MUAW MAIL 111, CATEGORY 4 OR 5, ,ADE P33 ORP34, CLASS C PER ASTM D-1248. IN uo SGAIE ADDITION, THE PIPE S►- COMPLY WITH ALL MATERIAL AND STIFFNESS PERMIT COUNTER REQUIREMENTS OF AA" D M294. 3ri5-�4 J Z w U 0 C) z w _w 0 U C U� m a rn LLJ w