December 1998 Criteria for Sewage Works Design Text from WAc 173-240-060 Explanation o Detailed outfall analysis or other disposal See 3(e)above. A detailed outfall analysis is a determination of the optimum method selected location and diffuser design required to meet the water quality standards cluding acute and chronic criteria as defined in Chapter 173-245 WAC at the boundaries of a permitted dilution zone. This should be accomplished by the use of a computer analysis using the most appropriate model(s)applicable to e situation. Field data shall be collected as necessary to calibrate the model and to develop site specific data (such as eddy diffusivity) that cannot be reasonably assumed. The analyses should be made of all conceivable critical situations. The low flow to be used shall be the 7Q10 flow or other regulated he outfall and diffuser shall be considered a basic unit of the treatment ystem and included in the data for 3(g) above. For land application of (m) a discussion of the method of final A sludge management plan that includes an evaluation of sludge quantities udge disposal and any altematives generated and potential disposal or utilization options, including regional sludge disposal and utilization options, must be included in or appended to the engineering report. The sludge management plan includes evaluating ludge treatment options at the plant and relating these sludge treatment options to the sludge disposal or utilization options considered; compliance with applicable laws and regulations(40 CFR 503 and 258); and Ecology's Minimal Functional Standards, local permits, etc. Guidance on the content of a sludge management plan is available from other sources A solids mass balance for the treatment plant is a part of the process of developing and comparing both the sludge treatment and wastewater treatment alternatives. a ranking of the various sludge handling alternatives necessary to implement the selected sludge handling alternative must be given. The selection of a sludge treatment and disposal process is part of the altematives analysis referred to in 3(f) and (g) above. (n) Provision for future needs This relates to the potential to expand a treatment plant on a given site, onstruct a new plant on an altemate site, locations to construct a new facility. ind the ability to extend the sewerage system. The population, industrial, and commercial growth of the service area must be considered. The time frame for this evaluation may range from five years for a phased project to 20 years for complete buildout of the service area. It is recommended that 20 years of treatment capacity be included in each project. (o)Staffing and testing requirements for the The staffing needs of each final treatment alternate considered must be made in order to properly compare the costs of the alternates. EPA's document Estimating Staffing for Municipal Wastewater Facilities"is an acceptabl estimating tool. During design, the facility will be evaluated for facility classification under Chapter 173-230 WAC An operator of this classification must be provided for in the staffing plan. The selected alternative should be in adequate detail for evaluating the facility classification. (p) An estimate of the costs and expenses of The cost estimate given here shall be the engineer's best opinion of probable the proposed facilities and the method of final costs based on an intermixed estimate of quantities and costs. If financial es. The tot sistance from Ecology for construction is anticipated, there shall be a shall include both capital costs roject financing (user charge)evaluation that includes the anticipated cology grant or loan funding and one that does not include any Ecology be presented in terms of total annual cost be done for each of the final alternates as part of the ranking process.must costs for the life of the project, and shall grant or loan funding. A present worth analysis that includes O&M costs This need only be a brief paragraph stating which plan is being followed Pollution Control act as amended
G1-24 December 1998 Criteria for Sewage Works Design Text from WAC 173-240-060 Explanation (l) Detailed outfall analysis or other disposal method selected. See 3(e) above. A detailed outfall analysis is a determination of the optimum location and diffuser design required to meet the water quality standards, including acute and chronic criteria as defined in Chapter 173-245 WAC at the boundaries of a permitted dilution zone. This should be accomplished by the use of a computer analysis using the most appropriate model(s) applicable to the situation. Field data shall be collected as necessary to calibrate the model and to develop site specific data (such as eddy diffusivity) that cannot be reasonably assumed. The analyses should be made of all conceivable critical situations. The low flow to be used shall be the 7Q10 flow or other regulated low flow. The outfall and diffuser shall be considered a basic unit of the treatment system and included in the data for 3(g) above. For