B08_Attachment_9__Water_System_Basis_Design_Report_SD_Submittal.pdf

ORGAN PIPE CACTUS NATIONAL MONUMENT

AJO, AZ

REHABILITATE PRIMARY PARK WATER SYSTEMS

ORPI

PMIS: 240821

BASIS OF DESIGN REPORT (BDR)

NATIONAL PARK SERVICE (NPS)

DENVER SERVICE CENTER (DSC)

BACKGROUND:

Distribution System: The Organ Pipe Cactus National Monument’s water distribution system was constructed circa 1960. The water system supplies water to the 208-site campground, 5 group campground sites, 10 VIP campground sites, Visitor Center, maintenance and office buildings, and 16 housing units. The system is now inefficient for current needs and causes significant disruption when it breaks down.

The existing system was constructed using asbestos-cement (AC) pipe. Some sections of the pipe have been replaced over the years since, but approximately 5500 linear feet of this pipe remains in service.

The AC pipe frequently fails as rubber gasketed joints become brittle leading to points of leakage.

Failure of these joints have drained the Park’s 100,000-gallon water storage tank on several locations.

The two water storage tanks have also exceeded their life expectancy and have deteriorated due to the mineral content of the water.

A schematic of the existing water system is shown below in Figure 1.

Figure 1. Schematic Layout

Tanks: The upper tank is a 100,000-gallon welded steel tank that provides domestic water storage for the Visitor Center, maintenance facility and law enforcement facility. The existing 100,000-gallon tank is accessed via an asphalt and gravel surfaced road and lacks a power connection. Existing cathodic protection controls and pressure valves are powered by a low-voltage cable. The existing tank has an external level gage to for monitoring water levels. The tank fill operation functions with the use of a float switches located within the tank and wired directly to the w ell house. The existing site topography generally is steep and rugged adjacent to the tank.

The lower tank is a 50,000-gallon welded steel tank that provides domestic water storage for the campground, group campground and a duplex residence. The existing 50,000-gallon tank is accessed via a gravel/dirt road and lacks a power connection. Existing cathodic protection controls and pressure valves are powered by a low-voltage cable. The existing tank has an external level gage to for monitoring water levels. The tank fill operation functions with the use of a pressure (altitude) valve on the fill line. The existing site topography generally is steep and rugged adjacent to the tank.

Wells: The system is supplied by two water wells located near the well house between the Visitor

Center and campground. The north well, (Well #6), was constructed in 2019, replacing an older well , Well #5, that is now used as a monitoring well. Well #4 is located south of Well #6, and is producing at levels unacceptable to the park’s needs, and will be replaced as part of this project. Degradation of the casing is occurring and iron deposits from oxidation are sealing perforations in the casing. Static water levels have dropped in recent years, reducing the elevation to below desired levels. Water consumption has increased steadily as the park sees more and more visitors annually. The documented lower water table necessitates the need to drill a deeper well to maintain these services at expected levels.

OBJECTIVE:

The intent of this project is to replace the aging water distribution system and tanks, as well as provide a new domestic well to increase the available water for the Park. The primary work of this project includes, but is not limited to, the design and construction for the replacement of 9550-lf of existing AC water main with the installation of over 15,000-lf of AWWA C-900 PVC pipe, replacement of service lines and exterior fixtures, removal and replacement of two water storage tanks and construction of a new domestic well. Fire sprinkler supply lines will be run to all residences and common gathering places for visitors and employees alike for safety purposes. Sustained fire flow will be increased with the improved and upsized distribution lines. The installation of fire hydrants in the campground will provide a much-needed level of fire protection to the area. Domestic potable water supply to all facilities will be improved with new service connections, meters and control valves. The two welded steel water tanks will be removed and replaced with glass lined steel storage tanks with a Supervisory Control and Data

Acquisition (SCADA) system.

The proposed design will improve the water system by doing the following;

1. Replacing older asbestos concrete water main with AWWA-compliant C-900 PVC pipe. This C-

900 pipe will provide a 50-year life for water system with less risk of leaks and/or breaks in the pipe.

2. Installing new domestic service connections with remote read meters to structures. This will allow NPS staff to monitor water usage and locate leaks more efficiently to reduce overall water consumption.

3. Installing new fire services to each structure to allow for fire sprinkler connections to reduce the risk of structure damage and personal injury due to fires.

4. Providing for fire flow based on the NFPA 1142 standards to structures within the system’s area.

5. Replacing water spigots within Twin Peaks campground and VIP campground.

6. Replacing fire hydrants in residential area and installing new hydrants in campground area. This will allow NPS staff to respond to fire incidents more efficiently.

7. Installing new truck filling station in campground. This will allow staff to use more water from

50,000 gallon tank during off-season to increase water turnover and help prevent water stagnation within the tank.

8. Replacing older bolted steel water storage tanks with appropriately sized glass-lined steel tanks.

Glass-lined steel tanks require significantly less maintenance in terms of interior coatings and are more resistant to leaking.

9. Tank cathodic protection systems, controls and valving will be replaced with modern equipment.

10. Installing SCADA controls at each tank site to allow staff to remotely monitor tank levels and receive alerts. This will enable staff to respond quicker to emergency conditions and prevent water waste and outages. This requires extending power to each tank site.

11. Construction of a new domestic well to improve well capacity and reduce demand on Well #6.

DESIGN CRITERIA:

The basic design criteria are summarized below;

1. Distribution System

a. Pipe type: Proposed design will specify AWWA C900 DR 25 pipe- sizes 4”-8” for water main and fittings. This pipe provides a pressure rating of 165 psi, and is certified for use in municipal water systems.

b. Pipe bury depth: 36” minimum to mitigate impacts of surface heat on pipe and prevent crushing from vehicle and other live loads. This also provides protection from occasional frost conditions, which are not common for the climate at ORPI.

c. Fire Flow: Proposed system will provide fire flow to structures within the ORPI area.

