ITB_ENG250425_Water_Treatment_Plant_No._2_GST_No._1_Construction_Updated_-_NEW_3.25.25_Exhibit_I_-_Geotechnical_Investigation_Report-_Ocala_WTP_2.pdf

August 12, 2024 Project No.: GPGT-23-0138

To: Kimley-Horn 1700 SE 17th Street, Suite 200

Ocala FL 34471

Attention: Mr. Alan J. Garri, PE

Subject: Report, Geotechnical Investigation for Ocala Water Treatment Plant (WTP) No. 2

Site, City of Ocala, Marion County, Florida

Dear Mr. Garri:

As requested, Andreyev Engineering, Inc. (AEI) has completed a geotechnical investigation for the above referenced project. The geotechnical investigation at the site included all the proposed WTP related structures like Finished Water Ground Storage Tanks, Concentrate Ground Storage Tanks, NF Process Building, Chemical Storage Building, Pump Building and Electrical Buildings and stormwater areas at the site. This report presents the results of our geotechnical investigation along with an evaluation of the soil and groundwater conditions encountered at the location of the proposed structures and stormwater areas. An interim geotechnical report for the proposed 2.0 Million Gallon (MG) Finished Water Ground Storage Tank (GST) #1 to be located at the northeast corner of the site was submitted on April 9, 2024. This report covers recommendations for site preparation and foundation design and construction of the all the proposed structures at the site and the aquifer parameters for the stormwater pond area design.

SITE LOCATION AND PROJECT DESCRIPTION

The proposed Ocala WTP No. 2 expansion will be located on an undeveloped 43-acre site located approximately 500 feet west of the junction of S. Pine Street (US Highway 27) and SE 17th Avenue in Section 32, Township 15 South and Range 22 East. The proposed water treatment plant will include the following structures:

• Two (2) 2.0 MG capacity 100-ft diameter finished water ground storage tanks, Finished Water GST No. 1 and Finished Water GST No. 3.

• One (1) 4.0 MG capacity 140-ft diameter finished water ground storage tank, Finished Water GST No. 2.

• Two (2) 4.5 MG capacity 149-ft diameter concentrate ground storage tanks, Concentrate Water GST No. 1 and Concentrate GST No. 2.

• Concentrate Pump Station Building with 19’ x 38’ footprint.

• Nanofiltration (NF) Process Building with 125’ x 259’ footprint.

• Odor Scrubber Pad with 33’ x 85’ footprint

• Clearwell/Degasifiers with 60’ x 100’ footprint

• Electrical Building No.2 with 22’ x 39’ footprint.

• Chemical Storage and Metering Building with 90’ x 129’ footprint

• High Service Pump Station Room with 63’ x 98’ footprint

• Electrical Building No, 1 with 35’ x 98’ footprint

Geotechnical Investigation for Ocala WTP #2, Ocala, Marion County, FL

In addition to the water treatment plant structures, the investigation included two stormwater retention areas in the eastern and southern portions of the site. The existing ground surface at the site is gently sloping upwards towards the north with ground surface elevations ranging from about 100 ft-NAVD88 to 130 ft-NAVD88. The site was an undeveloped wooded area that has been mostly cleared as part of the site development. The site’s vicinity is shown on a USGS topographic map on Figure 1. The N.R.C.S. web soil survey map of the site is shown on Figure 2.

SCOPE OF FIELD EXPLORATION

The scope of services for the entire site included drilling of fifty-nine (59) Standard Penetration Test (SPT) borings to a depth of 10 feet to 85 feet below the ground surface at the locations of the proposed structures at the site. At the locations of the proposed water retention areas, a total of eight (8) borings were drilled to a depth of 10 feet to 25 feet below the ground surface. The boring location plans are shown on Figures 3A and 3B. Representative portions of each soil stratum from the soil borings were packaged and sealed for transportation to our laboratory for further examination and visual classification.

SPT borings SB-33, SB-40 and SB-41 indicated raveled soil conditions with ‘weight-of-rod’ and ‘weight-of-hammer’ penetrations and as a result sixteen (16) Cone Penetration Tests (CPTs) were carried out to delineate the lateral extent of the raveled soil zones around those boring locations. The CPT sounding locations are shown in Figures 3A and 3B.

SOIL AND GROUNDWATER CONDITIONS

The soil types encountered at the boring locations are presented in the form of a soil profile on the attached Figures 4A thru 4F. The stratification presented on Figures 4A thru 4F is based on visual examination of the recovered soil samples, laboratory testing and the interpretation of the field logs by a geotechnical engineer.

In general, the borings encountered the following soil Strata:

• Light brown to brown fine sand to slightly silty fine sand (Stratum 1).

• Gray to light brown to dark brown silty to clayey fine sand (Stratum 2).

• Grayish green to green sandy clay to clay (Stratum 3).

• Brown to grayish green clayey fine sand to sandy clay with limestone and dolomitic limestone fragments (Stratum 4).

• Highly weathered limestone (lime silt) (Stratum 5).

• Weathered limestone with lime silt and silty clay (Stratum 6).

• Limestone (Stratum 7)

Standard Penetration Tests (SPTs) were carried out in general accordance with ASTM Standard D- 1586. Closely spaced SPT tests with split barrel sampling were performed in the upper 10 feet, with successive tests carried out at 5-foot intervals thereafter. The SPT blow counts or “N-Values” are shown adjacent to the boring profiles on Figures 4A thru 4F. The “N” values have been empirically correlated with various soil properties and are considered to be indicative of the relative density of cohesionless soils and the consistency of cohesive material. The SPT boreholes were grouted and backfilled with additional bentonite and soil materials.

