Attachment 7 - Septic System Design Black Jack CG.pdf

Engineer: Chris Miller, P.E.

Backhoe: Dwayne Simpson

A site investigation was performed February 11th , 2025 at the project location to determine design requirements to install a conventional septic system for a proposed 2 space RV host site. Three bore holes were excavated during the investigation to a depth of 144", see bore logs. Based on soil logs and ASTM tests this site is suitable for a conventional disposal system in accordance with Arizona Aquifer Protection requirements. This will require a 1,000 gallon septic tank. Installation of the distribution box is important to provide even distribution to infiltrators. Flow controls shall be installed in D-box to adjust distribution. The primary and reserve area are shown and spread out to distribute lateral loading.

See attached plans, design calculations and site investigation data. All offsets shall be per R18-9-A312. Site grading to direct surface runoff away from system shall be incorporated into final grading of site.

Sheet 1 Cover Letter Sheet 2 General Notes Sheet 3 Design Calculations

Sheet 4 Infiltrator Sizing Chart Sheet 5-10 Uniform Site Investigation

General Notes:

1) All construction must be in accordance with plans and specifications.

2) Contractor shall verify all utilities prior to starting excavation.

3) All materials shall be installed in accordance with the manufacturer’s recommendations.

4) Elevations and field grading shall be verified during layout to ensure proper system operation.

5) All offsets shall be in accordance with APP R18-9-312C.

6) All gravity lines shall have a minimum of 18" of cover and installed free draining with no dips or sags. Gravity lines shall be sloped as shown on the drawing but in no case less than 1% (1/8" per foot).

7) Excavated trenches shall be level prior to the placement of chambers.

The installation shall be in accordance with manufacturer's installation manual. Bedding within 6" of chambers shall be free of rocks greater than 1", this may require screening and or select bedding.

8) Energy dissipaters shall be installed in each chamber inlet to prevent scour, approximately 3' of 2" to 6" rock.

9) The layout of septic system shall be as shown on the drawings; changes must be approved by the engineer to insure proper operation of the system.

10) Cleanouts with screw caps shall be installed at house, every 50' and at bends greater than 45 degrees between guest house and septic tank.

11) Septic tank shall be installed level and water tightness test performed per the APP requirements, tank and risers should be protected from vehicles and construction activities

12) A shallow ditch or berm shall be constructed above chambers to direct surface runoff around disposal area.

13) It is recommended that 1" chicken wire be installed under chambers to prevent tunneling if gophers or prairie dogs are present.

14) On grades greater than 2% install 2-90 degree bends on incoming line to act as an energy dissipater to provide laminar even flow into 0-box.

All locations are approximate.

References: Aquifer Protection Permits; Title 18. Environmental Quality, Chapter

9. Department of Environmental Water Pollution Control (APP)

Revised 6/24

Conventional standard shallow ARC36 Infiltrator design for Eastern Portion of APN 204-46- 018C Concho, Arizona . References: Aquifer Protection Permits; Title 18. Environmental Quality, Chapter 9. Department of Environmental Quality Water Pollution Control (APP)

Design Parameters:

3 RV

From Bore Holes in disposal area, (Bl, B2 and B3) From ASTM Subsurface Soil Characterization SAR= 0.60 gpd/S.F. (Soil evaluation method) sandy loam soil layer. This is a vacant parcel with no utilities currently installed, municipal water will be brought to the property prior to construction. Slope in the disposal area is 1.5%. Setbacks per APP Rl 8-9-A312(C) Quantity/ Quality Wastewater - Domestic System Design Flow is calculated from Table 1-Unit Daily Design Flows, # RVs x 100 GPD/RV .

For this site: 3 RV use use 300 GPD Based on the proposed 3 RV design a 1000 gallons septic tank is required per Rl 8-9- A3l 4.

System Design Flow= 300 GPD Design:

Septic Tank:

From APP Rl8-9-A314(D)(l), selecting the proper Septic Tank Size, 3 RV units = 300 gpd * 2.1 = 630 Gallons. Tank shall meet all requirements of APP R18-9- A314. Tank shall be a minimum of 1000 gallons.

Disposal System:

System: Shall meet requirements of APP for a conventional trench, Less Than 3000 Gallons Per Daily Flow.

300 gpd /0.60 gpd/S.F. = 500 S.F.

Use a high-capacity 14 ARC 36 infiltrator per Chamber Sizing Chart (attached) requires a minimum of 14 chambers. •

Length of trench needed= 14 x 5' = 70' Use 1 -70 ft trenches with 14 - 5' chambers.

