B09_Geotech Report_Amend3.pdf

148 CHESTER COURT • BOWLING GREEN, KENTUCKY 42103 • PHONE (270) 843-2247 • FAX (270) 843-9323 www.ddsengineering.com

REPORT OF GEOTECHNICAL ENGINEERING INVESTIGATION

MACA SANITARY SEWER PROJECT

MAMMOTH CAVE NATIONAL PARK

MAMMOTH CAVE, KENTUCKY

PREPARED FOR

HDR

MR. RANDY STAHMER

1917 S 67TH

STREET

OMAHA, NEBRASKA 68106

PREPARED BY

DDS ENGINEERING, PLLC

148 CHESTER COURT

BOWLING GREEN, KENTUCKY 42103

MARCH 26, 2020

DDS PROJECT NUMBER – T5314G

TABLE OF CONTENTS

PAGE NO.

1 EXECUTIVE SUMMARY ……………………………………………..………. 1

2 PROJECT AND SITE INFORMATION ……………………………….………… 2

2.1 SITE GEOLOGY ………………………………………….………… 4

3 FIELD EXPLORATION ……………………………………...………..………. 8

3.1 SUBSURFACE PROFILE …………………………..………………... 8

3.2 WATER LEVEL MEASUREMENTS……….……………..….……...… 11

4 LABORATORY TESTING …………………………………………………….. 12

5 DESIGN RECOMMENDATIONS………………………………………….……. 12

5.1 NOTED AREAS OF CONCERN ………………………………………. 12

5.1.1. BEDROCK EXCAVATION ……………………………………. 12

5.1.2. GROUNDWATER ……………………………………………. 13

5.1.3. UNDOCUMENTED UNDERGROUND UTILITIES …………….… 13

5.1.4. KARST TOPOGRAPHY ……………………………………… 13

5.1.5. PIPELINE MATERIAL CONSIDERATIONS ………………….… 14

5.1.6. OLD PREVIOUSLY PLACED FILL …………………………

6 CONSTRUCTION RECOMMENDATIONS ………………………………………. 15

6.1 BEDDING RECOMMENDATION ……………………………….…….. 15

6.2 STRUCTURAL FILL FOR BACKFILL ..……………………………….. 15

6.3 GEOTEXTILE MATERIAL FOR RETENTION OF BASE SOILS …………. 17

6.4 GROUNDWATER CONTROL AND DEWATERING PROCEDURES……

6.5 STABILITY OF CUT/FILL SLOPES ………………………………...… 17

6.5 OSHA TEMPORARY EXCAVATION REQUIREMENTS ……………...… 18

6.6 OBSERVATION AND MONITORING DURING CONSTRUCTION……..…. 18

7 LIMITATIONS OF RECOMMENDATIONS ………………………………………. 18

APPENDIX

BORING LOCATION EXHIBIT (HDR GEOTECH/TOPOGRAPHIC SURVEY EXHIBIT)

BORING RECORDS

LABORATORY TEST DATA SUMMARY SHEET

LABORATORY TEST REPORTS

FIELD TESTING PROCEDURES

LABORATORY TESTING PROCEDURES

INFORMATION ABOUT YOUR GEOTECHNICAL REPORT

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1 EXECUTIVE SUMMARY

DDS ENGINEERING, PLLC (DDS) has completed a geotechnical engineering investigation for the sanitary sewer improvement project at Mammoth Cave National Park in Mammoth Cave, Kentucky.

The project includes repair or replacement of 8-inch, 6-inch, and 4-inch diameter gravity sewer pipes and manholes along the gravity sewer system, and replacement of air release valve’s (ARV’s) along the force sewer main system. Invert depths of the existing and proposed system are unknown at the time of this reports completion; however, we understand that invert depths will be less than 10 feet below the existing ground surface.

The purpose of this investigation was to provide design and construction recommendations for the project. To characterize the subsurface conditions of the site, the field exploration consisted of drilling ten (10) soil test borings and fifty-three (53) auger soundings along the existing sewer alignment(s).

Most of the boring sites were in grass covered or wooded areas where surface soils were judged to be moist to wet and soft to firm at the time of the field exploration. Below the surface soils, the borings primarily encountered lean to fat clay, sandy clay, and clayey sand soils to the auger refusal or boring termination depths. The borings and soundings were advanced to 10 feet below the surface or auger refusal, whichever was shallower. Thirty-six of the borings encountered auger refusal within 10 feet of the top of ground. Where encountered, auger refusal ranged from about 1 foot to 10 feet with an average refusal depth of about 6 ½ feet below the current top of ground.

At the completion of soil augering, 6 of the 63 exploratory locations had measurable water within the boreholes. Where water was encountered at the time of boring, the borehole was left open for a minimum of 24 hours for a second reading. The water level within the six boreholes ranged from at the ground surface to about 8 ½ feet below the ground surface.

No obvious karst related features were encountered within the borings. However, portions of the site are underlain by geologic formations with a high potential for Karst activity. It should be understood and accepted by the owner that there is a risk of future ground subsidence when developing in any region where Karst activity is known. Details and recommendations for this project are presented throughout the text of this report.

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2 PROJECT AND SITE INFORMATION

Project information was received through several phone calls with members of the HDR project team and review of an exhibit prepared by HDR titled GEOTECH/TOPOGRAPHIC SURVEY dated

10/10/2019. The exhibit illustrates the existing sanitary sewer alignment, existing pipeline sizes, and the planned geotechnical exploratory locations. The exhibit is provided in the Appendix of this report.

The project includes repair or replacement of 8-inch, 6-inch, and 4-inch diameter gravity sewer pipes and manholes along the gravity sewer system, and replacement of air release valve’s (ARV’s) along the force sewer main system. Based on review the exhibit, a summary of the planned improvements is provided in Table 1 below.