The thickness of the different soil strata encountered at the boring locations are shown on Figures 4A thru 4F. In general, the near surface fine sand to slightly silty fine sand layer (Stratum 1) extended to a depth of 2 to 4 feet below the ground surface and the relative density of the stratum was loose to medium dense. Medium dense to dense silty to clayey fine sand (Stratum 2) was encountered below the surficial fine sand and the thickness of the silty to clayey fine sand layer ranged from 4 feet to about 50 feet.

Grayish green sandy clay to clay (Stratum 3) was encountered below the Stratum 2 clayey fine sand layer. The SPT N-values in the Stratum 3 sandy clay to clay indicated stiff to very stiff consistency of the clayey layer. The thickness of the sandy clay to clay (Stratum 3) varied from 5 feet to about 40 feet.

Brown to grayish green clayey fine sand to sandy clay with limestone fragments (Stratum 4) was encountered below the Stratum 3 clayey sand to sandy clay. The thickness of the clayey fine sand to sandy clay with limestone fragments ranged between 5 to 15 feet. The SPT N-value in Stratum 4 ranged from 11 blow/foot to 50 blows for 6 inches of penetration.

Stratum 5 highly weathered limestone (limesilt) was encountered at SPT borings SB-33, SB-40 and SB-41 as shown in Figure 4C. At boring SB-33, Stratum 5 weathered limestone (limesilt) indicated 11 feet of raveled soil condition with 5 feet of (weight-of-rod) WR penetration and 6 feet of (weight-of-hammer) WH condition. At boring SB-41 the Stratum 5 layer indicated 3 feet of raveled soil with WH penetration.

Stratum 6 weathered limestone was encountered above the Stratum 7 limestone. The thickness of the weathered limestone (Stratum 6) ranged from 5 feet to about 25 feet. The SPT N-value in the Stratum 6 weathered limestone ranged between 15 blows/foot to 50 blows/foot.

Stratum 7 limestone was encountered at depths varying from 4 feet to 78 feet below the ground surface. The significant variation in the depths of Stratum 7 limestone is due to the karst topography of the site. The SPT N-values at the Stratum 7 limestone ranged from 54 blow/foot to 50 blows for 1 inch of penetration.

Correlation of the SPT-N values with relative density, unconfined compressive strength and consistency are provided in the following table:

Coarse-Grained Soils

Fine Grained Soils

Penetration

Resistance N (blows/ft)

Relative Density of

Sand

Penetration

Resistance N (blows/ft)

Unconfined

Compressive Strength of Clay

(tons/ft2)

Consistency of Clay

0-4

Very Loose

<2

<0.25

Very Soft 4-10

Loose

2-4

0.25-0.50

Soft

10-30

Medium-Dense

4-8

0.50-1.00

Medium 30-50

Dense

8-15

1.00-2.00

Stiff

>50

Very Dense

15-30

2.00-4.00

Very Stiff

>30

>4.00

Hard

SPT borings SB-33, SB-40 and SB-41 indicated raveled soil conditions with ‘weight-of-rod’ and

‘weight-of-hammer’ penetrations and as a result sixteen (16) Cone Penetration Tests (CPTs) were carried out to further delineate the lateral extent of the raveled soil zones around those boring locations. The CPT sounding locations are shown in Figures 3A and 3B. Cone Penetration Tests (CPTs) were carried out in general accordance with ASTM Standard D-5778. Cone Penetration Testing with Pore Pressure Measurement (CPTU) is a geotechnical investigation technique designed to evaluate subsurface conditions and geotechnical soil properties. Cone penetrometer tests are a quasi-static penetration test, meaning that the cone is pushed at a slow rate rather than driven with a hammer or rotary drilling. During a cone penetration test (CPT), a cylindrical metal cone is advanced below land surface at a constant and slow rate, normally by a hydraulic press. As the cone is advanced, computerized measurements are made and data is recorded that indicate the various soil properties encountered by the cone.

The CPT is designed to evaluate subsurface conditions based primarily on the resistance to penetration encountered by the cone tip. Resistance measurements are also recorded for the cone sleeve, or shaft. In the case of piezocones, subsurface pore pressure are also measured to assist the evaluation of soil types. The CPT is performed by continuously advancing the cone without withdrawing it from the borehole. This makes a CPT very time-effective when compared to other testing procedures such as Standard Penetration Test (SPT) where the split-spoon sampler must be withdrawn from the borehole at each test interval.

The CPT provides data that can be used to estimate various subsurface properties including soil type and strength. Piezocone penetrometer tests are highly effective for identifying sand, silt, and clay layers, as well as determining pore pressure. These tests are also moderately effective for determining other geotechnical engineering properties including friction angle, undrained shear strength, relative density, constrained modulus, coefficient of consolidation, permeability, horizontal stress, and over consolidation ratios. The CPT sounding locations are shown on Figures 3A and 3B and the CPT summary plots using the CPT interpretation software CPeT-IT are shown in Attachment A.

Cone Penetration Tests (CPTs) CPT-1 thru CPT-6 were performed around SPT boring SB-33 to delineate the lateral extent of the raveled soil zones. The CPT soundings CPT-1 thru CPT-6 did not indicate the presence of raveled soil with low Constrained Modulus (M) values of say less than 20 tsf.

Thus, the raveled soils encountered at SPT boring SB-33 are considered localized over a narrow area and appear to be indicative of the presence of a “Karst Chimney”. At present, there are no structures proposed at the location of SB-33, however, if any structure is located at that location in the future, soil stabilization with pressure (cement) grouting will be essential to minimize the possibility of detrimental settlement. As shown in the CPT sounding summary plots in Attachment A, CPT soundings CPT-7, CPT-9 and CPT-10 around SPT boring SB-40 and CPT soundings CPT-12, CPT- 15 and CPT-16 around SPT boring SB-41 indicated about 15 feet thick raveled soil zones with very low Constrained Modulus (M) values of less than 20 tsf. The very low Constrained Modulus (M) values indicate high compressibility like that of highly compressible peat (muck). At present, there are no structures proposed at the location of SB-40 and SB-41, however, if any structures are located at those locations in the future, soil stabilization with pressure (cement) grouting will be essential to minimize the possibility of detrimental settlement of the structures.

