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PERCOLATION INVESTIGATION/ SEPTIC SYSTEM DESIGN

RIVERSIDE FIRE STATION #53 59200 MORRIS RANCH ROAD

GARNER VALLEY AREA RIVERSIDE COUNTY, CALIFORNIA

APN 568-080-036

PREPARED FOR:

Attention: Tony Finaldi

STK ARCHITECTURE, INC. 42095 Zevo Drive, Suite A15 Temecula, California 92590

PREPARED BY:

INLAND FOUNDATION ENGINEERING, INC.

1310 South Santa Fe Avenue San Jacinto, California 92583

July 3, 2014 Project No.: S168-168

___________________________ Perc. Invest. – Fire Station #53 Project No. S168-168, July 2014 1 Inland Foundation Engineering, Inc.

INLAND FOUNDATION ENGINEERING, INC. Consulting Geotechnical Engineers and Geologists

1310 South Santa Fe Avenue/P. O. Box 937 San Jacinto, California 92581-0937

(951) 654-1555 Fax: (951) 654-0551 July 3, 2014 Project No. S168-168 Attention: Tony Finaldi STK ARCHITECTURE, INC. 42095 Zevo Drive, Suite A15 Temecula, California 92590 Re: Percolation Investigation/Septic System Design

New Septic System Riverside County Fire Station 53

59200 Morris Ranch Road, Garner Valley Area Riverside County, California

Dear Mr. Finaldi: Transmitted herewith are the results of our percolation testing performed on the referenced site. Our testing was performed in accordance with the current requirements of the County of Riverside, Department of Environmental Health as well as with contem-porary soil engineering principles and practice. We make no other warranty, either expressed or implied. Our field investigation was performed by a Certified Engineering Geologist. The field activities were performed under the supervision of Lawrence E. Strahm, a Registered Civil and Geotechnical Engineer. PROJECT DESCRIPTION The existing fire station site is located southeast of and adjacent to the intersection of State Highway 74 and Morris Ranch Road in the Garner Valley Area of Riverside County, California. The address for the site is 59200 Morris Ranch Road, Mountain Center, California. The property consists of approximately 0.33 acres. The Assessor’s Parcel No. for the site is 568-080-036. Following is a map and aerial photograph indicating the location of the property:


U.S.G.S. Topographic Map, Anza 7.5’ Quadrangle and Aerial Photograph (2010)

The purpose of this investigation was to determine the feasibility of a new upgraded onsite waste-water treatment system (OWTS) for the existing fire station. A licensed C-42 plumber examined the existing subsurface sewage disposal system. According to the C-42 report (attached), the existing septic system consists of a 1000 gallon septic tank and two plastic chambers each 60 feet long for sewage disposal. There are 42 Fixture Units in the station, which includes four bedrooms. The report reveals that the existing septic tank is deteriorating and is also undersized. The leach lines were observed to be failing at the time of the inspection. The proposed replacement OWTS will be located on the southerly portion of the fire station property. PERCOLATION INVESTIGATION This investigation consisted of the excavation of one backhoe exploration trench and testing of six percolation test holes. A log of the deep trench is appended along with copies of the percolation test data sheets recorded in the field. The deep trench did not encounter impermeable soils, bedrock or groundwater. Evidence of shallow groundwater was not observed during the excavation of the deep trench.

SITE


Following is a table indicating the percolation rates observed during testing:

Test No.

Depth (In.)

Rate (Min./In.)