Table 1 – Summary of Planned Sewer Replacement

The project site is located within Mammoth Cave National Park in Mammoth Cave, Edmonson County, Kentucky. The approximate 53,000 acre Park is in southcentral Kentucky to the west of Interstate 65, east of Kentucky Highway 259, and south of Kentucky Highway 1827. The Green River generally bisects the central portion of the Park. The sewer replacement project is mostly located within the developed areas near the center of the Park south of the Green River. DDS representatives Matt Rogers, PE and Alex Sutton, PE, visited the site prior to and during drilling operations to observe site surface conditions. The following is a general description of the site.

The site(s) of the sewer replacement vary from well developed areas with asphalt pavement and structures to grass covered areas with walking trails to remote densely wooded areas. Most of the gravity sewer replacement is in well-developed or grass covered areas while some of the ARV replacements are in remote wooded areas of the Park.

4" SS Replacement 922 linear feet

6" SS Replacement 5048 linear feet

8" SS Replacement 5839 linear feet

ARV Replacement 19 each

Manholes Replacement 79 each

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For site characterization purposes, the sewer alignment and exploratory locations were separated into several areas. Table 2 below summarizes our site observations and description of the different areas.

Area Exhibit

Page(s) Boring ID Site Description

Cottages 1 B-1 through B-6 Wooded, Fair Surface Drainage, Firm to Soft Surface Soils

Mammoth Cave

Hotel 2 B-7 through B-13

Well Developed Area Near

Visitors Center and Lodge, Good to Fair Surface Drainage, Firm to Soft Surface Soils

Hotel Cottages 2 B-14 through B-23

Partially Wooded and Grass Covered, Fair to Poor Surface Drainage, Firm to Stiff Surface Soils

Camp Store /

Campground 2-3 B-25 through B-30

Partially Developed / Wooded, Fair Surface Drainage, Soft to Firm Surface Soils

Staff Housing 3-4 B-31 through B-37

Partially Developed / Wooded, Poor to Fair Surface Drainage in Parts, Firm to Soft Surface Soils, Wet and Soft at B-37 and B-38

Maintenance

Facilities 4 B-38 through B-47

Mostly Well Developed, Some Asphalt, South End is Wooded, Firm Surface Soils, Good to Fair Surface Drainage

Remote ARV

Locations 5-8

B-48, B-49, B-54 through B-56

Wooded, Fair to Very Poor Surface Drainage, Soft and Wet Surface Soils

MACA Parkway

ARV

3-20

B-24, B-50 through

B-53, B-57 through

B-63

Developed within Road Right-of-Way, Good Surface Drainage, Firm Surface Soils

Table 2 – Site Conditions

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2.1 SITE GEOLOGY

Review of the Kentucky Geological Survey (KGS) published information reveals that the sanitary sewer alignment lies mostly within the Mammoth Cave Quadrangle (GQ-351) with the southern portion of the site near Diamond Cavern off Mammoth Cave Parkway being underlain by the Park City Quadrangle

(GQ-183). The published geology reveals the site is underlain by several different geologic formations.

Other than the far north section near the cottages and the maintenance facilities area, most of the gravity sewer alignment is underlain by the Big Clifty Sandstone Formation. The far north section and the area near the maintenance facilities of the sewer alignment is underlain by the Hardinsburg Sandstone

Formation. The sewer force main is underlain by the Big Clifty Sandstone, Haney Limestone, Girkin

Formation, and the St. Genevieve Limestone Formations.

Figure 1 – Geologic Map Expert from GQ-351 (Cottages, MACA Visitors Center, Lodge, Campground)

Figure 2 – Geologic Map Excerpt from GQ-351 (Staff Housing and Maintenance Facilities)

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Below is description of the noted geologic formations per the KGS Geologic Map Information Service.

Big Clifty Sandstone (Mgb) – The primary lithology of the The Big Clifty Sandstone Member of the

Golconda Formation is sandstone and shale with interbeds of sandstone and shale. The sandstone is described as grayish-white, light-yellowish-brown, and tan with very fine to medium grained quartz, thin bedded to massive, and weathers yellowish brown and brown.

Haney Limestone (Mh) – The primary lithology of the Haney Limestone of the Golconda Formation is limestone. The limestone is described as light-olive-gray, medium-gray, and light-brown, finely to medium-crystalline, and thin to thick bedded. The formation is described as extensively thinned due to removal of carbonate by percolating ground water resulting in collapse and slumping of overlying

Hardinsburg Sandstone. In many places the only evidence of the former presence of limestone is reddish-brown residual clay with porous white thin blocky chert.

Girkin Formation (Mg) - The primary lithology of the Girkin Formation is limestone, shale, and siltstone. The limestone of this formation is described as medium-light-gray to gray, finely to medium-crystalline, and thin to massive bedded. Locally, the upper part of formation unit contains think lenses of green shale and weathers light yellowish gray and gray.

Hardinsburg Sandstone (Mh) – The primary lithology of the Hardinsburg Sandstone is sandstone, siltstone, and shale. The sandstone of this formation is described as very light gray and yellowish-brown to reddish-brown, very fine to fine grained, and thin to thick bedded. Interbedded, medium-gray and light-brown siltstone and shale occur in parts. Fractures and joints between blocks of slumped and contorted sandstone commonly filled with red clay.

St. Genevieve Limestone (Msg) – The primary lithology of the St. Genevieve Limestone formation is limestone. The limestone is described as oolitic, white to light-gray, and thick bedded and interbedded with light-gray finely crystalline limestone. Dark to bluish gray and black chert occurs as tabular masses in lower part.