Groundwater Conditions

Groundwater was not encountered within the top ten (10) feet of the SPT borings at the proposed structure locations. Groundwater levels could not be measured below the 10-foot depth at the SPT borings due to the mud rotary drilling method, which uses a thick bentonite drilling slurry to maintain an open borehole.

Groundwater table was encountered at pond boring locations at depths of 16.7 feet to 24.2 feet below the ground surface. Based on the encountered subsurface conditions, nearby lake levels, our local experience, and antecedent rainfall conditions, the normal seasonal high groundwater level at the proposed structure locations is estimated to range in elevation from 80 to 90.0 feet (NAVD88). A temporary perched water table is expected to develop above the sandy clay to clay (Stratum 3)soil layers, after prolonged and intense rains.

NRCS Soil Survey

The U.S. Department of Agriculture, Natural Resources Conservation Service (NRCS) Web Soil Map was reviewed. A portion of the map which depicts the location of the subject site is shown on attached Figure 2. The soil map units for the proposed site are: #44 Kendrick Loamy Sand, 0 to 5% slopes and #46 Lockloosa Fine Sand, 0 to 5% slopes. The depth of seasonal highwater table in #44 Kendrick Loamy Sand according to the web soil survey is at a depth greater than 200 cm (6.6 feet) below the ground surface and for #46 Lochloosa Fine Sand is at a depth of 95 cm (3.1 feet) below the ground surface. Soil units #44 Kendrick Sand and #46 Lochloosa Fine Sand are classified as Hydrologic Soil Group “A”, indicating soil with high infiltration rate.

Ground Penetrating Radar (GPR) Survey and Karst Sensitivity

The Ground Penetrating Radar (GPR) Survey of the site was performed by GeoView Inc. along the transect lines shown on Figure 5. The GPR survey report is presented in Attachment B. The survey did not encounter any “GPR anomaly” and thus the GPR survey did not indicate a potential for sinkhole activity at the site. The Florida Subsidence Incidents Report Map prepared by Florida Geological Survey is shown in Figure 6. The incidents report map indicates numerous previously reported sinkholes within 5-mile radius of the site. However, there is no reported sinkhole within ½-mile radius of the site.

Regional Geology

The geologic map of the State of Florida published by the Florida Geological Survey is shown on Figure 7. The project area is located in the Ocala Karst District geomorphic region (FDEP Open File Map Series 100, Plate 3). The near surface sediments in the project area are mapped as Middle Miocene Coosawhatchie Formation (Thc) of Hawthorn Group. The Coosawhatchie Formation varies from a light gray to olive gray, poorly consolidated, variably clayey and phosphatic sand to moderately consolidated slightly sandy, silty clay (Scott, 2001).

Ocala Limestone (To) underlies the surface layer of Coosawhatchie Formation at the project area. At the northern part of the Ocala WTP #2 site, Ocala Limestone outcrops at a few isolated locations and at several borings performed for the project, Ocala Limestone was encountered within about 5 feet below the ground surface. The Ocala Limestone consists of nearly pure limestone and occasional dolostones. The upper facies of Ocala Limestone are a white, poorly to well indurated, poorly sorted, very fossiliferous limestone (grainstone, packstone and wackestone). The permeable, highly transmissive carbonates of the Ocala Limestone form an important part of the Floridan Aquifer System (Miller, 1986).

Ocala Limestone is about 100 feet thick in the project area. Avon Park Formation (Tap) underlies the Ocala Limestone and extends to depths of over several hundred feet. Avon Park Formation consists of cream to light-brown or tan, poorly indurated to well indurated, variably fossiliferous limestone.

Avon Park Formation is part of the Floridan Aquifer System.

EVALUATION AND RECOMMENDATIONS

General

The following conclusions and recommendations are based on the project characteristics previously described, the data obtained in our field exploration and laboratory testing, and our experience with similar subsurface conditions.

Based on the results of our study, we are of the opinion that the soil and groundwater conditions are suitable for construction of the proposed structures at the site using conventional shallow foundation design. However, it is recommended that a uniform densified engineered soil platform be prepared for the proposed 100 to 149-foot diameter ground storage tanks.

For the calculation of lateral earth pressures, we recommend use of the following parameters: moist =

110 lb/ft3, sat = 120 lb/ft3, c’ = 0, ’ = 32o; Rankine active earth pressure coefficient, Ka = 0.307, Rankine passive earth pressure coefficient, Kp = 3.25; and coefficient of lateral earth pressure at rest, Ko = 0.47. For the calculation of safety of foundations against sliding, we recommend the use of a coefficient of friction, f = 0.40.

For seismic design considerations, it may be noted that according to the USGS national seismic hazard map, Central Florida is mapped as a “lowest hazard” area. Based on the available SPT N-values from this investigation, the Seismic Site Classification according to IBC Site Classification system is “Site Class D: Stiff Soil”.