P-01 75 10 P-02 63 10.4 P-03 66 9.2 P-04 56 5.4 P-05 74 10 P-06 43 6.3

The test data reveal relatively fast absorption rates. Based upon a rate of 10.4 minutes per inch, a minimum application rate of 25 square feet per 100 gallons of septic tank capacity per day is indicated. GROUNDWATER Groundwater data compiled by the Western Municipal Water District Cooperative Well Monitoring Program was reviewed for this project. State Well No. 06S03E25P001S, located approximately 2,850 feet northeast of the site (34021 Morris Ranch Road), has been historically monitored. This well is located near the base of a valley and near a mapped “blue-line” stream, which drains to the southwest and crosses State Highway 74 approximately 360 feet north of the proposed on-site sewage disposal area on the site. This well was monitored on March 13, 2013. At that time the recorded depth to groundwater was 19.6 feet below the existing ground surface. Monitoring records for this well dating to 1996 were reviewed. The highest groundwater level between the period of 1996 and 2013 was on April 1, 1996. At that time, the reported depth to groundwater was 10 feet. Since that time, the record indicates fluctuating groundwater levels ranging from approximately 11 to 40 feet. A second nearby well, State Well No. 06S03E36C001S, is located approximately 1300 feet to the south-southeast of the site. This well is located at a similar geographical elevation (4538’ above msl) along the Garner Valley floor as the fire station site (4524’ above msl). The most recent record available for that well is a reading taken on March 31, 2013 indicating the depth to groundwater to be 35.9 feet. Groundwater records for this well dating to 1995 were reviewed. The highest groundwater level between the period of 1995 and 2013 was on May 5, 1995. At that time, the reported depth to groundwater was 12.3 feet. Since that time, the record indicates fluctuating groundwater levels ranging from approximately 16 to 67 feet.


The current exploration indicated no groundwater or evidence of seasonal high groundwater within the upper 16 feet. Obvious oxidation-reduction mottling in the exploratory trench was not observed. However, given the recent years of below average precipitation, it is our opinion that a historical high groundwater level of 12 feet should be conservatively used at the site for the purpose of designing the OWTS. Upon our review of well data and soil conditions present at the site, it appears to be reasonable to assume that there is a minimum separation of 5 feet of non-saturated soil between the shallow leach field and groundwater. The results of our investigation indicate that the use of a subsurface sewage effluent disposal system will be feasible on the site. This is provided that the system is constructed in accordance with the requirements of the County of Riverside, Department of Environmental Health, and the design that is attached. Our evaluation of the subsoils as observed within our exploration test holes indicates that the groundwater table should not be expected to encroach within the allowable limit currently set forth by County or State requirements. DISCUSSION It is proposed to replace the existing leach field and septic tank. Our analyses and design are based upon the following fixtures:

Fixture No. of Fixtures Fixture Units/Fixture Fixture Units Water Closet 4 6 24 Lavatories 4 1 4 Showers 3 2 6 Clothes Washer 1 2 2 Kitchen Sink 2 2 4 Dish Washer 1 2 2 TOTAL 42

The number of Fixture Units indicates that the septic tank should have a minimum capacity of 2000 gallons. The existing tank has a capacity of 1000 gallons and is in a deteriorated condition. Therefore, it is warranted to abandon the existing septic tank and install a new 2000 gallon capacity tank. The percolation rate and septic tank capacity indicate a minimum leach field area of 500 square feet. The existing system was observed to have approximately 360 square feet.


The insufficient leach field area and septic tank capacity are probably significant factors in the failure of the existing system. We are also advised that the use of the system may experience heavier than normal use which may also be a factor. Therefore, we recommend upgrading the septic tank to a 2000 gallon capacity and oversizing the leach field to accommodate heavier use. Because the only area reasonably available for a new leach field is at a higher elevation than the septic tank, pumping will be required. SEPTIC SYSTEM DESIGN SEPTIC TANK The septic tank will be located adjacent to the existing tank which will be abandoned in-place. A 2000-gallon capacity septic tank is recommended. Because the site of the septic tank may be subject to occasional traffic, we are recommending that it be able to support H-20 traffic loads. PUMPING STATION Because the leach field is slightly higher in elevation, a pump station is recommended rather than deepening the leach lines. We have recommended a 1000 gallon holding tank for this purpose. This tank should also be rated to support H-20 traffic loads. The holding tank has very little surge capacity. It is recommended to utilize the existing leach field for this purpose. This will also provide for limited use if the pump should fail and require service or replacement. Once the existing system is allowed to dry, it should be available to provide for limited flows for a 24-hour duration. The void space in the rock and pipe associated with the existing system will provide for over 500 gallons assuming no absorption. We’ve calculated a flow rate of approximately 14.5 gallons per minute under a total head of 18 feet. Therefore a 20 gpm pump is recommended. Our design is based upon an EasyPak Pump package available from Orenco Systems. This package includes the pump, filter, float and discharge assemblies and control panel with an alarm. DISTRIBUTION BOX We recommend a distribution box be utilized to provide for diversion of effluent into the existing leach field when excessive flows are encountered or in the event of a pump