Minimum spacing of trenches is 5 ft. or 2 x effective trench depth.

Use l 0 ft. minimum trench separation to accommodate construction.

Trenches shall be installed to minimize lateral loading and installed as shown on plans.

Trenches to be constructed in accordance with APP Rl 8-9-E317 (D3a-h), attached drawings and specifications.

Square Feet Required

Number of Chambers Required

Square Feet Required

Number of Chambers Required

Square Feet Required

Number of Chambers Required

Square Feet Required

Number of Chambers Required

< 1 Not Permitted --- --- --- --- --- --- --- ---

> 1, ≤ 3 1.20 125 12 250 12 375 12 500 14

3 1.10 136 12 273 12 409 12 545 16

4 1.00 150 12 300 12 450 13 600 17

5 0.90 167 12 333 12 500 14 667 19

7 0.75 200 12 400 12 600 17 800 23

10 0.63 238 12 476 14 714 20 952 27

15 0.50 300 12 600 17 900 25 1,200 34

20 0.44 341 12 682 19 1,023 29 1,364 38

25 0.40 375 12 750 21 1,125 32 1,500 42

30 0.36 417 12 833 24 1,250 35 1,667 47

35 0.33 455 13 909 26 1,364 38 1,818 51

40 0.31 484 14 968 27 1,452 41 1,935 54

45 0.29 517 15 1,034 29 1,552 43 2,069 58

50 0.28 536 15 1,071 30 1,607 45 2,143 60

55 0.27 556 16 1,111 31 1,667 47 2,222 62

> 55, ≤ 60 0.25 600 17 1,200 34 1,800 50 2,400 67

> 60, ≤ 120 0.20 750 21 1,500 42 2,250 63 3,000 83

The Arc 36 HC chambers are credited with 34.43 square feet of absorption area per chamber per A.A.C. R18-9-E302(C)(4).

The minimum recommended number of chambers per system is 12 (60 linear feet).

Percolation Rate

(min/in)

Application Rate

(gal/day/sq ft)

1 Bedroom 150 gal/day

2 Bedrooms 300 gal/day

3 Bedrooms 450 gal/day

4 Bedrooms 600 gal/day

Arizona Arc 36 HC Chamber Sizing Chart (34.43 sf/unit)

Uniform Site Investigation Report Form (A.A.C. R18-9-A310) for State of Arizona

ADEQ GWS FORM 423

(REV. AUGUST 10, 2006) PAGE i OF i i

DOWNLOAD THE LATEST UPDATE OF THIS FORM FROM THE ADEQ WEBSITE AT

http://www.azdeq.gov/environ/water/permits/download/investigation.pdf

INSTRUCTIONS FOR

UNIFORM STATE OF ARIZONA SITE INVESTIGATION REPORT

(A.A.C. R18-9-A310)

Instructions

The applicant for an onsite wastewater treatment facility pursuant to 18 A.A.C. 9, Article 3 shall ensure that an qualified investigator conducts the site investigation consisting of surface and subsurface characterizations, and submit the results with a Notice of Intent to Discharge pursuant to A.A.C. R18-9-A309(B). THE RESULTS OF THE SITE INVESTIGATION SHALL BE

SUBMITTED IN A FORMAT PRESCRIBED BY THE ARIZONA DEPARTMENT OF ENVIRONMENTAL

QUALITY. THIS FORM AND ATTACHMENTS IS THE FORMAT PRESCRIBED BY THE ARIZONA

DEPARTMENT OF ENVIRONMENTAL QUALITY.

NOTE: BEFORE COMPLETING THIS FORM, THE INVESTIGATOR SHALL DOWNLOAD THE LATEST

UPDATE OF THIS FORM FROM THE ADEQ WEBSITE AS NOTED AT THE BOTTOM OF THIS PAGE.

THE FORM USED SHALL BE THE LATEST VERSION AS OF THE “DATE OF INVESTIGATION”.

An investigator that meets the qualifications of A.A.C. R18-9-A310(H) shall perform the site investigation in conformance with A.A.C. R18-9-A310. The site investigator shall utilize ADEQ GWS Form 423, and Attachments 1, 2, 3, and 4 as appropriate. Space is provided for an Arizona-Registered Professional Engineer, Geologist or Sanitarian to seal their work products.

Site Investigation Report, Item 1: The authorization for site investigation shall be completed by the appropriate person before the field investigation begins.

