VOLUME 3 SECTION 4. Minimum Requirements for Waste Water Treatment Systems and Excreta Management in Jamaica

Transcription

1 Waste Water.qxp 01/05/ :46 AM Page 1 VOLUME 3 SECTION 4 Mnmum Requrements for Waste Water Treatment Systems and Excreta Management n Jamaca Regulated by Mnstry of Health - Envronmental Health Unt 2-4 Kngs Street Kngston

2 Waste Water.qxp 01/05/ :46 AM Page 2 TABLE OF CONTENT CHAPTER BACKGROUND CHAPTER GENERAL PROVISIONS FOR WASTEWATER TREATMENT AND EXCRETA DISPOSAL CHAPTER THE ENVIRONMENTAL HEALTH UNIT APPROVAL PROCESS CHAPTER RECOMMENDED WASTEWATER TREATMENT AND DISPOSAL SYSTEMS CHAPTER DESIGN CAPACITY CALCULATIONS CHAPTER TYPICALLY APPROVED COMBINATION OF TECHNOLOGIES CHAPTER ON-SITE PRIMARY TREATMENT TECHNOLOGIES CHAPTER DRY EXCRETA MANAGEMENT SYSTEMS CHAPTER TEMPORARY DISPOSAL SYSTEMS CHAPTER ON-SITE SECONDARY TREATMENT (INCLUDING SOIL ABSORPTIVE TECHNOLOGIES

3 Waste Water.qxp 01/05/ :46 AM Page 3 CHAPTER ON-SITE TERTIARY TREATMENT SYSTEMS CHAPTER AUXILIARY EQUIPMENT APPENDICES

4 Waste Water.qxp 01/05/ :46 AM Page 1 CHAPTER 1 BACKGROUND 1.0 INTRODUCTION Ths Secton of the manual s desgned to assst Developers, Engneers, Land Owners, Techncal Consultants, Regulatory Representatves and other Stakeholders to understand the mnmum requrements for the desgn and constructon of sewage treatment and excreta management systems to meet the Mnstry of Health s standards for approvng such systems. The requrements are establshed to ensure complance wth envronmental publc health standards for safe on-ste wastewater treatment unts. The Secton ncludes bref descrpton of central treatment desgn requrements and applcaton procedures as well as temporary treatment systems. Proponents requrng detaled desgn and constructon requrements for such systems should consult the Natonal Water Commsson s Developer s Manual whch also ncludes nformaton on aspects of water supply and rrgaton dscharge requrements. 1.1 OVERVIEW The Polcy of the Mnstry of Health s drven by consderatons for preservng human health and envronmental protecton. It requres that all wastewater generated n Jamaca receve approprate treatment usng approved treatment methods dctated n part by adopted effluent gudelnes before dsposal to the envronment.the Polcy also sets lmtatons on the types of systems to be used n the treatment of wastewater and places partcular emphass on the use of water savng devces whch s an approach to sustan the conservaton of the water resource and at the same tme, reduce the volume of wastewater generated. 1.2 THE ENVIRONMENTAL HEALTH UNIT The Envronmental Health Unt s (EHU) actvtes are regulatory n nature and n realty consttutes a regulatory Agency that makes recommendatons on water and wastewater systems, through a systematc apprasal of engneerng plans submtted to support the applcaton of subdvson and development projects, ncludng toursts resorts, and developments n the ndustral and agrcultural sectors. The legal bass for ths mandate s enshrned n the Publc Health Act and the Town and Country Plannng Act and the Local Improvements Act wheren the Parsh Councl s requred to consult and receve the advce and recommendaton on all sewage treatment systems dealng wth the treatment of wastewater from 1

5 Waste Water.qxp 01/05/ :46 AM Page 2 the Medcal Offcer (Health)/Local Health Department. Currently the legal provson n the Town and Country Plannng Act and the Local Improvements Act gves the Mnstry of Health drect authorty to revew development and subdvson applcatons for waste treatment faclty on behalf of the Parsh Councl. EHU recommendatons are crculated to the Local Plannng Authortes Health Department. In addton, the Publc Health Act through the Publc Health (Nusance) Regulatons gves the Mnster of Health and n extenson the Medcal Offcers (Health), authorty to take acton where any stuaton exstng or potental s lkely to endanger the health and well beng of the populaton. 1.3 INTERAGENCY COORDINATION The Envronmental Health Unt approaches ts mandate utlzng an nter-agency strategy and coordnates wth Natonal Envronment & Plannng Agency (NEPA) and Water Resources Authorty (WRA) n approvng desgns/systems. NEPA s the Competent Authorty to ssue Permts (to buld) and Lcences (to dscharge) nto the envronment whle the WRA prepares and supples Techncal Notes outlnng the level of sewage treatment requrements for partcular areas, based on the hydrogeology of the area. 2

6 Waste Water.qxp 01/05/ :46 AM Page 3 CHAPTER 2 GENERAL PROVISIONS FOR WASTEWATER TREATMENT AND EXCRETA DISPOSAL 2.0 CHOICE OF SEWAGE TREATMENT The choce of sewage treatment optons les wth the Developer or homeowner. The choce s constraned by the nature of the project, the topography and hydrogeology of the proposed buldng ste and prudent envronmental publc and envronment health concerns. The general preference s for developments to connect to exstng central or communty sewerage systems to reduce the mpact on the envronment. In cases where no central or communty sewerage system exsts or where such systems are not able to accommodate addtonal sewage flow, due to lack of capacty, hgh polluton loads or other reasons, or where a reasonable tme for the formal connecton to such systems has elapsed, on-ste treatment must be consdered as the alternatve opton On Ste Systems On-ste systems may be of four general types, these are: v dry excreta management systems (dry conservancy), sol absorptve methods lqud dscharge treatment facltes (frequently package plants, pond or constructed wetland systems) and evaporaton and/or transpraton systems wth no lqud dscharge. The EHU approves any of the above systems for stes based on the treatment level desred: Prmary, Secondary or Tertary. Detals for these types of systems are dscussed n chapters 6 to SOIL ABSORPTIVE SYSTEMS Where allowable, due to sol condtons and groundwater levels, sol absorptve systems are preferred due to cost consderatons and envronmental publc health concerns. However, not all potental buldng locatons can accommodate sol absorptve systems. For example, those wth hgh water table or wth very low percolaton rates may not be sutable. Smlarly locatons wth extremely hgh percolaton rates due to karstfcaton of lmestone or other smlar condtons are 3

7 Waste Water.qxp 01/05/ :46 AM Page 4 most tmes not sutable for sol absorptve systems. Sol absorptve systems (wthout sgnfcant nutrent removal) are no longer permtted n Kngston and much of St. Andrew due to concerns over ntrate and other sewage contamnants mpactng the water table. Most town centres and coastal areas are smlarly not sutable for sol absorptve technologes due to hgh groundwater levels and polluton load. 2.2 WATER RESOURCE AUTHORITY S ROLE The Envronmental Health Unt s guded, n most cases, by the Water Resource Authorty (WRA) Techncal Note whch recommends the level of treatment (prmary, secondary or tertary) requred. Proponents are therefore requred to obtan and submt the WRA s Techncal Note along wth other documents. 2.3 NRCA S ROLE Effluent dsposed va dry gully or other surface water source(s) from onste or central treatment systems must meet the Natural Resources Conservaton Authorty Act (NRCA) effluent standards (Table 6). Proponents/Developers are requred to contact the Natonal Envronmental Plannng Agency to verfy requrements and standards. 4

8 Waste Water.qxp 01/05/ :46 AM Page 5 CHAPTER 3 THE ENVIRONMENTAL HEALTH UNIT APPROVAL PROCESS 3.0 SUBMISSION OF APPLICATIONS 3.1 All applcatons submtted to the Mnstry of Health are drected to the Envronmental Health Unt (EHU) for evaluaton and recommendaton. Submssons should preferably be channelled through the relevant Parsh Councls or NEPA. The turnaround tme for revews s usually: Three weeks - when the Techncal Note from the Water Resources Authorty s crtcal to decson makng or f a ste vst s requred, and Two weeks for all other submssons. Submssons prevously revewed but not approved for varous reasons by the EHU and are resubmtted wth requred amendments are usually completed wthn a shorter tme frame. Amendments should be routed through the relevant Parsh Councl or NEPA. Fgure 1 provdes a comprehensve overvew of the approval processes. 3.2 SUBDIVISION APPLICATIONS Persons ntendng to subdvde undeveloped land or developed propertes are requred to submt a subdvson applcaton to the local Plannng Authorty (Parsh Councls), whether the property wll be used for commercal, ndustral or resdental purposes. The subdvson applcaton s usually done n one of the followng categores: Subdvson of propertes nne (9) lots or less Subdvson of propertes more than nne lots 5

9 Waste Water.qxp 01/05/ :46 AM Page NINE LOTS AND UNDER All applcatons for subdvson propertes nne lots or less are to be submtted to Kngston and St. Andrew Co-Operaton, or the Portmore Muncpalty or the local Parsh Councl. Dependng on the parsh, the local Councl wll ether send copes of the applcaton and drawngs to NEPA or process the applcatons nternally by way of a Subdvson Commttee. Where Councls have operatonal Subdvson Commttee the applcaton/s s forwarded to the relevant government agences, ncludng NEPA, for revew/comments. The revews from the varous agences are collated and used n decdng approval or rejecton of the subdvson at the Subdvson Commttee meetng. Presently, three parshes: Kngston and St. Andrew, St. Ann and St. 6

10 Waste Water.qxp 01/05/ :46 AM Page 7 Catherne process applcatons through Subdvson Commttees. Other parshes send copes of the applcaton and drawngs to NEPA for crculaton and complaton of comments/revew by NEPA Informaton Requred wth Applcaton Applcants are requred to submt the followng along wth submsson:. Completed applcaton forms (provded by the Parsh Councl) v Ste survey plans completed by a Certfed Land Surveyor Revew fee as publshed n the Jamaca Gazette. Engneers report (f requred) An Engneer s report must accompany the submsson n cases where: v The Proponent proposes to connect multple dwellngs to a wastewater treatment system The Developer proposes an alternatve treatment system. The ste condtons are envronmentally vulnerable to development The treatment technology or development of ste may create a publc health concern. A detaled Engneer s Report s not requred f the proponent proposes a tradtonal onste wastewater treatment system for sngle dwellngs. 3.4 MORE THAN NINE LOTS Applcatons for subdvsons wth more than nne (9) lots must be submtted to the KSAC, the local Parsh Councl or the Portmore Muncpalty.They, wll n turn, submt the copes of the applcaton and drawngs to the Natonal Envronment and Plannng Agency (NEPA), the Agency wth responsblty for forwardng the applcaton to relevant government agences, (Referral Agences), as lsted n Table 1. Each Agency wll conduct ndependent nternal revew and forward comments/recommendatons to the NEPA. A Subdvson Commttee, comprsng all the referral agences members meets once per month to undertake a combned 7

11 Waste Water.qxp 01/05/ :46 AM Page 8 revew of applcatons Informaton Requred wth Applcaton Applcants are requred to submt the followng along wth submsson: Completed applcaton forms (number determned by the Parsh Councl) An Engneer s Report, (secton 1.3). v v Ste survey plan showng proposed locaton of sewage treatment system. Detaled plan drawngs and specfcatons for proposed treatment equpment. Revew fee as publshed n the Jamaca Gazette Informaton submtted for approval shall be n such detal as to permt a comprehensve evaluaton to assure complance wth ths manual and other supportng documentaton. 3.5 SITE VISITS Pre-approval Ste Vsts Subdvsons that exceed nne lots or subdvsons wth unque envronmental publc health concerns can trgger a ste vst by relevant agences pror to approval. Constructon of temporary commercal and ndustral systems may also requre ste vsts pror to approval. In such cases the EHU wll contact the applcant on recept of the applcaton to organse the ste vst. The prelmnary or fnal engneer s report and relevant drawngs must be receved before a ste vst s conducted. In cases where a ste vst s mandatory no fnal approval wll be granted untl the vst and assessment are completed. Ste vst reports become a part of the Applcants fle. 8