Fire flow will be based on NFPA 1142 standards. Hydrants are proposed within the campground, but are not required to provide a minimum amount of fire flow or pressure since there are no structures except comfort stations. A minimum fire flow of

250 gpm will be available at each hydrant in the system.

d. Trenching: System trenching should reduce impact to native areas to reduce overall re-vegetation costs and reduce risk of impacts to cultural resources. Trenching will typically occur in existing road section on the side opposite of the existing water main.

This will allow the existing water main to remain in service during construction to reduce water outages to users and keep disturbance of asbestos concrete pipe to a minimum. Where trenching is required to occur in native areas, design will utilize existing trench as much as possible to reduce impacts, but maintain an adequate setback from existing asbestos concrete pipe to prevent disturbing pipe.

e. Service lines: Domestic service lines will be HDPE (PEX) pipe except for any above grade portions which will be Type K copper.

Directional drilling was considered for the campground area, but open trenching is preferred to the following factors;

i. Directional Drilling (DD) requires water main to be 6-ft deep minimum. Location of water main would be below an area rich in vegetation as well as concrete campsite pads and shade structures. Exposing pipe for emergency repairs would create a large impact that should be avoided.

ii. DD is preferred in locations where tees and services are minimal. Campground requires multiple tees for comfort station and spigots, therefore each location would need to be exposed reducing any efficiency or impact gains created by the DD method.

f. Asbestos Concrete Pipe Removal and Disposal:

i. Per Arizona Department of Environmental Quality (ADEQ) as long as AC pipe is not made friable, it’s handling, and disposal is not regulated.

ii. Project specifications will state that contractor is not to crush, saw, pulverize, or otherwise make AC pipe friable.

iii. Per State Historic Preservation Office (SHPO), existing water system dates from the Mission 66 era (1960s) and is therefore considered historic. SHPO recommends pipe remain in the ground to prevent the need for SHPO compliance.

iv. Design is locating new water mains in locations where direct impacts to AC pipe will be minimized and AC pipe can remain in current location with minimal disturbance.

2. Water Tank Sizing: Proposed water tanks will be sized as follows;

a. Provide the average daily demand during the peak month, plus

i. Average daily demand is based on meter readings provided by NPS for a 2 year period.

b. An equalization volume equal to the average daily demand, plus

c. Fire Storage Volume based on NFPA 1142, plus

d. Backwash Filter volume (if applicable), and

e. Dead storage volume of approximately 10% at the top of the tank

3. Water Tank Design

a. Proposed water tanks will be designed to minimize maintenance and improve monitoring capability. No specific performance of the tanks needs to be improved.

Specific requirements include;

i. Tanks will be glass-fused steel tanks

ii. Due to existing site topography, tanks will be placed on existing tank sites at same elevations. Existing tanks must be completely removed to allow for construction of new tank with similar footprint.

iii. Replace aging controls with modern equipment including SCADA system for remote monitoring of tank levels.

b. Tank Sizing (South Tank)

i. Required 40,595 gallons

ii. Domestic Storage (DS) (Peak Day x 2.0 Peak Day Factor) = 21,500 GPD

1. 17,587 gallon 30-day max day running average less 6837 gallons to serve Visitor Center/Residential Area = 10,750 gallons X 2.0 Peak Day

Factor.

iii. Fire Storage Volume (FSV) = 4,645 gallons per NFPA 1142 calculator based on estimated size of the Campground Duplex.

iv. Emergency Reserve Volume (ERV) = 10,750 gallons

1. 50% Peak Day Demand

2. Per requirement of NFPA 1400, minimum of 50% of fire storage.

3. Therefore, greater volume of 50% Peak Day Demand controls.

v. Dead Storage = 3,690 gallons

1. Equal to 10% of total volume to account for storage below outlet and storage above overflow.

vi. Required Volume (DomS @ 21,500 gal) + (FSV @ 4,655 gal) + ERV @ 10,750 gal)

+ (DS @ 3,690 gal) = 40,595 gal.

vii. Remove existing tank and replaced with 50,000-gallon (nominal) tank.

viii. Replicate existing tank plumbing for connection to existing distribution system.

ix. Installation of 2-way altitude valve to both replicate existing filling operation and to allow for the backflow through the fill pipe should fire flow be needed to pull from the hydrants connected to the fill line.

x. Campground uses to be temporarily closed during construction, therefore no temporary bypass condition required. Valving to fill 50,000 tank to be closed to allow water lines to be exposed and reconnected to new tank.

c. Tank Sizing (North Tank)

i. Tank Sizing: Required 96,716 gallons

ii. Domestic Storage (Peak Day) = 13,674 GPD

1. 17,587 gallon 30-day max day running average less 10,750 gallons to serve campground = 6,837 gallons X 2.0 Peak Day Factor.

iii. Fire Storage Volume = 49,500 gallons per NFPA 1142 calculator based on estimated size of the Future Law Enforcement Facility.

iv. Emergency Reserve Volume = 24,750 gallons

1. 50% Peak Day Demand

2. Per requirement of NFPA 1400, minimum of 50% of fire storage.

3. Therefore, greater volume of NFPA 1400 controls.

v. Dead Storage = 8,792 gallons

vi. Equal to 10% of total volume to account for storage below outlet and storage above overflow.

vii. Required Volume (DS @ 13,674 gal) + (FSV @ 49,500 gal) + ERV @ 24,750 gal) +

(DS @ 8,792 gal) = 96,716 gal.

d. Remove existing 100,000-gallon welded steel tank and replace with new 100,000-gallon

(nominal) Glass-fused Bolted Steek Tank.

e. Replicate existing tank plumbing for connection to existing distribution system.

f. Installation of float switches wired to well house for fill operations.

g. Provide temporary piping for bypass from well to lower water storage tank during construction.