Site Investigation Report, Items 2 – 10: To be completed by the qualified investigator.

Site Investigation Report Attachments 1, 2, 3, and 4: The qualified investigator shall complete all necessary Attachments to report findings for the site investigation report which is to be submitted pursuant to R18-9-A309(B)(1). Attach only those with required information, as identified in Site Investigation Report Item 9. The investigator shall use the appropriate continuation page for any Attachment requiring more than 1 page. The investigator shall add the page number in the blank spaces at the bottom of each continuation page used. The investigator shall include the page totals in the Item 9 on page 3 of the report form. Please use page ii of these instructions for the soil codes for ASTM Method 5921 in Attachment 1.

ADEQ GWS FORM 423 INSTRUCTIONS PAGE i i OF i i

(REV. AUGUST 10, 2006)

TEXTURE STRUCTURE

Loamy Sand – (LS) Sandy Loam – (SL) Silt Loam – (SiL) Loam – (L) Sandy Clay Loam – (SCL) Silty Clay Loam – (SiCL) Clay Loam – (CL) Sandy Clay – (SC) Silty Clay – (SiC) Clay – (C)

SAND SIZES

Coarse – (Co) Medium – (M) Fine – (F) Very Fine – (VF)

GRADE

Structureless Weak Moderate Strong

SIZE

Very Fine Fine Medium Coarse Very Coarse

SHAPE

Platy Prismatic --Columnar Blocky --Angular -- Subangular Granular No Structure --Single Grain -- Massive

(0) (1) (2) (3)

(VF)

(F) (M) (C)

(VC)

(PL)

(PR)

(CPR)

(BK)

(ABK)

(SBK)

(GR)

(SG)

(M)

No aggregation Barely observable Distinct peds Durable peds

Granular, Platy <1 mm 1-2 2-5 5-10 >10

Flat, plate-like Taller than wide Rounded tops Cubical Sharp edges Rounded edges Spherical

Sandy texture Finer textures

Angular, Subangular, Blocky <5 mm 5-10 10-20 20-50 >50

Prismatic, Columnar <10 mm 10-20 20-50 50-100 >100

ROCK FRAGMENTS MOTTLES BOUNDARY

CONSISTENCY

DRY MOIST SAR (gpd/ft2)

ROUNDED,

SUBROUNDED

ANGULAR,

IRREGULAR

Gravel – (GR) 2-75 mm Fine – (FGR) 2-5 mm Medium– (MGR) 5-20 mm Coarse – (CGR) 20-75 mm Pebbles – (PB) 2-75 mm Fine – (FPB) 2-5 mm Medium – (MPB) 5-20 mm Coarse – (CPB) 20-75 mm Cobbles – (CB) 75-250 mm Stones – (S) 250-600 mm Boulders – (B) ≥600 mm

FLAT

Channers – (CH) 2-150 mm Flagstones – (FL) 150-380 mm Stones – (ST) 380-600 mm Boulders – (BO) ≥600 mm

TYPE OF ROCK

Basalt – (BAS)

Cinders – (CIND)

Sandstone – (SST)

Limestone – (LST)

TERMS OF

SOIL/ROCK

Cemented – (CEM)

Ice or Frozen – (ICE)

Weathered – (WEA)

Unweathered –

. (UNWEA)

Fractured – (FRA)

Decomposed – (DEC)

Stratified – (ST)

QUANTITY

Few (F) -<2% Common (C) - 2-20% Many (M) - >20%

SIZE

Fine (1) - <5 mm Medium (2) - 5 -15 mm Coarse (3) - >15 mm

CONTRAST

Faint – (F) Distinct – (D) Prominent – (P)

NNOOTTEE:: RReeppoorrtt SSooiill CCoolloorr iinn ““CCoommmmeennttss”” wwhheenn MMoottttlleess aarree CCoommmmoonn oorr MMaannyy..

DISTINCTNESS

Abrupt (A) – Less than 2 cm

Clear (C) – 2 to 5 cm

Gradual (G) – 5 to 15 cm

Diffuse (D) – More than 15 cm

TOPOGRAPHY

Smooth (S) – A plane with few or no irregularities

Wavy (W) – Waves wider than deep

Irregular (I) – Waves deeper than wide

Broken (B) – discontinuous and interrupted

L = Loose

S = Soft

SH = Slightly Hard

MH = Moderately Hard

VH = Very Hard

H = Hard

R = Rigid

VR = Very Rigid

L = Loose

VFR = Very Friable

FR = Friable

FI = Firm

VFI = Very Firm

EFI = Extremely Firm

SR = Slightly Rigid

R = Rigid

VR = Very Rigid

See Arizona

Administrative

Code(A.A.C.)

