671-18-106 Design Analysis Report FINAL_Redacted.pdf

ISSUED FOR CONSTRUCTION

DESIGN SUBMISSION – BRINE

TANK & WATER SOFTENER

REPLACEMENT

DESIGN ANALYSIS

U.S. DEPARTMENT OF VETERANS AFFAIRS

AUDIE L. MURPHY MEMORIAL VA HOSPITAL

SAN ANTONIO, TEXAS

Project Number: 671-18-106

23 OCTOBER 2020

Issued for Construction Design Analysis

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TABLE OF CONTENTS

PART I. - GENERAL DESCRIPTION

1 PURPOSE

1.1 SCOPE OF WORK

1.2 AUTHORIZATION

1.2.1 DESIGN DIRECTIVE

1.2.2 A/E CONTRACT DATA

1.3 ENGLISH/METRIC

1.4 CRITERIA

1.5 PROJECT DESCRIPTION

1.5.1 PROJECT SITE

1.6 REVIEW MEETINGS

1.6.1 Kickoff Meeting – 9 August 2018

1.6.2 25% Review Meeting – 11 September 2018

1.6.3 50% Review Meeting – 4 October 2018, Teleconference

1.6.4 50% Resubmission Review Meeting – 21 February 2020

1.6.5 95% Review Meeting – 7 August 2020

1.7 COST ESTIMATE ................................. ERROR! BOOKMARK NOT DEFINED.

PART II. - STRUCTURAL EVALUATION

2 GEOTECHNICAL & STRUCTURAL ANALYSIS

2.1 GEOTECHNICAL AND MATERIAL EVALUATION

2.1.1 Brine Tank Area Evaluation

2.1.2 Water Softener Room Evaluation

2.2 STRUCTURAL EVALUATION & RECOMMENDATIONS

2.2.1 As-Built Plans

2.2.2 Site Observation Visits – 8 October 2019 and 21 February 2020

2.2.3 Structural Recommendations

2.2.3.1 Water Softener Room Walls

2.2.3.2 Water Softener Room Floor

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2.2.3.3 Existing Underground Brine Tank

2.3 BRINE LINE CCTV INSPECTION

2.4 CONCLUSIONS

2.4.1 Water Softener Room Walls

2.4.1.1 Southern and Eastern Walls (Non-load bearing)

2.4.1.2 Northern Wall (Exterior Wall)

2.4.2 Water Softener Room Floor

2.4.3 Water Softener Room Western Retaining Wall

2.4.4 Meter Room Western Wall

2.4.5 Western Column adjacent to Western Retaining Wall

2.4.6 Water Softener room Sanitary Drain

PART III. – WATER SOFTENER DESIGN

3 WATER SOFTENER DESIGN

3.1 AS-BUILT FILES

3.2 MONTHLY WATER USAGE

3.3 WATER USAGE PROFILE

3.4 SITE OBSERVATION VISITS

3.4.1 Initial Site Visit – 6 April 2018

3.4.2 Site Visit – 8 October 2019

3.5 HAZARDOUS MATERIALS LIMITED SURVEY

3.6 WATER SOFTENER SIZING

3.6.1 WATER SOFTENER PARAMETERS

3.6.1.1 Design Parameters/System Selection

3.6.1.2 Brine Day Tank

3.6.1.3 External Brine Transfer Pumps

3.6.1.4 Project Phasing

PART IV. – EXTERIOR BRINE TANK DESIGN

4 EXTERIOR BRINE TANK DESIGN

4.1 BRINE TANK SIZING

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4.2 STRUCTURAL DESIGN

4.2.1 STRUCTURAL CALCULATIONS

PART V. – ELECTRICAL DESIGN

5 ELECTRICAL DESIGN

5.1 BRINE TANK

5.1.1 INSTRUMENTATION & CONTROLS

5.1.2 BRINE DAY TANK FLOW MONITOR

5.2 BRINE TRANSFER PUMPS

5.2.1 INSTRUMENTATION & CONTROLS

5.3 WATER SOFTENER ROOM

5.3.1 INSTRUMENTATION & CONTROLS

APPENDIX A – CONSTRUCTION DRAWINGS

APPENDIX B – CONSTRUCTION SPECIFICATIONS

APPENDIX C – REVIEW MEETING MINUTES

APPENDIX D – BRINE TANK INSPECTION REPORT

APPENDIX E – STRUCTURAL OBSERVATION REPORT

APPENDIX F – MANUFACTURER CUTSHEETS

APPENDIX G – GROUND PENETRATING RADAR (GPR) SCAN REPORT

APPENDIX H – CONSTRUCTION COST PROJECTION

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PART I. - GENERAL DESCRIPTION

1 PURPOSE

The purpose of this narrative is to present the design criteria, proposed plans and rationale for the modification and design of a new water softener system at the Audie L. Murphy Memorial VA Hospital. This report also provides evaluation and recommendations for the condition of the Water

Softener room walls, floor and brine tank, and the geotechnical data analysis for the exterior area where the new brine tank will be placed.