4. Well Design

a. Refer to Hydrogeologic Assessment in Appendix for detailed information on existing site conditions and design criteria.

5. Electrical

a. Water Tanks Replacement The Organ Pipe Cactus National Monument has an existing

50,000 gallon water tank and an existing 100,000 gallon water tank will both be replaced. New permanent power will be provided at the two new water tanks. Arizona

Public Service is the serving electrical utility for the area. Arizona Public Service will provide a new 15KVA 240/120Volt transformer at each site that will be fed from Arizona

Public Service transformers that are adjacent to the two new water tanks. Each water tank will be provided with a meter enclosure with a 60 Ampere main circuit breaker and a 100 Ampere electrical panel. Each water tank will have two dedicated receptacles, one for the SCADA controls and the other for a dedicated convenience power receptacle.

b. Water Well #4 Replacement The Organ Pipe Cactus National Monument has an existing water well #4 that will be replaced with a new well approximately 50 feet south of the existing water well #4. A new pump will be provided for new water well #4. The new water well #4 pump will be powered by extending the existing water well #4 pump electrical connection.

6. Water Tanks and Truck Filling Station Foundation/Slabs

a. Foundation/Floor System A geotechnical report for the project has not been receive d at this time. The foundation system of the new tanks will consist of a reinforced concrete ring wall with aggregate base placed below the tank within the perimeter of the ring wall. The concrete ring wall, aggregate base, and truck filling station slab shall be designed according to the recommendations of the geotechnical report.

b. Structural Design Criteria and Material Strengths The structural design criteria and material strengths listed below are according to our best estimate at this time based on the information above. The criteria and strengths shall be verified by the design/build team as the design progresses and revised as needed. The structural design will be according to the 2021 International Building Code and ASCE 7-16 Minimum Design

Loads for Buildings and Other Structures, or the code in force at the time the project is designed. Preliminary design criteria are as follows:

Governing Building Code: 2021 International Building Code (IBC)

Risk Category: IV - for fire suppression water storage

Live Loads: IBC Section 1607

Lateral Loads:

Seismic Loads:

Short Period Spectral Acceleration SS = 0.342

One Second Spectral Acceleration S1 = 0.193

Importance Factor: 1.50

Seismic Design Category C

Site Class per geotechnical report

Response Modification Factor Determined by design team

Wind Loads:

Basic Wind Speed: 115 mph

Exposure Type C or as appropriate to site

Preliminary Working Stresses for Materials are as follows:

Concrete (28-day strengths):

Concrete Ring Walls f 'c = 4000 psi

Equipment Slabs f 'c = 4000 psi

Reinforcing Steel ASTM 615 Grade 60 fy = 60 ksi

WATER DEMAND ESTIMATION:

Master meter data from the existing pump house for the years 2018 through 2019 was provided by the

NPS and analyzed by SEH. The data represents a single daily reading of the master meter that feeds directly into the 100k gallon tank in a cyclical fashion, therefore daily system demand fluctuations could not be directly analyzed. Because daily meter data fluctuated based on the tank refill cycles, a 30-day moving average of the data was developed by taking the average of the previous 30 days of meter reading and dividing it by 30 to better estimate the daily demand flows in gallons per day (gpd). The figure below shows a graph of the 30-day moving average of meter reading for both years.

Figure 2. Daily demand data from master meter readings.

As show in the figure above, peak water demand is experienced in the spring, winter and fall, and the lowest demand is during the summer months. This is consistent with the fluctuation of visitation to the park throughout the year. The key design parameter for water tank sizing that was developed from this analysis is the highest recorded value of average daily demand during a peak month of 17,587 gpd under existing conditions. It should be noted that the current system has a documented history of leaks and pipe breaks. Past experience on National Park Service projects suggests that presumed leaks and water loss accounted for up to 30% of water usage for an aging system when analyzing the reduction in water used from meter data before and after a major renovation/replacement. Since a potentially substantial reduction in water use can be reasonably anticipated after the system is replaced, no growth factors were applied to this data and no considerations were made for minor future system expansions.

TANK SIZING:

The design criteria for water tank sizing is outlined previously in this report. Average daily demand during the peak month was taken from the above analysis of existing water usage and a peak day factor of 2 was applied. Fire storage volume for each tank was per NFPA 1142 and was taken as the highest calculated fire storage requirement for any single structure within the distribution system for each tank.

It should be noted that the provided water meter data was for the whole system and did not differentiate between the areas served by the 100k gallon tank (residences, Visitor’s Center, maintenance building) and the areas served by the 50k gallon tank (primarily the campground and campground duplex). In order to estimate the relative distribution of demands on these two tanks, it was assumed that the campground was not in use during the summer months, and that the demand on the 100k gallon tank was relatively consistent throughout the year. Therefore, the relative distribution of demand on the 100k gallon tank during peak season was taken as the ratio of the total system demands during the off-peak season and peak season.

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AVERAGE DAILY DEMAND

(30 DAY MOVING AVERAGE)

Calculations for the minimum tank size required are shown below.

Figure 3. Tank sizing

Fire Flow:

The proposed conditions were modeled with Bentley’s OpenFlows WaterGEMS software. A fire flow analysis was conducted in order to calculate the fire flow available at the approximate location of future hydrants within the proposed development. Required fire flow rates for each structure were calculated per NFPA 1142. The calculations are included as Appendix A.