failure. In such cases, the alarm in the control panel will be activated. The distribution box and lid are not traffic rated. Therefore, it has been positioned to the east of the proposed tanks and in-line with the existing gravity sewer line leading to the existing leach field. The distribution box should be protected from traffic by placing a barrier or bollard as required. DISPOSAL FIELD The purpose of the disposal field is to release the wastewater into the soil at the prescribed percolation rate. To provide for excessive flows, we recommend 200 linear feet of lead line. Each line should be underlain with 3 feet of leach line rock. Because the effluent will be pumped, we recommend a pressurized distribution system to provide for uniform application of effluent throughout the leach field. This should consist of 1.25 inch diameter Schedule 40 PVC pipe perforated with ⅛-inch diameter holes every 4 feet along the pipe. The disposal field will be located within an existing unpaved driveway. This driveway should be abandoned. LIMITATIONS It is important that the owner is aware of the location of the system and proper operation and maintenance procedures. It is also important that the owner is aware that the leach field area is not to be used for any purpose other than landscaping. Trees should be avoided. The leach field should be protected against ponding water. The primary and expansion systems should not be operated simultaneously. During construction, the leach field areas should be flagged off to avoid vehicular traffic. The findings and recommendations provided in this report are based upon an inter-polation of subsurface conditions between test and boring locations. The data obtained from the various points of observation and testing may only be representative of the condition at those specific locations. Therefore, conditions may be encountered during construction that appears to be different than those indicated herein. We cannot assume any responsibility for such unforeseen conditions, but should be notified if they occur in order to determine the necessity of revising our recommendations. Our con-clusions presented concerning groundwater are based upon our field observations, a limited literature review, and our knowledge of the general area. Therefore, our opinions are based upon limited data and may not accurately represent future or historical groundwater levels. The Health Department may have more thorough records, which may provide a more accurate representation of prior groundwater levels


PROJECT INFORMATION Assessor's Parcel Number: 568-080-036 Project Address or Legal Description: 59200 Morris Ranch Road,

Mountain Center, California

Client Name: STK Architecture, Inc. Address: 42095 Zevo Drive, Suite A15

Temecula, California 92590 Telephone No.: (951) 296-9110

SITE DESCRIPTION

Size of Proposed Disposal Area: Approximately 25 feet X 100 feet Slope of Proposed Disposal Area: Less than 2 percent Existing Use and Vegetation: The site of the proposed disposal field is clear

of surface vegetation and vacant. Several pine trees are present in the vicinity of the proposed system.

Rock Outcroppings: None Observed. Other Significant Features: None. Property Location By: Existing fence lines and discussions with the

County of Riverside Fire Department

SUBSURFACE CONDITIONS – TRENCH LOG

0.0-3.5 ft. Silty Sand (SM), Fine- to Coarse-Grained, Gray-Brown, Slightly Moist, Loose.

3.5-5.5 ft. Sand with Silt (SW-SM), Fine- to Coarse-Grained, Gray-Brown, Slightly Moist, Loose to Medium Dense.


5.5-9.0 ft. Silty Sand (SM), Fine- to Coarse-Grained, Light Brown to Gray-Brown, Moist, Loose to Medium Dense.

9.0-16 ft. Sand with Silt (SW-SM), Fine- to Coarse-Grained, Moist, Loose to Medium Dense. Caving Occurred.