1.1 SCOPE OF WORK

The original scope of the project includes the design for replacement of the four existing water softeners, including the composite water softener tanks and associated equipment. The initial phase of the project included an assessment of the existing underground concrete brine tank. The assessment, as discussed below, determined that the tank should be replaced. The VA has decided to replace with an above ground tank and abandon the existing tank in place. The design contract was modified to include design of the brine tank replacement as well. During the brine tank assessment, it was determined that the existing floors and walls of the water softener room had been damaged by salt absorption. The scope modification included an evaluation of the structural integrity of the existing walls and floors, the results of which are discussed herein. Contract drawings, specifications, cost estimates and design analysis will be provided as part of this project.

1.2 AUTHORIZATION

1.2.1 DESIGN DIRECTIVE

Task Order on Contract No. . is identified by a letter dated 21 July 2018, to from

, Contracting Officer. This Task Order established a Construction Cost

Limitation (CCL) of for the water softener replacement. The contract modification, dated 21 August 2019, added the design of an above ground brine tank replacement and a structural evaluation of the existing

Water Softener room floor and walls, but it did not adjust the CCL.

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1.2.2 A/E CONTRACT DATA

The design work under this contract is being performed by under the contract for Architect/Engineer Services, . Notice of proceed date for this project was

1 August 2018. A modification P0004 was executed on 21 August 2019 to provide design of new above ground brine tank and further structural evaluation of the existing Water Softener room walls and floors and brine line.

1.3 ENGLISH/METRIC

The design information for this project will utilize English dimensions.

1.4 CRITERIA

Design of the proposed project will be accomplished in accordance with the following criteria (latest version unless specific date is noted):

VA Design Criteria.

[1] International Building Code (2018) [2] International Plumbing Code (2018) [3] International Energy Conversation Code (2018) [4] NFPA 70: National Electric Code (2017) [5] OSHA Code: Occupational Safety and Health Administration Code [6] Plumbing Design Manual: VA Office of Construction & Facilities

Management (Nov 2014) [7] Whole Building Commissioning Process Manual: VA Office of

Construction & Facilities Management (May 1, 2013) [8] Site Development Design Manual (February 2013)

1.5 PROJECT DESCRIPTION

1.5.1 PROJECT SITE

Installation: Audie L. Murphy Memorial VA Hospital

Latitude 29.506803, Longitude -98.579875, Elevation approximately 970 feet above sea level

Site: The physical address of the hospital is 4700 Merton Minter Blvd, San

Antonio, TX 78229.

The project work will occur generally at two locations, where the exterior brine tank is located, and where the water softeners themselves are located.

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The two are connected by an underground 2-inch brine line that runs from the brine tank underground to the mechanical basement space, and then above grade through the mechanical basement space to the water softener room.

The existing exterior brine tank is located on the northeastern part of the

Audie L. Murphy Memorial Hospital property. The area encompassed by the existing underground tanks encompass an area of approximately 570 square feet (the main tank is 31 ft by 11 ft; mixing tank is 7 ft x 9 ft; tanks are approximately 11 feet deep). Refer to Figure 1.1.1 below for layout of the area.

Figure 1.1.1 – Area of Interest

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Figure 1.1.2 – Brine Tank location

The Water Softener room is located approximately 300 feet due south of the brine tank. Refer to the green outline for approximate location of the

Water Softener room with respect to the brine tank. Figure 1.1.3 below shows the entrance to the Water Softener room.

Figure 1.1.3 – Water Softener room entrance

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1.6 REVIEW MEETINGS

The meeting minutes for these review meetings can be viewed in Appendix

C.

1.6.1 Kickoff Meeting – 9 August 2018

The kickoff meeting for this design included reviewing the scope, requesting available design documents and as-builts, discussing plans to capture data for an asbestos survey of the Water Softener room and structural assessment of the exterior brine tanks.

1.6.2 25% Review Meeting – 11 September 2018

The 25% review meeting included discussing the new softener design, remaining data collection, and construction phasing, and performing a field assessment of the underground tank. Per this assessment recommendations were made and accepted by the VA to replace the existing underground brine tank.

1.6.3 50% Review Meeting – 4 October 2018, Teleconference

As part of this meeting, the Asbestos survey report (provided as an attachment in Appendix B – 95% DD Specifications) and Brine Tank

Inspection Report (provided in Appendix D), construction phasing, Water

Softener design, brine measuring tank location, construction phasing, and

Water Softener room structural integrity were reviewed. VA personnel emphasized that they want to pursue the following items:

• A/E recommends replacement of the both brine tanks with above ground tanks

• VA wants N+1 redundancy in the Water Softener system design. VA prefers to have 4 tanks even though 3 tanks satisfies N+1

• Water Softener room walls and floors should be further evaluated for structural integrity

• Consider locating the brine measuring tank outside to reduce salt corrosion and provide more space inside the room for the softeners.

1.6.4 50% Resubmission Review Meeting – 21 February 2020

As part of this meeting, the design team reviewed the 50% Resubmission report with the VA to discuss structural recommendations and potential add services to the current design. The A/E recommended the following items:

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• VA consider replacing the northern wall with CMU block to meet current code requirements. VA was accepting of this recommendation.