12 Waste Water.qxp 01/05/ :46 AM Page 9 Table 1 Members of the Subdvson Commttee Natonal Envronmental Plannng Agency 1 Mnstry of Health / Envronmental Health Unt Natonal Irrgaton Commsson Natonal Works Agency Offce of Dsaster Preparedness and Emergency Management Mnes and Geology Dvson Jamaca Bauxte Insttute Water Resources Authorty Surveyor s Assocaton 2 1 Agency Representatve s meetng charperson 2 Representatve s not a member of Commttee, but regularly attends Ste Vsts to Developments under Constructon Most major projects, especally those wth centralsed sewage treatment systems, wll generate a constructon ste vst at the 50% and 90% constructon ponts. Ths requrement s specfcally mentoned n the letter of recommendaton of the Project. It s ncumbent on the Developer or Proponent to alert EHU at the approprate tme to allow for schedulng of ths constructon ste vst. Constructon Ste Vsts are used to confrm/verfy that the type, sze and locaton of the proposed sewage treatment soluton s beng constructed n accordance wth the approved desgn. 3.6 REVISION OF APPROVED PLANS Devatons from approved plans and/or specfcatons must be submtted n wrtng to the MOH/EHU for revew and approval. Changes n desgns may adversely affect the capacty flow or operaton of unts, thus the stpulaton. EHU wll submt the necessary recommendatons to NEPA (for amendment etc.) before changes are mplemented. Revsed plans and/or specfcaton shall be submtted a mnmum of 30 days pror to the commencement of constructon to permt suffcent tme for revew and approval. Specal consderaton wll be gven to emergency feld condtons. Waver of the wrtten approval and 30-day requrement wll be at the dscreton of the MOH/EHU. Structural revsons or other mnor changes, not affectng capactes, flows or operaton may be permtted durng constructon wthout approval.the proponent must however, advse the EHU on changes made.as bult plans clearly showng all alteratons shall be submtted to be placed on fle wth the 9

13 Waste Water.qxp 01/05/ :46 AM Page 10 MOH/EHU after the completon of work. 3.7 MODIFICATIONS AND EXPANSIONS OF EXISTING FACILITIES Modfcatons and expanson of exstng facltes shall be submtted for revew as per standard subdvson/development submssons. In addton to the requrements outlned at 3.6, the Proponent must submt as-bult drawngs of the exstng treatment system. Addtonally, proposed te-ns and schedule should be addressed to mnmse downtme. If requred, a descrpton of any temporary measures to be employed durng constructon phase to prevent or mnmse loss of servce shall be dscussed and approved before commencng constructon. 3.8 TEMPORARY SYSTEMS (E.G.SPECIAL EVENTS) Temporary wastewater treatment systems, ncludng portable chemcal tolets are employed durng constructon phases n cases where of there s a specal event on a property or pror to nstallaton of a permanent treatment system. The MOH/EHU lmts approval of temporary treatment systems pror to constructon and mplementaton of a permanent system. The proponent must submt a detaled letter that outlnes the reason for the temporary nstallaton along wth engneerng desgn and specfcatons. A tme schedule should also be submtted that outlnes the start up date for the permanent treatment system. Proponents shall consult the local Parsh Councl and Parsh Health Departments when plannng a specal event that requres temporary wastewater treatment systems. A type of portable chemcal tolet can be seen on page 73 n A Drectory of Envronmentally Sound Technologes for the Integrated Management of Sold, Lqud and Hazardous Waste for SIDS n the Carbbean Regon ). 3.9 ENGINEER S REPORT An engneer s report must accompany the applcaton forms along wth detaled engneerng drawngs f the proponent proposes any of the followng: Development that exceeds nne (9) lots 10

14 Waste Water.qxp 01/05/ :46 AM Page 11 v v An onste wastewater treatment system that s consdered new or alternatve An onste wastewater treatment system that wll be connected to more than one dwellng(s)or to a group of dwellngs Ste condtons are envronmentally vulnerable to development Treatment technology or development of ste may create publc health concerns. Applcaton forms may be obtaned from NEPA, the KSAC or the Parsh Councls. Drawngs, fnal report and constructon supervson should be undertaken by a Professonal Engneer(s) lcensed n Jamaca. The Engneer s Seal shall be affxed to the drawngs and ttle page of the fnal report. The engneer s responsble for ensurng that the treatment system/s, once approved, s bult accordng to the approved drawngs. Proponents may submt a Prelmnary Desgn Report pror to the fnal report for ntal revew. Ths report shall detal the concept for the development. Although the MOH/EHU may offer comments on the prelmnary desgn and may conduct a ste vst, the development wll not be approved untl an Engneer s Report, pertnent drawngs and other requested nformaton are provded GENERAL PROJECT INFORMATION The followng general nformaton s requred wth applcatons: v v Proposed and future areas to be served, ncludng proposed wastewater flow rates, wastewater characterstcs and volumes of ndustral and commercal areas Ste topography, sol type and meteorologcal nformaton Vulnerablty of the ste regardng floodng, landsldes, geologcal faults and storm surges. Sol percolaton test (f an absorptve dsposal method s proposed) Envronmental publc health stuaton n the surroundng areas. Supportng data wth regard to darrhoeal dsease, typhod endemc areas, gastroenterts and other dseases are useful to 11

15 Waste Water.qxp 01/05/ :46 AM Page 12 support the submsson. v Toursm potental of the surroundng area SEWAGE TREATMENT SYSTEM AND APPURTENANCES The followng nformaton must be provded on sewage treatment systems and appurtenances. v v v v v x Plant locaton, plant ste plan, ncludng a descrpton of the surroundng areas. Partcular reference shall be made to the proxmty of present and future developments, wells, streams, lakes, water plants, ndustral stes, and other areas, whch wll be affected envronmentally by the treatment plant. A detaled analyss of the method of treatment and ts effcency and ablty to meet dscharge requrements. Desgn calculatons showng sze and capacty of each unt or component part n relaton to the provded desgn crtera. The calculatons should show retenton tmes, surface loadngs, wer loadngs, pump szng, sludge wastng pumpng rates and any other pertnent nformaton regardng plant desgn. Detal dscusson on the means of effluent utlzaton or dsposal Desgn calculatons for each sewer showng present and future flows wth mnmum and maxmum veloctes. Capablty of exstng nterceptors to carry present and future flows. Desgn calculatons for all sewage lft statons ncludng wet well szng and pump curves. Locaton of any bypasses and a detaled analyss of antcpated use. The means of grt, grease, screenngs, sludge utlzaton and dsposal shall be dscussed n detal, accompaned by the necessary desgn calculatons. 12

16 Waste Water.qxp 01/05/ :46 AM Page OPERATIONS AND MAINTENANCE The followng nformaton must be provded the operatons and mantanance to be put n place: v v v v A tme schedule for completon of plant constructon and plant start-up Operaton and mantenance manual to nclude mantenance of all major equpment and appurtenances (Appendx 1). Staffng levels by trade or job classfcaton and proposed tranng schedule Lst of analytcal (testng) capabltes to be provded and avalable to operaton and mantenance staff. Spare parts lst Sze and type of emergency generator provded, f any. Emergency response plan 3.13 DRAWINGS The followng drawngs are to be provded: Ste plan showng locaton of all major sewer lnes, lft statons, buldngs and major equpment, nclude topographcal devatons. Flow dagrams llustratng process treatment processes. Equpment dagrams for major equpment and appurtenances such as clarfers, aeraton or oxdaton processes, dgesters, etc. 13

17 Waste Water.qxp 01/05/ :46 AM Page 14 CHAPTER4 RECOMMENDED WASTEWATER TREATMENT AND DISPOSAL SYSTEMS 4.0 RECOMMENDED SYSTEMS The followng sewage treatment and dsposal systems or processes are acceptable methods of treatment (dependng upon ste specfc crcumstances) and are currently recommended: v v v v v x x x x x xv xv Ventlated Improved Double Vault Pt Latrne (VIDP) Ventlated Improved Pt Latrne (VIP) Absorpton Pt Soak-away Pt Septc Tank Aerated Septc Tank Tle Feld Evapotranspraton Bed Reed Bed (constructed wetland) Mound System Intermttent Sand Flter Recrculatng Sand Flter Bodgester Septc Tank Mechancal systems (Oxdaton Dtch, Contact Stablzaton Tank, Rotary Bologcal Contactor, Trcklng Flter, Aerated Sludge Systems and Anaerobc systems) Pond Systems (aerobc and anaerobc ponds). The combnaton of these systems or processes, provde a complete sewage soluton. These combnatons are ste specfc and must correspond to the level of treatment requred as provded by the gudance n the Water Resources Authorty Techncal Note. 4.1 CONNECTION TO EXISTING CENTRAL TREATMENT SYSTEMS Connecton to exstng central wastewater treatment systems requres approval and acceptance from the owner and/or operator of the sewage treatment system. Most of these systems are owned and operated by the Natonal Water Commsson (NWC). Acceptance from the NWC or other Operator must be outlned n an offcal letter sgned by an authorsed person, statng the effectve 14

18 Waste Water.qxp 01/05/ :46 AM Page 15 date for connecton Informaton Requred The followng nformaton s requred: v v v that only domestc sewage wll be accepted. the desgn flow rate of sewage antcpated by the Development. desgn capacty of the treatment plant current load beng treated by the plant calculated extra capacty of the plant at least sx months performance data of the treatment plant (current data). 4.2 NON APPROVAL No approval wll be gven for connectng to an exstng central system that does not meet the dscharge standards set by NEPA or f the central treatment plant meets the dscharge standards but does not have extra capacty. 4.3 PROCEDURE FOR ASSESSING NEW TECHNOLOGY The Mnstry of Health welcomes new technology, but ts performance should be documented or demonstrated before approval. The procedure for assessng new technologes s outlned n Fgure 2. 15

19 Waste Water.qxp 01/05/ :46 AM Page 16 Fgure 2. Procedure for Assessng New Technology 16

20 Waste Water.qxp 01/05/ :46 AM Page 17 CHAPTER 5 DESIGN CAPACITY CALCULATIONS 5.0 POTABLE WATER REQUIREMENTS Every developer must provde adequate quanttes of potable water at reasonable pressure to meet the needs of occupants wthn the development. Generally, ths wll be by connecton to a publc water supply source from the NWC, Local Parsh Councl or prvate water provder. In nstances where the proposed development area s not currently suppled by potable water, the developer s requred to provde an alternate source/ supply of potable water, ether va development of ground water resources or by other means, for example, ran water harvestng. Proposals for usng alternatve systems must be accompaned by detaled plans, calculatons and technology to dsnfect the water to meet potablty standards Resdental Developments For resdental developments, the nomnal water consumpton s assumed to be 230 L / person per day. For the purpose of system capactes, the followng should be consdered: Starter Homes Studo - 2 persons 1 bedroom homes - 3 persons 2 bedrooms and greater - 2 persons per bedroom For starter homes, whch are expected to be enlarged, t may be necessary to consder a desgn based on a reasonable buld-out potental for the specfc home/project. If alternatve per capta water consumpton s proposed, the proponent must state the bass for such alternatve water consumpton rate and the justfcaton, for approval by the MOH Commercal Development For commercal developments or other types of constructon, capacty may be developed by methods such as fxture count or by other means, whch are acceptable to MOH. Table 2 shows the water usage per fxture whle Table 3 shows the water usage of varous types of facltes. These fgures are not absolute and are to be used as a gude only. 17