land application of wastewater, see (4) below. (m) A discussion of the method of final sludge disposal and any alternatives considered. A sludge management plan that includes an evaluation of sludge quantities generated and potential disposal or utilization options, including regional sludge disposal and utilization options, must be included in or appended to the engineering report. The sludge management plan includes evaluating sludge treatment options at the plant and relating these sludge treatment options to the sludge disposal or utilization options considered; compliance with applicable laws and regulations (40 CFR 503 and 258); and Ecology’s Minimal Functional Standards, local permits, etc. Guidance on the content of a sludge management plan is available from other sources. A solids mass balance for the treatment plant is a part of the process of developing and comparing both the sludge treatment and wastewater treatment alternatives. A ranking of the various sludge handling alternatives considered and selection of the best alternative must be made. The reasons for not selecting the other alternatives must be given. A listing of the actions necessary to implement the selected sludge handling alternative must be given. The selection of a sludge treatment and disposal process is part of the alternatives analysis referred to in 3(f) and (g) above. (n) Provision for future needs. This relates to the potential to expand a treatment plant on a given site, construct a new plant on an alternate site, locations to construct a new facility, and the ability to extend the sewerage system. The population, industrial, and commercial growth of the service area must be considered. The time frame for this evaluation may range from five years for a phased project to 20 years for complete buildout of the service area. It is recommended that 20 years of treatment capacity be included in each project. (o) Staffing and testing requirements for the facilities. The staffing needs of each final treatment alternate considered must be made in order to properly compare the costs of the alternates. EPA’s document “Estimating Staffing for Municipal Wastewater Facilities” is an acceptable estimating tool. During design, the facility will be evaluated for facility classification under Chapter 173-230 WAC. An operator of this classification must be provided for in the staffing plan. The selected alternative should be in adequate detail for evaluating the facility classification. (p) An estimate of the costs and expenses of the proposed facilities and the method of assessing costs and expenses. The total amount shall include both capital costs and also operation and maintenance costs for the life of the project, and shall be presented in terms of total annual cost and present worth. The cost estimate given here shall be the engineer's best opinion of probable final costs based on an intermixed estimate of quantities and costs. If financial assistance from Ecology for construction is anticipated, there shall be a project financing (user charge) evaluation that includes the anticipated Ecology grant or loan funding and one that does not include any Ecology grant or loan funding. A present worth analysis that includes O&M costs must be done for each of the final alternates as part of the ranking process. (q) A statement regarding compliance with any applicable state or local water quality management plan or any such plan adopted pursuant to the federal Water Pollution Control Act as amended. This need only be a brief paragraph stating which plan is being followed
GeneralEngineering Requirements December 1998 G125 Text from WAc 173-240-060 Explanation (r) A statement regarding compliance with This is best accomplished by including a copy of the SEPA checklist, a SEPA and NEPA, if applicabl reference to an applicable FEIs, and the final SEPa declarations in the ngineering report. the action taken that requires sEPa is the adoption of the ngineering report and its recommended project. If NEPA is required( for derally funded projects), an environmental assessment or reference to an plicable FEIS and final NEPA action must be appended in the engineering report. A final SEPA declaration by local government must be made prior to pproval of the engineering report. If the project anticipates sRF loan funding, it must also pass through the SERP process. This process is in addition to the SEPA process, but can be replaced by NEPA See G1-2.6 for more information about SERP The en g report for projects utilizing 4)(c)refers to the availability of public sewers connected to a conventional cility. On lly for grant/loan considerations)fo rigation, and subsurface disposal, shall determining if conveyance and treatment of sewage at a WTP in lieu of include information on the following togethe eatment on-site is on a 20-year present worth basis. If it is of equal or lower with appropriate parts of subsection C(3)of ost (present worth basis)to convey wastewater to a larger, conventional this table, as determined by Ecology: facility than it is to treat it in an approved on-site wastewater treatment facility a) Soils and their permeability. then conveyance and treatment should be considered as the chosen aItemative. If it is less costly to use an approved on-site treatment process, (b)Geohydrologic evaluation of such factors and site soils are suitable and other environmental and local concerns are also addressed. the on-site treatment should be the alternative selected. The election process is related to long-term reliability of the treatment and disposal process. (4)(d)means that there should be at least enough separate movement during different times of ea for 100-percent replacement of the drain field if subsurface disposal is he year. the chosen treatment and disposal process(see DOH's Design Standards for () Water balance analysis of the Large On-Site Sewage Systems") See Chapter E3 for determining the ground water quality criteria for land application process. ound water in NOTE: WAC 173-240-035 restricts the use of subsurface wastewater disposal by other land systems if other methods are available. Satisfying the above requirements will satisfy the reasonability test (WAC 173-240-035 (c) Availability of public sewers (d) Reserve areas for additional subsurface G1-4.2 Plans and specifications This section describes contents and approval requirements for plans and specifications G1-4.2.1 Objective The objective of this section is to describe documentation by means of plans, specifications, and other materials incident to design that adequately represent the design engineer's intent and are used as instruments to facilitate the construction of the project. Plans and specifications are defined in WAC 173- 240-020(2). The requirements for plans and specifications are found in WAC 173-240-070 G1-4. 2.2 Contents of plan A. General The design should be consistent with federal, state, and local requirements The design plan, together with the specifications and other appropriate
General Engineering Requirements December 1998 G1-25 Text from WAC 173-240-060 Explanation (r) A statement regarding compliance with SEPA and NEPA, if applicable. This is best accomplished by including a copy of the SEPA checklist, a reference to an applicable FEIS, and the final SEPA declarations in the engineering report. The action taken that requires SEPA is the adoption of the engineering report and its recommended project. If NEPA is required (for federally funded projects), an environmental assessment or reference to an applicable FEIS and final NEPA action must be appended in the engineering report. A final SEPA declaration by local government must be made prior to approval of the engineering report. If the project anticipates SRF loan funding, it must also pass through the SERP process. This process is in addition to the SEPA process, but can be replaced by NEPA. See G1-2.6 for more information about SERP. 060(4) Land Application Discharges The engineering report for projects utilizing land application, including seepage lagoons, irrigation, and subsurface disposal, shall include information on the following together with appropriate parts of subsection C(3) of this table, as determined by Ecology: (a) Soils and their permeability. (b) Geohydrologic evaluation of such factors as: (i) Depth to ground and ground water movement during different times of the year. (ii) Water balance analysis of the proposed discharge area. (iii) Overall effects of the proposed facility upon the ground water in conjunction with any other land application facilities that may be present. (c) Availability of public sewers. (d) Reserve areas for additional subsurface disposal. (4)(c) refers to the availability of public sewers connected to a conventional treatment facility. One criteria (especially for grant/loan considerations) for determining if conveyance and treatment of sewage at a WWTP in lieu of treatment on-site is on a 20-year present worth basis. If it is of equal or lower cost (present worth basis) to convey wastewater to a larger, conventional facility than it is to treat it in an approved on-site wastewater treatment facility, then conveyance and treatment should be considered as the chosen alternative. If it is less costly to use an approved on-site treatment process, and site soils are suitable and other environmental and local concerns are also addressed, the on-site treatment should be the alternative selected. The selection process is related to long-term reliability of the treatment and disposal process. (4)(d) means that there should be at least enough separate area for 100-percent replacement of the drain field if subsurface disposal is the chosen treatment and disposal process (see DOH’s ”Design Standards for Large On-Site Sewage Systems”). See Chapter E3 for determining the ground water quality criteria for land application process. NOTE: WAC 173-240-035 restricts the use of subsurface wastewater disposal systems if other methods are available. Satisfying the above requirements will satisfy the reasonability test (WAC 173-240-035). G1-4.2 Plans and Specifications This section describes contents and approval requirements for plans and specifications. G1-4.2.1 Objective The objective of this section is to describe documentation by means of plans, specifications, and other materials incident to design that adequately represent the design engineer’s intent and are used as instruments to facilitate the construction of the project. Plans and specifications are defined in WAC 173- 240-020(2). The requirements for plans and specifications are found in WAC 173-240-070. G1-4.2.2 Contents of Plans A. General The design should be consistent with federal, state, and local requirements. The design plan, together with the specifications and other appropriate