• VA consider replacing the entire slab of the room, including the Meter

Room behind

• VA consider repairing the western retaining wall that supports the

Water Softener room slab

• VA consider further investigation during demolition of the structural integrity beneath the slab, northern wall supports, and western structural column.

1.6.5 95% Review Meeting – 7 August 2020

As part of this meeting, the design team reviewed the 95% comments and discussed the project deliverables. The design decisions table which shows the responses to the review comments can be found in Appendix C.

1.6.6 100% Review Meeting – 13 October 2020

As part of this meeting, the VA had a few final questions after an on-site walk through with the VA staff. These questions were responded to by the design team and applicable comments are addressed in the final submission. Comments from this meeting can be viewed in Appendix C.

1.7 CONSTRUCTION COST PROJECTION

The construction cost projection includes line items for the proposed work of this project and also the add alternates that are discussed in the sections of this report. An updated cost estimate is provided in Appendix H.

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PART II. - STRUCTURAL EVALUATION

2 GEOTECHNICAL & STRUCTURAL ANALYSIS

2.1 GEOTECHNICAL AND MATERIAL EVALUATION

2.1.1 Brine Tank Area Evaluation

Core samples were taken of the existing tanks to determine the subsoil composition. Two borings were collected to depths of 10 and 75 feet below the existing ground surface. A summary of the findings are as follows:

The borings encountered approximately 6 to 7 inches of concrete over 6 to

12 inches of crushed gravel fill material.

The soil conditions were consistent with the mapped geology. Boring B-1 encountered mottled dark gray, gray, and light gray clay beneath the crushed gravel fill to about 7 ½ ft. This clay appears to be fill material likely placed during construction of the below-ground pit. Beneath the fill material, light gray clay was encountered to 9 ½ to 10 feet, the clay was underlain by light gray and tan marlstone. Visually, the near-surface clays encountered in the upper 10 feet appeared to be highly-plastic with a very high shrink/swell potential.

Water was not observed during dry drilling operations. If encountered groundwater seepage could be controlled using sumps and pumps to allow for the construction of the new tanks.

Drilled piers may be used to support the new tank structure. The drilled piers should have a minimum diameter of 24 inches extend a minimum of 5 feet into the marlstone materials encountered at about 10-ft depth.

The abandoned tank can be left in place and backfilled with flowable fill.

2.1.2 Water Softener Room Evaluation

Core samples of the walls and floor slab were collected and evaluated. Two locations were cored to determine the condition of the interior slab. A summary of the findings are as follows:

The slab thickness varied from 5 to 6 inches thick. Both cores broke apart during removal; intact samples for strength testing were not recovered. R-meter readings indicated the slab contained reinforcing steel on 6-inch centers each way, suggesting the reinforcement consisted of wire-mesh. R-

Water Softener/Brine Tank Replacement Page 12 meter readings performed on the walls did not indicate vertical steel reinforcement. Probe holes were taken in the existing CMU wall at two locations on the Eastern wall (refer to report for coring locations). The existing CMU blocks were observed to be hollow. Neither grout-filled cells nor reinforcing were found within the probe holes.

The observed condition of the interior cores suggests the interior slab is in

“poor” condition. A discontinuity was observed at about 2 to 3 inches below the top of the slab. The discontinuity appeared to be a cold-joint; possibly a topping slab installed as part of a previous repair.

Detailed geotechnical findings for the samples of both the brine tanks and

Water Softener room is provided as an attachment in Appendix B – 95%

DD Specifications.

2.2 STRUCTURAL EVALUATION & RECOMMENDATIONS

2.2.1 As-Built Plans

The VA provided partial as-built plans for portions of the original water softener room area from 1973. These plans show the structural framing for the building including the first-floor beams and deck above and the basement floor beams below the water softener room. The water softener floor slab details are shown and limited details for the wall sections are provided. From the plans it appears that the water softener room slab was originally a 6-inch slab on grade with unknown reinforcing. The slab is shown to be tied to the grade beams with # 3 dowels at 30 inches on center and to the retaining wall with #3 dowels at 24 inches on center. This differs somewhat from the field observations, as discussed below. Limited details for the Water Softener room walls were shown on the provided plans. It appears that the north wall was originally an exterior wall (brick façade exterior and CMU interior) and is founded on a structural beam that is part of the basement foundation structure. The south wall of the Water Softener room is also supported on a foundation grade beam. The east Water

Softener room wall is not shown but appears to be constructed upon the

Water Softener room slab.

The Water Softener room sits about 5’-8” feet higher than the mechanical basement level but is open to the rest of the mechanical space. There is a retaining wall (referred to as the western retaining wall in this report) that creates the step down from the Water Softener room to the mechanical basement. The plans show that the western retaining is part of the

Water Softener/Brine Tank Replacement Page 13 foundation system, supports the masonry walls positioned above the retaining wall, the west end of the foundation grade beams positioned beneath the north and south Water Softener room walls, as well as supporting the surcharge loads from the Water Softener room slab.