21 Waste Water.qxp 01/05/ :46 AM Page WATER SAVING DEVICES Developers proposng the nstallaton and use of water savng devces may be permtted to reduce the per capta consumpton rate. Table 2 Water Use per Fxture 1 Fxture Water Use Per Day/Fxture Ltres US Gallons Bath Tub 30 8 Faucet Shower Tolet Urnal adapted from Metcalf/Eddy Wastewater,Treatment and Dsposal, 3rd edton (pg. 17 Table 3. Water Use by Faclty Type 1 Type of Faclty Water Use per Day Ltres US Gal Capta Bar/Cocktal Lounge Per Seat Hotel Resort Per Guest Hotel Non Resort Per Guest Industral Buldng (employees only) Per Employee Offce Buldng Per Employee Hosptal Per Bed Restaurant Per Seat Per Meal Served Theatre/Assembly Hall Per Seat Church Servce Staton Per Vehcle Served School w/cafetera Per Student 1 adapted from Metcalf/Eddy Wastewater,Treatment and Dsposal, 3rd edton (pg ) 18

22 Waste Water.qxp 01/05/ :46 AM Page SEWAGE SYSTEM CAPACITY Basc Prncples The EHU adopts the followng basc prncples n determnng sewage system capacty: For on-ste sewage treatment systems, the calculaton of the sewage system capacty s assumed to be the same as the water consumpton. For central sewage systems, the effect of nfltraton and nflow wll ncrease the sewage system flow above the water consumpton fgures Addtonal Flows The actual addtonal flows wll depend upon ste-specfc condtons such as: v length of sewer lnes sol type condton of sewer lnes and depth of water table Infltraton Rates Engneers may use the standard method (L/cm dameter/km or US gallon/n dameter/mle) n provdng submsson of calculatons and the desgn bass for nfltraton rates. Table 4 provdes data on standard nfltraton rates Central Treatment Systems For wastewater treatment systems employng central treatment system components (sewer mans, treatment technologes) and relevant appurtenances, the developer shall consult Natonal Water Commsson s Developer s Manual. 19

23 Waste Water.qxp 01/05/ :46 AM Page 20 TABLE 4. STANDARD SEWER INFILTRATION RATES FOR CENTRAL WASTEWATER TREATMENT FACILITIES 1 Mm Sewer Dameter nch US Gal/day /1000 feet Infltraton Ltre/ Day /100 metres ,136 1, ,705 2, ,557 3, ,409 4, ,261 5, ,114 6, ,818 8, Table s constructed usng standard rate of 750 US Gal/day/nch. mle. 5.3 RAW SEWAGE STRENGTH AND COMPOSITION For domestc applcatons, the raw sewage strength and composton arrvng at the wastewater treatment plant may be taken as medum strength wth composton as shown n Table 5. If a developer wshes to utlze alternate concentratons or compostons, the justfcaton for alternatves must be provded and approved by EHU. TABLE 5. TYPICAL MEDIUM STRENGTH DOMESTIC SEWAGE Parameter Total Suspended Solds,TSS Chemcal Oxygen Demand, COD Bochemcal Oxygen Demand, BOD 5 Total Ntrogen (as N) Total Phosphorous (as P) Total Colform Bactera Desgn Value 220 mg/l 500 mg/l 250 mg/l 40 mg/l 8 mg/l MPN/100ml 5.4 TREATED WASTEWATER QUALITY STANDARDS Systems whch dscharge treated wastewater must comply wth effluent standards lad down by the NEPA per the nature of dscharge. 20

24 Waste Water.qxp 01/05/ :46 AM Page Effluent Standards The current NEPA standard for treated wastewater s shown n Table 6. Ths standard sets the mnmum water qualty to be obtaned from NEPA by any system, whch has lqud dscharge of wastewater. A lcence must be obtaned to dscharge to surface water such as to a rver, stream or gully. The process for obtanng permts s descrbed n Chapter 2. Developers are requred to check wth NEPA for nformaton on requrements. 5.5 IRRIGATION WATER QUALITY STANDARD The nterm Jamaca Irrgaton Standards s shown n Table 6. The water qualty standard s more strngent for rrgaton water than for dscharge of wastewater. Subsurface or drp rrgaton systems are preferred especally n areas where spray rrgaton may cause a nusance, such as close to roadways. If sprnklers are used, the spray should not be hgher than 1 meter. Sprnklers wth hgher sprays wll not be permtted n areas where the aerosols could become a publc health hazard. Table 6. NRCA Sewage Effluent Regulatons (2004) Parameter Unts Water Qualty Crtera Drect Dscharge Irrgaton Chemcal Oxygen Demand mg/l 100 <100 Bologcal Oxygen Demand mg/l Total Suspended Solds mg/l Total Ntrogen mg/l 10 NA 1 Phosphates P mg/l 4 NA 1 Ph 6 NA 1 Faecal Colform MPN / 100 ml Resdual Chlorne mg/l Ol and Grease mg/l NA 1 10 Garda Cyst # / 100 ml NA 1 <1 1 NA = not applcable 5.6 DESIGN CONSIDERATIONS Maxmum Housng Densty The maxmum housng densty for on ste systems has been establshed as follows: Dwellng unts n excess of seven (7) per acre and aggregate 21

25 Waste Water.qxp 01/05/ :46 AM Page 22 populaton of greater than 300 persons shall be served by central sewage systems. Ths requres developers proposng projects havng a densty greater than seven (7) dwellngs unts per acre or those larger developments (whch shall house more than 300 persons) to submt plans for the desgn and constructon of central sewage treatment systems. Developments havng more than 300 persons wth treatment of sewage on ndvdual lots may be consdered f justfcaton s provded and approval s gven by MOH Flood Potental Sol absorptve systems cannot be approved for areas that may be prone to floodng wthout approved flood mtgaton measures. The EHU s guded by the WRA n determnng areas prone to floodng. Flood mtgaton measure should be approved by the Natonal Works Agency Proxmty to Wells, Ground and Surface Waters Sol absorptve systems are only allowed on the recommendaton of the WRA where the hghest ground water levels are below 1.2 m from the bottom of the absorptve system. Smlarly, the locaton of the septc tank and sol absorptve system must comply wth the proxmty gudelnes shown n Table 3.6. Sol absorptve systems are not allowed n areas wth karstc condtons. Table 7. Sol Absorpton System - Proxmty Locaton Allowances Component Object Mnmum Dstance metre Septc Tank Buldng Foundaton 1.5 Septc Tank Property Lne 1.5 Septc Tank Tle Feld or Alternate 6 Tle Feld or Alternate Septc Tank 0.5 Tle Feld or Alternate Property Lne 3 Tle Feld or Alternate Buldng Foundaton 6 Tle Feld or Alternate Well - uncased 30 Tle Feld or Alternate Well cased to at least 7.5 m 15 Tle Feld or Alternate Rver/Stream hgh water mark 45 Tle Feld or Alternate Fractured rock formaton 3 Absorpton or Soak Away Pt Neghbourng Pt 3 X Pt Dameter 22

26 Waste Water.qxp 01/05/ :46 AM Page Slopng Ground Steep grades requre specal attenton to ensure good dstrbuton of septc tank effluent to the tle feld and/or other subsurface system. Subsurface Absorpton systems shall be constructed n parallel wth topographc contours. The mnmum spacng requrements for absorpton or soak away pts may be ncreased f system s constructed on slopng ground. 23

27 Waste Water.qxp 01/05/ :46 AM Page 24 CHAPTER 6 TYPICALLY APPROVED COMBINATION OF TECHNOLOGIES 6.0 SPECIFICATIONS FOR COMPONENTS Ths chapter defnes and provdes specfcatons for components of potental treatment methods and recommends combnatons of components that wll meet treatment requrements. Alternatve or new treatment technologes are dscussed wthn paragraph 4.3. Chapter 7 to 12 descrbe the mnmum standards for each treatment component. Refer to Chapter 5 for ste condton requrements and desgn capacty consderatons. 6.1 CATEGORIES OF TREATMENT The Envronmental Health Unt makes recommendatons on wastewater treatment systems treatment qualty requrements for specfc ste condtons. The treatment qualty levels are dvded nto three (3) categores: prmary, secondary and tertary Prmary treatment Defned smply as physcal treatment pror to fnal dsposal Secondary treatment Defned as the removal of organc load (COD and BOD) and requres physcal treatment and bologcal treatment pror to fnal dsposal Tertary treatment Defned as nutrent removal / polshng step and s usually requred when proposed developments are located wthn an envronmentally senstve area or area of publc health concern.ths treatment requres physcal and advanced bologcal treatment. Sometmes chemcal treatment may be used n combnaton wth to obtan effluent requrements. 6.2 TYPICAL TREATMENT SYSTEMS Tables 8 and 9 outlne typcal treatment systems approved by the EHU. Alternatves from the recommended treatment systems may be approved by MOH 24

28 Waste Water.qxp 01/05/ :46 AM Page 25 f the proponent provdes suffcent verfcaton that the system wll meet dscharge standards. 6.3 DRY EXCRETA MANAGEMENT Dry excreta management systems are good alternatve treatment solutons where adequate potable water s not avalable n an area. Examples of any excreta management solutons are VIDP, VIP. Care must be taken, however, n sghtng n these types of solutons so as not to contamnate water table or otherwse mpact on the ground water levels. They must be properly desgned and constructed to specfcatons. Category Dry Excreta Management Prmary Treatment Secondary Treatment Tertary Treatment Table 8. Typcal on-ste Treatment Systems and Correspondng Treatment Requrement Treatment Typcal Treatment Systems Requrements Ventlated Improved Double Pt Latrne Not applcable Ventlated Pt Latrne Bolatrne (compostng) Settle solds Septc tank + absorpton pt Imhoff tank + absorpton pt Septc Tank + Tle Feld Settle solds and Septc Tank + Mounded Tle Feld bologcal Septc Tank + Sand Flter treatment Septc Tank + Tled Chamber System Bodgester Septc Tank + Tle Feld Physcal and Septc Tank + Evapotranspraton Bed bologcal Septc Tank + Reed Bed (Subsurface) treatment. May Septc Tank + Sand Flter + Reed Bed (subsurface) also nclude Bodgester Septc Tank + Reed Bed (Subsurface) chemcal treatment Bodgester Septc Tank + Evapotranspraton Bed 25