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We reviewed the KGS Geologic Map Information Service website for Karst potential and for closed depressions. Several closed depressions (i.e.-sinkholes) were mapped within the Park. We did not observe obvious surface indications of sinkhole activity along the sewer alignment or within the borings;

however significant Karst features are evident throughout the Park and Mammoth Cave is the longest cave system known in the world. The KGS website indicates the site to have a low to very high potential for karst activity. Typically, the upper sandstone bedrock has a low risk activity. In areas where the sewer traverses limestone, the risk is high. Table 3 provides more detail on the Karst risk relative to each formation.

Sampling of refusal material within the borings along the sewer alignment was beyond the scope of work. To characterize the bedrock along the alignment, a geophysical survey such as electrical resistivity and/or rock coring would be required. A more detailed discussion of Karst conditions is provided in the discussions section of this report.

Figure 3 – KGS Karst Potential (Cottages, MACA Visitors Center, Lodge, Campground)

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Figure 4 – KGS Karst Potential (Staff Housing and Maintenance Facilities)

A summary of the geologic formations that underly the sewer alignment is provided in Table 3 below.

Geologic Formation Boring No. Dominant Lithology Karst Potential

Class (Per KGS)

Big Clifty Sandstone

(Mgb)

B-2 through B-37, B-41, B-44, B-46, B-47, B-48, B-50, B-51, B-55, B-58, B-61, B-62

Sandstone and Minor Shale Non-Karst

Haney Limestone

(Mgh)

B-1, B-38, B-39, B-40, B-42, B-43, B-45,B-49,B-52, B-53, B-54, B-56, B-57, B-59, Limestone and Minor Shale High

Girkin Formation

(Mg) -- Limestone, Fine Grained Very High

Hardinsburg Sandstone

(Mh) B-60 Sandstone and Minor Shale Non-Karst

St. Genevieve Limestone

(Msg) B-63 Limestone, Fine Grained Very High

Table 3 – Summary of Published Geology

A brief review of the National Resources Conservation Service (NRCS) soil web survey website indicates several soil types along the gravity sewer alignment. In order of prominence, the soils were classified as Clarkrange Silt Loam (CoB and CoC), Lily Loam (LyC2 and DyD2), Rosine Silt Loam

(RoB) and Riney Silt Loam (ReC2). The NRCS website suggest that the soils are generally clay, silt, and sandy soils.

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3 FIELD EXPLORATION

The subsurface exploration consisted of drilling 10 soil test borings and 53 auger soundings. The borings were identified as B-1 through B-63 and were also identified by the nearest manhole or air release valve structure number. The abbreviations of MH and ARV were used for structure identification of manholes and air release valves. Some boring locations were moved prior to mobilization to explore areas for a potential new alignment between the Mammoth Cave Hotel and the Hotel Cottages. These borings were identified as (OB-1, OB-2, and

OB-3). The borings were staked in the field by others and were generally located in accordance the with HDR

GEOTECH/TOPOGRAPHIC SURVEY Map Exhibit dated 10/10/2019. DDS representatives Matt Rogers, PE and Alex Sutton, PE, visited the site prior to and during drilling operations to observe site surface conditions and to aid in interpreting the subsurface data.

The soundings and soil test borings were advanced using hollow stem augers powered by a track mounted CME 45 drill rig. The exploratory locations were advanced to 10 feet below the surface or auger refusal, whichever was shallower. Select soil samples were obtained within soil test borings through split barrel sampling from standard penetration tests (SPT). The SPT is a process in which a

140-pound hammer is dropped 30 inches driving the sampler into the ground. The number of blows needed to drive the sampler 12 inches is called the N value, which is the basis for many empirical design criteria in Geotechnical Engineering. During drilling, soil samples were visually classified and transported to the laboratory for further classification and testing. Procedures used during our field exploration were performed in general accordance with ASTM procedures and established engineering practice.

3.1 SUBSURFACE PROFILE

As mentioned in earlier sections of this report, most of the borings were drilled in grass covered or wooded areas. Surface soils in the grass covered and wooded areas were judged to be moist to wet and soft to firm at the time of the field exploration. Topsoil encountered in the soil test borings ranged from about 2 inches to 12 inches thick and averaged about 6 ½ inches thick. Two (2) of the soundings were advanced through asphalt pavement near the maintenance facilities. The asphalt ranged from about 4 to

6 inches thick and was underlain by about 4 inches of crushed limestone fill. Old previously placed fill was encountered in 4 of the soil test borings at different sections of the site. The old fill ranged from

5314 MACA SANITARY SEWER, HDR, GEOTECH REP 03262020 Page 9 of 20 about 2 ½ feet to 6 feet thick and consisted of soft to stiff brown to dark brown clay with some gravel.

Some of the old clay fill was organic laden.

Below the surface organics, asphalt pavement section, or previously placed fill, the soil test borings primarily encountered lean to fat clay, sandy clay, and clayey sand soils to the auger refusal or boring termination depths. We generally grouped the subsurface soils into 3 strata.

Stratum 1 – Soft to Firm, Clay, Some Silt and Sand, Brown to Reddish Brown. Where present, this clay stratum generally extended below the surface organics or previously placed fill to about 3 ½ feet below the surface. The SPT N-values within this stratum ranged from 2 blows per foot (bpf) to 13 bpf indicating a very soft to stiff soil consistency. Soil plasticity tests (Atterberg Limits) were performed on select split spoon samples recovered. The tests produced liquid limits ranging from 38 to 22 and plasticity indices of 18 to 6. According to our laboratory tests and the Unified Soil Classification System

(USCS), we classified this stratum as “CL”, lean clay or “CL-ML” sandy silty clay.

Stratum 2 – Stiff to Very Stiff, Sandy Clay, Orangish Red to Yellowish Orange. This stratum extended below stratum 1 to about 6 feet below the surface. The SPT N-values within this stratum ranged from 11 bpf to 28 bpf indicating a stiff to very stiff soil consistency.

