INTERNATIONAL ASSOCIATION OF PLUMBING AND MECHANICAL OFFICIALS

Transcription

1 INTERNATIONAL ASSOCIATION OF PLUMBING AND MECHANICAL OFFICIALS INTERIM GUIDE CRITERIA FOR AEROBIC BACTERIAL GENERATOR FOR INSERT INTO SEPTIC TANKS, GREASE INTERCEPTORS AND GREASE TRAPS IAPMO IGC PURPOSE 1.1 The purpose of this Standard is to establish a generally acceptable performance standard for Aerobic Bacterial Generators (ABG s) designed for installation inside septic tanks, grease interceptors and grease traps for the purpose of restoration and preservation of the soil s ability to absorb and treat the effluent. The intent is to serve as a guide for producers, distributors, architects, engineers, contractors, installers, inspectors and users; to promote understanding regarding materials, manufacture and installation, and to provide for identifying ABG s complying with this standard. 1.2 The provisions of this standard are not intended to prevent the use of any alternate material or method of construction provided that any such alternate meets the requirements of the standard. 2. SCOPE 2.1 This standard covers reference standards, definitions, general requirements, testing requirements, installation instructions, and marking and identification for Aerobic Bacteria Generators (ABGs). ABGs covered by this standard include an aerated chamber for introduction of a colony of aerobic bacteria, provide a flow of aerated effluent over this culture, and contain a matrix capable of providing an attachment surface for a fixed aerobic bacterial film. They shall be designed so that they are free standing and can be installed in an existing septic tank, grease interceptor or grease trap without structural change to the tank. 3. REFERENCE STANDARDS 3.1 The standards referenced herein shall be the current edition of the standards, as published in Table 14-1 of the Uniform Plumbing Code. ASTM D1785 Poly (Vinyl Chloride) (PVC) Plastic Pipe, Schedules 40, 80, and 120 ASTM D2665 Poly (Vinyl Chloride) (PVC) Plastic Drain, Waste, and Vent Pipe and Fittings ASTM D3034 Type PSM Poly(VinylChloride) (PVC) Sewer Pipe and Fittings ASTM F810 Smoothwall Polyethylene (PE) Pipe for Use in Drainage and Waste Disposal Absorption Fields Copyright 2002 by International Association of Plumbing and Mechanical Officials. All rights reserved. Printed in the United States IGC Aerobic Bact Gen page 1 of 7

2 AWWA AWWA B100 IAPMO PS 1 UL 1450 UL 1951 Standard Methods for the Examination of Water and Wastewater Granular Filter Material Prefabricated Septic Tanks Motor-Operated Air Compressors, Vacuum Pumps, and Painting Equipment Standard for Electric Plumbing Accessories 4. DEFINITIONS 4.1 ABG - An ABG is a manufactured unit designed for installation inside a standard septic tank, grease interceptor or grease trap. ABGs aerate and cause a current to pass over a fixed colony of bacteria living on a fixed film matrix. The current passing over the fixed film provides a steady stream of suspended bacteria that digests the biodegradable material within the tank and is discharged to a receiving leach field. 4.2 Aerated Fixed Film Matrix - The fixed-film matrix in contact with the aerated effluent is part of the ABG that provides a surface for attachment of either introduced or indigenous aerobic bacteria. 4.3 BOD5 - Five day biological oxygen demand. 4.4 CFU - Colony forming units. 4.5 Pea Gravel - double washed gravel that is 3/8 inch to 1/2 inch in dimension. 4.6 TSS - Total suspended solids. 5. GENERAL REQUIREMENTS 5.1 Materials An ABG shall be constructed of materials capable of resisting biological or physical deterioration within a septic tank, grease interceptor, or grease trap. Acceptable materials include PVC and PE PVC schedule 40 pipe shall comply with the requirements of ASTM D PVC DWV pipe shall comply with the requirements of ASTM D PVC sewer pipe shall comply with the requirements of ASTM D Polyethylene drainage pipe shall comply with the requirements of ASTM F Unit Size The diameter of an ABG shall be less than 20 inches so that it will be small enough to allow insertion into a septic tank, grease interceptor or grease trap through existing openings. The height of the ABG shall be less than the liquid depth in the septic tank, grease interceptor, or grease trap the ABG is designed for installation in. Copyright 2002 by International Association of Plumbing and Mechanical Officials. All rights reserved. Printed in the United States IGC Aerobic Bact Gen page 2 of 7