29 Waste Water.qxp 01/05/ :46 AM Page 26 Table 9. Typcal Central Systems and Correspondng Treatment Requrement Category Treatment Typcal Treatment Systems Requrements Secondary Settle solds and Septc Tank + Tle Feld Treatment bologcal Septc Tank + Mounded Tle Feld treatment Septc Tank + Sand Flter Septc Tank + Tled Chamber System Bodgester Septc Tank + Tle Feld Mechancal systems (Aerated Septc Tank, Oxdaton Dtch, Contact Stablzaton Tank, Rotary Bologcal Contactor, Trcklng Flter, Anaerobc systems) Tertary Physcal and Septc Tank + Evapotranspraton Bed Treatment bologcal Septc Tank + Reed Bed (Subsurface) treatment. May Septc Tank + Sand Flter + Reed Bed (subsurface) also nclude Bodgester Septc Tank + Reed Bed (Subsurface) chemcal Bodgester Septc Tank + Evapotranspraton Bed treatment Waste Stablzaton Ponds + Reed Bed Mechancal systems wth nutrent removal 6.4 SUBSURFACE ABSORPTION TECHNOLOGIES If socal-economc and other factors do not allow for water coverage systems, where ste condtons are sutable, subsurface sol absorpton s usually the best onste method of wastewater dsposal, for a sngle dwellng or cluster of dwellngs, because of ts smplcty, stablty and low cost. Varyng pre-treatment technologes may be requred before dsposal va subsurface absorpton system, such as septc tank, aerated septc tank or bodgester septc tank, or equvalent Unacceptable Condtons for Sol Absorpton Methods No approval wll be gven for onste sol absorpton treatment methods f any of the followng condtons apply to the ste locaton: v Connecton to publc sewer system s practcal. Sol condtons or topography are of such that ndvdual dsposal systems cannot functon satsfactorly. Groundwater condtons are of such that ndvdual dsposal systems may cause polluton of the groundwater supply. Installatons may create an unsantary condton or publc health 26

30 Waste Water.qxp 01/05/ :46 AM Page 27 nusance (overtme) v Denstes hgher than 7 dwellngs unts per acre or the aggregaton exceeds 300 persons Gude to Desgnng Absorpton Components The followng parameters are to be used as gude n desgnng the absorpton components. I v v Contnuous saturaton of the nfltraton system s avoded Aerobc condtons n sol mmedately below dstrbuton system s mantaned Dose the entre absorpton system s unform Compacton and smearng of the nfltratve surface s avoded A large amount of sdewall surface as compared to the bottom surface area s provded Percolaton Rate Absorpton before desgnng any subsurface absorpton system applcants must frst determne that sol condtons are sutable.the sol shall have an acceptable percolaton rate wthout nterference from groundwater or mpervous strata below the level of the absorpton system (Table 10). Tle felds, absorpton beds or equvalent technologes are acceptable only f they meet each one of the followng condtons: Depth to ground water Table 10. Mnmum Percolaton Rate for Specfed Groundwater Depth Sol Percolaton Rate Requred depth to groundwater mn/n mn/cm feet metre or slower 4.0 or slower

31 Waste Water.qxp 01/05/ :46 AM Page 28 Sol Percolaton Rates Sols should have percolaton rates between mn/cm 2. Sols out of ths range should have desgned a treatment system that does not employ sub-surface absorpton system, such as ntermttent sand flters, aerobc treatment systems or evapotranspraton systems. Hydraulc Loadng Rates Sol Stratfcaton Hydraulc loadng rates for tle felds may be calculated based upon sol percolaton rates usng methods publshed by Unted States Publc Health Servce (USPHS, 1967). See Appendx 2 to correlate sol percolaton rates to desgn hydraulc loadng rates. If sol percolaton tests are not avalable the maxmum hydraulc loadng rate 60 L/d/m2 must be used as a gude. In calculatng loadng rate t s recommended that, only the trench(es) bottom area, (trench wdth X trench length) s used and not the trench sde wall area. Rock formatons or other mpervous strata and maxmum elevaton of the groundwater table shall be at a depth greater than one metre below the bottom of each dsposal trench or dsposal pt. 6.5 TERTIARY TREATMENT SYSTEMS Tertary treatment systems protect the surroundng envronment from ntruson of nutrent and bologcal polluton. Typcally t ncludes: Small package plants that dscharge treated wastewater effluent to a gully or rver Systems wth zero effluent dscharge (evaporaton/transpraton systems) and Constructed wetlands, frequently referred to as reed beds Tertary treatment systems are recommended when ste condtons do not support secondary treatment technologes or publc health s lkely to be at rsk. 28

32 Waste Water.qxp 01/05/ :46 AM Page 29 Treatment levels are determned usng a combnaton of factors such as sol type, depth to ground water table, proxmty to sprng, wells and recreatonal water bodes, proxmty to fault lnes etc Treatment Systems wth Lqud Effluent Dscharge Proponents proposng the use of these systems must submt a detaled engneer s report provdng verfcaton that wastewater effluent wll meet NRCA dscharge standards Treatment Systems wth Zero Lqud Effluent Dscharge Evapotranspraton Bed Systems wth pror connecton to a septc tank technology s an acceptable onste wastewater treatment system n Jamaca. These systems are approved by EHU f evaporaton and transpraton exceeds precptaton and nflow n the proposed area Constructed Wetlands or Reed Beds Constructed wetlands may be used to provde fnal or tertary treatment provded suffcent prelmnary treatment s done usng approprate technology (septc tank, bodgester septc tank, packaged plant). Subsurface flow constructed wetlands are preferred to reduce the potental for mosquto breedng. 29

33 Waste Water.qxp 01/05/ :46 AM Page 30 CHAPTER 7 ON-SITE PRIMARY TREATMENT TECHNOLOGIES 7.0 PRIMARY TREATMENT TECHNOLOGIES Ths chapter addresses technologes that treat raw wastewater. On-ste prmary treatment technologes are desgned to remove settable and floatable solds from raw sewage. Typcally, these technologes are used n combnaton wth a secondary or tertary dsposal/treatment technology n an effort to reduce cloggng or overloadng of systems. Absorpton pts are not an acceptable method of prmary treatment unless a septc tank s nstalled pror to dscharge nto the pt. 7.1 SEPTIC TANKS Septc tanks or plan settng tanks s a watertght tank that s desgned to slow the movement, temporarly store and partally treat raw wastewater. The man purpose of the tank s to remove floatable materal and as much of the settleable porton of the suspended solds n sewage as possble so that the tank effluent maybe treated and dsposed by sol absorpton. All commercal, resdental and ndustral propertes utlzng on-ste absorpton or non-absorpton treatment technologes for sewage are requred to nstall a septc tank, or ts equvalent. All septc tanks shall conform to Fgure 3. Mnor varaton n desgn may be permtted. Septc tanks do not accomplsh a hgh degree of removal of bactera or norganc materal and hence should not be dscharged on the ground surface or to deep dranage wells, fssures, lakes or streams Desgn and Constructon - Mnmum Standards Septc tanks shall have a lqud capacty of at least the average volume of sewage flowng nto the tank durng any 36-hour perod, but n no case shall the lqud capacty of the tank be less than 2,650 Ltres (700 US gallons). Table 4.3 provdes an estmated septc tank volume for resdences per populaton. 30

34 Waste Water.qxp 01/05/ :46 AM Page 31 Table 11. Mnmum Requred Capacty of Resdental Septc Tanks # persons served Capacty (Ltres) Capacty (gallons) , v v v The effectve depth for calculatng capacty s taken from the nvert of the outgong dran to the average bottom of the tank and shall not be less than 1.5 metre or 5ft. The wdth shall not be less than 0.07m or 2ft 6 nches nor less than one half of the length. A separate tank ventlatng ppe shall be provded f requred by the buldng Sutable access shall be provded n the tank slab on the centre lnes of ncomng and outgong drans and located to enable all connectng ppes to be properly mantaned and servced. Tanks must be constructed of structurally sound, watertght and corroson and decay resstant materal, such as concrete, vtrfed clay block, fbreglass, heavy-weght concrete block, ferrocement, burned brck or heavy-duty plastc The walls and base of all tanks shall be securely bonded together or be of monolthc or keyed constructon. Walls and base of poured-n-place tanks shall have a mnmum thckness of 100 mllmetres (4 nches) throughout. A mnmum thckness of 75 mllmetres (3 nches) s allowed n pre-cast tanks that have been properly renforced. These thcknesses do not apply to fbreglass and ferrocement tanks. A septc tank nstalled under a drveway or parkng area shall have adequate renforcement to support any antcpated load and access manholes brought up to grade. 31

35 Waste Water.qxp 01/05/ :46 AM Page 32 Septc tank covers shall be suffcently strong to support antcpated loads and adequately secured to prevent nfltraton of drt or other foregn matter and the escape of odorous gases. Each compartment wthn a tank shall have an nspecton port stuated above the outlet baffle. v Septc tanks may have sngle or multple compartment(s) of approved shape that provde settlng of solds and accumulaton of sludge and scum. It should have at least 2 compartments. As measured from the nvert elevaton of the outlet, the frst compartment shall have at least two-thrds of the total requred lqud capacty. Rectangular, ellptcal and sem-ellptcal septc tanks shall have a length of at least twce but not more than three tmes the wdth. The lqud depth of such tanks generally shall not be less than 1.2 metres (4 feet) nor more than 1.8 metres (6 feet). Tanks of other shapes and dmensons wll be consdered for approval when accompaned by data substantatng ther effectveness. v x At least a 300 mm (12-nch) freeboard or vod s requred between the sewage level and undersde of the tank cover. Inlet and outlet constructon Inlet and outlet connectons of each compartment of a septc tank shall be so desgned and nstalled as to retan sewage solds, scum and sludge effectvely. The nvert or flow lne of the outlet ppe shall be set at a mnmum of 300 mm (12 nches) below the bottom of the tank cover and the nlet ppe 50 mm (2 nches) hgher. Outlet control devces are requred for each for the tank and any compartments.these shall consst of baffles made of durable materal extendng from sdewall to sdewall or of ppe tees not less than 100 mm (4 nches) n dameter.the 32

36 Waste Water.qxp 01/05/ :46 AM Page 33 bottom of the baffle or tee shall extend at least 300mm (12 nches) above the surface of the lqud and the top shall be at least 100 mm (4 nches) above the nvert of the outlet and not less than 50 mm (2 nches) below the bottom of the cover Locaton No tank shall be located wthn 2.5 m (10 feet) of a buldng or ste boundary. Provson must be made for cesspool emptyng vehcles to park wthn 3m of the tank. The septc tank s to be located n complance wth Table 7. Dstances from trees, swmmng pools, sdewalks, drveways shall be such to prevent cave-n durng constructon. v The septc tank s to be nstalled at such depth that the top, or an approved access manhole to the tank, wll be not more than 15 cm (6 nches) below the ground surface. The tank cover shall be adequately renforced to support the load mposed. The ptch of the house sewer from the structure stubout to the tank should not exceed 20 mm per metre. Otherwse, an acceptable method such as drop manholes must be employed to assure a moderate entrance velocty of the raw sewage nto the tank. 33

37 Waste Water.qxp 01/05/ :46 AM Page 34 Fgure 3. Typcal Septc Tank 34

38 Waste Water.qxp 01/05/ :46 AM Page ABSORPTION PITS An absorpton pt s an excavated, boulder-lned pt, whch receves lqud waste that percolates through the surroundng sol. Ths treatment method s not an acceptable treatment for raw wastewater. Absorpton pts are acceptable to treat septc tank effluent or equvalent, f ste condtons are approprate. Ths method may also be used as fnal dsposal after selected secondary or tertary treatment technologes Acceptable Crtera Areas that meet the followng crtera may be acceptable for usng ths method: v v Low populaton densty Seasonal hgh water table exceeds 1.2 m from bottom of pt Potable water well, surface water, open water supples s greater than 30 m from proposed pt locaton. Cesspool emptyng truck shall have easy access to pt openng wth three (3) metres. Lmestone features, such as snk holes and faults are greater than 1.2 m. from proposed locaton of pt Desgn and Constructon (Mnmum Standards) Effectve depth s taken from the nvert of the ncomng dran to the bottom of the excavaton and should not be less than three (3) metres, measured from face to face of rubble stone lnng. The pt be of crcular plan that s lned wth properly packed 300 mllmetres thck rubble stone ted wth 200 mllmetres concrete belt courses mmedately beneath the ncomng and at three (3) metres ntervals on centre. The dameter at the bottom of the pt shall be greater than 2.4 metres. The nsde slope of the pt s no less than 1:6. v Absorpton pts termnate at least 1.2 metre above the statc groundwater level. 35