Soil plasticity tests (Atterberg Limits) were performed on select split spoon samples recovered. The tests produced liquid limits ranging from 28 to 56 and plasticity indices of 13 to 31. According to our laboratory tests and the Unified Soil Classification

System (USCS), we classified this stratum as either “CL”, sandy lean clay or “CH” sandy fat clay.

Stratum 3 – Very Firm to Very Dense, Clayey Fine Sand, Brownish Orange. Where encountered, this stratum extended below stratum 2 to the boring termination depth. The SPT N-values within this stratum ranged from 24 bpf to 71 bpf indicating a very firm to very dense relative compactness.

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Thirty-six of the exploratory locations encountered auger refusal within 10 feet of the surface. Where encountered, auger refusal ranged from about 1 foot to 10 feet below the surface and averaged about 6 ½ feet below the surface. Auger refusal is defined as the depth below the ground surface at which the earth sampling auger can no longer be advanced with the drilling technique used. Refusal and boring termination depths from the exploratory locations are provided in Table 4 below.

BORING

NO.

STRUCTURE

ID

TERM.

DEPTH (FT)

REFUSAL

(YES / NO)

BORING

NO.

STRUCTURE

ID

TERM.

DEPTH (FT)

REFUSAL

(YES / NO)

B – 1 MH 84 10.0 NO B – 33 MH 38A 10.0 NO

B – 2 MH 83 10.0 NO B – 34 MH 37 10.0 YES

B – 3 MH 82 a 10.0 NO B – 35 MH 38 E 6.9 YES

B – 4 MH 80 10.0 NO B – 36 MH 43 10.0 NO

B – 5 MH 78 10.0 NO B – 37 MH 42 10.0 NO

B – 6 MH 77 9.0 YES B – 38 MH 45 3.7 YES

B – 7 MH 72 9.3 YES B – 39 MH 45A 6.3 YES

B – 8 ARV 1 1.5 NO B – 40 MH 45B 10.0 NO

B – 9 MH 71 5.1 YES B – 41 MH 46 9.8 YES

B – 10 OB 3 4.6 YES B – 42 MH 47 C 10.0 NO

B – 11 MH 68 b 1.0 NO B – 43 MH 47 D 9.7 YES

B – 12 MH 68 3.5 YES B – 44 MH 47 6.9 YES

B – 13 OB 1 10.0 NO B – 45 MH 47 F 10.0 NO

B – 14 MH 63 5.4 YES B – 46 MH 48 10.0 NO

B – 15 MH 212 7.8 YES B – 47 MH 49 10.0 NO

B – 16 MH 18 D 1.0 YES B – 48 ARV 16 7.0 YES

B – 17 MH 218 3.5 YES B – 49 ARV 17 8.9 YES

B – 18 OB2 6.2 YES B – 50 ARV 3 6.4 YES

B – 19 MH 18 G 8.5 YES B – 51 ARV 4 10.0 NO

B – 20 MH 18 I 5.2 YES B – 52 ARV 5 10.1 YES

B – 21 MH 20 6.0 YES B – 53 ARV 6 3.2 YES

B – 22 MH 21 10.0 NO B – 54 ARV 19 10.0 NO

B – 23 MH 22 A 10.0 NO B – 55 ARV 21 10.0 NO

B – 24 ARV 2 8.1 YES B – 56 ARV 20 5.8 YES

B – 25 MH 23 10.0 NO B – 57 ARV 06 5.2 YES

B – 26 MH 24 10.0 NO B – 58 ARV 08 N 5.4 YES

B – 27 MH 25AA 8.2 YES B – 59 ARV 08 S 4.6 YES

B – 28 MH 26 5.9 YES B – 60 ARV 11 10.0 NO

B – 29 MH 27 6.5 YES B – 61 ARV 12 10.0 NO

B – 30 MH 27 A 9.8 YES B – 62 ARV 13 7.6 YES

B – 31 MH 40 10.0 NO B – 63 ARV 14 10.0 NO

B – 32 MH 39 5.5 YES

Table 5 – Auger Refusal / Boring Termination Depth Table

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The individual boring records are provided in the Appendix. In areas of limestone, refusal can be obtained by layers of limestone “floaters” suspended in a matrix of clay, rock pinnacles rising above the surrounding the bedrock surface, or widened joints in the bedrock that may extend below the surrounding bedrock. The soil stratification symbols shown on the boring logs represent the approximate boundary of the subsurface strata. However, the transition may be more gradual than shown.

3.2 WATER LEVEL MEASUREMENTS

At the completion of soil augering, water was encountered in 6 of the exploratory locations (B-7, B-26, B-29, B-36, B-37, and B-55). Initial water level readings ranged from water being at the ground surface to about 8 feet below the surface. Where water was encountered during drilling, the borings were left open a minimum of 24 hours for an additional reading. The water level from the second reading ranged from water at the ground surface to about 8 ½ feet below the surface. The sidewalls of the boreholes caved in at some of the borings between readings. Table 6 below summarizes the water level readings.