The below analysis was performed under peak day steady state conditions with a minimum residual system pressure of 20 psi maintained throughout the system during a fire event at each location. Typical

Hazen-Williams coefficient (C-Value) for new PVC pipes were applied. Static pressures were estimated from the relative elevations of system components taken from GIS topography data. As shown, some of the locations were modeled under a variety of pipe sizing configurations to analyze their effect on the estimated fire flow. The selected scenario for the schematic design is highlighted.

Total Demand (Average daily demand during peak month, GPD)

Storage (2x

Peak Day

Factor

50k Gallon Tank 10,750 21,500 + 4,645 + 10,750 + 3,690 = 40,585

100k Gallon Tank 6,837 13,674 + 49,500 + 24,750 + 8,792 = 96,716

Total 17,587

Fire

Storage

(Gal.)

Emergency

Reserve (Gal.)

Dead Storage

(Gal.)

Total Req'd

(Gal.)

Figure 4. Modeled fire flow

Fire Flow Model Results (50k Tank Distribution Area):

Under existing conditions, a 4” pipe outlets from the 50k gallon tank and serves the campground area.

As shown above, this pipe will need to be upsized to 6” in order to deliver the required fire flow to the campground duplex. Running 6” pipe to the remainder of the campground hydrants results in fire flows well above the specified required minimum. Running 4” pipe from the campground duplex to the remainder of the campground hydrants results in marginal fire flows that barely exceed the minimum flow. The schematic design calls for new 6” water main from the 50k tank to the last hydrant in the campground to ensure adequate fire flow is provided.

Location Scenerio

Needed Fire Flow

(gpm)

Static Pressure

(psi)

Fire Flow Available at 20 psi min system residual pressure (gpm) Pass?

Existing 4" from 50k Tank, New 6" from first water service 358 No

New 6" From 50K Tank to hydrant 783 Yes

6" from 50k Tank to Campground Duplex, 4" Distribution Piping to both hydrants 250 52 to 58 287 to 380 Yes

6" from 50k Tank to Campground Duplex, 6" Distribution Piping to both hydrants 250 52 to 58 635 to 655 Yes

6" from 100k tank to Law Enforcement hydrant 974 No

8" from 100k Tank to Maintenance

Building, new 6" from Maintenance

Building to Law Enforcement 1318 Yes

8" from 100k Tank to CG road intersection, new 6" south of CG

Intersection to Law Enforcement 1426 Yes

8" from 100k Tank to Law Enforcement 1843 Yes

Maintenance

Facility

8" from 100k Tank to Maintenance

Building, new 8" from Maintenance

Building to Law Enforcement 750 96 to 99 1563 to 1723 Yes

8" from 100k tank to maintenance building, new 6" from Maintenance

Building to Law Enforcement 595 to 714 Yes

8" from 100k tank to CG road intersection, new 8" south of CG

Intersection to Law Enforcement 611 to 741 Yes

6" Distribution Piping, Tie into existing 4" at NW area of development, 6" from 100k tank to Law Enforcement hydrant 500 61 to 87 506 to 1,050 Yes

6" Distribution Piping, Tie into existing 4" at NW area of development, 8" from 100k tank to Law Enforcement hydrant 500 61 to 87 570 to 1,900 Yes

Visitors Center 500 97

Law Enforcement

Bldg.

1000 106

Campground

Hydrants

Residences

Modeled Results

Campground

Duplex 500 43

Fire Flow Model Results (100k Tank Distribution Area):

As shown above, a number of pipe sizing configurations were modeled, mostly with different combinations of 8” and 6” pipes leading from the 100K gallon tank to the law enforcement building. At a minimum, an 8” pipe is required from the 100k gallon tank to the maintenance building to ensure minimum flows at all locations. Extending a 6” line from the maintenance building to the law enforcement technically results in passing fire flow results; however, extending an 8” line from the maintenance building to the law enforcement building increases fire flow at the law enforcement by about 40% compared to a 6” line and will allow for greater flexibility as the law enforcement building design evolves. Because most of the construction cost is associated with the pipe installation and the final cost between a 6” and 8” pipe installation is relatively marginal, an 8” pipe extending from the 100k gallon tank to the law enforcement building was selected for the design.

It should be noted that the water model assumed a two-way altitude valve at the inlet side of the 50k tank which allows for water to flow from the 50k gallon tank back through the feedline when the pressure on the inlet side drops. This valve installation and proper function is critical, because if water is restricted from flowing back from the 50k gallon tank the feedline will act as a dead end at a relatively high elevation, and negative system pressures will develop during a fire flow event.

Temporary Condition (100k Tank Offline):

There are two temporary conditions that will take place during construction that were analyzed – replacing the 100k gallon tank and replacing the 50k gallon tank.

When the 50k gallon tank is being replaced, it will be taken offline. The NPS has stated that the campground area can be shut down during construction, so the temporary removal of this tank will not affect the system conditions.

During the replacement of the 100k gallon tank, the existing tank will be taken offline and the piping at the 50k gallon tank will be reconfigured so that it will serve the entire system during this period. The 50k gallon tank is approximately 85 feet lower than the 100k tank which will reduce the static pressures in the areas previously served by the 100k tank by about 37 psi, with additional friction losses due to the increased travel distance. The figures below depict the static pressures throughout the system during an estimated peak hour flow. The first figure represents normal operation with both tanks online, and the second figure shows the entire system being served by the 50k gallon tank (temporary condition).

System pressures remain above 20 psi in the temporary condition, however there are many more areas in the residential loop that exhibit static pressures in the lower working range of 20 to 40 psi. Note that the node downstream from the 50k gallon tank is below 20 psi, but this is usually considered acceptable because the node is adjacent to the tank.

Figure 5. Static pressures under normal operating conditions, peak hour.