39 Waste Water.qxp 01/05/ :46 AM Page 36 v v The outlet from the septc tank be a mnmum of 100 mllmetres above the bottom of the dstrbuton ppe. Use of dynamte and jackhammer s prohbted n constructon of absorpton pts. v The pt shall be covered wth a renforced concrete slab 1 6 metrc greater n dameter than the top of the excavaton and fnshng not less than 1 0 metrc below assocated ground levels v The slab be desgned to support a mnmum mposed load of 244 kg/m2 and no vehcles should be drven wthn 10 m of t except cesspool emptyng trucks. x The mnmum requred capacty method s based on emprcal data for absorpton pts. It provdes an estmate for the requred capacty (Table 12). Table 12. Mnmum Requred Capacty for Absorpton Pts Number of Persons Served Capacty (ltres) Capacty (U.S. gallons) 1-5 9,085 2, ,113 3, ,142 4, ,035 4, Locaton Mnmum spacng between pts on the same contour must be three tmes the pt dameter (3.5 m mnmum spacng). Absorpton pt be located greater than 1.5 m (5 feet) from buldng foundaton. Other proxmty requrements for pts are provded n Table

40 Waste Water.qxp 01/05/ :46 AM Page 37 Fgure 4. Absorpton Pt (Gray 2001) 7.3 SOAK - AWAY PIT (SEEPAGE PIT) A soak away pt or leachng pt conssts of one or more deep pts, flled wth clean, coarse flter materal. Pts should not be used where percolaton tests shown an absorpton rate of less than one nch per home.ths system shall only receve (1) grey water from laundry, shower or snks and (2) ktchen snks that have passed through a grease trap. The wastewater seeps through the flter materal and nfltrates through sdewalls nto adjacent porous subsurface sol Desgn and Constructon Mnmum Standards The effectve absorpton areas shall be consdered as the outsde surface of the vertcal sdewall area calculated below the nlet ppe, exclusve of any unsutable sol or bedrock formatons and the bottom area. The mnmum effectve sdewall absorpton depth shall be 1.2 m (4 feet) of sutable sol formaton. The bottom of the pt shall termnate at least 1.2 m (4 feet) above the seasonal hgh ground water level n the dsposal area. The mnmum dameter shall be 0.9 m (3 feet). v Seepage pts shall be flled wth coarse stone that ranges from mm ( nches) n dameter and s free from fnes, sand, clay or organc materal. Lnngs of brck, stone, block or smlar materals shall have a mnmum thckness of 100 mm (4 37

41 Waste Water.qxp 01/05/ :46 AM Page 38 nches) and shall be lad wth overlappng, tght-butted jonts. Below the nlet level, mortar shall be use n the horzontal jonts only. Above the nlet, all jonts shall be fully mortared. v v v v x x A structurally sound and otherwse sutable top shall be provded that wll prevent entrance of surface water, drt, or other foregn materal, and be capable of supportng the overburden of earth and any reasonable load to whch t s subjected. The top of the pt shall be covered wth a mnmum of 150 mm (6 nches) backfll. Hollow dsposal pts are prohbted. Seepage pts shall be constructed n a manner n whch wll prevent or correct any smearng of the sdewall surface areas. Breathers or nspecton ppes may be placed n all seepage pts. The breather shall consst of perforated ppe placed vertcally wthn the backfll of the pt. The ppe shall extend from the bottom of the pt to several nches (centmetres) above the ground level. Proponents shall consder nstallaton of multple seepage pts. Mnmum spacng between pts on the same contour shall be three tmes the pt dameter (3.5 m (12 ft) mnmum spacng). Open jont or perforated dstrbuton ppe shall run across each pt and then extend as a tght lne ppe connectng pts n seres. Mnmum dameter of the dstrbuton ppe shall be 50 mm (2 nches). A vertcal perforated ppe at least 100 mm (4 nches) n dameter shall be placed wthn the backfll of the pt.the ppe shall extend from the dstrbuton ppe to the bottom of the pt. Use of dynamte and jackhammer s prohbted n constructon of percolaton pts Locaton A replacement area equvalent to 100% of the ntal area shall be avalable for replacement seepage pt.ths space shall not be used for permanent structures. Proxmty requrements for seepage pts are gven n Table II-6. Constructon should not be permtted over percolaton pts. 38

42 Waste Water.qxp 01/05/ :46 AM Page 39 v Vehcular traffc should not be permtted n the percolator pts area any tme after ts constructon. 7.4 IMHOFF TANKS An Imhoff tank operates smlar to a conventonal septc tank n the separaton of settable and floatable solds and the decomposton of accumulated sludge. Unlke a conventonal septc tank, the Imhoff tank has two chambers stacked vertcally n whch sedmentaton occurs n the upper compartment and decomposton n the lower compartment (Fgure 4.3) (Metcalf/Eddy 1029). The deflectors n the settlng chamber prevents dsturbance of ths zone by gases produced n the sludge chamber and the sludge partcles rsng wth these gasses. Ths therefore means a better clarfed effluent than what can be acheved n a conventonal septc tank. Imhoff tanks may be substtuted for a conventonal septc tank and shall be constructed to conventonal septc tank mnmum standards provded care should be exercsed n locatng nch off tanks because of the possblty of odour nusance Desgn and Constructon Mnmum Standards. v v Overflow rates should not exceed 24.4 cm3/m2 (600 US gallons/ft2) at the average flow rate, wth detenton of no less than three (3) hours. A deflector shall be nstalled at the base of the sedmentaton chamber to prevent entrance of gases. A gas vent shall be nstalled at 30 percent of the sludge compartment area. Invert nlet shall be a mnmum of 300 mllmetres (12 nches) to water lne. A sludge wthdrawal ppe shall be nstalled to remove accumulated sludge from the sedmentaton chamber. 39

43 Waste Water.qxp 01/05/ :46 AM Page 40 Fgure 5. Imhoff Tank 40

44 Waste Water.qxp 01/05/ :46 AM Page 41 CHAPTER 8 DRY EXCRETA MANAGEMENT SYSTEMS 8.0 DRY EXCRETA SYSTEMS Dry excreta dsposal systems are waterless tolet systems used when potable water s not accessble or lmted dry seepage pts are not envronmentally acceptable or n urban areas where land s scarce. Pts constructed per absorpton pt recommendatons for dry excreta dsposal are acceptable n areas where leachate does not cause any polluton to water sources and do not mpose a threat to human health. When leachate or odour s a concern mproved pt desgns may be employed: Ventlated Improved Pt Latrne and Ventlated Improved Double Pt Latrne. Other systems may be nstalled upon approval from relevant government agences 8.1 VENTILATED IMPROVED DOUBLE PIT LATRINE (VIDP) AND VENTILATED IMPROVED PIT (VIP) Although t s usually best to provde large deep pts, ths may not be possble where rock or groundwater les wthn one or two metres of the ground surface. VIP and VIDP systems are pt latrnes wth one or two watertght tanks (Fgure 6). These dry latrnes are desgned to receve faecal matter, urne and small amounts of water. To reduce odour, these mproved pt latrnes have a vent ppe extendng from the tank to a mnmum of 45 cm above the superstructure. In an effort to dscourage mosquto breedng, the superstructure s kept partally dark at all tmes, a cover s nstalled on the latrne seat and the vent ppe has a fly screen secured to the top. The VIDP s a varaton of the VIP latrne whereby t has two shallow pts sde by sde under a sngle superstructure. The pts are usually lned wth brcks or blocks. The hole for the ventlaton ppe for the pt not n use s sealed. Each pt may have ts own squat hole or seat. Alternatvely, slabs may be moveable, one wth a hole for the pt n use and a plan slab for the other pt. Whchever desgn s used, only one hole must be avalable for defecaton at any tme. The latrne may be provded 41

45 Waste Water.qxp 01/05/ :46 AM Page 42 wth two ventlaton ppes (one for each pt) but more usually only one s ftted, to the pt n use. Each tank or vault shall have a volume szed to handle excreta generated by the household(s) usng the latrne over a perod of 2 3 years. After 2 years of use, the waste should be allowed to compost undsturbed, for another 2 years before t s removed. Durng ths tme of compostng, the second hole wll be used. The latrne may be provded wth two ventlaton ppes (one for each pt) but usually only one s ftted to the pt n use. Fgure 6. Ventlated Improved Pt Latrne (VIP) Fgure 7. Ventlated Improved Double Pt Latrne 42

46 Waste Water.qxp 01/05/ :46 AM Page 43 The waste s stored untl pathogen reducton has occurred and metals concentraton and other regulated parameters are suffcently low. If waste s to be used, for example, applcaton, to sol permsson s requred from the Local Plannng Authortes Desgn and Constructon - Mnmum Standards v v v The tanks shall be constructed of structurally sound, watertght and constructed wth corroson and decay resstant materal, such as concrete, vtrfed clay block, fbreglass, heavy-weght concrete block, ferrocement or burned hard brck. Another alternatve s heavyweght plastc tanks. In no case shall the volume be less than 1 m3 (35 ft3). A ventlaton ppe shall extend from a mnmum of 15 cm (6 nches) nto the tank(s).the ppe shall be no less than 10 cm (4 nches) n dameter. A fly screen shall be securely nstalled at the ppe end that extends above the superstructure. The mesh aperture must not be larger than 1.2mm x 1.5 mm. The superstructure shall be desgned to lmt the amount of lght enterng the buldng. The mnmum sze of ventlaton openngs nto the superstructure should be at least three tmes the crosssectonal area of the vent ppe. Each tank shall have an access to port to easly remove stablzed excreta Locaton Improved pt latrnes shall be a mnmum of 15 m (50 feet) from potable water sources, 30 m (100 feet) from ktchens and m ( feet) from buldng foundatons. The base of the pt shall be a mnmum of 1.2 metres (4 feet) above the lmtng zone or the seasonal hgh water table. Constructon of latrnes s not allowed n flood prone areas. 43

47 Waste Water.qxp 01/05/ :46 AM Page ABSORPTION PIT DRY EXCRETA DISPOSAL Ths system uses a pt, as per absorpton pt constructon standards. Snce the system s waterless, no septc tank shall be nstalled pror to the pt, nstead the seat shall be nstalled drectly over the pt. The proponent shall follow the absorpton pt requrements for the cap. The absorpton pt system shall be used as a waterless tolet n lmted crcumstances. 8.3 BIOLATRINE The technology on Bolatrne has been n exstence for a long tme and s stll beng exercsed at dfferent levels n many parts of the world. Bolatrne also referred to as Santary Unts were ntroduced n Tanzana as a further step n bogas technology explotaton and n order to contrbute to the efforts aganst the growng problems of rural santaton Characterstcs Bolatrnes are relatvely small unts deployed at famly or nsttutonal level and are connected drectly to bodgesters. These, fulfllng the purpose of normal septc tanks, bear the followng addtonal characterstcs: v They do not requre water; urne s suffcent as a softenng agent; They are drectly connected to the latrne, so avodng an addtonal nfrastructural transfer mechansm between the source of wastes and bodgester postons The process of dgeston s anaerobc; therefore bogas and dgested slurry are the man products. Whle bogas s used for energy purposes, slurry s appled on sols to mprove fertlty; They are cheap n relaton to other methods of wastewater treatment (Fg. 7). Rural communtes, ncludng Insttutons such as schools, clncs, etc., have the opton of usng pt latrnes. These latrnes cannot be empted due to a lack of sucton mechansms and they therefore have to be abandoned once they are full and new ones dug. 44