Boring No. Water at TOB (Ft) 24 Hr. Reading (Ft) Notes

B-7 8.2 8.5 --

B-26 5.3 2 Side Walls Caved-In at 2.7 Ft BTW Readings

B-29 3 0.3 Side Walls Caved-In at 1.8 Ft BTW Readings

B-36 Ground Surface Ground Surface Side Walls Caved-In at 3.6 Ft BTW Readings

B-37 Ground Surface Ground Surface Side Walls Caved-In at 4.3 Ft BTW Readings

B-55 Dry 1.5 Side Walls Caved-In at 7 Ft BTW Readings

Table 5 – Water Level Readings

Groundwater levels fluctuate with seasonal and cyclical climate variations in precipitation and may be higher or lower at other times. Typically, water conditions affecting construction projects in the site area are related to trapped or perched water which occurs in irregular, discontinuous locations within the soil overburden, or near the soil/rock interface. When these water bearing strata are exposed in excavations, such as cut slopes, utility or footing trenches, they can produce widely varying seepage durations and rates depending on recent rainfall activity and other site-specific characteristics of the area. In areas with Karst bedrock, the stable groundwater table is typically encountered below the

5314 MACA SANITARY SEWER, HDR, GEOTECH REP 03262020 Page 12 of 20 bedrock surface. To more accurately monitor water levels at this site, piezometers would be required to be installed.

We anticipate that excavations for the sewer replacement will encounter water, particularly near the staff housing area near borings B-36 and B-37. Water levels were at the surface of the borings at the time of exploration and at the second reading at these locations. From conversations of MACA personnel, we understand this area is often saturated.

4 LABORATORY TESTING

Laboratory tests were conducted on select soil samples obtained during our exploration. Laboratory tests included 10 natural moisture content, 10 sieve analysis with #200 sieve wash, and 10 Atterberg limits plasticity tests. Laboratory test reports and a summary of laboratory tests data is provided in the

Appendix of this report. The field and laboratory procedures used were in general accordance with

ASTM procedures and established geotechnical engineering practice.

5 DESIGN RECOMMENDATIONS

Our recommendations are based on the design information provided to us, the data obtained during the previously described exploration, and our experience. They do not reflect variations in the subsurface conditions which may exist between our borings and in unexplored areas of the site. If variations become apparent during construction, it will be necessary for us to re-evaluate our conclusions and recommendations based upon on-site observations.

5.1 NOTED AREAS OF CONCERN

5.1.1 Bedrock Excavation

The proposed sewer will be embedded into the ground as much as 10 feet deep. Thirty-six of the exploratory locations encountered auger refusal within 10 feet of the surface. Where encountered, auger refusal ranged from about 1 foot to 10 feet below the surface and averaged about 6 ½ feet below the surface. Based on the data from our soundings and borings, it appears that the sewer alignment will encounter bedrock during trench excavation at some locations. Locations underlain by limestone, bedrock removal can be difficult and expensive.

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5.1.2 Groundwater

Most of the borings were dry at the time of boring. However, as noted in Section 3.2 of this report, water was encountered in 6 of the exploratory locations (B-7, B-26, B-29, B-36, B-37, and B-55). We anticipate that excavations for the sewer replacement will encounter water seepage at some locations, particularly near the staff housing area near borings B-36 and B-37. More discussion on groundwater dewatering is provided in later sections of this report.

5.1.3 Undocumented Private Underground Utilities

KY 811 was notified prior to the field exploration to mark public utilities and MACA personnel located known private utilities near the boring locations. Underground utilities were encountered in Borings B-

8 (ARV-1) and B-11 (MH-68B) at 1 ½ feet and 1 foot below the surface, respectively. We suspect that the undocumented utilities encountered are old services that are no longer active. However, we recommend a utility locate service contractor be retained the scan the sewer alignment prior to construction.

5.1.4 KARST TOPOGRAPHY

No obvious karst related features were encountered within the borings. However, a portion of the site is underlain by limestone bedrock of the Girkin and St. Genevieve Limestone Formations. As discussed in the site geology section of this report, the KGS website indicates that the areas underlain by limestone site to have a high to very high potential for karst activity and maps several sinkholes within about ¼ mile of the sewer alignment. Sinkholes generally form from the bottom up. During periods of high precipitation, water rises into voids near the top of the limestone bedrock. When the water recedes, wet soil falls into the subsurface voids creating a soil dome. Over time, the soil “dome” reaches the surface where a drop out will occur. All areas underlain by potentially soluble rock such as limestone are at risk due to solutioning and sinkhole activity.

Solution features which are in the process of forming a soil drop-out or sinkhole represent a risk to the project because they are difficult to detect even during construction. To completely explore a site to such an extent as to fully identify the possibility of future karst related problems is not cost effective. It should be understood and accepted by the owner that there is a risk of future ground subsidence when developing in any region where karst activity is known.

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Several methods are available to remediate sinkholes to reduce, but not eliminate, the risk of future damage to structures. Each sinkhole should be evaluated by the geotechnical engineer if remediation is required. If remediation is required, a common practice is to excavate all the soil from within the solution feature to competent bedrock and install an inverted filter constructed of crushed limestone fill.

For the crushed limestone inverted filter procedure, once all the soil and debris has either been removed to the throat of the sinkhole or a specific depth, the bottom and sides of the excavation are lined with a non-woven geotextile fabric. Crushed limestone is then placed in lifts into the excavation with larger rock at the bottom and progressively smaller stone to the top. The geotextile fabric is then lapped over of the crushed stone and a clay cap is then placed and compacted on top of the fabric. DDS should be contacted if a sinkhole is encountered during construction for guidance.

5.1.5 SEWER PIPELINE MATERIAL CONSIDERATIONS

We understand the existing sanitary sewer pipeline consist of PVC and clay piping. The type of pipe replacement is unknown. Per the NRCS soil survey website, most of the subsurface soils have a moderate to high risk of corrosion of steel. The NRCS soil survey says the “Risk of Corrosion” pertains to potential soil-induced electrochemical or chemical action that corrodes or weakens uncoated steel.

The rate of corrosion of uncoated steel is related to such factors as soil moisture, particle size distribution, acidity, and electrical conductivity of the soil. We recommend that if ductile iron pipe is used, it should be coated to protect from corrosion.