As-built plumbing plans for the discharge and supply piping in the Water

Softener room have not been located. A metal grate covering a 6-inch

“backwash” sump drain is centrally located inside the room to dispense the salt discharge. A manhole cover and storm drain inlet are located in the exterior pavement at the northern entrance to the Water Softener room; but, received as-built plans do not indicate any further information on the routing of this inlet. As part of the data gathering process for the 50% Resubmission phase, the A/E contracted a plumbing company to video the plumbing line that is attached to the salt discharge grate. The video showed that the existing cast iron pipe is badly damaged, with pieces of cast iron pipe dislodged within the pipe. Video of the pipe assessment was not recoverable, but the VA has indicated they will provide an approximate layout of this line location. At the time of this report, this diagram has not been provided. The contract documents indicate that the Contractor shall evaluate all existing lines connected to this system to determine if they are sufficiently viable to ensure a functional system. If the Contractor verifies the findings of the plumbing company, the VA may be required to provide a mod to the Contractor to replace this line with a corrosion-resistant material.

The civil as-builts show the location of the brine tanks, supply lines, sanitary sewers and dimensions of the tanks (refer to Figure 2.2.1). The exterior brine tank is compartmentalized into three sections: two main salt storage tanks sized 15’x11’ each and a smaller tank sized at 8’ x 7’. The brine tank is configured in a “T” shape and is 10’-11” deep, which correlates with the field measurement of the tanks. A 2-inch PVC brine line extends from the southeastern portion of the tank, a 2-inch copper encased hard water line supplies water to the tanks from the north, and sanitary line (size undetermined from as-builts) exits the tanks from the southwestern side of the smaller brine compartment. A ground penetrating radar (GPR) scan was conducted on-site on 6 November 2019 and confirmed the location of the 2-inch brine line and sanitary line (which is a 4-inch line) that run towards the Water Softener room. The findings from the GPR scan can be found in

Appendix G.

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Figure 2.2.1 – Civil As-Built showing Brine Tank and Utilities

2.2.2 Site Observation Visits – 8 October 2019 and 21 February 2020

Structural observations were made during a site visit on 8 October 2019 and

21 February 2020. Additional comments can be found in the Structural

Observation Report in Appendix E. Recommendations based on the site visit and geotechnical data are provided below.

2.2.3 Structural Recommendations

2.2.3.1 Water Softener Room Walls

Heavy efflorescence, delamination, and signs of corrosion were observed in all of the partition masonry walls surrounding the room. Damage was observed on both sides of the walls all around the room. The presence of efflorescence on the back sides of the walls is evidence of salt and water transmission through the walls and is generally a sign of internal deterioration. The delamination that was observed appears to be isolated to the outside face shells of the masonry block. Signs of corrosion were observed only around the door jambs.

The most extensive damage was observed near the bases of the walls.

The heaviest deposits of salts were observed along the joint lines. This is expected, as the lower portions of the walls would have been most routinely exposed to salts used in the water softening process.

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In addition to damage to the walls surrounding the Water Softener room, the common wall between the Water Softener room and the Meter room

(AB20b) beyond the water softeners was damaged. A large ‘stair-step’ crack was also observed on the west wall of the Meter room.

The common wall between the Water Softener room and the Meter room and the west wall of the Meter room do not appear to be load-bearing based on a visual observation from an opening in the ceiling. The walls are not attached to the structure above. The top of the north wall of the Water

Softener room could not be observed from the opening in the ceiling. Per the structural framing plan shown on I-S72 the floor structure above the

Water Softener room is supported by concrete encased steel beams, thus the north wall is not load-bearing. Further per detail 7/I-S80 on the structural as-builts, the north wall appears to be a double wythe exterior masonry wall with exterior brick wythe and 4” CMU interior wythe. This type of wall structure does not typically contain vertical reinforcing and from the plans is likely an infill wall. Typically, these wall types would not have been used as load-bearing walls and under current model building codes, this type wall is no longer allowed for exterior walls. Since this wall is still technically an exterior wall and subject to wind loading, if it is to be demolished and replaced, the design would likely require a different wall system. Refer to figures 2.2.1 through 2.2.4 for enhanced photos above the ceiling spaces and location of the concrete encased steel column in the Water Softener room.

The walls were generally determined by the geotechnical engineer to be hollow and unreinforced. The exception to this may be adjacent to the doorway openings on the north wall. Grouted and reinforced vertical cells and masonry lintels above the doorways would be expected in order to carry the weight of the wall above those openings.

Interior partition walls are required by the 2018 International Building Code

(IBC) to be capable of withstanding incidental lateral pressures. Given the condition of the walls, lack of structural reinforcing, the walls do not appear adequate for supporting these internal pressures.

The A/E recommends replacing the existing partition walls along the south and eastern side of the Water Softener room and the north wall of the Water

Softener room. Because of project budget, the VA has asked to not impede the area of the Water Softener room that houses the medical vacuum pumps, and thus a portion of the north wall will remain. An add alternate

Water Softener/Brine Tank Replacement Page 16 will be provided as part of this design package for the VA to include the repair of the entire Water Softener room floor, including the medical vacuum area. Load-bearing walls should not be removed.