Figure 6. Static pressures under temporary operating conditions, peak hour.

dstewart Text Box

APPENDIX A: FIRE FLOW CALCULATIONS

ORPI- RESIDENTIAL DUPLEX, CAMPGROUND

Building Foot Print Length = Width = Sq. Ft. = 3,400

Total Sq. Ft. = 3,400

*Add height for each floor Ceiling Height = 8.5 Cu. Ft. = 28,900

*Note: take 1/2 of pitched roof height Attic Height = Cu. Ft. = -

Additional space: Cu. Ft. = -

(porch, etc.) Length Width Height

Total Cu. Ft. = 28,900

Total Cu. Ft. = 28,900 OHC = 7 Gallons = 4,129

*Note* Occupancy Hazard Classification number is 7 for dwellings, small office complexes and similar constructed facilities. Refer to NFPA 1142 for other types of structures.

Gallons = 4,129 CCN = 0.75 Gallons = 3,096

*Note* Type II Construction .75. Ex: Cinderblock, approved non-combustible material.

Type III Construction 1.0. Ex: Brick vaneer, approved non-combustible material etc.

Type V Construction 1.5. **Dwellings max 1.0 CCN per NFPA 1142**

Gallons = 3,096 Exp = 1 Gallons = 3,096.43

*Note* Any structure within 50' of burn structure is considered an exposure and requires total gallons to be multiplied by 1.5. DO NOT add .5 for each additional exposures.

**In accordance with NFPA 1403, an additional water supply in the amount of 50% of total required fire flow must be available to handle unforseen situations.**

Gallons = 3,096 at 500 GPM for about 6

Minutes

3,096 Gallons x 1.5 = 4,645

NFPA 1403

requirement

Total GPM for NFPA 1142

250 GPM

1000 GPM

500 GPM

750 GPM

GPMTotal Gallons Required Up to 2,499 Gallons

20,000 or more

2,500 to 9,999 Gallons

10,000 to 19,999 Gallons

ORPI- FUTURE LAW ENFORCEMENT FACILITY

Building Foot Print Length = 100 Width = 220 Sq. Ft. = 22,000

Total Sq. Ft. = 22,000

*Add height for each floor Ceiling Height = 10 Cu. Ft. = 220,000

*Note: take 1/2 of pitched roof height Attic Height = 4 Cu. Ft. = 88,000

Additional space: Cu. Ft. = -

(porch, etc.) Length Width Height

Total Cu. Ft. = 308,000

Total Cu. Ft. = 308,000 OHC = 7 Gallons = 44,000

*Note* Occupancy Hazard Classification number is 7 for dwellings, small office complexes and similar constructed facilities. Refer to NFPA 1142 for other types of structures.

Gallons = 44,000 CCN = 0.75 Gallons = 33,000

*Note* Type II Construction .75. Ex: Cinderblock, approved non-combustible material.

Type III Construction 1.0. Ex: Brick vaneer, approved non-combustible material etc.

Type V Construction 1.5. **Dwellings max 1.0 CCN per NFPA 1142**

Gallons = 33,000 Exp = 1 Gallons = 33,000.00

*Note* Any structure within 50' of burn structure is considered an exposure and requires total gallons to be multiplied by 1.5. DO NOT add .5 for each additional exposures.

**In accordance with NFPA 1403, an additional water supply in the amount of 50% of total required fire flow must be available to handle unforseen situations.**

Gallons = 33,000 at 1000 GPM for about 33

Minutes

33,000 Gallons x 1.5 = 49,500

NFPA 1403

requirement

Total GPM for NFPA 1142

250 GPM

1000 GPM

500 GPM

750 GPM

GPMTotal Gallons Required Up to 2,499 Gallons

20,000 or more

2,500 to 9,999 Gallons

10,000 to 19,999 Gallons dstewart Text Box

APPENDIX B: HYDROGEOLOGIC REPORT

107854-001

400 North 34th Street Suite 100 PO Box 300303 Seattle, Washington 98103-8636 206 632-8020 Fax 206 695-6777 www.shannonwilson.com

January 5, 2022

Mr. Darren Stewart, P.E.

SEH, Inc.

934 Main Ave, Unit C Durango, CO 81301

RE: DRAFT HYDROGEOLOGIC ASSESSMENT, NATIONAL PARK SERVICE WATER

SUPPLY WELL, ORGAN PIPE CACTUS NATIONAL MONUMENT, ARIZONA

Dear Mr. Stewart, Shannon & Wilson prepared this letter and participated in this project as a subconsultant to Short Elliott Hendrickson, Inc. (SEH). Our scope of services was specified in our Subcontract Agreement for Professional Services with SEH, dated August 6, 2021, SEH Contract No. 140P2019D0015. This Agreement is in support of water supply improvements at Organ Pipe Cactus National Monument (OPCNM) as specified by National Park Service (NPS) Contract No. 140P2019D0015. This letter presents our design and hydrogeologic assessment of a 48-hour pumping test and was prepared by the undersigned.

We appreciate the opportunity to be of service to you on this project. If you have questions concerning this letter, or we may be of further service, please contact us.

BACKGROUND

The NPS is the process of improving its aging water system, including supply, storage, and distribution components for visitor and staff facilities at and around the Kris Eggle Visitor Center and Twin Peaks Campground. In 2019, a new water supply well, the replacement North Well (Well 6), was installed to provide water to the park water system. The NPS plans to install a second new well to replace the existing failing Old South Well (Well 4) and secure a stable and reliable water supply for the future use of OPCNM.

We understand that the pumping test conducted in 2019 after construction of Well 6 to determine its well capacity was not adequate to provide insight into proper spacing for an additional well. We were requested to run a longer pumping test to determine the cone of influence of Well 6 and gain further understand of the hydraulic properties of the aquifer.

http://www.shannonwilson.com/

107854-001 Letter DRAFT JSB comments (002).docx 107854-001

We conducted a 48-hour constant rate pumping test on Well 6 and monitored water levels at two other wells to inform recommendations for the location and design of the new well.