5.1.6 OLD PREVIOUSLY PLACED FILL

Old previously placed fill was encountered in soil test borings B-7 (MH-72) located east of and between the Visitors Center and Lodge, B-33 (MH-38a) and B-37 (MH-42) located in the Staff Housing Area, and B-44 (MH-47) located in the Maintenance Facilities area near the fueling station. The old fill ranged from about 2 ½ feet to 6 feet thick and consisted of soft to stiff brown to dark brown clay with some gravel. Some of the old clay fill was organic laden in B-44 (MH-47) in the maintenance facility area near the fueling station. Pipes or manhole structures should not be founded on soft or organic laden fill. If old soft or organic laden fill is encountered during trench excavation, we recommend that the trenches be undercut to stiff residual soils and backfilled with approved structural backfill.

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6 CONSTRUCTION RECOMMENDATIONS

6.1 BEDDING RECOMMENDATIONS

Bedding is required to establish line and grade and to provide a firm, but not hard, pipe support. All bedding materials and methods should be in accordance with the specific pipe manufacturer’s recommendations. Typical bedding consists of a 6 inch thick layer of compacted angular material such as #9M, #67, or #57 sized crushed limestone.

We understand the proposed sewer will be embedded up to 10 feet below the top of ground. Based on the data from our soundings and borings, bedrock will be encountered at several locations along the sewer alignment. Sewer pipes should not be founded directly on bedrock due to risk of point loading which could eventually damage the pipe. If bedrock is encountered during the sewer excavation, the bedrock should be undercut a minimum of 6 inches below the bottom of the pipe and backfilled with the specified bedding material.

As mentioned in Section 5.1.6. of this report, some previously placed organic laden fill was encountered in 4 of the soil test borings. The thickness ranged from about 2 ½ feet to 6 feet thick. If any organic laden fill of very soft soils are encountered at the planned bottom of trench, we recommend that soils be undercut to stiff residual soils or remediated in place and backfilled to the bottom of pipe with the specified bedding material.

6.2 STRUCTURAL FILL TO BE USED AS BACKFILL

Haunch Area

The haunching area of the backfill envelope provides the majority of the resistance against soil and traffic loading. The backfill material should be installed uniformly in lifts on each side of the pipe. The backfill should be shoveled under the pipe while taking care to fill the void space. All backfill materials and methods in the haunch area should be in accordance with the specific pipe manufacturer’s recommendations. Typical backfill in the haunch area consists of 4 inch thick lift(s) of compacted angular material such as #9M, #67, or #57 sized crushed limestone from the top of bedding to the pipe spring line.

5314 MACA SANITARY SEWER, HDR, GEOTECH REP 03262020 Page 16 of 20

Initial Backfill

Initial backfill above the spring line must provide adequate pipe support and protect the pipe from potential coarser materials from the final backfill. The initial backfill should extend a minimum of 12 inches above the crown of the pipe. We recommend that the initial backfill consist of the same angular material used for the haunch such as #9M, #67, or #57 sized crushed limestone. The contractor should exercise caution when placing and compacting the haunching envelope and initial backfill to avoid deformation or damage to the pipe.

Final Backfill

Typically, soil containing less than three percent of organic material by volume, plasticity index (PI) less than 35, maximum particle size of 3 inches, and a minimum standard Proctor maximum dry density of

95 pounds per cubic foot can be used as final backfill. Final backfill should be placed in lifts of uniform thickness. The lift thickness should not exceed that which can be properly compacted throughout its entire depth with the equipment available, usually no more than eight inches. We recommend that final backfill be compacted to 95 percent of the standard Proctor maximum dry density (ASTM D-698. The soil moisture content should be maintained between about +/- 2% of its standard Proctor optimum moisture content.

Based on subsurface conditions encountered in the soil test borings, most of the soils excavated from the trench can be re-used as final backfill. The following paragraph discuss areas where some excavation spoils may not be able to be used as final backfill. During trench excavation, care should be taken to separate all soils not meeting the aforementioned criteria from soils that are suitable for use as final backfill.

Some previously placed organic laden fill was encountered in some of the soil test borings. Organic laden soils should not be used as final backfill. Some fat clay was encountered in the borings. When placing high plasticity clay, strict control of the moisture content should be maintained to reduce shrink/swell potential and potential pumping and rutting of the subgrade. Fat clays with a plasticity index greater than 35 should not be used as final backfill. Water was recorded in 6 of the exploratory borings and 3 of those boring recorded water in the upper 3 inches. These soils will likely be unsuitable for use as final backfill due to excessive moisture content.

5314 MACA SANITARY SEWER, HDR, GEOTECH REP 03262020 Page 17 of 20

6.3 GEOTEXTILE MATERIAL FOR RETENTION OF BASE SOILS

Groundwater and drainage flow during and after construction causes migration of fines when coarse and open-graded material is placed adjacent to finer material which often occurs along the trench wall. This migration of fines can cause degradation of the pipe envelope and result in excessive deformation and poor performance of the pipe. As noted in earlier section of this report, water was recorded in 6 of the exploratory borings and in 3 of those borings, the water level was recorded in the upper 3 inches. These subsurface conditions can lead to migration of fines and result in poor pipe system performance.

To reduce the potential for migration of base soils, consideration should be given to specify a non-woven geotextile filtration and separation fabric to line the bottom and sidewalls of the trench excavation. The fabric should encompass and be lapped around the bedding, haunch, and initial backfill envelope.