Figure 2.2.1 – Ceiling space above Water Softener room showing concrete column

Figure 2.2.2 – Ceiling space above Water Softener room showing north wall and structural beam

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Figure 2.2.3 – Ceiling space above Water Softener room and

Meter room

Figure 2.2.4 – Concrete column located near western retaining wall inside Water Softener room

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2.2.3.2 Water Softener Room Floor

The upper surface of the floor slab has cracked and delaminated throughout the Water Softener room. Compressive tests of cores were requested, but the geotechnical engineer was unable to obtain intact samples. It is our understanding that the cores fell apart upon retrieval.

While the new water softener tanks will sit directly on a ground-supported floor slab, the existing floor slab appears to be unsuitable for new loads. At a minimum, this design replaces the floor slab that will support the new water softener tanks. Ideally, it would be best to replace the entire floor slab within the Water Softener room, including under the medical vacuum equipment, to replace all the salt damaged floor. The slab replacement underneath the medical vacuum area is provided as an add alternate design, which will. likely require the installation of a temporary medical vacuum system while the existing one is moved and the slab and foundation are replaced.

2.2.3.3 Existing Underground Brine Tank

A field assessment was conducted on 11 September 2018 to determine the condition of the existing brine tank. Inspection of the east tank was performed with a pole mounted camera. Photos and videos were taken as part of the assessment. A summary of the findings are as follows:

• The top of the tank is heavily cracked and warped.

• The walls are in relatively better condition than the ceiling and top of the tank but show some signs of cracking and spalling.

• The beams (supporting the top of tank) are more severely damaged.

One shows extensive spalling and the rebar is visible and corroding for the salt environment.

• The bottom of the tank was not visible because of the salt that was still in the tank. However, maintenance personnel that were present noted that the bottom is “broken up.”

Since the overall condition of the tank is in poor condition, a replacement above ground tank is provided as part of this design and is discussed further in Chapter 4 Exterior Brine Tank Design. A detailed report of the existing underground brine tank inspection can be found in Appendix D.

The structural design of the new above ground brine tank is provided in section 4.2 Structural Design.

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2.3 BRINE LINE CCTV INSPECTION

Due to concerns for possible contamination of the potable water source by introducing CCTV cameras into the brine line for inspection, the VA recommends that the A/E provide specifications for the contractor to pressure test the line during construction so the line condition can be determined without contaminating the line. If the line is in good condition, the VA prefers to reuse the existing 2-inch PVC brine line instead of re-piping the line above ground.

2.4 CONCLUSIONS

Based on the gathered data and evaluations as mentioned above, the A/E recommends the following for the remodel of the Water Softener room and surrounding areas:

2.4.1 Water Softener Room Walls

2.4.1.1 Southern and Eastern Walls (Non-load bearing)

The southern and eastern walls of the Water Softener room will be replaced with grouted CMU or some other reinforced wall type. Refer to Figure 2.4.1 for location of the walls.

2.4.1.2 Northern Wall (Exterior Wall)

The northern wall is needed per code since it is an existing exterior wall and protects the equipment in the Water Softener and the Meter rooms from the environment. The northern wall should be replaced based on the following information:

• The wall does not appear to be load bearing from visual observations and plan (refer to section 2.2.3.1 Water Softener Room Walls for more information and photos). But, the as-built plans indicate this is likely an infill wall and non-load bearing.

• The A/E inspected this wall with a pole camera during the 21

February 2020 site visit and visually verified that this wall is non-load bearing.

• The structural integrity of the foundation below the northern wall is inconclusive from the GPR scans and visual inspections. Further data analysis is recommended to evaluate the condition of the grade beam below the wall (which would likely entail removing the surrounding earth during construction and visually inspecting the

Water Softener/Brine Tank Replacement Page 20 grade beam while replacing the floor slab). The A/E recommends having the structural engineer field verify the condition of the grade beam during construction and providing a bid alternate to minimize uncertainty for the contractor. To save potential construction costs, grade beam repairs are spilt into separate alternates in case the condition of the north and south grade beams significantly differ:

o Bid Alternate #3 would require the contractor to replace the entire grade beam and the northern wall.

o Bid Alternate #4 would require the contractor to replace the entire grade beam on the southern wall.

2.4.2 Water Softener Room Floor

At a minimum, the floor slab underneath the water softeners should be removed and replaced.

• Bid Alternate #2 - The floor slab underneath the medical vacuum pumps should also be considered for replacement as part of this scope to avoid compromising the new walls and slab.

• In the adjacent Meter room (which appears to be a continuous slab with the Water Softener room) is in similarly poor condition as the

Water Softener room – the VA should consider replacing this area as part of a future contract.

• Refer to Figure 2.4.2 for outline showing the floor areas in scope.

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Figure 2.4.2 – Current Scope of Project

2.4.3 Water Softener Room Western Retaining Wall

The western retaining wall (which is out of this scope of work) shows signs of significant damage and should be considered for potential replacement as part of this scope of work to avoid compromising the repaired Water

Softener room slab and walls.

• Add Alternate #1 – Design includes repairs to this retaining wall to ensure it will properly support the new Water Softener room slab and surrounding structures.

• Refer to Figure 2.4.3 for layout of locations and 2.4.4 through 2.4.7 photos of damaged retaining wall.