3 5.3 Aerobic Conditions Aeration shall be provided by the ABG so that the fluid contains a measurable amount of oxygen that is available to ensure aerobic conditions for the fixed bacterial colony. 5.4 Electrical Components - Electrical components, including air pumps, shall comply with UL 1450 or UL TESTING REQUIREMENTS 6.1 Aerator Location - An aerator shall be located within the ABG to create a flow of aerated effluent over the fixed film bacterial matrix. 6.2 Additional Components - ABGs shall be tested while fitted with the exact components, including air diffuser and air pump, to be marketed with the unit. The test report shall identify all added components, including the air diffuser and air pump, used in the testing. 6.3 Effluent Processing Test Install two 1,200 gallon septic tanks, manufactured in compliance with IAPMO PS 1, at a municipal wastewater facility (WWTP). Plumb the septic tanks to receive flow from the influent to the primary clarifier of the WWTP. Support the septic tanks as needed for filling with water. Install three replicate leach field test units downstream of each septic tank in accordance with the diagram shown in Figure 1. Install a dosing pump in the outlet chamber of each septic tank to provide effluent flow to the leach field test units Leach Field Test Unit Construction - Construct each leach field test unit inside of a four foot diameter two foot tall round barrel or pipe in accordance with sections Bottom Layer - Install a slotted 1-1/2 inch PVC sub-flow drainage pipe at the bottom of each leach field test unit. Cover the sub-flow drainage pipe with a 3 inch layer of double washed pea gravel (3/8 inch 1/4-1/2 3/4 inch dimension). This pipe will exit to a flow measuring apparatus calibrated to measure flow from the sub-flow drainage pipe at an accuracy of ± 2 gpd sump where capture of sub-flow can be made to monitor flow of effluent percolating through sand layer above Second Sand Layer - Place a 4 inch layer of dry, triple washed silica sand into each leach field test unit on top of the bottom pea sand inches thick above the gravel layer at the bottom. The sand shall comply with the requirements of AWWA B100 for silica sand, with an effective size of 0.5 mm and a coefficient of uniformity of when tested in accordance with AWWA section entitled Sieve Analysis. Level the top of the sand surface before applying the third layer Third Layer - Place an 8 inch layer of dry, triple washed sand into each leach field test unit on top of the 4 inch sand layer. The sand shall comply with the requirements of AWWA B100 for silica sand, with an effective size of 0.6 mm and a coefficient of uniformity of when tested in accordance with AWWA section entitled Copyright 2002 by International Association of Plumbing and Mechanical Officials. All rights reserved. Printed in the United States IGC Aerobic Bact Gen page 3 of 7

4 Sieve Analysis. Level the top of the sand surface before applying the fourth layer. unclarified effluent from WWTP septic tank #1 (install ABG) septic tank #2 (control) leach field test unit overflow sub-flowdrainage overflow back to WWTP Figure Measuring Well - Install a vertical measuring well into each leach field test unit resting on the surface of the 8 inch sand layer. The measuring well shall consist of an openended 4 inch PVC pipe with a removable cap placed over the top end of the pipe to keep foreign materials out. The monitoring well will allow the depth of liquid pooling over the sand interface to be measured Fourth Layer - Place an 8 inch layer of double washed pea gravel into each leach field test unit on top of the 8 inch sand layer. Place the gravel around the monitoring well thereby supporting the well Overflow - Drill a hole into the sidewall of each leach field test unit just below the upper rim. Fit a 1 inch diameter pipe through the hole to allow excess effluent to flow to drainage. Copyright 2002 by International Association of Plumbing and Mechanical Officials. All rights reserved. Printed in the United States IGC Aerobic Bact Gen page 4 of 7