6.4 GROUNDWATER CONTROL AND DEWATERING PROCEDURES

Most of the borings were dry at the completion of soil augering. However, as noted in Section 3.2 of this report, water was encountered in 6 of the exploratory locations. Groundwater seepage is expected during excavations at some locations, particularly near the staff housing area near borings B-36 and B-

37 where water levels were measured at the surface at the time of drilling and after the minimum 24 hour second reading. Assessment of the need for groundwater control and installation of appropriate dewatering equipment is the contractor’s responsibility at the time of construction. Good excavation procedures should include an adequate dewatering plan to lower and maintain the water level at least a few feet below the lowest adjacent grade. We anticipate that at a minimum, conventional pump(s) and sump arrangement will be needed at some locations. Control of the groundwater should be accomplished in a manner that will preserve the strength of the foundation soils, will not cause instability of the excavation, and will not result in damage to adjacent structures.

6.5 STABILITY OF CUT/FILL SLOPES

At the time of this report’s completion, planned cut and fill slopes are not known. Based on our understanding of the project, we do not anticipate cut of fill slopes greater than 3 feet. A detailed slope stability analysis for any temporary or permanent conditions was beyond the scope of this report. The

5314 MACA SANITARY SEWER, HDR, GEOTECH REP 03262020 Page 18 of 20 contractor is solely responsible for designing and constructing stable, temporary excavations and should shore, slope, or bench the sides of the excavations as required to maintain stability of the sides and bottom of the excavations. All excavations should be performed in accordance with Subpart P of OSHA

Standards for the Construction Industry (29 CFR Part 1926 Subpart P). Care should be taken to not disturb the base soils or to undermine the existing adjacent structures during trench excavations.

6.7 OSHA TEMPORARY EXCAVATION REQUIREMENTS

Trench excavations should be shored, laid back to a stable slope or some other equivalent means to provide safety for workers and protection to adjacent structures in accordance with OSHA guidelines.

Assessment of the need for excavation sloping, use of trench boxes, or other measures required to provide a stable excavation, and the use of appropriate construction practices and/or equipment is the contractor’s responsibility. All excavations should be performed in accordance with Subpart P of

OSHA Standards for the Construction Industry (29 CFR Part 1926 Subpart P). Care should be taken to not disturb the base soils or to undermine the existing adjacent structures during trench excavations.

6.7 OBSERVATION AND MONITORING DURING CONSTRUCTION

We recommend that trench excavation and backfill be monitored during construction to verify that construction is performed in conformance with project specifications. We recommend that DDS be retained to provide these services. DDS routinely provides materials testing services and is an accredited testing laboratory. This will allow us to observe that construction is completed per our recommendations and that any changes necessary can be completed in a timely manner in the best interest of the owner. We cannot be responsible for interpretation of the data contained herein by others.

7 LIMITATIONS OF RECOMMENDATIONS

The conclusions and recommendations presented herein are based on our observations, data obtained from the subsurface exploration, and experience using the degree of care and skill ordinarily exercised under similar circumstances by competent members of the engineering profession. No guarantees can be made regarding the continuity of conditions between borings. The soil and rock conditions at other locations on the site may differ from those reflected by the boring locations referenced in this report.

5314 MACA SANITARY SEWER, HDR, GEOTECH REP 03262020 Page 19 of 20

This office is not responsible for the conclusions, opinions, or recommendations of others based on the information contained in this report.

Our scope of services did not include any environmental assessment of site conditions including the presence of wetlands or hazardous or toxic material present in the subsoil or bedrock. Any references to odors, colors, or irregular conditions are from visual observations and informational purposes only.

Any revision in the plans for any of the proposed structures should be brought to the attention of the geotechnical engineer so that we may determine whether any changes in the foundation recommendations are necessary or additional exploration is required. If deviations from the noted subsurface conditions are encountered during the construction, they should also be brought to the attention of the geotechnical engineer. When the final design is complete, our office should be given the opportunity to provide the additional service of reviewing the foundation plan, grading plan, and other portions of the project impacted by this report. This review will allow us to check whether these documents are consistent with our recommendations.

We recommend that the owner hire our firm to perform all observation, testing, and inspection services related to recommendations contained in this report. This will allow us to observe that site preparation, engineered fill, and foundation construction is completed per our recommendations and that any changes necessary can be completed in a timely manner in the best interest of the owner. We cannot be responsible for interpretation of the data contained herein by others.

5314 MACA SANITARY SEWER, HDR, GEOTECH REP 03262020 Page 20 of 20

APPENDIX

BORING AND SITE LOCATION EXHIBIT

BORING RECORDS

LABORATORY TESTING DATA SUMMARY

LABORATORY TESTING DATA SHEETS

FIELD TESTING PROCEDURES

LABORATORY TESTING PROCEDURES

INFORMATION ABOUT YOUR GEOTECHNICAL REPORT

PREPARED BY

MARCH 26, 2019

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GEOTECH/TOPOGRAPHIC SURVEY

PAGE: 1 OF 23

MAMMOTH CAVE

0 200Feet O #7 STP Boring

"S Bedrock Sounding

&É Air Release Valve Replacement Waters of the U.S.

PEMA Wetland PFOA Wetland

!!2 Manhole No Replacement

!!2 Manhole Replace Topographic Survey

No Replacement needed 4" Replace

6" Replace 8" Replace

Replace Unknown Size

= Force Sewer Main - No Replacement

2 3 4

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Sunset Point Lift Station Grease Trap

Great Relief Hall Lift Station

Hotel Cottage Lift Station

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GEOTECH/TOPOGRAPHIC SURVEY

PAGE: 2 OF 23

MAMMOTH CAVE

0 200Feet O #7 STP Boring

"S Bedrock Sounding

&É Air Release Valve Replacement Waters of the U.S.