Figure 2.4.3 – Western Retaining wall, structural column locations

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Figure 2.4.4 – Lower western retaining wall, exposed rebar (green area in Figure 2.4.3)

Figure 2.4.5 – Lower western retaining wall, exposed rebar north of

Water Softener room (North of green area in Figure 2.1.3)

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Figure 2.4.6 – Lower western retaining wall, cracking on face (Green area in Figure 2.4.3)

Figure 2.4.7 – Lower western retaining wall, spalling on concrete top

(Green area in Figure 2.4.3)

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2.4.4 Meter Room Western Wall

• The condition of the western wall inside the Meter room (which is out of scope) is damaged similarly like the Water Softener room and should be considered for removal or repair. The VA has indicated because of budgetary reasons this will be considered for a future project. Refer to Figure 2.4.1 showing this wall.

Figure 2.4.1 – Western Wall of Meter Room

2.4.5 Western Column adjacent to Western Retaining Wall

The western column located within the Water Softener room (refer to Figure

2.4.3 for the location of this column) may be damaged similarly to the western retaining wall. This area is currently out of scope for this project but should be considered for a future project since it affects the structural integrity of the floor above it.

2.4.6 Water Softener room Sanitary Drain

The drain line that extends underneath the Water Softener room was further evaluated via camera inspection by Beyer Plumbing on 24 February 2020 to determine if a leak is a source of recurring salt damage to the surrounding areas. The inspection revealed that the existing cast iron piping is in poor condition, with pieces of the pipe lodged within the pipe. If Contractor determines any existing line connected to the new water system is too damaged to properly function, the Contractor shall notify the Contracting

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Officer immediately for direction. The drain locations are shown in Figures

2.4.8 and 2.4.9.

Figure 2.4.8 – Water softener discharge drain

Figure 2.4.9 – Storm manhole opening and approx.

location of discharge drain line from Water Softener room

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PART III. – WATER SOFTENER DESIGN

3 WATER SOFTENER DESIGN

3.1 AS-BUILT FILES

The A/E received an electronic (PDF) copy of drawing number I-P70 from the original As-Builts dated 1 October 1973. There are, unfortunately, no newer plans or CAD plans available for this portion of the hospital. It would be helpful to have more mechanical and plumbing plans, as well as electrical power plans, of this area from the 1973 As-Builts if they are available. At the time of this submission, no further As-Builts for this area have been provided.

3.2 MONTHLY WATER USAGE

The A/E also received the monthly water usage for the past three years (last information is from 2016). The average daily usage from this data is approximately 94,000 gallons per day (GPD). The peak flow in gallons per minute (GPM) has also been requested to help size the water softener inlet and outlet pipes. The original As-Built plans show two domestic water booster pumps at 400 GPM each plus one pump at 200 GPM. This coincides with common engineering practice sizing of the 8-inch domestic water line serving the hospital.

3.3 WATER USAGE PROFILE

After the 25% Review Meeting, Mr. Roger Kiker also provided the water usage profile from August 2016 which is consistent with the maximum flow that he had reported through Mr. Albert Evans. The data is recorded in 15-minute intervals and varies from a low of about 90 GPM to a high of about

320 GPM. Refer to Appendix F for details.

3.4 SITE OBSERVATION VISITS

3.4.1 Initial Site Visit – 6 April 2018

Tim Jensen with O’Brien Engineering, Inc. (OEI) and Sam Johnson with JQ

Infrastructure (structural sub-consultant to OEI) made a pre-proposal site visit and met with Mr. Allen Onwuchekwa on 6 April 2018.

One of the two existing underground, concrete brine tanks is not being used due to a damaged or blocked brine discharge pipe. And the other tank may not be fully functional since a smaller, above ground, brine tank in the Water

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Softener room is being used for manual addition of salt for regenerating the water softeners.

One end of the original Water Softener room now has a medical vacuum pump system in it. This has taken over ten feet of space and leaves approximately 23’-11” long by 14’-0” wide area for the new replacement water softeners and brine tank. The room height is approximately 13’-5”.

The original 1973 design had three large water softeners (capacity unknown). These were replaced with the current four smaller softeners.

The softener tanks were manufactured by Pentair and are labeled as 63x67.

The complete water softeners, however, are not labeled with a manufacturer but were installed by Mueller Water Conditioning, Inc. out of

San Antonio, Austin, and Houston. The capacity of these softeners is unknown but the physical size of the Pentair tanks is five feet in diameter.

The cold-water inlet and softened water outlet pipes appear to be 3” which appear to be on the small side, depending upon the actual flowrates.

3.4.2 Site Visit – 8 October 2019

After the mod was received to perform the additional services to replace the exterior under-ground brine tank, an additional site visit was conducted to coordinate with the geotechnical engineers and further evaluate the structural integrity of the room and brine tanks. Details of this evaluation can be found in section Part II. - Structural Evaluation.

3.5 HAZARDOUS MATERIALS LIMITED SURVEY

Asbestos testing was performed on the Water Softener room and no asbestos was found in these samples. No requirements for asbestos abatement have been identified for this project. Per VA standard specifications, existing assessments shall be provided to the Contractor for reference as part of the contract documents. The A/E has provided the complete survey report as Appendix B of the specifications.