48 Waste Water.qxp 01/05/ :46 AM Page 45 Fgure 8 Santary Bolatrne Unt. Source SRC Desgn and Constructon - Mnmum Standards An average of 120 days retenton tme should be used n szng the system.ths allows for unpredctable feed addtons. A method for expellng or utlzng the bogas produced from the tank shall be consdered n the desgn Locaton Normally, the postonng of such latrnes n many cases s due to lmtatons such as the proxmty of latrnes to be reached durng the hours of nght, requrng latrnes to be close to sleepng places. In addton, other exstent permanent or sem-permanent nfrastructure (buldngs, roads, etc.) determne the locaton of latrnes. 45

49 Waste Water.qxp 01/05/ :46 AM Page 46 CHAPTER 9 TEMPORARY DISPOSAL SYSTEMS 9.0 TEMPORARY TOILET FACILITIES Temporary tolet facltes are often requred when () () large gatherng of persons exceeds normal capacty of exstng facltes or pror to constructon of a permanent santaton faclty. To accommodate these condtons or other smlar crcumstances temporary dsposal systems may be nstalled. Pror to nstallaton, the proponent must contact the local health department to regster the event and obtan any necessary permts. Proper mantenance ncludng servcng and cleanng schedules s essental to the proper operaton of temporary systems. The holdng capacty and number of tolets shall be suffcent for the number of attendees/users to allow a realstc mantenance schedule. Use of temporary facltes requres approval from the Local Health Department pror to locatng/stng. 9.1 HOLDING TANK A holdng tank shall be permtted only as an nterm to the constructon of a publc sewer; as an overflow faclty or as a means of sewage dsposal for lmted, mnor or temporary applcatons. If a holdng tank wll be used as a permanent treatment component, the proponent wll requre specal approval by EHU wth arrangements through a lcensed cesspool empter. Pror to nstallng the holdng tank, the proponent must submt a copy of a Memorandum of Understandng wth a seepage contractor wth a detaled descrpton of emptyng schedule, ncludng prmary and alternatve dsposal stes. Holdng tanks nstalled as permanent systems must have a septc tank nstalled pror to the holdng tank. For these systems, the proponent shall consder separaton of grey and black waters. The grey water may be treated f ste condtons permt. 46

50 Waste Water.qxp 01/05/ :46 AM Page Desgn and Constructon - Mnmum Standards The tanks shall be constructed of structurally sound, watertght and corroson/decay resstant materal. Acceptable materal ncludes concrete, vtrfed clay block, fbreglass, heavy-weght concrete block, burned hard brck or steel The openng requred for emptyng the contents must be easly accessble for (1) cesspool emptyng equpment and (2) nspecton. Adequate provson shall be made for cesspool emptyng vehcles to park wthn three (3) metres (10 feet) of holdng tank. 9.2 CHEMICAL TOILETS Chemcal tolets are waterless temporary tolet facltes that are prefabrcated wth a seat and excreta holdng chamber. A caustc soluton s mantaned n the chamber to deodorze, dsnfect and lquefy excreta for easy dsposal. Ths system shall be nstalled for temporary use at mass gatherngs, constructon stes or other temporary establshments Desgn and Constructon Mnmum Standards v v The portable chemcal tolet systems shall have proper ventlaton, chemcal soluton, seat and door lock. One seat shall be provded for every 25 women and one seat and one urnal shall be provded for every 35 persons. When these numbers conflct, use the greater value. There should be one hand-washng unt for every 10 persons. Waste removal of these systems shall be completed when the holdng chamber s equal to or less than two-thrds full. The chemcal soluton shall be one (1) of the followng: Four (4) kg lye (potassum hydroxde) per m3 of vault capacty. Ten (10) kg caustc soda or potash (sodum hydroxde) per seat n 50 Ltres of water. One (1) kg chlornated lme n 21 ltres water or One (1) kg copper sulphate n 21 ltres water a Salvato 650/1 47

51 Waste Water.qxp 01/05/ :46 AM Page 48 CHAPTER 10 ON-SITE SECONDARY TREATMENT (INCLUDING SOIL ABSORPTIVE TECHNOLOGIES 10.0 BIODIGESTER SEPTIC TANK A Bodgester Septc Tank (BST) s an on ste santaton unt whch utlzes the anaerobc technology to treat sewage and other wastewater. The by-products of ths process are bogas (a mxture of methane, carbon doxde and trace amounts of other gases such as hydrogen sulphde) and a lqud effluent contanng nutrents. Hence the BST s usually followed by a nutrent removal technology such as an evapotranspraton bed, wetland, pond or tle feld. The follow-up technology s usually determned frstly by the envronmental senstvty of the dsposal area and secondly by the avalable space and layout of the property. The treatment of wastewater nsde the BST s by anaerobc dgeston. It s done by putrefactve bactera, whch break down the organc matter under arless condtons. The dgeston process conssts of two man phases acd formng and methane formng. In the frst phase, complex organc matter s broken down nto smpler forms whle bogas s formed n the second phase. The composton of bogas s usually methane (CH4, %), carbon doxde (CO2, 20 40%), hydrogen sulphde (H2S, 0.5 1%) and other gases. The bogas can be pped to consumpton pont such as a modfed gas stove, water heater, modfed gas refrgerator, gas lamp, generator or desel engne Advantages of Bodgester The BST has many advantages over the tradtonal septc tank. These are as follows: Better treatment of sewage due to the longer retenton tme nsde the BST (6 days) and the ppng system, whch passes the ncomng wastewater through the sludge bed. Lower mantenance cost due to nfrequency of sludge removal. The BST s an anaerobc reactor wthn whch most of the organc solds becomes lquefed and hence no need for sludge wthdrawal even after several years. The system pays for tself snce a useable gas s produced from waste that would otherwse have no economc beneft. The larger 48

52 Waste Water.qxp 01/05/ :46 AM Page 49 the system the shorter the pay back perod. v A second nlet to the BST can be attached to receve organc waste from the ktchen and garden. Ths wll ncrease gas producton and shorten the pay back perod Desgn and Constructon Mnmum Standards. v v The bodgester septc tank should be desgned wth a mnmum detenton tme of sx (6) days. The dome should always be coated to safeguard aganst leaks. A method for expellng or utlzng the bogas produced from the tank shall be consdered n the desgn. The mnmum heght between the nvert of the termnal manhole and the top of the dome shall be 20 cm. A BST nstalled under a drveway or parkng area shall have adequate renforcement to support any antcpated load and access manholes brought up to grade Locaton No tank shall be located wthn 1.5m or 5ft of a buldng or ste boundary. Setback dstances are smlar as those outlned for the septc tank. Dstances from trees, swmmng pools, sdewalks, drveways, etc., shall be such to prevent cave-ns durng constructon. Fgure 9. Schematc of Bodgester Septc Tank 49

53 Waste Water.qxp 01/05/ :46 AM Page UPFLOW ANAEROBIC SLUDGE BLANKET REACTOR The Upflow Anaerobc Sludge Blanket Reactor (UASB) s an anaerobc contact process that requres lttle to no energy n treatng wastewater. Untreated waste or septc tank effluent enters at the base of the reactor and passes through the sludge blanket. Methane (CH4) and carbon doxde (CO2) are produced when the raw sewage reacts wth the sludge blanket. These gases create a natural nternal crculaton, whch helps mantan the sludge granules n suspenson. The free gas and attached gas that rse to the surface strke a degassng baffle, whch causes the attached gas to be released and escape through the top of the reactor to the gas collector (Metcalf/Eddy p428). Solds settle nto the sludge blanket, whle clarfed effluent leaves the system through an upper baffle or equvalent. An UASB reactor typcally requres a subsurface wetland or other nutrent removal technology pror to fnal dsposal. The reactor may be substtuted for a Bodgester Septc Tank (BST). The retenton tme of 6 to 12 hours, as compared to the BST havng 6 days, means that the UASB has a smaller footprnt. Ths type of treatment system s usually for larger developments and requres more operaton and mantenance than the BST Fgure 10. Schematc of an Upflow Anaerobc Sludge Blanket Reactor Desgn and Constructon Mnmum Standards. To mantan the sludge blanket n suspenson, the upflow mnmum velocty of the raw sewage should range from 0.6 to

54 Waste Water.qxp 01/05/ :46 AM Page 51 metres/hour. Pre-treatment of the sewage s mportant. Screens and grt chambers must be nstalled to remove norganc materal before the sewage enters the sludge bed. A method for expellng or utlzng the gas produced from the tank should be consdered n the desgn. v The reactor heght should be no less than 3.5 m Locaton The treatment plant and all ts components should be at least 20 ft from the nearest property boundary. Adequate access way should be provded for servce vehcles AERATED SEPTIC TANK Aeraton may be ntroduced nto a septc tank f the organc loadng rate s greater than the capacty of a conventonal septc system. The ntroducton of aeraton n the frst chamber promotes the growth of aerobc mcro-organsms, whch convert and remove bodegradable organc matter. In turn, the reduced organc and suspended solds content n the effluent may reduce the requred subsurface dsposal system. Mantenance of ths system s greater than the conventonal septc tank because of a hgher producton of sludge and the use of blowers or pumps to provde aeraton. These systems are typcally approprate for small hotels, schools, apartment complexes, and very large resdences wth many occupants Desgn and Constructon Mnmum Standards. Aerated septc tanks may be substtuted for a conventonal septc tank. The mnmum standards outlned for septc tanks apply. A chamber after the aeraton chamber shall be constructed to clarfy the wastewater. Pumps or blowers nstalled to provde aeraton, should be provded wth spares ether as nstalled standby spares or as boxed spares located on-ste. 51

55 Waste Water.qxp 01/05/ :46 AM Page Locaton No tank shall be located wthn 5-0 of a buldng or ste boundary. Setback dstances are smlar as those outlned for the septc tank. Dstances from trees, swmmng pools, sdewalks, drveways, etc., shall be such to prevent cave-nn durng constructon ABSORPTION TRENCH (TILE FIELD) An absorpton trench system s a seres of perforated ppes placed n narrow trenches. Ths technology utlzes the natural bologcal composton of sol to treat effluent from septc tanks or ts equvalent. Beyond a secondary treatment technology, tle felds may be used as a fnal dsposal of effluent from tertary treatment systems. The trench system conssts of: v v feed lne, an absorpton area, a dstrbuton network, a cap, and top sol. The septc tank effluent s pumped or gravty-fed nto the absorpton area through a seres of perforated ppes located n the upper part of the coarse aggregate.the wastewater passes through the aggregate and nfltrates the trenches.treatment of the wastewater occurs as t passes through the trenches and the unsaturated zone of the natural sol. The cap, usually a fner textured materal than the fll, sheds precptaton, and retans mosture for a good vegetatve cover. The topsol provdes a growth medum for the vegetaton. The szng of tle felds for treatment of settled wastewater (after treatment n a septc tank) can be determned based on sol percolaton rates Desgn and Constructon Mnmum Standards A watertght lne shall connect the septc tank, dverson valve f used and the dsposal trenches. Dstrbuton ppe shall run the length of each trench and connect each trench n seres. Dstrbuton ppe for gravty flow absorpton systems shall 52