5 distribution pipe measuring well effluent flow overflow fourth layer third layer second layer sub-flow drainage pipe bottom layer Leach Field Test Unit Figure Distribution Pipe - Install an 8 inch long piece of 4 inch PVC pipe vertically in the upper surface of the 8 inch pea gravel layer of each leach field test unit in accordance with Figure 2. Bury the bottom end of the 4 inch pipe approximately 2 inches deep into the upper surface of the pea gravel. Effluent from the septic tanks will flow out the bottom end of the distribution pipe such that the effluent is distributed by gravity as it trickles across the pea gravel above the sand Fill the septic tanks with septage obtained from local septic tanks. Once the septic tanks are full, introduce flow of unclarifed effluent from the WWTP into the septic tanks and continue for 60 days prior to initiating the test. Allow the overflow from the septic tanks to return to the WWTP. Take samples of the effluent being fed to the tanks once per week for two weeks prior to initiating the effluent processing test to confirm that the average effluent quality exceeds the following limits: BOD5-130 mg/l when tested in accordance with Standard Methods for the Examination of Water and Wastewater. TSS -80 mg/l when tested in accordance with Standard Methods for the Examination of Water and Wastewater After the effluent in the septic tank has aged for at least 60 days and the effluent quality Copyright 2002 by International Association of Plumbing and Mechanical Officials. All rights reserved. Printed in the United States IGC Aerobic Bact Gen page 5 of 7

6 meets the BOD5 and TSS requirements in Section 5.3.3, feed the septic tank with identical effluent at a rate of 330 gpd in 11 doses between 6:00 AM and 12:00 midnight. Allocate equal flows of at least 8 gpd/ft 2 to each of the leach field test units Continue effluent flow to the leach field test units until discharge from the sub-flow drainage pipe, as measured by the flow measuring apparatus is reduced by biomat clogging to an average of 1.2 gpd/ft 2 of surface area or less Take weekly samples of the influent and effluent draining from the base of the leach field test units. Test each sample for the BOD5, TSS and fecal coliform as CFU/100 ml in accordance with Standard Methods for the Examination of Water and Wastewater Install the ABG in the inlet chamber of one of the septic tanks once the soil absorption rate meets the 1.2 gpd/ft 2 threshold. The other tank will be left as a control. Start aeration immediately. If the ABG is intended to be inoculated with a supplied bacterial culture, inoculate it in accordance with the manufacturer s instructions Feed the septic tanks with 330 gpd of unclarified primary effluent coming from the WWTP and discharge to the leach field test troughs at a rate of 2.4 gpd/ft 2 for a period of 30 days. The initial flow distribution shall be such that approximately 1.2 gpd/ft 2 flows out the overflow and approximately 1.2 gpd/ft 2 discharges through the bottom of each leach field test unit Test weekly effluent samples for a period of thirty days during the second test phase as described in section Performance Requirement. An ABG shall be deemed to have met the requirements of the standard if it recovers leach function of the leach field test units within a day period following the installation of the ABG. Recovery of the leach field function shall be demonstrated by repeating the dosing test using the same protocol as used for the initial dosing test. Recovery of leach field function shall be deemed to have occurred when the entire 2.4 gpd/ft 2 of effluent flows through each leach field test unit and exits via the bottom outlet. This should be at the same point at which the overflow rate drops to zero in each leach field test unit when the subflow for each leach unit loaded by the ABG tank equals at least 3.5gpd/sq. ft. and the mean flow for all ABG leach units equals at least 5.0 gpd/sq. ft. Subflow through the leach units loaded by the ABG shall further be at least twice the flow rate as those loaded by the aerated control tank. 7. INSTALLATION INSTRUCTIONS 7.1 The installation instructions shall contain the following requirements: a) the air supply line shall be plumbed using 1/2 inch schedule 40 PVC pipe b) entry of the air line into the septic tank or grease interceptor shall be made using a service riser approved by the local Authority Having Jurisdiction. 8. MARKINGS AND IDENTIFICATION Copyright 2002 by International Association of Plumbing and Mechanical Officials. All rights reserved. Printed in the United States IGC Aerobic Bact Gen page 6 of 7

