david w. coombs, pe
DAVID W. COOMBS, P.E REGISTERED PROFESSIONAL
ENGINEER
WATER AND WASTEWATER TREATMENT ON-SITE SEPTIC SYSTEM DESIGN STORMWATER MANAGEMENT SITE DEVELOPMENT
April 10, 1997
Bastrop County Department of Health and Sanitation P.O. Box 802 Bastrop, Texas 78602 Attention: Mr. L.C. Smith, Sanitation Officer
Subject: Septic System Design for Lot 54, Blk 1, Pine Forest Phase III, Unit 7; John Williams
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Dear Mr. Smith: The attached calculations and design drawings have been revised to provide an LPD septic system to serve the proposed 1,943 sq ft, 3 bedroom residence at the above referenced address. The system is sized based on a 4-bedroom equivalency, in excess of the requirements of the OSSF Rule, Chapter 285, Texas Administrative Code. 12196. Potable water is to be supplied by an existing community system. Asummary
of the proposed system components is as follows:
- A 1,250 gal. two-compartment - A 500 gal1-compartment
septic tank.
pump tank.
- A 0.5 hp effluent pump. and controls. - 625 linear: feet of LPD drainfield trench in two beds, to be alternated by a manual Jandy valve. If you have any comments regarding this application, please call me at (512)281-3500.
David: W; Coombs, P:E
Attachments
Mail: Post Office Box 966 Elgin, Texas 78621
Office: (512)303-9300 Home: (512)281-3500 Fax: (512)303-6646
Office: 1620 Industrial Street Bastrop, Texas 78602
Sheet 1 of 3 DESIGN CALCULATIONS FOR: -----------------------------------------------
Owner: John Williams Site: Lot 54, Blk 1, Pine Forest Phase III, Unit 7 SITE DATA Excavations on the the site showed the following, by visual and manual examination: PH1
0-14" 14"+
Tan gravelly loamy sand/sandy loam Red/brown sandy clay
The textural soil classification for drainfield sizing is Class 3. DRAINFIELD CALCULATIONS The proposed residence is 3 bedrooms, 1,943 sq ft; LPD drainfield sizing (per Carlile, et. al.) for 4 bedrooms equivalent is used. No reduction is made for the use of low-flow water fixtures: Area req'd
= Q / Ra = 375
GPO / 0.2 GPO/SF
= 1875 SF
Allowing 3 SF of absorption area for each linear foot of LPO trench, a total of 625 linear feet of LPO trench is required. It is proposed to use two beds, alternated by a manual Jandy valve. SEPTIC TANK CALCULATIONS Tank volume req'd = 1,250 gal for 4 bedroom (equivalent) residence.
GENERAL NOTES NOTE: This septic system is designed to treat and dispose of a maximum of 375 gallons of domestic waste water per day. 1. Construction of this system shall conform to the requirements set forth in the OSSF Rule, Chapter 285, Texas Administrative Code 12/96, as well as the regulations of the approving agency. 2. The installer shall not deviate from these plans without written consent of the approving agency and the engineer, 3. Installer shall backfill all percolation test and soil profile holes after authorization to do so by the approving agency. 4. The installer is responsible for locating all underground utilities on site. The installer shall verify the location and elevation of the house stubout prior to excavation of tank holes. 5. The installer and the owner shall coordinate for the preservation of desirable vegetation, Distribution laterals may be adjusted for this purpose with engineer's permission. 6. The installer is responsible for contacting the approving agency and the engineer to schedule construction inspections. Notification to the engineer is required at the following points: - After trenches are excavated but before placement of gravel. - When pipe and gravel are installed, tanks set, pump and alarm operable. - After final landscaping. Engineer requires min. 48 hr. notice for inspection visits. 7. The installer shall insure that all surface and roof drainage is directed away from tanks and drainfields by guttering, berms, etc. 8. The installer shall be responsible for informing the owner regarding proper system operation and maintenance, including location and operation of pump alarm and switching valve. 9. The use of low volume flush toilets (1,6 gal), low flow shower heads (2,75 gpm @ 80psi) and faucets (2,2 gpm @ 60 psi) is required.