Site Preparation

The initial step in site preparation should be the complete removal of all existing topsoil, trees, major root systems and other deleterious materials. Due to the loose soil conditions encountered near the ground surface, we recommend that the tank structure area (i.e., proposed area under the ground storage tanks) be over-excavated to a depth of 4 feet below the proposed foundation bottom elevation. The excavation shall extend a minimum of 5 feet outside the perimeter of the foundation of the structure. The depth of excavation at the building structure areas should be to a depth of 2 feet below the foundation depth. The exposed subgrade should then be proof rolled using a heavy vibratory roller (Dynapac CA-25 or equivalent). A non-vibratory roller should be used within 75 feet of any existing structure. Proofrolling of the tank foundation area should consist of at least ten (10) overlapping passes in each of two perpendicular directions and should be observed by a geotechnical engineer. The purposes of the proof rolling will be to detect any areas where unsuitable soils are present as well to densify the near-surface loose soils. The excavated Stratum 1 fine sand can be used as backfill material for the over-excavated area and the backfill shall be well compacted in uniform 12-inch thick lifts to a minimum of 95% of the soil’s modified Proctor maximum dry density

(ASTM D-1557).

Please note that at any time during mass grading, over-excavation or site preparation, if a cavity, sinkhole, or karst chimney feature is encountered, then AEI should be notified immediately to review the conditions. Small chimney features should be identified and filled with grout as quickly as possible after identification, to properly fill and seal any potential future surface connections to the subsurface.

Fill Placement

After the over-excavated foundation areas have been backfilled with well compacted clean sand and accepted by the geotechnical engineer, any fill required to bring the site to final grade may be placed and properly compacted. All fill materials should be inorganic, non-plastic, granular soil with less than 10% passing the number 200 sieve. The fill should be placed in level lifts not to exceed 12 inches loose and should be compacted to a minimum of 95 percent (%) of the soil's modified Proctor maximum dry density as determined by ASTM Standard D-1557. In-place density tests should be performed on each lift by an experienced engineering technician working under the direction of a licensed geotechnical engineer to verify that the recommended degree of compaction has been achieved. We suggest a minimum testing frequency of one (1) test per lift per 2,500 square feet of area within structural limits. The fill should extend a minimum of 5 feet beyond tank perimeter line to prevent possible erosion or undermining of foundation soils. Further, fill slopes should not exceed 2 horizontal to 1 vertical (2H:1V). For fill placed in restricted working areas, compaction should be accomplished with lightweight, hand-guided compaction equipment and lift thicknesses should be limited to a maximum of 4 inches loose thickness.

2.0 MG Finished Water Ground Storage Tank (GST) 1 Foundation

SPT borings SB-17, SB-53 and SB-54 were performed at the location of the proposed 100-foot diameter Finished Water ground storage tank GST #1. Based on our test boring results, the proposed tank can be supported by a shallow foundation system (reinforced slab/ring foundation). The ground storage tank foundation system should bear on properly placed and compacted cohesionless (sand) structural fill. As discussed in the site preparation recommendations above, after site stripping and grubbing, and prior to construction of the slab/footing system, over-excavation and replacement needs to be completed to ensure a 4-foot thick buffer (platform) of properly prepared and compacted engineered fill below the proposed bottom of foundation level, based on the elevations of the final grade.

The excavated bottom areas should be improved by vibratory compaction, as described earlier in this report, to provide uniform subgrade conditions and densify the encountered subgrade soil. This is intended to limit the total and differential settlements of the tank. The backfill material consisting of clean sand with less than 10% fines may then be placed back and compacted in uniform 12-inch lifts. The Stratum 1 fine sand can be used as backfill. Any fill required to bring the tank foundation to final grade shall be properly compacted in accordance with the recommendations described earlier. Compaction operations should be controlled by the contractor so as to not adversely impact any adjacent structures.

We understand the proposed Finished Water GST #1 will be a 100-foot diameter prestressed concrete tank with a 4-inch-thick membrane floor. We understand that the finished floor level will be at elevation 124 ft- NAVD88. The existing ground surface at the tank location varies between EL 118.5 to 122 ft - NAVD88. With an average fill height of 3.75 feet and the tank load of 2,300 psf, the total foundation load of the tank and new fill is estimated to be 2,750 psf.

The settlement of the 2.0 MG Finished Water GST #1 at boring location SB-54 was calculated for (a)

33.5 feet of sandy soil, (b) consolidation settlement of 5.5 feet of Stratum 3 medium stiff sandy clay to clay between the depths of 8.0 feet and 13.5 feet and (3) consolidation settlement of 5 feet of Stratum 5 soft limesilt between the depths of 33.5 feet and 38.5 feet. The settlement of the sandy layers was calculated using Burland and Burbridge (1985) method, with average SPT N-value, Navg of the sand layers as 19.9 blows/foot. The settlement of the medium stiff sandy clay to clay (Stratum 3) between 8 to 13.5 feet was calculated assuming: w n = 30%, eo = 0.81, Cc = 0.30, Cr = 0.06, OCR =

4.0, Cv = 0.1 ft2/day and CCc = 0.04. The settlement of the Stratum 5 limesilt between 33.5 feet to 38.5 feet was calculated assuming: w n = 35%, eo = 0.95, Cc = 0.35, Cr = 0.07, OCR = 3.0, Cv = 0.1 ft2/day and CCc = 0.04. The calculated total settlement of the tank due to the sand and clay layers is 2.69 inches. Assuming that for clayey soils, the differential settlement is 50% of the calculated total settlement, the calculated differential settlement between the center and perimeter of the finished water tank GST #1 is 1.35 inches. With l = 50.0 feet (distance between center and edge of tank), the calculated angular distortion /l is (1.35/(50.0x12)) = 0.0022 = 1/446. The tolerable angular distortion of the membrane floor due to differential settlement is generally considered as /l = 1/300 and thus the calculated angular distortion is well within the tolerable limits for prestressed concrete tanks.