3.6 WATER SOFTENER SIZING

Typical water hardness for this area of San Antonio is 17 grains per gallon

(gpg) which is equal to 290 ppm. Water above 10.5 gpg is considered “very hard”. The 17 gpg falls within the typical hardness range of 15 to 20 gpg that is noted on the San Antonio Water System (SAWS) website. We requested a water sample test so that the water softener vendor(s) could

Water Softener/Brine Tank Replacement Page 28 review for other minerals and constituents in the water that could potentially affect the softener capacity, but none was available. We have been told that iron and free chlorine is not an issue so we do not have a great concern.

Therefore, the requirement that the contractor perform a water sample test prior to softener selection.

The required “exchange” capacity of a water softener can be calculated by multiplying the water hardness in grains per gallon by the water use in gallons (over a given time period). On average capacity required is

1,600,000 Grains per day (GPD) (17 gpg times 94,000 GPD).

The synthetic zeolite or polystyrene resin that is generally used in modern water softeners has a typical exchange capacity of 20,000 to 30,000 grains per cubic foot. The high end of the range being achieved by using more salt during regeneration. Therefore, the softeners will need between 53 and

80 cu.ft. of resin to soften an average day’s water use. Large industrial size softeners range in resin capacity size of 50 to 200 cu.ft.

In addition to needing the overall volume of resin required, the water softeners must also be sized for the expected continuous and peak water flowrates. With the information supplied by Mr. Roger Kiker, which showed a peak of 320 GPM, the system will be sized to handle over twice this flowrate to allow not only some expansion, but also additional safety factor.

Please see additional discussion below. Water softener calculations are shown in Table 3.6.1.

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Table 3.6.1 – Water Softener Calculations

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3.6.1 WATER SOFTENER PARAMETERS

3.6.1.1 Design Parameters/System Selection

The VA requires N+1 redundancy (confirmed at the 25% review meeting) for the water softener systems. The goal is to design a system of multiple water softeners such that:

• Each softener has sufficient resin capacity for an average day’s water use (94,000 GPD and 1,600,000 grains exchange capacity min.)

• The system will consist of (4) tanks designed to operate in parallel to meet the maximum flow scenario of 1,000 GPM. The sequence of operation consists of (3) tanks that will run with a minimum of (1) tank in service mode, and the others in standby mode. When product flow rises above a pre-defined setpoint, the tank in standby mode will enter service mode.

• The system is designed so that three softeners will provide soft water to the hospital while the fourth is in regeneration/recovery mode. It takes approximately 78 minutes for the regeneration process to complete

Given the VA requirement to design a system that will fit within dimensional constraints of the Water Softener room in its entirety, an Evoqua, four-softener system complete with day tank, has been selected as the basis of design. Each softener will have a maximum flowrate of 392 GPM and a minimum flowrate of 40 GPM allowing (1) softener to be offline for maintenance as needed.

More specifications for the Evoqua softener system which is used as a basis of design is provided in Appendix F.

3.6.1.2 Brine Day Tank

Currently there is an above ground brine day (measuring) tank temporarily just inside the Water Softener room. The VA is currently utilizing this day tank to manually load salt for the regeneration process. Per conversation with Mr. Garcia of the maintenance department on 21 February 2020, they are currently loading 10 bags of salt three times per day to keep the current system recharged. In addition to requiring regular maintenance, the existing day tank leaks brine water onto the Water Softener room floor for 10-15 minutes when the tank is filled from the brine water (from the external brine

Water Softener/Brine Tank Replacement Page 31 tank). This requires regular attention by the maintenance and is a source of deterioration for the Water Softener room floor and walls.

The new day tank will help alleviate the maintenance and deterioration issues as discussed above. This tank is 60 inches in diameter by 72 inches

(tall) and has an operating weight of 7,407 lbs. Refer to Appendix F for more information about the day tank.

3.6.1.3 External Brine Transfer Pumps

As part of the design, a duplex brine transfer pump system is supplied to distribute the brine solution from the external brine tank 300 feet away from the water softeners. The basis of design consists of a duplex alternating pump skid that is rated for external environmental factors and has a control panel for pump operation. Refer to Table 3.6.2 for pump design characteristics:

Table 3.6.2 – Brine Transfer Pump Characteristics

Property Capacity

Flow Rate 20 GPM Pressure 30 PSI

Horsepower 2 HP

RPM 3450

Voltage/Phase/Freq. 460V/3PH/60HZ

Refer to Appendix F and the plans for more information on this pump system.

3.6.1.4 Project Phasing

The physical space available for the contractor to work in the Water

Softener room may be limited. Refer to the phasing plan for the A/E recommendations on demolition and installation of the systems. Included in the phasing options are bid alternates to provide temporary soft water from a (rented) trailer mounted softener system so that demolition and installation could be performed more easily and quickly. After further evaluation of the systems, the temporary water softener will need to be placed outside near the exterior brine tank due to height, slope and space restrictions within the tunnel. The manufacturer typically provides 50 feet of flexible hose and then the contractor will be responsible for the remaining

200-300 feet of temporary piping. Per VA request, the temporary piping will

Water Softener/Brine Tank Replacement Page 32 be hung from the structure above to try to minimize the impact of VA operations within the tunnel. Also per VA request at the 100% meeting on

13 October 2020, a note has been added to the drawings so the contractor can provide a ramp over the temporary piping so the VA staff will have access the structures adjacent to the temporary piping. Refer to the phasing plan, structural and plumbing details for more information.