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Flow! Lat, GPM 3.2461 5,6575 8.994 4.0169 7.3038 5.7742 34.993
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ENGINEER
WATER AND WASTEWATER TREATMENT ON-SITE SEPTIC SYSTEM DESIGN STORMWATER MANAGEMENT SITE DEVELOPMENT
April 10, 1997
Bastrop County Department of Health and Sanitation P.O. Box 802 Bastrop, Texas 78602 Attention: Mr. L.C. Smith, Sanitation Officer
Subject: Septic System Design for Lot 54, Blk 1, Pine Forest Phase III, Unit 7; John Williams
K -e... 0 ~ ::):
e:;--.-.....
Dear Mr. Smith: The attached calculations and design drawings have been revised to provide an LPD septic system to serve the proposed 1,943 sq ft, 3 bedroom residence at the above referenced address. The system is sized based on a 4-bedroom equivalency, in excess of the requirements of the OSSF Rule, Chapter 285, Texas Administrative Code. 12196. Potable water is to be supplied by an existing community system. Asummary
of the proposed system components is as follows:
- A 1,250 gal. two-compartment - A 500 gal1-compartment
septic tank.
pump tank.
- A 0.5 hp effluent pump. and controls. - 625 linear: feet of LPD drainfield trench in two beds, to be alternated by a manual Jandy valve. If you have any comments regarding this application, please call me at (512)281-3500.
David: W; Coombs, P:E
Attachments
Mail: Post Office Box 966 Elgin, Texas 78621
Office: (512)303-9300 Home: (512)281-3500 Fax: (512)303-6646
Office: 1620 Industrial Street Bastrop, Texas 78602
Sheet 1 of 3 DESIGN CALCULATIONS FOR: -----------------------------------------------
Owner: John Williams Site: Lot 54, Blk 1, Pine Forest Phase III, Unit 7 SITE DATA Excavations on the the site showed the following, by visual and manual examination: PH1
0-14" 14"+
Tan gravelly loamy sand/sandy loam Red/brown sandy clay
The textural soil classification for drainfield sizing is Class 3. DRAINFIELD CALCULATIONS The proposed residence is 3 bedrooms, 1,943 sq ft; LPD drainfield sizing (per Carlile, et. al.) for 4 bedrooms equivalent is used. No reduction is made for the use of low-flow water fixtures: Area req'd
= Q / Ra = 375
GPO / 0.2 GPO/SF
= 1875 SF
Allowing 3 SF of absorption area for each linear foot of LPO trench, a total of 625 linear feet of LPO trench is required. It is proposed to use two beds, alternated by a manual Jandy valve. SEPTIC TANK CALCULATIONS Tank volume req'd = 1,250 gal for 4 bedroom (equivalent) residence.
GENERAL NOTES NOTE: This septic system is designed to treat and dispose of a maximum of 375 gallons of domestic waste water per day. 1. Construction of this system shall conform to the requirements set forth in the OSSF Rule, Chapter 285, Texas Administrative Code 12/96, as well as the regulations of the approving agency. 2. The installer shall not deviate from these plans without written consent of the approving agency and the engineer, 3. Installer shall backfill all percolation test and soil profile holes after authorization to do so by the approving agency. 4. The installer is responsible for locating all underground utilities on site. The installer shall verify the location and elevation of the house stubout prior to excavation of tank holes. 5. The installer and the owner shall coordinate for the preservation of desirable vegetation, Distribution laterals may be adjusted for this purpose with engineer's permission. 6. The installer is responsible for contacting the approving agency and the engineer to schedule construction inspections. Notification to the engineer is required at the following points: - After trenches are excavated but before placement of gravel. - When pipe and gravel are installed, tanks set, pump and alarm operable. - After final landscaping. Engineer requires min. 48 hr. notice for inspection visits. 7. The installer shall insure that all surface and roof drainage is directed away from tanks and drainfields by guttering, berms, etc. 8. The installer shall be responsible for informing the owner regarding proper system operation and maintenance, including location and operation of pump alarm and switching valve. 9. The use of low volume flush toilets (1,6 gal), low flow shower heads (2,75 gpm @ 80psi) and faucets (2,2 gpm @ 60 psi) is required.
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