December 1998 Criteria for Sewage Works Design supplemental documents, shall constitute the contract documents. They facilities without excessive clarification from the design engineer. plan shall be sufficiently clear that a third party can interpret and construct sets,in general, shall be comprised of a title sheet and plan sheets, plan and profile sheets, and others as may be appropriate to sufficiently detail and outline the facilities being designed. Plan sheets shall be consecutively numbered and consist of plan views, elevations, sections, profiles, general layouts, and supplemental views used to adequately represent the intended design. Plans should be clear, legible, and drawn to a scale which permits all necessary information to be shown plainly Numerical units should be expressed consistently throughout the plan set Plan sets shall be of a common engineering drawing size(30 inches by 42 inches maximum)and contain relevant information including, but not limited to. the following (1)Project title; owner's name; date; seal and signature of design engineer with date of license expiration. (2) Index to sheets and vicinity map with project site location. ()Master site plan and/or general layout map (4)List of abbreviations, definitions, and symbols used within th ans (5) Each sheet shall contain a general designation indicating the project title, an appropriate sheet title, date, north arrow, and a scale as well as a graphical bar (6)Plans for sewers, sewage pump stations, sewage treatment plant and their discharge facilities shall all include the following The plan view should be drawn at a horizontal scale no greater than 1 inch equaling 100 feet. Profile view should be drawn at vertical scale no greater than I inch equaling 10 feet, with the horizontal scale corresponding with the plan view Show existing and proposed topography with contours and/or spot elevations as well as indicate all significant natural or manmade features such as streams, lakes, streets, buildings, etc Indicate the basis of all horizontal and vertical datum Indicate normal stream flow and 100-year flood elevations high Show ownership lines indicating properties, district, or municipal boundaries, and the service area boundary proposed to be served by the proje Show location of all known structures or possible obstructions both above and below ground, which potentially may interfere with proposed construction, particularly utility lines such as gas, water, power, telephone, storm sew (7)Any additional information which may be helpful in understand the designer s intent or that provides further project clarity
G1-26 December 1998 Criteria for Sewage Works Design supplemental documents, shall constitute the contract documents. They shall be sufficiently clear that a third party can interpret and construct the facilities without excessive clarification from the design engineer. Plan sets, in general, shall be comprised of a title sheet and plan sheets, plan and profile sheets, and others as may be appropriate to sufficiently detail and outline the facilities being designed. Plan sheets shall be consecutively numbered and consist of plan views, elevations, sections, profiles, general layouts, and supplemental views used to adequately represent the intended design. Plans should be clear, legible, and drawn to a scale which permits all necessary information to be shown plainly. Numerical units should be expressed consistently throughout the plan set. Plan sets shall be of a common engineering drawing size (30 inches by 42 inches maximum) and contain relevant information including, but not limited to, the following: (1) Project title; owner’s name; date; seal and signature of design engineer with date of license expiration. (2) Index to sheets and vicinity map with project site location. (3) Master site plan and/or general layout map. (4) List of abbreviations, definitions, and symbols used within the plans. (5) Each sheet shall contain a general designation indicating the project title, an appropriate sheet title, date, north arrow, and a scale as well as a graphical bar. (6) Plans for sewers, sewage pump stations, sewage treatment plants, and their discharge facilities shall all include the following information: • The plan view should be drawn at a horizontal scale no greater