R18-9-A312(D) for SAR value.

(REV. AUGUST 10, 2006) PAGE 1 OF 3

1 Authorization For Site Investigation I certify that I am (check one) the Owner, the Authorized Representative or an Other Person and have authority to grant the investigator access to the property for this site investigation and authorize the work certified in this site assessment.

Name & Address (Printed) __________________________________________________________________________________________

Signature _______________________________________

2 Project Identification Property Owner or Project Name

3 Site Information [A.A.C. R18-9-A309(B)(2)(a)] Address City Parcel Number Lot Number Township Range Section Latitude º ‘ “ N Longitude º ‘ “ W

4 Investigator Information [A.A.C. R18-9-A310(H)] Name Phone Title Firm Name Mailing Address City State Zip E-Mail

5 Surface Characterization [A.A.C. R18-9-A310(C)]

Identify the presence or absence of all of the following possible limiting conditions in the intended location of the treatment works and the primary and reserve areas of the on-site wastewater treatment facility:

A) The surface slope is greater than 15 % at the intended location of the on-site wastewater facility YES No B) Setback distances do NOT meet all the minimum values specified in R18-9-A312(C) YES No NOTE: Check YES if the location or size of the dwelling or other improvements, or the bedroom count or the fixture unit count is UNKNOWN to the site investigator.

C) Surface drainage characteristics could adversely affect the ability of the facility to function properly YES No NOTE: If YES, please describe in Attachment 4.

D) A 100-year flood hazard zone, as indicated on the applicable flood insurance rate map, is located within the property on which the on-site wastewater treatment facility will be installed YES No NOTE: If YES, please specify the FEMA Flood Insurance Map Number or Other Source________________________________________ E) An outcropping of rock that cannot be excavated is present and could impair the function of soil receiving the discharge . YES No F) Fill material deposits are present YES No

If the answer is YES to any of the above potential surface limiting conditions, please show location and note the condition type on Site Investigation Map (Item 7).

6 Subsurface Characterization Method [A.A.C. R18-9-A310(D)]

Check method used to perform subsurface characterization per A.A.C. R18-9-A310(D)(1) and (3)

A) ASTM D5921 used? Yes No (if Yes, please enclose Attachment 1)

B) Percolation test method used? Yes No (if Yes, please enclose Attachment 2)

C) Seepage performance test method used? Yes No (if Yes, please enclose Attachment 3)

D) Other ADEQ approved method? Yes No (if Yes, please provide in Attachment 4 the method and data)

(REV. AUGUST 10, 2006) PAGE 2 OF 3

7 Site Investigation Map Showing the Location of Limiting Conditions and Setbacks from Features and Improvements [A.A.C. R18-9-A309(B)(2)(a)]

A. CHECK below the features shown on the Site Investigation Map. WRITE N/A if item is NOT PRESENT.

RECORD below the separation (feet) that will be maintained between the system and the checked feature.

Water supply well ____ (ft) Water main or branch water line ____ (ft) Domestic service water line ____ (ft) Drinking water intake from a surface water source ____ (ft) Perennial or intermittent stream ____ (ft) Lake, reservoir, or canal ____ (ft) Pond or other water feature ____ (ft) Swimming pool ____ (ft) Planned building ____ (ft) Existing building ____ (ft)

Boundary of 100-year flood hazard zone ____ (ft) ____ Drainage easement or wash with drainage area more than twenty acres ____ (ft) ____ Other Easement ____ (ft) ____ Downslope cut banks and culvert or roadway ditches ____ (ft) Planned cut bank over 2 feet deep ____ (ft) Wall or planned wall over 2 feet high ____ (ft) Driveway or parking area ____ (ft) Storage Area ____ (ft) ____ Earth fissure _____ (ft) ____ Other ____ (ft) Describe: ___________________________

B.

Minimum setback distances are within the limits specified in R18-9-A312(C); Yes UNKNOWN No Check UNKNOWN if the dwelling location or size (including building footprint, bedroom count & fixture unit count), or the location of other improvements is not known to the person performing the site investigation.

C.