The prestressed concrete storage tank can be constructed directly on the compacted platform and if perimeter strip or wall foundations are used, the wall footings should be proportioned using a maximum net allowable uniform bearing pressure of 2,500 pounds per square feet. All wall footings (if used) should be embedded a minimum of 24 inches below adjacent compacted grade on both sides and should be a minimum of 3.0 feet in width. This minimum footing size should be used regardless of whether or not the allowable bearing pressure dictates a smaller size. For the design of the membrane floor of the prestressed concrete tank resting on well compacted platform, we recommend a modulus of subgrade reaction, K value of 150 pci (lb/in3).

Pipe grades and pipe connections within 20 feet of the tanks should be designed considering the expected settlement.

The settlement of the ground storage tank should be monitored during the initial filling of the tank.

The tank manufacturer should incorporate settlement monitoring points to permit this operation.

Initially, we recommend that 25% loading increments be utilized and held for say one week each until the tanks are 100% full. Monitoring of the settlement points will determine the actual loading frequency. Pipe connections to and under the tanks should be connected after the initial filling.

2.0 MG Finished Water Ground Storage Tank (GST) 3 Foundation

SPT borings SB-16, SB-55 and SB-56 were performed at the location of the proposed 100-foot diameter Finished Water ground storage tank GST #3. Based on our test boring results, the proposed tank can be supported by a shallow foundation system (reinforced slab/ring foundation). The ground storage tank foundation system should bear on properly placed and compacted cohesionless (sand) structural fill. As discussed in the site preparation recommendations above, after site stripping and grubbing, and prior to construction of the slab/footing system, over-excavation and replacement needs to be completed to ensure a 4-foot thick buffer (platform) of properly prepared and compacted engineered fill below the proposed bottom of foundation level, based on the elevations of the final grade.

The excavated bottom areas should be improved by vibratory compaction, as described earlier in this report, to provide uniform subgrade conditions and densify the encountered subgrade soil. This is intended to limit the total and differential settlements of the tank. The backfill material consisting of clean sand with less than 10% fines may then be placed back and compacted in uniform 12-inch lifts. The Stratum 1 fine sand can be used as backfill. Any fill required to bring the tank foundation to final grade shall be properly compacted in accordance with the recommendations described earlier. Compaction operations should be controlled by the contractor so as to not adversely impact any adjacent structures.

We understand the proposed Finished Water GST #3 will be a 100-foot diameter prestressed concrete tank with a 4-inch-thick membrane floor. We understand that the finished floor level will be at elevation 124 ft- NAVD88. The existing ground surface at the tank location varies between EL 124 to 128 ft - NAVD88. With an average cut of 2 feet and tank load of 2,300 psf, the net total foundation load of the tank and the 2 ft of cut is estimated to be 2,060 psf.

The settlement of the 2.0 MG Finished Water GST #3 at boring location SB-55 was calculated for (a)

23.5 feet of sandy soil, (b) consolidation settlement of 5 feet of Stratum 3 stiff sandy clay to clay between the depths of 23.5 feet and 28.5 feet and (3) consolidation settlement of 10 feet of Stratum 3 stiff sandy clay to clay between the depths of 33.5 feet and 43.5 feet. The settlement of the sandy layers was calculated using Burland and Burbridge (1985) method, with average SPT N-value, Navg of the sand layers as 15.3 blows/foot. The settlement of the stiff sandy clay to clay (Stratum 3) between

23.5 to 28.5 feet was calculated assuming: w n = 30%, eo = 0.81, Cc = 0.30, Cr = 0.03, OCR = 4.0, Cv

= 0.1 ft2/day and CCc = 0.04. The settlement of the Stratum 3 clayey sand to clay between 33.5 feet to 43.5 feet was calculated assuming: w n = 30%, eo = 0.81, Cc = 0.30, Cr = 0.03, OCR = 3.0, Cv = 0.1 ft2/day and CCc = 0.04. The calculated total settlement of the tank due to the sand and clay layers is

1.23 inches. Assuming that for clayey soils, the differential settlement is 50% of the calculated total settlement, the calculated differential settlement between the center and perimeter of the finished water tank GST #3 is 0.62 inches. With l = 50.0 feet (distance between center and edge of tank), the calculated angular distortion /l is (0.62/(50.0x12)) = 0.0010 = 1/973. The tolerable angular distortion of the membrane floor due to differential settlement is generally considered as /l = 1/300 and thus the calculated angular distortion is well within the tolerable limits for prestressed concrete tanks.

The prestressed concrete storage tank can be constructed directly on the compacted platform and if perimeter strip or wall foundations are used, the wall footings should be proportioned using a maximum net allowable uniform bearing pressure of 2,500 pounds per square feet. All wall footings (if used) should be embedded a minimum of 24 inches below adjacent compacted grade on both sides and should be a minimum of 3.0 feet in width. This minimum footing size should be used regardless of whether or not the allowable bearing pressure dictates a smaller size. For the design of the membrane floor of the prestressed concrete tank resting on well compacted platform, we recommend a modulus of subgrade reaction, K value of 150 pci (lb/in3).

Pipe grades and pipe connections within 20 feet of the tanks should be designed considering the expected settlement.

The settlement of the ground storage tank should be monitored during the initial filling of the tank.

The tank manufacturer should incorporate settlement monitoring points to permit this operation.

Initially, we recommend that 25% loading increments be utilized and held for say one week each until frequency. Pipe connections to and under the tanks should be connected after the initial filling

4.0 MG Finished Water Ground Storage Tank (GST) 2 Foundation

SPT borings SB-14, SB-15, SB-57, SB-58 and SB-59 were performed at the location of the proposed 140-foot diameter Finished Water ground storage tank GST #2. Based on our test boring results, the proposed tank can be supported by a shallow foundation system (reinforced slab/ring foundation).