than 1 inch equaling 100 feet. Profile view should be drawn at vertical scale no greater than 1 inch equaling 10 feet, with the horizontal scale corresponding with the plan view. • Show existing and proposed topography with contours and/or spot elevations as well as indicate all significant natural or manmade features such as streams, lakes, streets, buildings, etc. Indicate the basis of all horizontal and vertical datum control. • Indicate normal stream flow and 100-year flood elevations and/or high and low tidal elevations, as may be applicable. • Show ownership lines indicating properties, district, or municipal boundaries, and the service area boundary proposed to be served by the project. • Show location of all known structures or possible obstructions, both above and below ground, which potentially may interfere with proposed construction, particularly utility lines such as gas, water, power, telephone, storm sewer, etc. (7) Any additional information which may be helpful in understanding the designer’s intent or that provides further project clarity
GeneralEngineering Requirements December 1998 G127 Plans for sewers, sewage pump stations, sewage treatment plants, and discharge facilities shall also include information outlined in B. C.D. and E bel B. Plans for sewers See Chapter CI for design information and requirements. In addition to the requirements outlined in G1-42 2A, sewer plans shall include the (1)Forms of land use(commercial, residential, agricultural, etc. ) existing or proposed within 50 feet of either side of the center line of the pipeline's center line (2) Location of any domestic wells within the vicinity (3)Location, size, type, and flow direction of all existing and proposed sewer lines in the project area. (4)Manholes should be numbered and labeled in both the plan and profile Indicate a station, size, and type, as well as the invert and surface elevation of each (5)Locations and details for all special details such as inverted siphons, stream crossings, concrete encasements, elevated sewers special joints or connections, and so on (6) Details of all sewer appurtenances such as manholes, cleanouts, etc (7)Elevation and location of building basement floors. If basements are to be served, they should be plotted in profile in those areas where the sewer depth may be questionable, and/or the elevation of the lowest serviceable floor elevation should be indicated C. Plans for Sewage Pump Stations See Chapter C2 for design information and requirements. In addition to requirements outlined in G1-422A, sewage pump station plans shall include the following information (1)Details and elevation views of the completed pump station from suction pump(wetwell) to discharge piping, including all isolation check, and gate valves. Plans should be submitted for projects involving construction of a new station or substantial modification of an existing station (2) Location and details of an existing and proposed pump station, ()Elevation of high water at the site, maximum elevation of sewage in the collection system, and location where sewage would failure (4)Maximum hydraulic gradient in a downstream gravity sewer when all installed pumps are in operation (5)Test borings and ground water elevations D. Plans for Sewage treatment plants See Chapters T1, T2, T3, T4, and T5 for design information and requirements for sewage treatment plants. In addition to the requirements
General Engineering Requirements December 1998 G1-27 Plans for sewers, sewage pump stations, sewage treatment plants, and discharge facilities shall also include information outlined in B, C, D, and E, below. B. Plans for Sewers See Chapter C1 for design information and requirements. In addition to the requirements outlined in G1-4.2.2A, sewer plans shall include the following information: (1) Forms of land use (commercial, residential, agricultural, etc.), existing or proposed within 50 feet of either side of the center line of the pipeline’s center line. (2) Location of any domestic wells within the vicinity. (3) Location, size, type, and flow direction of all existing and proposed sewer lines in the project area. (4) Manholes should be numbered and labeled in both the plan and profile. Indicate a station, size, and type, as well as the invert and surface elevation of each. (5) Locations and details for all special details such as inverted siphons, stream crossings, concrete encasements, elevated sewers, special joints or connections, and so on. (6) Details of all sewer appurtenances such as manholes, cleanouts, etc. (7) Elevation and location of building basement floors. If basements are to be served, they should be plotted in profile in those areas where the sewer depth may be questionable, and/or the elevation of the lowest serviceable floor elevation should be indicated. C. Plans for Sewage Pump Stations See Chapter C2 for design information and requirements. In addition to requirements outlined in G1-4.2.2A, sewage pump station plans shall include the following information: (1) Details and elevation