Site Description

The Site is in the south part of OPCNM, in Pima County, Arizona. The Site is approximately five miles north of the town of Lukeville, about 22 miles south of the town of Why, and 200 yards west of State Route 85. The Site is accessible by a short dirt road spur from a park road, Twin Peaks Road, and is adjacent to an ephemeral stream in a dry wash, running North-South, just west of the Site.

The Site consists of three wells: Old South Well (Well 4), Old North Well (Well 5) and the replacement North Well (Well 6). The Well 6 location is approximately latitude 31.95032 North, longitude 112.8015 West, as shown in Figure 1. The other two wells, used as observation wells during the test, are approximately 83 feet to the southeast (Well 5) and 263 feet to the south (Well 4) from Well 6, the pumping well.

WELL ASSESSMENT AND PUMPING TEST

Shannon & Wilson completed our well assessment and pumping test between August 26, 2021 and November 19, 2021. The well assessment and test process consisted of:

1. Reviewing existing boring logs, construction records, and other well data;

2. Performing a site reconnaissance visit;

3. Coordinating with NPS to perform a constant rate pumping test;

4. Monitoring water levels and pumping rate during the pumping test; and

5. Analyzing the pumping test data.

Well Assessment and Site Reconnaissance

We visited the Site on August 26, 2021 along with representatives of NPS and SEH. We examined Wells 4, 5, and 6 and received reports including boring logs and construction logs for Well 6, and more limited information for Wells 4 and 5. We received further information from personal communications with NPS staff.

Well 6

The pumping well used for our test, Well 6, was drilled and installed in September 2019 to replace the failing Well 5. Well 6 is currently the primary active supply well for the OPCNM. The well was drilled using the mud rotary method and completed to a depth of 550 feet below ground surface (bgs). The upper 20 feet was drilled as an 18.5-inch diameter borehole. The borehole was then reduced to a 13.75-inch diameter for the remaining 530 feet of drilling.

According to the boring log, the upper 20 feet of the borehole comprised of sedimentary conglomerate. The remainder of the borehole was drilled through volcanic rocks of various composition, with broken volcanic rock encountered between 320 and 530 feet bgs. We assume the broken volcanic rock to be the water-bearing unit that comprises the aquifer.

Water was encountered during drilling at 340 feet. To a depth of 20 feet bgs, a 10-inch diameter outer steel casing was installed. To a depth of 330 feet bgs and from 530 to 550 feet bgs, an 8-inch diameter steel casing was installed. An 8-inch diameter 100-slot (0.100-inch perforation width) wire wrap screen was installed from 330 to 530 feet bgs.

A 0.25-inch gravel pack was installed in the annular space between the borehole wall and the steel casing or wire wrap screen from 300 to 550 feet bgs. A bentonite seal was installed between the borehole wall and the steel casing from 20 to 300 feet bgs, and a concrete surface seal installed between the outer and inner casing from the ground surface to 20 feet bgs. After well construction, the reported static water level was 346 feet bgs.

In October 2019, a 15-horsepower submersible electric pump was installed at 473 feet bgs and a pumping test was conducted. Prior to the test, the static water level was reported as 346 feet bgs. The well was pumped at 50 gallons per minute (gpm) for 11 hours and 5 minutes, with the water level during pumping stabilizing at a reported 347.5 feet bgs (1.5 inches of drawdown). No further water level measurements were recorded during recovery.

A copy of the Well Driller Report and Well Log, as well as the Well Test Report, referenced in this section are included in Appendix A.

Well 5

Well 5, used as an observation well for our pumping test, is currently used as a monitoring well by NPS. We understand the well has a total depth of 410 feet bgs. The entirety of the well has a 12-inch steel casing installed aside from two 10-foot screen sections: from 350 to 360 feet bgs and from 400 to 410 feet bgs.

A pumping test was conducted at Well 5 in August 1974. Prior to the test, the static water level was reported as 310.71 feet bgs. The well was pumped at approximately 114 gpm for 935 minutes, with a total reported drawdown of 6.78 feet. After 740 minutes of recovery, the water level had recovered to the pre-test static water level.

A copy of the Well Test Report referenced in this section is included in Appendix A.

Well 4

Well 4, used as an observation well for our pumping test, is currently used as a back-up water supply well by NPS. We understand that although currently active, the well is failing due to degradation of the casing and iron deposition. The borehole was drilled to a depth of 430 feet in November 1957. During drilling, water was encountered at 330 feet bgs, and was reported to have risen 20 feet in the boring during drilling.

A 12-inch diameter steel casing was installed to a depth of 428 feet bgs, with the bottom left open. The casing was installed with a section of ½-inch wide torch-cut perforations from 365 to 425 feet bgs. After well installation, the static water level was reported as 310 feet bgs.

During the 1974 Well 5 pumping test, water levels at Well 4 were monitored. No static water level was reported prior to the test, however after 125 minutes of pumping, the water level was reported as 307.60 feet bgs. After 929 minutes of pumping, the water level was reported as 307.78, a drawdown of 0.18 feet since the first water level measurement.

A copy of the Well Schedule and Driller Log, as well as the Well Test Report referenced in this section is included in Appendix A.

Pumping Test

Shannon & Wilson coordinated with NPS staff to conduct a 48-hour constant rate pumping test in November 2021. On November 14, NPS staff shut off the pump at Well 6 to allow water levels to return to static prior to the pumping test.

We arrived at the Site on November 15 and met NPS Regional Hydrologist, Salek Shafiqullah. Well 6 had a locked steel cover over the casing stick-up and was inaccessible until the following day when NPS staff opened it. The water level at Well 5 was measured with a manual water level indicator as 353.96 feet bgs. The water level at Well 4 was measured with a manual water level indicator as 352.65 feet bgs.