The ground storage tank foundation system should bear on properly placed and compacted cohesionless (sand) structural fill. As discussed in the site preparation recommendations above, after site stripping and grubbing, and prior to construction of the slab/footing system, over-excavation and replacement needs to be completed to ensure a 4-foot thick buffer (platform) of properly prepared and compacted engineered fill below the proposed bottom of foundation level, based on the elevations of the final grade. The excavated bottom areas should be improved by vibratory compaction, as described earlier in this report, to provide uniform subgrade conditions and densify the encountered subgrade soil.

This is intended to limit the total and differential settlements of the tank. The backfill material consisting of clean sand with less than 10% fines may then be placed back and compacted in uniform 12-inch lifts.

The Stratum 1 fine sand can be used as backfill. Any fill required to bring the tank foundation to final grade shall be properly compacted in accordance with the recommendations described earlier.

Compaction operations should be controlled by the contractor so as to not adversely impact any adjacent structures.

We understand the proposed Finished Water GST #2 will be a 140-foot diameter prestressed concrete tank with a 4-inch-thick membrane floor. We understand that the finished floor level will be at elevation 124 ft- NAVD88. The existing ground surface at the tank location varies between EL 120.5 to 127.5 ft - NAVD88. With an average cut/fill heigh of 0 feet and tank load of 2,300 psf, the net total foundation load of the tank is estimated to be 2,300 psf.

The settlement of the 4.0 MG Finished Water GST #2 at boring location SB-59 was calculated for (a)

13.5 feet of sandy soil and (b) consolidation settlement of 20 feet of Stratum 3 stiff sandy clay to clay between the depths of 13.5 feet and 33.5 feet. The settlement of the sandy layers was calculated using Burland and Burbridge (1985) method, with average SPT N-value, Navg of the sand layers as 30.1 blows/foot. The settlement of the stiff sandy clay to clay (Stratum 3) between 13.5 to 33.5 feet was calculated assuming: w n = 30%, eo = 0.81, Cc = 0.30, Cr = 0.03, OCR = 4.0, Cv = 0.1 ft2/day and CCc = 0.04. The calculated total settlement of the tank due to the sand and clay layers is 1.16 inches.

Assuming that for clayey soils, the differential settlement is 50% of the calculated total settlement, the calculated differential settlement between the center and perimeter of the finished water tank GST #3 is 0.58 inches. With l = 70.0 feet (distance between center and edge of tank), the calculated angular distortion /l is (0.58/(70.0x12)) = 0.0007 = 1/1454. The tolerable angular distortion of the membrane floor due to differential settlement is generally considered as /l = 1/300 and thus the calculated angular distortion is well within the tolerable limits for prestressed concrete tanks.

The prestressed concrete storage tank can be constructed directly on the compacted platform and if perimeter strip or wall foundations are used, the wall footings should be proportioned using a maximum net allowable uniform bearing pressure of 2,500 pounds per square feet. All wall footings (if used) should be embedded a minimum of 24 inches below adjacent compacted grade on both sides and should be a minimum of 3.0 feet in width. This minimum footing size should be used regardless of whether or not the allowable bearing pressure dictates a smaller size. For the design of the membrane floor of the prestressed concrete tank resting on well compacted platform, we recommend a modulus of subgrade reaction, K value of 150 pci (lb/in3).

Pipe grades and pipe connections within 20 feet of the tanks should be designed considering the expected settlement.

The settlement of the ground storage tank should be monitored during the initial filling of the tank.

The tank manufacturer should incorporate settlement monitoring points to permit this operation.

Initially, we recommend that 25% loading increments be utilized and held for say one week each until

4.5 MG Concentrate Ground Storage Tank (GST) 1 Foundation

SPT borings SB-2, SB-3, SB-48 and SB-49, and CPT soundings CPT-3 and CPT-5 were performed at the location of the proposed 149-foot diameter Concentrate ground storage tank GST #1. Based on our test boring results, the proposed tank can be supported by a shallow foundation system (reinforced slab/ring foundation). The ground storage tank foundation system should bear on properly placed and compacted cohesionless (sand) structural fill. As discussed in the site preparation recommendations above, after site stripping and grubbing, and prior to construction of the slab/footing system, over-excavation and replacement needs to be completed to ensure a 4-foot thick buffer (platform) of properly prepared and compacted engineered fill below the proposed bottom of foundation level, based on the elevations of the final grade. The excavated bottom areas should be improved by vibratory compaction, as described earlier in this report, to provide uniform subgrade conditions and densify the encountered subgrade soil. This is intended to limit the total and differential settlements of the tank. The backfill material consisting of clean sand with less than 10% fines may then be placed back and compacted in uniform 12-inch lifts. The Stratum 1 fine sand can be used as backfill. Any fill required to bring the tank foundation to final grade shall be properly compacted in accordance with the recommendations described earlier. Compaction operations should be controlled by the contractor so as to not adversely impact any adjacent structures.

We understand the proposed Concentrate GST #1 will be a 149-foot diameter prestressed concrete tank with a 4-inch-thick membrane floor. We understand that the finished floor level will be at elevation 118 ft- NAVD88. The existing ground surface at the tank location varies between EL 117 to 122 ft -

NAVD88. With an average cut of 1.5 feet and tank load of 2,300 psf, the net total foundation load of the tank will be 2,120 psf.

The settlement of the 4.5 MG Concentrate GST #1 at boring location SB-2 was calculated for (a) 18.5 feet of sandy soil and (b) consolidation settlement of 15 feet of Stratum 3 stiff sandy clay to clay between the depths of 18.5 feet and 33.5 feet. The settlement of the sandy layers was calculated using Burland and Burbridge (1985) method, with average SPT N-value, Navg of the sand layers as 23 blows/foot. The settlement of the very stiff sandy clay to clay (Stratum 3) between 18.5 to 33.5 feet was calculated assuming: w n = 25%, eo = 0.675, Cc = 0.25, Cr = 0.025, OCR = 5.0, Cv = 0.1 ft2/day and

CCc = 0.04. The calculated total settlement of the tank due to the sand and clay layers is 0.98 inches.