56 Waste Water.qxp 01/05/ :46 AM Page Trench Desgn be 100 mm-perforated PVC ppe. Dstrbuton ppe for gravty-flow absorpton systems shall be n straght lengths and have a mnmum of two rows of round holes; each 6 13 mm dameter and located at approxmately 150 mm ntervals. The perforatons shall be placed as to permt equal dranage along the length of the ppe and open ends of ppes shall be capped. In gravty-flow absorpton systems wth multple dstrbuton lnes, the sewer ppe from the septc tank shall not be n drect lne wth any one of the dstrbuton lnes, except where drop boxes or dstrbuton boxes are used. Any secton of dstrbuton ppe lad wth non-perforated ppe, shall not be consdered n determnng the requred absorpton area. Breathers shall be placed at all ends of absorpton trenches. The breather shall consst of perforated ppe at least 100 mm n dameter, placed vertcally wthn the backfll of the trench. Dsposal trenches shall be a mnmum of 300 mm wde. Bottom of the trench shall be a mnmum of 1.0 metre above statc groundwater level. Each trench shall be not more than 30 m n length. Loadng rate shall be 61 l/m2/day f no percolaton test was been done. (U.S. Manual of Septc Tank Practce, 1967). See Appendx 2. Undsturbed materal should be left between trenches. 53

57 Waste Water.qxp 01/05/ :46 AM Page 54 Fgure 11 Layout of a typcal tle feld Each trench shall have parallel contour lnes. Mnmum spacng between trenches on the same contour shall be two tmes the total trench depth. Trenches not on the same contour shall be spaced as follows (Table 13): Table 13. Trench Spacng Slope of Ground Between Trenches Mnmum spacng Between Trenches 0% to 5% 2.0 tmes the total trench depth 5% to 10% 2.5 tmes the total trench depth 10% to 20% 3.0 tmes the total trench depth Over 20% 4.0 tmes the total trench depth Trench Constructon Trenches shall be constructed perpendcular to groundwater flow when such knowledge exsts. Backfll shall be at least 300 mm of natve sol over a protectve layer of untreated buldng paper or other pervous materal, such as a synthetc flter fabrc to prevent nfltraton of backfll nto the flter materal. Sol placed over trenches shall be compacted so that depressons wll not occur. Rock gravel fll shall extend from the bottom of the trench to 100 mm above the dstrbuton ppe. Rock or gravel fll shall be clean and of unform sze, preferably 19 mm to 50 mm n dameter. v Absorpton system excavatons may be made by machnery 54

58 Waste Water.qxp 01/05/ :46 AM Page 55 provded that the sol n the bottom and sdes of the excavaton s not compacted. Strct attenton shall be gven to the protecton of the natural absorpton propertes of the sol. Absorpton system shall not be excavated when the sol s wet enough to smear or compact easly. Some smearng damage s lkely to occur. All smeared or compacted surfaces should be raked to a depth of 25 mm, and loose materal removed before the flter materal s placed n the absorpton area. v v v Use of dynamte or jackhammer s prohbted n constructon of dsposal trenches. Absorpton areas shall not be constructed under paved or other mperous areas. Both dstrbuton ppe and trench bottom shall be approxmately level. Use of Vshaped trenches s prohbted, except where sol condtons make constructon of vertcal wall mpossble Locaton If possble, a tle feld replacement area equvalent to 100% of the ntal area shall be avalable for replacement of tle feld.ths space shall not be used for permanent structures. No tank shall be located wthn 6 m of a buldng foundaton or 3m to the property lne. Tle feld should not be placed below the road surface CHAMBERED TRENCH SYSTEMS A chambered trench system s a type of absorpton trench system whereby the meda s a dome, open-bottom chamber structure of an approved materal and desgn. The open bottom permts nfltraton of septc tank effluent nto natve or fll sols. The chamber provdes allowance for peak flows. Ths system may substtute for the absorpton trench systems. Chamber Trench Systems shall follow desgn and constructon mnmum standards as conventonal trench systems except where stated. 55

59 Waste Water.qxp 01/05/ :46 AM Page Desgn and Constructon Mnmum Standards v Access ports shall be constructed to nvestgate chambers. Chambers shall be placed over natve sol or fll that meets percolaton rate requrements. No allowance wll be permtted for chambers to be placed over gravel or mpermeable sols. System nstallaton shall follow manufacturer s nstructons. Chamber systems shall be consdered expermental treatment methods MOUND TRENCH/BED DISPOSAL SYSTEMS Typcal subsurface absorpton systems, ncludng tle felds, are not acceptable methods of dsposng of septc tank effluent when an mpervous sol layer or groundwater s less than 1.2 m from surface. An alternatve system s the mound or rased trench system, whch s an absorpton bed or trench system elevated above the natural sol surface n a sutable fll materal. Mound Systems shall be constructed to the satsfacton of the absorpton trench (tle feld) dsposal system, unless stated. Mound trench systems shall be consdered f: The natural sol s of slow permeablty wth percolaton rates exceedng 472 mn/100 mm The natural sol lay s hghly permeable and shallow (less than 0.9 metres) over an mpervous layer wth percolaton rates less than 7.9 mn/100 mm or The natural sol s hghly permeable wth the seasonal groundwater of less than 0.6 metres from surface. Mound trench systems shall not be consdered f: The sol n the area conssts of fll. The natural sol layer has been compacted, The proposed locaton s above a falng conventonal system, or The area does not have the mnmum depths of sol specfed. (Referencng of the 2003 Internatonal Prvate Sewage Dsposal Code) 56

60 Waste Water.qxp 01/05/ :46 AM Page Desgn and Constructon Mnmum Standards Suffcent area at the natve and fll nterface shall be suffcent to permt proper dranage of wastewater away from the mound. Mounds must be long and narrow and placed along topographc contours of the ste. Fgure12.Cross secton of a mound system Fgure 13. Cross Secton of a Septc Tank Mound System 10.6 INTERMITTENT SAND FILTER SYSTEM Sand flter systems are another alternatve technology to the tle feld system. Ths technology s typcally used n areas where the sol s not sutable for effectvely treatng septc tank effluent or the seasonal groundwater level s less than 1.2 metres from the surface. Intermttent sand flters are typcally shallow beds wth mm of sand wth surface dstrbuton and bottom under-dran systems. These systems are dosed ntermttently durng the day wth septc tank effluent or equvalent Effluent collected n the under-dran may be (1) drectly dsposed to a dsposal feld or (2) surface water source or dry gully followng dsnfecton. The requred level of 57

61 Waste Water.qxp 01/05/ :46 AM Page 58 treatment n the area determnes the fnal dsposal method. Intermttent sand flters may be desgned to provde free access (open flters) or may be bured n the ground (bured flters). Both open and bured systems desgned to recrculate effluent through the system s dscussed n the next secton Desgn and Constructon Mnmum Standards v v v Bured flters shall be structurally sound, watertght and constructed of materals resstant to corroson or decay, such as concrete, vtrfed clay, block, fbreglass, heavy weght concrete block, burned hard brck or heavy-duty plastc. Open flters shall be constructed completely above ground or wthn the natural sol. Sand flters shall be covered wth a sutable materal that wll to reduce odour condtons, to avod encroachment of weeds and nfltraton of precptaton but wll encourage ar flow to the flter, such as non-compacted, mounded sol. Flter beds shall be dousng twelve to twenty-four (12-24) tmes per day. The dousng system shall be desgned to flood the entre flter durng each cycle. Flter meda shall be coarse sand (wth an effectve sze rangng from mm) or any washed durable granular materal that s low n organc materal. Flter meda should be compacted after t s put n place. Care shall be taken to nsure that meda does not stratfy wth fne layer over coarse. Flter meda should be n a m deep bed.the area of the bed should be 1.5 m2/person (usng the system) or 0.35 l/m2/day, whchever gves a larger area. Dstrbuton and under dran lnes shall be constructed of an acceptable materal wth a mnmum dameter of 100 mm. If contnuous ppelne s used, conventonal perforated ppe wth 6-13 mm dameter holes placed approxmately 150 mm apart s approprate. The perforatons shall be placed as to permt equal dranage along the length of the ppe and open ends of ppes shall be capped. All ppelnes shall be vented wth vertcal rsers to the ground surface. Dstrbuton lnes shall be vented downstream and under drans vented upstream.the network shall be a drp network. 58

62 Waste Water.qxp 01/05/ :46 AM Page 59 v v x Dstrbuton lnes shall be level and spaced at mnmum 900 mm on centre. Approxmately 250 mm of graded gravel mm shall be used for ppelne beddng. Under dran lnes shall be lad drectly on the flter floor, whch should be slghtly ptched to carry flter effluent to the dran lne. Ppelnes shall be provded for each 3.5 metres of trench wdth. The beddng materal for under dran lnes shall have a mnmum of 250 mm washed graded gravel or stone wth szes rangng from 6 13 mm. The gravel or stone shall be overlan wth a mnmum of 60 mm of washed pea gravel nterfacng the flter meda. The dousng tank should be equal n volume to the daly desgn flow. 59

63 Waste Water.qxp 01/05/ :46 AM Page 60 CHAPTER 11 ON-SITE TERTIARY TREATMENT SYSTEMS 11.0 CONSTRUCTED WETLANDS The use of wetland systems n the treatment of onste wastewater dsposal s commonly used at schools, commercal enttes and rural resdences. Typcally, subsurface flow systems are used nstead of free surface flow wetland systems n an effort to avod developng mosquto-breedng areas. A subsurface flow wetland system provdes treatment va a flter meda wthn an aerobc root zone. The flter meda s a gravel bed that s not drectly exposed to the atmosphere. If desgned properly, wetland systems wll reduce bologcal oxygen demand, total suspended solds and some nutrents. Free surface flow wetland systems are typcally not recommended for small onste treatment systems Desgn and Constructon Mnmum Standards v Flter meda Flter meda shall be of gravel, washed clean, rounded and resstant to crushng or breakage. The meda sze n the treatment zone shall be mm, wth the top 10 cm of 5-20 mm. Inlet and outlet zone areas shall have meda of larger sze, mm to prevent washouts. Vegetaton shall have suffcent root zone and be an acceptable speces for the clmate and wetland condtons. Multple types of natve plants wth varyng root lengths are preferable. Suspended solds shall be removed va septc tank or comparable pre-treatment technology to prevent cloggng. Further pretreatment may be requred. The depth of actve flter meda shall be 0.5 to 0.6 metres. v The n pore hydraulc retenton tme shall be no less than three (3) days. v v Recommended surface loadng rate for wetlands shall be approxmately 1.6 gal/m2d. The bottom slope shall be percent, whle the top slope 60

64 Waste Water.qxp 01/05/ :46 AM Page 61 shall be approxmately zero (0) percent. v x The aspect rato (L:W) s not usually a factor that has a great deal to do wth the effectveness of treatment.a suggested aspect rato s approxmately 2:1. Constructed wetlands shall be lned wth clay or a synthetc, mpermeable lner. Effluent shall be dsposed n a manner that s suffcent for treatment requrements. Typcal dsposal methods nclude dsnfecton, followed by drect dsposal to gully or further treatment va sub-surface absorpton system. Fgure 14 Cross Secton of a Subsurface Flow Constructed Wetland (Cooper, 1993) 11.1 EVAPOTRANSPIRATION SYSTEM Evapotranspraton systems are smlar to a constructed subsurface flow wetland, except the system s desgned to have no effluent. Influent wastewater s dsposed va transpraton through vegetaton or evaporaton from bed surface. These systems shall only be employed f all other technologes are defcent. Typcally, evapotranspraton systems are nstalled n areas wth (1) shallow groundwater or (2) groundwater s already compromsed by wastewater contamnaton. Ths system shall only be nstalled n areas were evapotranspraton exceeds precptaton. Systems may be consdered n areas where a sngle month precptaton exceeds evapotranspraton, f suffcent storage s desgned wthn the bed. Some areas may support an evapotranspraton system wth an absorpton technology followng. Ths system allows for a smaller requred ET area. Ths 61