On November 16, NPS staff installed 1.5-inch fire hose from the well system connection point at the Well 5 wellhouse and ran the hose to the ground surface at the dry wash nearby.

We installed pressure dataloggers at Well 5 and Well 6, as well as a barometric pressure datalogger inside the Well 5 wellhouse. At Well 4, the sounding tube was too narrow to fit the pressure datalogger, so we attempted to install the datalogger into the well casing outside of the sounding tube. The datalogger became stuck in the pump wiring above the static water depth, at about 100 feet bgs, so as a result no datalogger data is available for Well 4. Pumping test and recovery water levels at Well 4 used for analysis are manual measurements that have been manually adjusted to compensate for barometric pressure.

Pumping test and recovery water levels at Wells 5 and 6 are derived from the pressure datalogger data and barometric compensation.

The static water level prior to the test at Well 4 was measured as 352.75 feet bgs. The static water level prior to the test at Well 5 was measured as 353.83 feet bgs. The static water level prior to the test at Well 6 was measured as 353.68 feet bgs.

On November 16, at 9:29:45, the Well 6 pump was turned on at full capacity, at which point the 48-hour constant rate pumping test began. Discharge water was routed to the dry wash and the flow rate was measured periodically by observing the NPS flow meter totalizer over one-minute intervals. The flow rate remained constant throughout the duration of the test and the average flow rate was approximately 55 gpm. The pump was shut off at 9:29:45 on November 18, after 2880 minutes of pumping, at which point the pumping test concluded and the recovery period began.

Water levels at each of the three wells were stable by the end of the pumping test. The drawdown at Well 6 after the 48 hours of pumping was 1.23 feet, resulting in a specific capacity of 44.7 gpm per foot of drawdown. The drawdown at Well 5 was 0.57 feet. The drawdown at Well 4 was 0.38 feet.

We continued to observe water levels at the wells for over 24 hours of recovery time. The water level at Well 6 recovered to within 0.07 feet of the static water level prior to the test.

The water level at Well 5 recovered to within 0.02 feet of the static water level prior to the test. The water level at Well 4 recovered to within 0.05 feet of the static water level prior to the test.

The observed drawdown and recovery for Wells 4, 5, and 6 are shown in Figures 2 through

4. Figure 5 shows the radial distance of each well to the pumping well plotted against the total drawdown.

Pumping Test Analysis

Based on our observations of the water levels at the pumping well and two observation wells during the pumping test, the aquifer can produce at least 55 gpm over a sustained period of time. All three wells stabilized with little drawdown after less than 48 hours of pumping. All three wells recovered to their respective pre-test static water levels within the 24 hours of observed recovery time.

We analyzed the pumping test data using the Theis (1935) and Cooper-Jacob (1946) solutions, assuming a confined aquifer. These methods assume the discharge from the pumping well comes only from the storage of the confined aquifer in which the screened portion of the pumping well is located. Our analysis also assumes the bottom of the aquifer at 530 feet bgs, along the unit boundary observed at the time of Well 6 drilling, and the top of the aquifer at the static water level we observed at Well 6 prior to the pumping test,

353.68 feet bgs. As a result, the assumed aquifer thickness is 176.32 feet. We analyzed the pumping test data using the solutions of drawdown and recovery data plotted against elapsed time and against radial distance from the pumping well. Based on our analysis of the pumping test data, we have estimated values for the following interpreted aquifer parameters:

Transmissivity (T) of the pumped aquifer ranges from 8205.4 to 11,830 ft2 /day based on Theis drawdown and recovery solutions; T ranges from 7347.3 to 13,650 ft2/day based on Cooper-Jacob solutions.

Storativity (S) of the pumped aquifer ranges from 0.00603 to 0.05391 based on Theis solutions; S ranges from 0.001433 to 0.03887 based on Cooper-Jacob solutions.

Analysis of the radial distance-drawdown data indicates a T value for the aquifer of 13,386 ft2/day and S value of 0.0015.

See Table 1 for complete pumping test results and interpreted aquifer parameters.

RECOMMENDATIONS AND CONCLUSIONS

Based on our assessment of the well data, and analysis of the pumping test data, Shannon & Wilson believes that the aquifer is suitable for construction and operation of an additional water supply well.

We understand that NPS does not plan to pump both the existing Well 6 supply well and the new supply well at the same time, so there is not likely to be a significant risk of interference between the wells’ zone of influence. Even if concurrent pumping was necessary, Well 4 experienced only minimal drawdown and subsequent rapid recovery from the pumping at Well 6. We believe installing and operating the new well in the vicinity of Well 4, with a pump intake of similar depth to that of Well 6 would produce similar pumping and discharge results as observed at Well 6. This location and intake depth would allow for sustained pumping at a rate sufficient for our understanding of OPCNM’s requirements. Assuming the same static water level and intake depth, there will be an available drawdown of greater than 100 feet, adequate for water supply in the long-term, even if there is a continued long-term decline in the water level of the aquifer. Figure 6 shows the recommended approximate location for the new replacement well.

Due to the lack of information of any potential aquifer boundaries or low permeability zones to the south of Well 4, we do not recommend constructing the new well significantly south of Well 4, unless further testing or exploration occurs.

We recommend that instead of using one well as the primary supply well and only using the other well as a contingency in case of issues with the primary well, each well is used relatively evenly in an alternating fashion.

LIMITATIONS

We have prepared the document "Important Information About Your Geotechnical/ Environmental Report" to assist you and others in understanding the use and limitations of this report. Please read this document to learn how you can lower your risks for this project.