Also, if Bid Alternate #2 is selected to remove the medical vacuum system to replace the floor and equipment pad underneath, a temporary medical vacuum system will be required to ensure the system is running continuously throughout construction.

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PART IV. – EXTERIOR BRINE TANK DESIGN

4 EXTERIOR BRINE TANK DESIGN

4.1 BRINE TANK SIZING

The proposed brine tank will require a minimum storage capacity for 30 tons of salt for 3 months of softening. Based on a typical delivery load of 25 tons per load, the proposed tank, as shown on the plans, was sized to hold 50 tons of salt to allow for two full truck loads.

Basis of design for the exterior brine tank is a Marlo MBM 50-ton brinemaker. The brinemaker is capable of handling either granulated or rock/solar salt. The following equipment in Table 4.1 is recommended to ensure smooth and efficient operation of the system design:

Table 4.1 - Exterior Brine Tank Specifications

Equipment Type Standard / Optional

Notes

Passive Pneumatic Salt Fill Pipe Standard Air Vent Pipe w/Dust Control Filter Standard

Access Ladder Standard Liquid Level Controller Standard

Automatic Water Refill Valve Standard Upper & Lower Access Manway Ports Standard Freeze Protection System (Insulation &

Heat Controls) Optional

Insulation recommended at minimum

Salt Level Sensor Standard

4.2 STRUCTURAL DESIGN

The new tank will be located on top of the existing buried brine storage tank.

The existing tank will be abandoned in place due to its deteriorated structural condition. The tank will be filled in with flowable fill material.

The existing top slab will be removed and the upper 3 feet of portions of the tank walls will be cut off. The new brine tank will be supported by a structurally suspended slab on grade beams supported by drilled piers.

4.2.1 STRUCTURAL CALCULATIONS

The slab is designed to support the tank and to span between supporting grade beams. The grade beams are designed to span between the drilled piers. The slab, grade beams, and piers have been designed to withstand flexural, shear, and tensile stresses.

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All structural elements are designed to withstand dead, live, and wind loads.

Additionally, the piers have been analyzed for uplift due to adhesion between the piers and surficial clay soils.

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PART V. – ELECTRICAL DESIGN

5 ELECTRICAL DESIGN

5.1 BRINE TANK

The brine tank will have 2 transfer pumps, each will have 2 hp motors. The pump motors will operate individually in lead-lag pattern. The operating voltage will be 480 Volts, 3 phase. The 480 Volt source will be the former brine venturi pump from the 480 Volt motor control center (MCC) near the water softener area. The power circuit will be routed in above ground conduit for most of the route. The final distance to the brine tank will be underground.

The brine day tank will not require electrical power, except possibly tank heaters to prevent granulation if the brine solution temperature gets in the

50° F range for a long period of time.

The plan is for the brine tank-transfer pump manufacturer to provide a single point of connection electrical cabinet containing all circuit breakers, transformers, terminal blocks, etc for a functioning 480V, 120V, 24V system.

5.1.1 INSTRUMENTATION & CONTROLS

The brine tank will have a control panel to monitor the tank water level, tank salt level; control the water level, tank heater operation. The panel will local alarm for XX, YY and remote alarm for XX, YY. Suggest as minimum alarm for low water level.

5.1.2 BRINE DAY TANK FLOW MONITOR

The brine day tank will have high and low fluid level switches which send stop and start signals to the brine transfer pumps control panel.

The design intent is to have a single point of 480 Volt, 3 phase power with stepdown control power transformers each for the brine tank and brine transfer pump control panels. Instrumentation and control wires will be routed above and underground as necessary.

5.2 BRINE TRANSFER PUMPS

5.2.1 INSTRUMENTATION & CONTROLS

The brine transfer pumps will have a control panel to operate the two pumps in a lead-lag pattern; the idle pump of the first operation will the next to

Water Softener/Brine Tank Replacement Page 36 operate. The start/stop signal will originate from the level switch located at the brine day tank, located near the water softeners. The panel will local alarm for motor failure, XX and remote alarm for XX, YY. Suggest as minimum alarm for pump fail.

5.3 WATER SOFTENER ROOM

Existing electrical outlets in the room will be relocated as necessary to remain usable.

An electrical substation outside the north wall, west of the double doors, will require relocation if the wall is moved per Add Alternate #2. Otherwise it should be protected in place.

5.3.1 INSTRUMENTATION & CONTROLS

The water softener system will have a control panel to operate the water softeners in a rotating sequential operation: one tank will be active, the next two will be on standby, and the last will be regenerating.

The control panel will monitor "Product Flow”, “Drain Flow” per duplex tanks and “Total Flow” for the system. The panel will have a local alarm for "Water

Softener High Flow” for each set of the duplex tanks, YY and remote alarm for XX, YY.

The water softener controls are specified to be compatible with a BAS hookup to the facility.