views of the completed pump station from suction pump (wetwell) to discharge piping, including all isolation, check, and gate valves. Plans should be submitted for projects involving construction of a new station or substantial modification of an existing station. (2) Location and details of an existing and proposed pump station, including provisions for installation of future pumps or ejectors. (3) Elevation of high water at the site, maximum elevation of sewage in the collection system, and location where sewage would overflow in the event of a power failure. (4) Maximum hydraulic gradient in a downstream gravity sewer when all installed pumps are in operation. (5) Test borings and ground water elevations. D. Plans for Sewage Treatment Plants See Chapters T1, T2, T3, T4, and T5 for design information and requirements for sewage treatment plants. In addition to the requirements
December 1998 Criteria for Sewage Works Design outlined in G1-422A, plans for sewage treatment plants shall include the (1) Show the treatment plant in relation to the remainder of the system. Sufficient topographic features should be included to indicate the plants location in relation to streams, point of discharge of treated effluent, and existing buildings and their types within 700 feet of the plant site property (2)Size and location of plant structures (3)Schematic process flow diagrams showing the flow through various plant units, and showing utility systems serving the plant processes. An example of a process flow diagram is shown in Figure G1-2, which shows many of the possible treatment components. See Chapter T3 for details on the content of a process flow diagram (4)All design data and hydraulic profiles. A mass balance should be submitted for all sewage treatment plants of I mgd or larger, plants receiving a significant industrial loading, and plants with unusually complex processes. The mass balances should include loadings to each unit process and operation, including all recycle flows. Mass balances should include the following initial and design operating conditions: maximum. minimum and average flow: BOd and upended solids loadings; and maximum, minimum, and average materials handled and direction of flow through pipes shall be (5)Piping, including any arrangements for bypassing individual ur (6) Minimum, average, and maximum hydraulic profiles showing flow of sewage, supernatant liquor, and sludge (7)Test borings and ground water elevations (8)Location, dimensions, and elevations of all existing and proposed (9)Pertinent data concerning the rated capacity of all pumps, blowers, motors, and other mechanical devices. All or part of such data can be included in the specifications if the equipment is identified on the plan (10)Minimum, average, and maximum hydraulic flow in profile (11) Adequate description of any features not otherwise covered by the pecifications or engineering report
G1-28 December 1998 Criteria for Sewage Works Design outlined in G1-4.2.2A, plans for sewage treatment plants shall include the following information: (1) Show the treatment plant in relation to the remainder of the system. Sufficient topographic features should be included to indicate the plant’s location in relation to streams, point of discharge of treated effluent, and existing buildings and their types within 700 feet of the plant site property. (2) Size and location of plant structures. (3) Schematic process flow diagrams showing the flow through various plant units, and showing utility systems serving the plant processes. An example of a process flow diagram is shown in Figure G1-2, which shows many of the possible treatment components. See Chapter T3 for details on the content of a process flow diagram. (4) All design data and hydraulic profiles. A mass balance should be submitted for all sewage treatment plants of 1 mgd or larger, plants receiving a significant industrial loading, and plants with unusually complex processes. The mass balances should include loadings to each unit process and operation, including all recycle flows. Mass balances should include the following initial and design operating conditions: maximum, minimum, and average flow; BOD and suspended solids loadings; and maximum, minimum, and average nutrient loadings. (5) Piping, including any arrangements for bypassing individual units (materials handled and direction of flow through pipes shall be shown). (6) Minimum, average, and maximum hydraulic profiles showing flow of sewage, supernatant liquor, and sludge. (7) Test borings and ground water elevations. (8) Location, dimensions, and elevations of all existing and proposed plant facilities. (9) Pertinent data concerning the rated capacity of all pumps, blowers, motors, and other mechanical devices. All or part of such data can be included in the specifications if the equipment is identified on the plans. (10) Minimum, average, and maximum hydraulic flow in profile. (11) Adequate description of any features not otherwise covered by the specifications or engineering report