This report was prepared for the exclusive use of SEH, the NPS, and their representatives for use in the design of water supply well at the Site. This report should be provided to prospective contractors for information of factual data only, and not as a warranty of subsurface conditions, such as those interpreted from the exploration log and discussions of subsurface conditions included in this report.

The analyses, conclusions, and recommendations contained in this report are based on Site conditions as they presently exist. We assume that the results of the exploration made for this project represent the subsurface conditions throughout the Site, i.e., the subsurface conditions everywhere are not significantly different from those disclosed by the explorations.

Within the limitations of the scope, schedule, and budget, the analyses, conclusions, and recommendations presented in this report were prepared in accordance with generally accepted professional hydrogeologic principles and practice in this area at the time this report was prepared. We make no other warranty, either express or implied.

Unanticipated subsurface conditions are commonly encountered and cannot be fully determined by merely taking soil or rock samples or completing subsurface explorations.

Such unexpected conditions frequently require that additional expenditures be made to attain a properly constructed project. There, some contingency fund is recommended to accommodate such potential extra costs.

The scope of our services for this report did not include any assessments or evaluations regarding the presence or absence of wetlands, cultural resources, or hazardous or toxic substances on or below the Site. If a service is not specifically indicated in this report, do not assume that it was performed.

REFERENCES

Cooper, H. H. and Jacob, C. E., 1946, A generalized graphical method for evaluating formation constants and summarizing well field history: American Geophysical Union Transactions, v. 27, p. 526-534.

Theis, C. V., 1935, The relation between the lowering of the piezometric surface and the rate and duration of discharge of a well using ground-water storage: Transactions of the American Geophysical Union, v. 16, p. 519-524.

Sincerely, SHANNON & WILSON

Nathan Cutler Jim Bailey, LHG Geology Staff Well Services Director

NAC:JSB/xxx:xxx

Enc. Table 1 – Summary of Pumping Test Results and Interpreted Aquifer Parameters Figure 1 – Wells Location Map Figure 2 – Well 6 Hydrograph Figure 3 – Well 5 Hydrograph Figure 4 – Well 4 Hydrograph Figure 5 – Distance-Drawdown Plot Figure 6 – New Well Recommended Location Map Appendix A – Well Drilling Logs, Construction Reports, Drawings, and Historical

Pumping Test Data Important Information About Your Geotechnical/Environmental Report c: National Park Service

Draft Hydrogeologic Assessment Organ Pipe Cactus National Monument, Arizona

Well No. Well Location

Well Designatio n During

Test

Radial Distance to Pumping

Well

Approx.

Grade

Elevation2

Static Groundwat er Level Depth

Approx.

Static

Groundwat er Level

Elevation

Screen(s)/P erforated

Casing Top Depth

Screen(s)/P erforated Casing Bottom Depth

Screen(s)/P erforated Casing Length

Screen(s)/P erforated

Casing Top Elevation

Screen(s)/P erforated Casing Bottom

Elevation Test Dates Pumping Duration

Approx.

Pumping

Rate

Drawdown at End of Pumping

Specific Capacity

Aquifer Model

Transmissivit y (Drawdown)

Transmissiv ity

(Recovery) Storativity

(Drawdown) Transmissiv ity Storativity

Transmissivit y (Distance-drawdown)

Storativity (Distance-drawdown)

(lat. dd, long.

dd) (feet) (feet

NAVD88) (feet bgs) (feet NAVD88) (feet bgs) (feet bgs) (feet) (feet

NAVD88)

(feet

NAVD88) (mm/dd/yy) (minutes) (gpm) (feet) gpm/ft (feet2/day) (feet2/day) (feet2/day) (feet2/day)

Well 4 31.949603, -112.8016193 Observation

Well 263.44 1661 352.75 1308.25 365 425 60 1296 1236 11/16/21- 11/19/21 2880 55 0.385 - Confined 9059.5 8205.4 0.00603 7347.3 0.002909 - -

Well 5 31.950481, -112.8016893 Observation

Well 82.87 1665 353.83 1311.17 350

11/16/21- 11/19/21 2880 55 0.57 - Confined 8857.2 8930.7 0.05179 10,010 0.03887 - -

Well 6 31.95032, -112.80154

Pumping Well 0.33 1664 353.68 1310.32 330 530 200 1334 1134 11/16/21-

11/19/21 2880 55 1.236 44.7 Confined 9404 11,830 0.05391 13,650 0.001433 - -

Combined (All) - - - - - - - - - - - 11/16/21-

11/19/21 2880 55 - - Confined - - - 10,790 0.007996 13,386 0.0015

NOTES:

lat. dd = latitude decimal degrees; long. dd = longitude decimal degrees; NAVD88 = North American Vertical Datum of 1988; bgs = below ground surface; gpm = gallons per minute

1. Well 4 has one section of torch-cut perforated steel casing; Well 5 has two sections of screen; Well 6 has one section of 100-slot wire wrap screen

2. Approximate grade elevations from Google Earth

3. Location estimated from Google Earth

4. Location from 'Well 6 Final As-Built' Drawings, Site Plan C1

5. Drawdown at end of pumping value for Well 4 is closest available data to end of pumping, at elapsed time = 2810 minutes

6. Drawdown is average of values over last 10 minutes of pumping

Table 1 - Summary of Pumping Test Results and Interpreted Aquifer Parameters

Approximate Well Construction Details1 Pumping Test Results Theis Solution

Interpreted Aquifer Parameters

General Well Information Cooper-Jacob Solution

107854-001 Page 1 of 1 Table_1.xlsx - 1/5/2022

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Well 5

Well 6

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FIG. 1

WELLS LOCATION MAP

Hydrogeologic Assessment Organ Pipe Cactus National Monument, Arizona

January 2022

0 80 160

Scale in Feet

Well 4 Boring Designation and Approximate Location

LEGEND

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Kris Eggle Visitor Center

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