PEMA Wetland PFOA Wetland

!!2 Manhole No Replacement

!!2 Manhole Replace Topographic Survey

No Replacement needed 4" Replace

6" Replace 8" Replace

Replace Unknown Size

= Force Sewer Main - No Replacement

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Fire Station Road Green River Ferry Road

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Employee Lift Station (Re-coat Wet Well)

Fire Pump Building

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GEOTECH/TOPOGRAPHIC SURVEY

PAGE: 3 OF 23

MAMMOTH CAVE

0 200Feet O #7 STP Boring

"S Bedrock Sounding

&É Air Release Valve Replacement Waters of the U.S.

PEMA Wetland PFOA Wetland

!!2 Manhole No Replacement

!!2 Manhole Replace Topographic Survey

No Replacement needed 4" Replace

6" Replace 8" Replace

Replace Unknown Size

= Force Sewer Main - No Replacement

2 3 4

14 15

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Employee Lift Station (Re-coat Wet Well)

Fire Pump Building

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GEOTECH/TOPOGRAPHIC SURVEY

PAGE: 4 OF 23

MAMMOTH CAVE

0 200Feet O #7 STP Boring

"S Bedrock Sounding

&É Air Release Valve Replacement Waters of the U.S.

PEMA Wetland PFOA Wetland

!!2 Manhole No Replacement

!!2 Manhole Replace Topographic Survey

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6" Replace 8" Replace

Replace Unknown Size

= Force Sewer Main - No Replacement

2 3 4

14 15

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GEOTECH/TOPOGRAPHIC SURVEY

PAGE: 5 OF 23

MAMMOTH CAVE

0 200Feet O #7 STP Boring

"S Bedrock Sounding

&É Air Release Valve Replacement Waters of the U.S.

PEMA Wetland PFOA Wetland

!!2 Manhole No Replacement

!!2 Manhole Replace Topographic Survey

No Replacement needed 4" Replace

6" Replace 8" Replace

Replace Unknown Size

= Force Sewer Main - No Replacement

2 3 4

14 15

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Elevator Lift Station (Re-coat

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GEOTECH/TOPOGRAPHIC SURVEY

PAGE: 6 OF 23

MAMMOTH CAVE

0 200Feet O #7 STP Boring

"S Bedrock Sounding

&É Air Release Valve Replacement Waters of the U.S.

PEMA Wetland PFOA Wetland

!!2 Manhole No Replacement

!!2 Manhole Replace Topographic Survey

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6" Replace 8" Replace

Replace Unknown Size

= Force Sewer Main - No Replacement

2 3 4

14 15

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ACCESS

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GEOTECH/TOPOGRAPHIC SURVEY

PAGE: 7 OF 23

MAMMOTH CAVE

0 200Feet O #7 STP Boring

"S Bedrock Sounding

&É Air Release Valve Replacement Waters of the U.S.

PEMA Wetland PFOA Wetland

!!2 Manhole No Replacement

!!2 Manhole Replace Topographic Survey

No Replacement needed 4" Replace

6" Replace 8" Replace

Replace Unknown Size

= Force Sewer Main - No Replacement

2 3 4

14 15

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ACCESS

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GEOTECH/TOPOGRAPHIC SURVEY

PAGE: 8 OF 23

MAMMOTH CAVE

0 200Feet O #7 STP Boring

"S Bedrock Sounding

&É Air Release Valve Replacement Waters of the U.S.

PEMA Wetland PFOA Wetland

!!2 Manhole No Replacement

!!2 Manhole Replace Topographic Survey

No Replacement needed 4" Replace

6" Replace 8" Replace

Replace Unknown Size

= Force Sewer Main - No Replacement

2 3 4

14 15

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GEOTECH/TOPOGRAPHIC SURVEY

PAGE: 9 OF 23

MAMMOTH CAVE

0 200Feet O #7 STP Boring

"S Bedrock Sounding

&É Air Release Valve Replacement Waters of the U.S.

PEMA Wetland PFOA Wetland

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!!2 Manhole Replace Topographic Survey

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GEOTECH/TOPOGRAPHIC SURVEY

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MAMMOTH CAVE

0 200Feet O #7 STP Boring

"S Bedrock Sounding

&É Air Release Valve Replacement Waters of the U.S.

PEMA Wetland PFOA Wetland

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!!2 Manhole Replace Topographic Survey

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6" Replace 8" Replace

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= Force Sewer Main - No Replacement

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GEOTECH/TOPOGRAPHIC SURVEY

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MAMMOTH CAVE

0 200Feet O #7 STP Boring

"S Bedrock Sounding

&É Air Release Valve Replacement Waters of the U.S.

PEMA Wetland PFOA Wetland

!!2 Manhole No Replacement

!!2 Manhole Replace Topographic Survey

No Replacement needed 4" Replace

6" Replace 8" Replace

Replace Unknown Size

= Force Sewer Main - No Replacement

2 3 4

14 15

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GEOTECH/TOPOGRAPHIC SURVEY

PAGE: 12 OF 23

MAMMOTH CAVE

0 200Feet O #7 STP Boring

"S Bedrock Sounding

&É Air Release Valve Replacement Waters of the U.S.

PEMA Wetland PFOA Wetland

!!2 Manhole No Replacement

!!2 Manhole Replace Topographic Survey

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6" Replace 8" Replace

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2 3 4

14 15

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GEOTECH/TOPOGRAPHIC SURVEY

PAGE: 13 OF 23

MAMMOTH CAVE

0 200Feet O #7 STP Boring

"S Bedrock Sounding

&É Air Release Valve Replacement Waters of the U.S.

PEMA Wetland PFOA Wetland

!!2 Manhole No Replacement

!!2 Manhole Replace Topographic Survey

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6" Replace 8" Replace

Replace Unknown Size

= Force Sewer Main - No Replacement

2 3 4

14 15

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Mammoth Cave Parkway

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GEOTECH/TOPOGRAPHIC SURVEY

PAGE: 14 OF 23

MAMMOTH CAVE

0 200Feet O #7 STP Boring

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