Assuming that for clayey soils, the differential settlement is 50% of the calculated total settlement, the calculated differential settlement between the center and perimeter of the Concentrate GST #1 is 0.49 inches. With l = 74.5 feet (distance between center and edge of tank), the calculated angular distortion

/l is (0.49/(74.5x12)) = 0.00055 = 1/1817. The tolerable angular distortion of the membrane floor due to differential settlement is generally considered as /l = 1/300 and thus the calculated angular distortion is well within the tolerable limits for prestressed concrete tanks. Settlement of the GST #1 was also calculated based on the CPT sounding results at CPT-3 and CPT-5 using the Cone Penetration Analysis Software CPeT. The output of the settlement calculation is shown in Attachment A. The CPeT calculated settlement of GST #1 at CPT-5 is 2.16 inches. Assuming that for clayey soils, the differential settlement is 50% of the calculated total settlement, the CPeT calculated differential settlement between the center and perimeter of the Concentrate GST #1 is 1.08 inches. With l = 74.5 feet (distance between center and edge of tank), the calculated angular distortion /l is (1.08/(74.5x12)) = 0.0012 = 1/828. The tolerable angular distortion of the membrane floor due to differential settlement is generally considered as /l = 1/300 and thus the calculated angular distortion is well within the tolerable limits for prestressed concrete tanks.

The prestressed concrete storage tank can be constructed directly on the compacted platform and if perimeter strip or wall foundations are used, the wall footings should be proportioned using a maximum net allowable uniform bearing pressure of 2,500 pounds per square feet. All wall footings (if used) should be embedded a minimum of 24 inches below adjacent compacted grade on both sides and should be a minimum of 3.0 feet in width. This minimum footing size should be used regardless of whether or not the allowable bearing pressure dictates a smaller size. For the design of the membrane floor of the prestressed concrete tank resting on well compacted platform, we recommend a modulus of subgrade reaction, K value of 150 pci (lb/in3).

Pipe grades and pipe connections within 20 feet of the tanks should be designed considering the expected settlement.

The settlement of the ground storage tank should be monitored during the initial filling of the tank.

The tank manufacturer should incorporate settlement monitoring points to permit this operation.

Initially, we recommend that 25% loading increments be utilized and held for say one week each until

4.5 MG Concentrate Ground Storage Tank (GST) 2 Foundation

SPT borings SB-35, SB-36, SB-50, SB-51 and SB-52 were performed at the location of the proposed 149-foot diameter Concentrate ground storage tank GST #2. Based on our test boring results, the proposed tank can be supported by a shallow foundation system (reinforced slab/ring foundation).

The ground storage tank foundation system should bear on properly placed and compacted cohesionless (sand) structural fill. As discussed in the site preparation recommendations above, after site stripping and grubbing, and prior to construction of the slab/footing system, over-excavation and replacement needs to be completed to ensure a 4-foot thick buffer (platform) of properly prepared and compacted engineered fill below the proposed bottom of foundation level, based on the elevations of the final grade. The excavated bottom areas should be improved by vibratory compaction, as described earlier in this report, to provide uniform subgrade conditions and densify the encountered subgrade soil.

This is intended to limit the total and differential settlements of the tank. The backfill material consisting of clean sand with less than 10% fines may then be placed back and compacted in uniform 12-inch lifts.

The Stratum 1 fine sand can be used as backfill. Any fill required to bring the tank foundation to final grade shall be properly compacted in accordance with the recommendations described earlier.

Compaction operations should be controlled by the contractor so as to not adversely impact any adjacent structures.

We understand the proposed Concentrate GST #2 will be a 149-foot diameter prestressed concrete tank with a 4-inch-thick membrane floor. We understand that the finished floor level will be at elevation 118 ft- NAVD88. The existing ground surface at the tank location varies between EL 113 to 116.5 ft - NAVD88. With an average fill height of 3.25 feet and tank load of 2,300 psf, the net total foundation load of the tank is estimated to be 2,690 psf.

The settlement of the 4.5 MG Concentrate GST #2 at boring location SB-36 was calculated for (a)

28.5 feet of sandy soil, (b) consolidation settlement of 5 feet of Stratum 3 stiff sandy clay to clay between the depths of 28.5 feet and 33.5 feet and (3) consolidation settlement of 16.5 feet of Stratum 3 stiff sandy clay to clay between the depths of 43.5 feet to 60 feet. The settlement of the sandy layers was calculated using Burland and Burbridge (1985) method, with average SPT N-value, Navg of the sandy layers as 19.9 blows/foot. The settlement of the stiff sandy clay to clay (Stratum 3) between

28.5 to 33.5 feet was calculated assuming: w n = 30%, eo = 0.81, Cc = 0.30, Cr = 0.06, OCR = 4.0, Cv

= 0.1 ft2/day and CCc = 0.04. The settlement of the stiff sandy clay to clay (Stratum 3) between 43.5 to 60.0 feet was calculated assuming: w n = 30%, eo = 0.81, Cc = 0.30, Cr = 0.03, OCR = 4.0, Cv = 0.1 ft2/day and CCc = 0.04. The calculated total settlement of the tank due to the sand and clay layers is

1.42 inches. Assuming that for clayey soils, the differential settlement is 50% of the calculated total settlement, the calculated differential settlement between the center and perimeter of the Concentrate GST #1 is 0.81 inches. With l = 74.5 feet (distance between center and edge of tank), the calculated angular distortion /l is (0.71/(74.5x12)) = 0.0008 = 1/1267. The tolerable angular distortion of the membrane floor due to differential settlement is generally considered as /l = 1/300 and thus the calculated angular distortion is well within the tolerable limits for prestressed concrete tanks.