65 Waste Water.qxp 01/05/ :46 AM Page 62 system may not be acceptable n all areas. Dstrbuton and under-dran lnes shall be nstalled as stated for ntermttent sand flters, unless where stated Desgn and constructon Mnmum Standards. v v v v v x x The loadng rate shall be 10.7 l/m2/day. An artfcal lner s requred between the evapotranspraton bed and natural sol f percolaton of natural sol s less than 5 mnutes / 25 mm or f no percolaton test has been done. Flter meda shall be of clean sand wth suffcent capllary rse capabltes. A 50mm topsol cap shall be placed on top of sand flter medal. If requred, a storage area may be constructed below the dstrbuton ppes. Ths area shall be a clean rock meda wth a maxmum depth of 300 mm. The pt shall be 0.7 m deep wth 20 cm of gravel as bottom layer wth perforated dstrbuton ppes runnng through. The gravel should be overlan wth a layer of buldng felt wth 0.5 m of sand above. ETB shall have a montorng well n a corner. Sand wcks may be ncorporated n the gravel to provde contnuous capllary rse n sand. Influent to ET system shall be effluent from septc tank or comparable pre-treatment technology. The nfluent shall have lmted suspended solds to prevent premature cloggng of system. Employ low-flow devces or grey water to soak-away pt to reduce sze of ET bed. Top of ETB shall have a slope suffcent to prevent nfltraton of precptaton. Interor sdes of ETB below ground level shall have a slope of 1:1. Vegetaton shall be smlar to wetland flora. The vegetaton shall have a deep root zone and leaves shall support proper transpraton. 62

66 Waste Water.qxp 01/05/ :46 AM Page 63 x Systems may be approved for an allowance of a gven percentage of effluent. Ths wll reduce the requred bed sze. Typcally, effluent s treated va seepage pt or other sub-surface absorpton system. Fgure 15. Cross secton of an Evapotranspraton Bed 63

67 Waste Water.qxp 01/05/ :46 AM Page 64 CHAPTER 12 AUXILIARY EQUIPMENT 12.0 GREASE AND SEPTAGE HANDLING Auxlary equpment for central sewerage system ncludng pumps, lft statons, wet wells, manholes, cleanouts, sewer ppelne and other appurtenances are not dscussed wthn ths manual. Proponents employng ths equpment shall consult the Natonal Water Commsson s Developer s Manual GREASE AND SEPTAGE HANDLING Separaton and removal of septage, sludge and grease from wastewater wll result n adverse affects n the fnal effluent qualty or qualty of sol absorpton treatment. Unfortunately, proper treatment of sludge, grease and septage contnue to be of grave concern n Jamaca due to the lmted treatment stes avalable on the sland. Fgure 16. Secton Through a Grease Trap 12.2 SCREENS AND GRIT CHAMBER Many secondary and tertary treatment systems requre pre-treatment steps by means of screens and grt chambers to remove norganc materal from the wastewater for an optmzed performance of the treatment system. Screens remove plastcs, twgs, peces of cloth, rocks etc. that may end up n the wastewater stream. Grt chambers allow smaller peces of rock, metal and bone whch are denser than organc materal, to settle out of the waste stream. The wastewater s slowed down just enough for the solds to settle out. If these are allowed to reman n the wastewater, they could cause damage to pumps through abrason, 64

68 Waste Water.qxp 01/05/ :46 AM Page 65 cloggng of ppelnes or reducton of the effectve volume for wastewater treatment n the sewage treatment plant. Varous types of mechancally and manually cleaned screens and grt chambers are avalable on the market. Fgures 15 and 16 show a mechancal screen and a manual screen respectvely. Fgure 17. Mechancal Bar Screens Fgure 18. Manual Bar Screen 12.3 CONTACT INFORMATION For further nformaton please contact: The Drector Envronmental Health Unt (EHU) Mnstry of Health 2-4 Kng Street Kngston Tel: (876) Fax: (876) Emal: [email protected] webste: 65

69 Waste Water.qxp 01/05/ :46 AM Page OPERATION AND MAINTENANCE MANUAL, EHU/MOH 1.0 INTRODUCTION Proper operaton of new or modfed sewerage works and mproved operaton of exstng facltes are essental f effluent qualty standards are to be met. In an effort to ncrease the probablty of meetng effluent qualty standards, t s mandatory that each sewerage works operator has access to an operaton and mantenance manual whch wll act as a gude n all aspects related to the system operaton and mantenance. The desgn Engneer shall, therefore submt four (4) copes of an operaton and mantenance manual to the Envronmental Health Department for revew and approval pror to the ssuance of a certfcate to operate. Upon fnal acceptance of the manual, the Engneer shall furnsh four (4) copes of the corrected manual to the Owner. The Owner shall locate the operaton and mantenance manual n a place accessble to the operator on the ste of the sewage treatment works. 1.1 GENERAL REQUIREMENTS The operaton and mantenance manual shall be desgned for use by the operator. It should, therefore, be wrtten on a readng level approprate for the grade of operator necessary for the partcular plant. Readablty should be ncreased by use of short sentences, smplfed vocabulary, etc. Use of llustratons s encouraged, especally where they can supplement nvolved nstructons. It s recommended that all manuals be n loose leaf form for expanson and updatng purposes. If the manual s large, t s recommended that t be produced n at least two volumes. Manufacturer s manuals should be grouped together and should be cross-referenced to the man text, as approprate. The manuals should be ndexed and tabbed to smplfy usage. 1.2 FORMAT REQUIREMENTS Appendx 1 The operaton and mantenance manual of all sewerage works shall contan, but not be lmted to, the followng sectons Lft Statons - Each unt of the lft staton shall be related to ts functon. Schematc dagrams shall be used to show the locaton of all valves, pumps, controls, etc. and how they relate to the overall staton operaton. Items

70 Waste Water.qxp 01/05/ :46 AM Page whch should be consdered are: pumps level controls valves and ppng v ventlaton equpment v dehumdfers v sumps v bar screens or baskets Appendx Plant Layout and Flow Pattern - The plant type and a descrpton of the basc process wll be requred. Each unt of the plant shall be related to ts functon and to the other unts ncluded n the process. Schematc dagrams shall be used to show the locaton of all valves, pumps, controls, etc., and how they relate to the over-all operaton.addtonal dagrams shall contan enlarged detals of the complcated ppng areas. Items whch should be consdered are: v v v v v x x x x x xv xv xv xv xv xx xx xx pumpng pre-treatment systems screenng and commnuton grt removal prmary clarfcaton aeraton and re-aeraton secondary sedmentaton trcklng flters sand flters sludge dgeston sludge condtonng sludge dsposal sludge dryng beds gas control and use dsnfecton effluent reuse systems wastewater lagoons odour control systems chemcal addton effluent polshng systems other processes Expected Effcency of the System and the Prncpal Desgn Crtera A detaled outlne of the expected treatment effcency n removng the requred dscharge consttuents shall be presented. Prncpal desgn crtera shall be gven wth unt szes, retenton tmes, loadng rates, etc., for each

71 Waste Water.qxp 01/05/ :46 AM Page part of the sewerage system. Appendx Detaled Operatonal and Control Procedures Routne procedures of operaton and control shall be detaled as well as alternate methods and emergency procedures. The ppelnes, valves, and controls should be clearly marked as referenced n the detaled operaton procedures. A descrpton of the varous controls wth recommended settngs shall be gven as related to: v v v v manual controls automatc controls physcal controls chemcal controls bologcal controls ndustral waste montorng safety features. Pump calbraton curves, chemcal makeup charts and other graphcal ads whch assst the operator shall be ncluded Laboratory Controls A bref dscusson on requred laboratory tests, why these tests are requred, nterpretaton of the test results, and samplng procedures shall be presented as appled to: Each unt of the process montorng of effluent and recevng waters water qualty standards Records Recommended laboratory testng manuals or books should be referenced wth names and addresses of publshers. The operaton and mantenance manual shall stress the mportance of record keepng and graphng test results. Sample forms shall be enclosed whch apply to: process operatons laboratory analyss

72 Waste Water.qxp 01/05/ :46 AM Page v v reports requred by the regulatory agences mantenance Appendx Mantenance The manual shall contan a detaled recommended mantenance schedule for all facets of sewerage system mantenance.these schedules shall be for: v normal equpment mantenance schedules as per manufacturer s recommendatons preventve mantenance summary schedules specal tools and equpment housekeepng schedules, such as weed control, etc Trouble Shootng Gude A trouble shootng gude shall be provded for each system unt (bologcal and mechancal) wth a ready reference chart descrbng short-term and long-term solutons, and a bref descrpton of the cause Safety Procedures The operaton and mantenance manual shall dscuss safety procedures as related to: v v v v sewers electrcal equpment mechancal equpment exploson and fre hazards health hazards handlng of chlorne and other hazardous chemcals open tank hazards A lst of recommended safety equpment shall be an ntegral part of the manual. It s recommended that the WPCF Manual of Practce No. 8 be used n conjuncton wth OSHA n addressng safety procedures Emergency Operatng Plans and Procedures The operaton and mantenance manual for lft statons and treatment plants shall descrbe the effectve automatc response for probable emergency stuatons whch may be caused by the followng: v

73 Waste Water.qxp 01/05/ :46 AM Page v Power Falure entre plant treatment process pumpng statons false alarms Appendx 1 v v v v v x x x flood, hurrcane, earthquake, fre, wndstorms, freezng, explosons. contamnaton of potable water supply hydraulc overloadng, ruptures, and stoppages by-passng equpment breakdowns and process falures falure of emergency warnng equpment labour strkes splls of ols, toxc or hazardous materals nto sewers or at treatment works personnel njury other types of emergency stuatons A general response pattern shall be establshed for each type of emergency and should follow the general response actons of v v early warnng report nvestgaton assess severty of the stuaton (ncludng threat to the publc health, water supples, etc.) determne response course of acton and mplement approprate emergency plan) follow approprate notfcaton schedule (local-state-federal) dependng on the type of emergency Emergency Readness Program The operaton and mantenance manual shall also contan an emergency readness program.the manual shall descrbe the approprate program for mantanng readness by addressng the followng: equpment and parts nventory and chemcal supples necessary to handle emergency personnel tranng on emergency operatng procedures charts on locaton of facltes sewers pump statons sewer overflow ponts v

74 Waste Water.qxp 01/05/ :46 AM Page v v v v Appendx 1 flow regulators, valves, and controls wastewater storage Alert and response system for each type of emergency early warnng systems where applcable to warn downstream water users of splls, etc. ndustral waste montorng and warnng system wthn sewer networks to alert plant operators of splls and changes n waste consstency or hydraulc condtons that may adversely affect waste treatment Utltes A map of all utltes showng key shut-off ponts shall be ncluded n the manual for: v electrcal gas water heat Manufacturer s Equpment Data Each manual shall contan data from equpment supplers whch contans: v parts lsts assembly drawngs equpment trouble shootng gudes lst of recommended spare parts and nstructons for orderng equpment Appendx The appendx of the manual shall contan: v v v v v x schematcs valve ndces sample forms lst of chemcals used n the plant and handlng procedures lst of chemcals used n the laboratory effluent dscharge permt and standards. detaled desgn crtera lst of equpment supplers wth addresses and telephone numbers suppler s manual v

75 Waste Water.qxp 01/05/ :46 AM Page v x x x local ordnances operator certfcaton and staffng requrements detals for reportng splls Appendx 1 v

76 Waste Water.qxp 01/05/ :46 AM Page Appendx 2