16 ft. End of Trench. No Groundwater or Oxidation-Reduction Mottling Observed. Placed 3” diameter perforated PVC pipe with mesh sock and backfilled with native soils.

TEST SUMMARY

Test No. Depth

(in) Rate

(Min./In.) P-01 75 10 P-02 63 10.4 P-03 66 9.2 P-04 56 5.4 P-05 74 10 P-06 43 6.3

SEPTIC SYSTEM DESIGN

Recommended Design Rate: 25 sq. ft. per 100 gallons Estimated Daily Wastewater Flow: 2000 gallons/day Overburden Factor: 1.0 Leach line Required: 500 sq. feet Is there room for future construction? Yes X No Yes, but should be reviewed by Health Authority


COUNTY OF RIVERSIDE, DEPARTMENT OF HEALTH STANDARD PERCOLATION TEST PROCEDURES FOR LEACH LINES,

TECHNICAL GUIDANCE MANUAL VERSION A

DESCRIPTION This test method is for determining the percolation rate to be applied to leach line and leach bed designs. This method requires the use of a water reservoir and provides a continuous volume of water in the hole during the pre-soak period. After a predetermined volume of water has seeped through the test hole, the measurement of the percolation rates shall commence.

PROCEDURES

Excavation: Test excavation shall be construction so as to facilitate placement of 5 gallon reservoir of water over test hole. Excavation shall extend to within 13 inches of actual test depth which corresponds to approximate depth of leach line or bed trench bottom.

TEST HOLE: 1. Auger or hand excavated. 2. The test hole shall have a diameter between 8” and 12” or

between 7” and 11” on side if square. 3. Test hole depth is 13” minimum. (Below test excavation bottom) 4. All loose material is removed from test hole and bottom is

natural, undisturbed soil.

5. The sides of the hole shall remain undisturbed (not smeared) after drilling and any cobbles and boulders encountered shall be left in place.

6. Place 2 inches of gravel over the bottom of the test hole. A perforated pipe is then placed in the hole to prevent caving and to support the water bottle. The pipe length shall be approximately the same as the test hole depth.


PRE-SOAKING: Invert a full 5 gallon bottle of clear water over the hole (in bottle support) so that the water flow into the hole holds constant at least 8 inches above the gravel at the bottom of the hole.

When the 5 gallon bottle of water has percolated through the test

hole or after 15 hours from initiating pre-soak, testing may commence.

TESTING:

A. Same Day Testing: In sandy soils, the tests may proceed the same day as the pre-soak if two consecutive measurements show 6 inches of water seeps away in less than 25 minutes.

1. Adjust water level to 6 inches over the gravel.

2. Take measurements for one hour at 10 minute

intervals. Refill to 6 inches over the gravel after each measurement. The drop that occurs during the final 10 minutes should be used to calculate the percolation rate.

X

B. Next Day Testing (15 – 26 hours after initiating pre-soak): In non-sandy soils, the tests may proceed as next day testing if all the water has percolated while the tester is present or after 15 hours. In no water remains in the test hole after the initial soaking, testing must start no later than 26 hours from initiating pre-soak.

1. Remove bottle and adjust water level to 6 inches

over the gravel. 2. Take measurements for six hours at 30 to 60

minute intervals. Measurements must be taken with a precision of at least 0.25 inches. Refill to 6 inches over the gravel after each measurement. The drop that occurs during the final reading should be used to calculate the percolation rate.

21 Not to Scale

SEPTIC TANK/DISTRIBUTION BOX /PUMP STATION CROSS-SECTION

11 Not to Scale

SITE PLAN

41 Not to Scale

VICINITY MAP

PROPERTY DESCRIPTION:

PREPARED FOR: STK ARCHITECTURE, INC.42095 Zevo Drive, Suite A-15Temecula, California 92590(951) 296-9110

59200 Morris Ranch RoadGarner Valley AreaRiverside County, California

PERCOLATION RATE:

FIXTURE UNITS:

SEPTIC TANK CAPACITY:

LEACH LINE AREA:

NUMBER OF LEACH LINES:

DEPTH OF LEACH LINES:

42

2000 Gallons

500 Square Feet (minimum)

2 Lines @ 3 Feet Wide X 100 Feet Long

3 Feet below Distribution Pipe

25 Square Feet/100 Gallons Effluent/Day

LEACH LINE PIPE:

PERFORATIONS:

EQUIVALENT LEACH LINE AREA:

100'

Percolation Test Location

Backhoe Pit Location

P-1

P-2P-3

P-4

P-5

P-6

(Drill 1/8" diameter at 4' centers)

ON-SITE WASTEWATER TREATMENT SYSTEM REPLACEMENT/UPGRADERIVERSIDE COUNTY FIRE DEPARTMENT STATION 53

59200 Morris Ranch RoadGarner Valley Area

Riverside County, CaliforniaSITE

Mor

ris R

anch

Roa

d

State Rte. 74

Septic Tank/Pump Station(Details Sheet 2)

Existing Leach Lines to Remain

New Leach Field(Plan View Detail Sheet 2)

Existing Unpaved Driveway to be Abandoned

Orenco BEP20TDD-CW-MFVEasyPak Pump Package

Pro-Cast H-1000 Holding TankDistribution BoxPro-Cast Model D-6 PC -2000 Septic Tank

24" Dia. Risers as necessary Bolt Down Cast-iron Frames and Lids

Pump Vault

Filter Cartridge

FloatStem

1.25" Schedule 40 PVC Pressure Discharge

Not to Scale

LEACH FIELD PROFILE31

1

Hose Rack

Propane Tank

FIRE STATION 53

APPARATUS BAYS

Existing Septic Tank

1.25" Pressure Discharge

1.25 Inch Schedule 40 PVC

1/8 Inch Dia. at 4 foot Centers - Face Down

1000 Square Feet

DESIGN FLOW RATE:

TOTAL DYNAMIC HEAD:

14.5 GPM

18.3 Feet

24" 24"

APN 568-080-036

12

SEPTIC TANK/DISTRIBUTION BOX /PUMP STATION PLAN VIEW

42

LEACH FIELD PLAN VIEW

0 2 4 6 10

0 5 10 20 30 50

32 Not to Scale

DISTRIBUTION BOX PROFILE

22 Not to Scale

DISTRIBUTION BOX PLAN VIEW

Outlet to Pump StationInlet from Septic Tank

Existing Sewer

Slide Gate Valve

"Overflow" Outlet to Existing Leach Field

Pro-Cast Model D-6

Existing Septic Tank (Abandon in-place)

Model D-6 Distribution Box

Existing Sewer (Abandon in-place)

Existing Sewer to Remain from "Overflow" connection to existing Leach Field

Connect "Overflow" to Existing Sewer

1.25" Schedule 40 PVC Pressure Sewer to New Leach Lines

Install New Bollard

ON-SITE WASTEWATER TREATMENT SYSTEM REPLACEMENT/UPGRADERIVERSIDE COUNTY FIRE DEPARTMENT STATION 53

59200 Morris Ranch RoadGarner Valley Area

Riverside County, California

Pro-Cast Model PC S2000

With H-20 rated Risers and Lids

PUMP STATION

Pro-Cast Model PC H1000

With H-20 rated Riser and Lid

SEPTIC TANK

"Overflow" Outlet

Slide Gate Valve

Inlet from Septic Tank

Connect "Overflow" to Existing Sewer

Existing Sewer(to be removed)

Place 6-inch risers to grade

Pro-Cast Model D-6

2

100'

Existing Driveway (unpaved) to be abandoned

PRIMARY LEACH FIELD

1.25" Pressure Discharge(Schedule 40, PVC)

1.25" Schedule 40 PVC1/8 Inch Perforations @ 4' O.C.

Pressure Manifold1.25 Inch Schedule 40 PVC

100% Expansion

inland foundation engineerin+g, inc · the field activities were performed under ... reasonable to...

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