Show all soil test locations. Show any condition or feature observed during the site investigation which may affect on-site system design & is located within the SITE INVESTIGATION AREA (defined as the planned excavation boundaries for the treatment works, primary disposal area and reserve disposal area plus the surrounding area out to 100 feet) including :

(1) Show land surface contours at appropriate intervals when the elevations across the Site Investigation Area differ by more than 5 feet, and

(2) Any other factor is observed that may affect system design regardless of property ownership (please include the

Site Investigation Map with Attachment 4 if the information cannot be depicted on the below Grid).

Uni

ADEQ

form Site Investigation Report Form (A.A.C. R18-9-A310) for State of Arizona

GWS FORM 423

(REV. AUGUST 10, 2006) PAGE 3 OF 3

8 Subsurface Limiting Conditions [A.A.C. R18-9-A310(D)(2)]

Identify the presence or absence of all of the following possible limiting conditions in the intended location of the primary and reserve disposal areas of the on-site wastewater treatment facility to a depth of at least 12 feet below land surface or to an impervious soil or rock layer if encountered at a shallower depth:

A) The soil absorption rate determined under A.A.C. R18-9-A312(D)(2) is:

1. More than 1.20 gallons per day per square foot? Yes No

2. Less than 0.20 gallons per day per square foot? Yes No

3. A site-specific soil absorption rate (SAR) is required per A.A.C. R18-9-A312 (D)(2)(b)? Yes No

B) The vertical separation distance from the bottom of the lowest point of the disposal works to the seasonal high water table is less than the minimum vertical separation specified in A.A.C. R18-9-A312(E)(1)? Yes No

C) Does seasonal saturation occur within surface soils that could affect the performance of the on-site wastewater treatment facility? Yes No If Yes, describe evidence:

D) Do any of the following subsurface limiting conditions that may cause or contribute to surfacing of wastewater occur within 12 feet of the land surface:

1. An impervious soil or rock layer? Yes No

2. A zone of saturation that substantially limits downward percolation from the disposal works? Yes No

3. Soil with more than 50 percent rock fragments? Yes No

E) Do any of the following subsurface limiting conditions that may promote accelerated downward movement of insufficiently treated wastewater occur within 12 feet of the land surface:

1. Fractures or joints in rock that are open, continuous, or interconnected? Yes No

2. Karst voids or channels? Yes No

3. Highly permeable materials such as deposits of cobbles or boulders? Yes No

F) Does subsurface conditions exist that may convey wastewater to a Water of the State and cause or contribute to an exceedance of a water quality standard established in 18 A.A.C. 11, Articles 1 and 4? Yes No

G) Depth to groundwater below land surface ________ feet as determined by Trench or boring, Subdivision report, Published groundwater data or Relevant well data.

If the answer is Yes to any of the above subsurface limiting conditions, please show location and note the associated limiting condition type on Site Investigation Map (Item 7).

9 Site Investigation Attachments # Attachment Description Attached?

Yes, total of _____ pages.

Yes, total of _____ pages.

Yes, total of _____ pages.

10 Investigator Certification A) Arizona-registered Professional engineer Certification Number: Expiration Date:

B) Arizona-registered Professional geologist Certification Number: Expiration Date:

C) Arizona-registered Sanitarian Registration Number: Expiration Date:

D) A certificate of training from a course recognized by ADEQ

Course Name: Completion Date:

E) Qualifies under another category designated in writing by ADEQ. Please use Attachment 4 to provide approved Qualification Category & Date Approved.

By signing this section, I certify that I am qualified to conduct this investigation as specified in R18-9-A310(H) and have inspected the property identified in Item 3 for purposes of performing a site investigation. I have performed this site investigation in accordance with R18-9-A310 and have completed this investigation to the best of my knowledge.

Printed Investigator Name/ Date of Investigation:

Investigator Signature/ Date Signed

Professional Seal

ADEQ GWS FORM 423 ATTACHMENT 1

(REV. AUGUST 10, 2006) PAGE 1 OF _1__

DOWNLOAD THE LATEST UPDATE OF THIS FORM FROM THE ADEQ WEBSITE AT

http://www.azdeq.gov/environ/water/permits/download/investigation.pdf

ATTACHMENT 1 – ASTM 5921 METHOD FOR SUBSURFACE SOIL CHARACTERIZATION

Facility Address: Parcel Number:

Tested by: Depth to Groundwater: PLEASE REPORT IN ITEM 8.G

Date Test Completed:

Test Hole #

Depth Interval Below Land Surface (Inches)

Texture Structure Rock Fragments %

Mottles % Boundary Dry Consistency

Moist Consistency

SAR

Comments: Professional Seal

Test ____ Test ____ Test ____ Test ____