7 8.1 The main body of the ABG shall be permanently and legibly marked with the manufacturer s name or trademark so as to be visible before installation. 8.2 All other components, including the air pump and diffuser, shall be permanently and legibly marked with the ABG manufacturer s name and trademark or the name or trademark of the manufacturer of the component. Adopted October, 2002 Copyright 2002 by International Association of Plumbing and Mechanical Officials. All rights reserved. Printed in the United States IGC Aerobic Bact Gen page 7 of 7

8 INTERNATIONAL ASSOCIATION OF PLUMBING AND MECHANICAL OFFICIALS IAPMO GUIDE CRITERIA FOR AEROBIC BACTERIAL GENERATOR FOR INSERT INTO SEPTIC TANKS, GREASE INTERCEPTORS AND GREASE TRAPS IAPMO IGC PURPOSE 1.1 The purpose of this standard is to establish a generally acceptable performance standard for Aerobic Bacterial Generators (ABG s) designed for installation inside new or existing septic tanks, grease interceptors and grease traps for the purpose of restoration and preservation of the soil s ability to absorb and treat the effluent. The intent is to serve as a guide for producers, distributors, architects, engineers, contractors, installers, inspectors and users; to promote understanding regarding materials, manufacture and installation, and to provide for identifying ABG s complying with this standard. 1.2 The provisions of this standard are not intended to prevent the use of any alternate material or method of construction provided that any such alternate meets the requirements of the standard. 2. SCOPE 2.1 This standard covers reference standards, definitions, general requirements, testing requirements, installation instructions, and marking and identification for Aerobic Bacteria Generators (ABGs). ABGs covered by this standard include an aerated chamber for introduction of a colony of aerobic bacteria, provide a flow of aerated effluent over this culture, and contain a matrix capable of providing an attachment surface for a fixed aerobic bacterial film. They shall be designed so that they are free standing and can be installed in an existing septic tank, grease interceptor or grease trap without structural change to the tank. 3. REFERENCE STANDARDS 3.1 The standards referenced herein shall be the current edition of the standards, as published in Table 14-1 of the Uniform Plumbing Code. ASTM D1785 Poly (Vinyl Chloride) (PVC) Plastic Pipe, Schedules 40, 80, and 120 ASTM D2665 Poly (Vinyl Chloride) (PVC) Plastic Drain, Waste, and Vent Pipe and Fittings ASTM D3034 Type PSM Poly (VinylChloride) (PVC) Sewer Pipe and Copyright 2003 by International Association of Plumbing and Mechanical Officials. All rights reserved. Printed in the United States IGC ABG page 1 of 7