The prestressed concrete storage tank can be constructed directly on the compacted platform and if perimeter strip or wall foundations are used, the wall footings should be proportioned using a maximum net allowable uniform bearing pressure of 2,500 pounds per square feet. All wall footings (if used) should be embedded a minimum of 24 inches below adjacent compacted grade on both sides and should be a minimum of 3.0 feet in width. This minimum footing size should be used regardless of whether or not the allowable bearing pressure dictates a smaller size. For the design of the membrane floor of the prestressed concrete tank resting on well compacted platform, we recommend a modulus of subgrade reaction, K value of 150 pci (lb/in3).

Pipe grades and pipe connections within 20 feet of the tanks should be designed considering the expected settlement.

The settlement of the ground storage tank should be monitored during the initial filling of the tank.

The tank manufacturer should incorporate settlement monitoring points to permit this operation.

Initially, we recommend that 25% loading increments be utilized and held for say one week each until

Concentrate Pump Station Foundation

SPT boring SB-34 was drilled at the location of the proposed Concentrate Pump Station Building.

Based on the available information, the proposed Concentrate Pump Station structure will have a plan area of 19’ x 38’ and a distributed foundation loading of 2,500 psf.

The settlement of the proposed mat foundation of the Concentrate Pump Station at boring location SB-34 was calculated for (a) 6 feet of sandy soil and (b) consolidation settlement of 7.5 feet of Stratum 3 stiff sandy clay to clay between the depths of 6 feet and 13.5 feet. The settlement of the sandy layers was calculated using Burland and Burbridge (1985) method, with average SPT N-value, Navg of the sand layers as 12 blows/foot. The settlement of the stiff sandy clay to clay (Stratum 3) between 6 to

13.5 feet was calculated assuming: w n = 25%, eo = 0.675, Cc = 0.25, Cr = 0.025, OCR = 5.0, Cv = 0.1 ft2/day and CCc = 0.04. The calculated total settlement of the foundation due to the sand and clay layer is 0.93 inches.

Assuming our recommendations of over-excavation of 2 feet and replacement with compacted fill described under site preparation section are followed, post-construction total settlement is estimated to be less than 1” and differential settlement of less than 3/4 inch. The allowable bearing capacity of the mat foundation for the Concentrate Pump Station is estimated to be 5,000 psf and thus exceeds the applied load of 2,500 psf. We recommend that the mat foundation for the Concentrate Pump Station should be embedded a minimum of 12 inches below the compacted finished grade. For the design of the mat foundation resting on a well compacted platform, we recommend a modulus of subgrade reaction, K value of 150 pci (lb/in3).

NF Process Building Foundation

SPT boring SB-9 thru SB-11, SB-24 thru SB-27 and SB-46 were drilled at the location of the proposed NF Process Building. Based on the available information, the proposed NF Process Building structure will have a plan area of 125’ x 259’ and a distributed foundation loading of 2,500 psf. We understand that the finished floor level will be at elevation 122 ft- NAVD88. The existing ground surface at the proposed NF Process Building location varies between EL 116 to 125 ft -NAVD88. With an average fill height of 1.5 feet and distributed building load of 2,500 psf, the net total foundation load is estimated to be 2,680 psf.

The settlement of the proposed mat foundation of the NF Process Building at boring location SB-24 was calculated for (a) 23.5 feet of sandy soil and (b) consolidation settlement of 20 feet of Stratum 3 stiff sandy clay to clay between the depths of 23.5 feet and 43.5 feet. The settlement of the sandy layers was calculated using Burland and Burbridge (1985) method, with average SPT N-value, Navg of the sand layers as 14.4 blows/foot. The settlement of the stiff sandy clay to clay (Stratum 3) between

23.5 to 43.5 feet was calculated assuming: w n = 30%, eo = 0.81, Cc = 0.30, Cr = 0.03, OCR = 4.0, Cv

= 0.1 ft2/day and CCc = 0.04. The calculated total settlement of the foundation due to the sand and clay layer is 1.64 inches.

Assuming our recommendations of over-excavation of 2 feet and replacement with compacted fill described under site preparation section are followed, post-construction total settlement of the mat foundation is estimated to be less than the allowable settlement of 2 inches and differential settlement is expected to be less than 1 inch. The allowable bearing capacity of the mat foundation for the NF Process Building is estimated to be 5,000 psf and thus exceeds the applied load of 2,680 psf. We recommend that the mat foundation for the NF Process Building should be embedded a minimum of 12 inches below the compacted finished grade. For the design of the mat foundation resting on a well compacted platform, we recommend a modulus of subgrade reaction, K value of 150 pci (lb/in3).

Odor Scrubber Pad Foundation

SPT boring SB-44 was drilled at the location of the proposed Odor Scrubber Pad. Based on the available information, the proposed Odor Scrubber Pad structure will have a plan area of 33’ x 85’ and a distributed foundation loading of 2,500 psf. We understand that the finished floor level will be at elevation 122 ft- NAVD88. The existing ground surface at the proposed Odor Scrubber Pad location varies between EL 127.5 to 129.5 ft -NAVD88. With an average cut of 6.5 feet, the net total foundation load is estimated to be 1,720 psf.

The settlement of the proposed mat foundation of the Odor Scrubber Pad at boring location SB-44 was calculated for 50 feet of sandy soil between the depths of 0 feet and 50 feet. The settlement of the sandy layers was calculated using Burland and Burbridge (1985) method, with average SPT N-value, Navg of the sand layers within the zone of influence of 23.5 blows/foot.