9 ASTM F810 IAPMO PS 1 UL 1450 UL 1951 Fittings Smoothwall Polyethylene (PE) Pipe for Use in Drainage and Waste Disposal Absorption Fields Prefabricated Septic Tanks Motor-Operated Air Compressors, Vacuum Pumps, and Painting Equipment Standard for Electric Plumbing Accessories 4. DEFINITIONS 4.1 ABG - An ABG is a manufactured unit designed for installation inside a standard septic tank, grease interceptor or grease trap. ABGs aerate and cause a current to pass over a fixed colony of bacteria living on a fixed film matrix. The current passing over the fixed film provides a steady stream of suspended bacteria that digests the biodegradable material within the tank and is discharged to a receiving leach field. 4.2 Aerated Fixed Film Matrix - The fixed-film matrix in contact with the aerated effluent is part of the ABG that provides a surface for attachment of either introduced or indigenous aerobic bacteria. 4.5 Pea Gravel - double washed gravel that is 1/4 inch to 3/4 inch in dimension. 5. GENERAL REQUIREMENTS 5.1 Materials An ABG shall be constructed of materials capable of resisting biological or physical deterioration within a septic tank, grease interceptor, or grease trap. Acceptable materials include PVC and PE PVC schedule 40 pipe shall comply with the requirements of ASTM D PVC DWV pipe shall comply with the requirements of ASTM D PVC sewer pipe shall comply with the requirements of ASTM D Polyethylene drainage pipe shall comply with the requirements of ASTM F Unit Size The diameter of an ABG shall be less than 20 inches so that it will be small enough to allow insertion into a septic tank, grease interceptor or grease trap through existing openings. The height of the ABG shall be less than the liquid depth in the septic tank, grease interceptor, or grease trap the ABG is designed for installation in. 5.3 Aerobic Conditions Aeration shall be provided by the ABG so that the fluid contains a measurable amount of oxygen that is available to ensure aerobic conditions for the fixed bacterial colony. Copyright 2003 by International Association of Plumbing and Mechanical Officials. All rights reserved. Printed in the United States IGC ABG page 2 of 7

10 5.4 Electrical Components - Electrical components, including air pumps, shall comply with UL 1450 or UL TESTING REQUIREMENTS 6.1 Aerator Location - An aerator shall be located within the ABG to create a flow of aerated effluent over the fixed film bacterial matrix. 6.2 Additional Components - ABGs shall be tested while fitted with the exact components, including air diffuser and air pump, to be marketed with the unit. The test report shall identify all added components, including the air diffuser and air pump, used in the testing. 6.3 Effluent Processing Test Install two 1,200 gallon septic tanks, manufactured in compliance with IAPMO PS 1, at a municipal wastewater facility (WWTP). Plumb the septic tanks to receive flow from the influent to the primary clarifier of the WWTP. Support the septic tanks as needed for filling with water. Install three replicate leach field test units downstream of each septic tank in accordance with the diagram shown in Figure 1. Install a dosing pump in the outlet chamber of each septic tank to provide effluent flow to the leach field test units Leach Field Test Unit Construction - Construct each leach field test unit inside of a four foot diameter two foot tall round barrel or pipe in accordance with sections Bottom Layer - Install a slotted 1-1/2 inch PVC sub-flow drainage pipe at the bottom of each leach field test unit. Cover the sub-flow drainage pipe with a 3 ±1 inch layer of pea gravel (1/4 inch - 3/4 inch dimension). This pipe will exit to a sump where capture of sub-flow can be made to monitor flow of effluent percolating through the sand layer above Sand Layer - Place a inch layer of sand into each leach field test unit on top of the bottom pea gravel layer Third Layer - Place an 8 ±1 inch layer of pea gravel (1/4 inch - 3/4 inch dimension) into each leach field test unit on top of the sand layer. Place the gravel around the base of the distribution pipe to support it. Copyright 2003 by International Association of Plumbing and Mechanical Officials. All rights reserved. Printed in the United States IGC ABG page 3 of 7

11 unclarified effluent from WWTP septic tank #1 (install ABG) septic tank #2 (control) leach field test unit overflow sub-flowdrainage overflow back to WWTP Figure Overflow - Drill a hole into the sidewall of each leach field test unit just below the upper rim. Fit a 1 inch diameter pipe through the hole to allow excess effluent to flow to drainage Distribution Pipe - Install an 8 inch long piece of 4 inch PVC pipe vertically in the upper surface of the 8 inch pea gravel layer of each leach field test unit in accordance with Figure 2. Bury the bottom end of the 4 inch pipe approximately 2 inches deep into the upper surface of the pea gravel. Effluent from the septic tanks will flow out the bottom end of the distribution pipe such that the effluent is distributed by gravity as it trickles across the pea gravel above the sand Introduce flow of unclarifed effluent from the WWTP into the septic tanks. Allow the overflow from the septic tanks to return to the WWTP. Copyright 2003 by International Association of Plumbing and Mechanical Officials. All rights reserved. Printed in the United States IGC ABG page 4 of 7

12 distribution pipe effluent flow overflow third layer sand layer sub-flow drainage pipe bottom layer Leach Field Test Unit Figure Direct effluent flow to the leach field test units until discharge from the subflow drainage pipe, as measured by the flow measuring apparatus is reduced by biomat clogging to an average of 1.0 gpd/ft 2 of surface area or less Begin an initial dosing test as described in sections to verify that the following flow reductions have been achieved, a) the sub-flow through each leach field test unit shall be reduced by biomat clogging to 1.6 gpd/ft 2 or less. b) the average sub-flow of all three leach field test units shall be reduced to 1.0 gpd/ft 2 or less, Calibrate the flow of effluent from the dosing pump to each leach field test unit Dose each leach field test unit with 1.0 ±0.5 gallons of effluent administered over a 70 ± 30 second period. Dose each leach field test unit a second time after 20 minutes and again a third time after another 20 minutes interval Collect and measure all effluent flowing from the sub-flow drainage pipe of Copyright 2003 by International Association of Plumbing and Mechanical Officials. All rights reserved. Printed in the United States IGC ABG page 5 of 7

13 each leach field test unit for a period of 1 hour. Begin collecting the effluent at the beginning of the first dosing cycle. At this time effluent should also be leaving the test unit from the overflow pipe Calculate the volume flowing through each sub-flow drainage pipe. Record each flow rate Calculate the percolation rate for each leach field test unit in gallons per day per square foot of leach field test unit surface area (gpd/ft 2 ) Install the ABG in the inlet chamber of one of the septic tanks once the average percolation rate meets the 1.0 gpd/ft 2 threshold. Install an air diffuser identical to that used in the ABG in the inlet chamber of the second septic tank. The second tank will be left as a control. Start aeration immediately using identical air pumps for each tank. If the ABG is intended to be inoculated with a supplied bacterial culture, inoculate it in accordance with the manufacturer s instructions Continue feeding the septic tanks with unclarified primary effluent coming from the WWTP and discharge to the leach field test troughs at a rate of at least 3 gpd/ft 2 for the duration of the test Once the leach field test units have recovered leach function, repeat the dosing test in sections Performance Requirement. An ABG shall be deemed to have met the requirements of the standard if it recovers leach function of the leach field test units within a 90 day period following the installation of the ABG. Recovery of leach field function shall be demonstrated by repeating the dosing test using the protocol in sections Recovery of leach field function shall be deemed to have occurred for each leach field test unit when the following conditions have been achieved: a) subflow for each leach field test unit loaded by the ABG tank equals at least 3.5 gpd/ft 2. b) the average subflow through all three units equals 5.0 gpd/ft 2 or more c) subflow through the leach field test units loaded by the ABG tank equals at least twice the flow rate as those loaded by the aerated control tank. Copyright 2003 by International Association of Plumbing and Mechanical Officials. All rights reserved. Printed in the United States IGC ABG page 6 of 7 7. INSTALLATION INSTRUCTIONS 7.1 The installation instructions shall contain the following requirements: a) the air supply line shall be plumbed using 1/2 inch schedule 40 PVC pipe b) entry of the air line into the septic tank or grease interceptor shall be made using a service riser approved by the local Authority Having Jurisdiction.

14 8. MARKINGS AND IDENTIFICATION 8.1 The main body of the ABG shall be permanently and legibly marked with the manufacturer s name or trademark so as to be visible before installation. 8.2 All other components, including the air pump and diffuser, shall be permanently and legibly marked with the ABG manufacturer s name and trademark or the name or trademark of the manufacturer of the component. Adopted: October 2002 Revised: May, 2003 Copyright 2003 by International Association of Plumbing and Mechanical Officials. All rights reserved. Printed in the United States IGC ABG page 7 of 7