Wednesday, February 24, 2010

Cleaning an environmental media here – Contaminating an environmental media there

The cleaning of an environmental media resulting in the pollution of others is the outcome from lack of communication, cooperation, and exercised bureaucracy between environmental protection agencies. For instance, Methyl-tertiary-butyl ether (MTBE), a gasoline additive created to reduce air pollution, resulted in severe water pollution in the Santa Monica, Lake Tahoe, and San Diego Basin.

MTBE became an environmental disaster by the time it was banned in 2004. MTBE leached from fuel storage tanks into the groundwater where it dissolves easily, resulting in faster and further migration, thus contaminating public water systems and private drinking wells. MTBE does not degrade easily and is difficult and costly to remove, it is one of the most persistent pollutants in the environment.

Nowadays, under Mission Valley in San Diego lies the largest pocket of MTBE pollution in the region, location of one of the most precious groundwater sources of the city which has a pumping potential capacity of two (2) million gallons of water a day that could provide water supply for eight thousand family units a day however the major problem is the costly removal of this pollutant.

The California Environmental Protection Agency (Cal-EPA) was created to reorganize and unify all environmental agencies and perform under one integrated protection program and strategy, unfortunately, Cal-EPA continues to operate as a collection of boards and commissions without a coherent environmental protection policy. Each board and commission is responsible for a specific type of pollution. Decision-makers do not focus on how their choices affect other areas of the environment.

EPA shall be more aggressive in the implementation of a successful strategic plan, bringing all agencies together and establishing a clear vision of the problem so as to minimize the transfer of pollutants across all media – air, land, and water. Full commitment from the boards and commissions is necessary to paint a picture of where the pollution prevention shall end up and the expected outcomes. The goal in mind is to provide efficient economical solutions for the integration of a unified EPA to prevent further environment disasters.

Tuesday, February 23, 2010

Take a tour of a wastewater treatment plant and follow the path of water as it gets treated

The Sanitation Districts of Los Angeles County operate ten water reclamation plants and one ocean design facility (Joint Water Pollution Control Plant). It offers tours to schools, clubs, organizations, and the general public of any of their facilities.

Today, February 23, 2010 I toured the San Jose Creek Water Reclamation Plant located next to the City of Whittier. It is the Sanitation Districts’ largest reclamation plant (100 mgd) serving a population of approximately one million people. Fifty (50) percent of the reclaimed water produced at this plant is reused, mostly for groundwater recharge.

Water recycling significantly reduces the Los Angeles Basin’s dependence on costly imported water and helps to replenish a large percentage of the ground water used by the region. The remainder water treated is put into the San Gabriel River and flows to the ocean.

In densely population areas the sewage is collected by a network of underground pipes that convey raw sewer to a wastewater treatment facility. Once in the treatment plant, wastewater goes through a series of actions which will help to clean the water. A wastewater treatment plant’s basic function is to quicken the natural processes by which water purifies itself.

At present the San Jose Creek Water Reclamation Plant uses a basic three (3) stages in the treatment of wastes: primary, secondary, and tertiary treatment.

Primary Treatment Process

It starts with the screening of the wastewater entering the treatment facilities. Water flows through a screen to remove large objects such as wood, rocks, rags, and even dead animals that may cause problems later in the treatment process clogging pumps and small pipes. After the sewage has been screened it passes into what is called a grit chamber where sand, grit, cinders and small stones are allowed to settle to the bottom to later be disposed. With screening completed and grit removed, the sewage still contains suspended solids which are gradually allowed to settle to the bottom of a long concrete rectangular sedimentation tank. The settled material is called primary sludge and it is mechanically remove from the sedimentation tanks.

Secondary Treatment Process

After the sewage leaves the settling tank in the primary stage, it is pumped to an aeration tank where it is mixed with air and sludge loaded with microorganisms that use oxygen to breathe and break down the organic matter. Sewage at the aeration tank remains for several hours allowing the process to removes up to 90% of the organic matter.

Meanwhile, the sewage flows from the aeration tank to another sedimentation tank to remove the microorganisms were they clump together, settle to the bottom, and are removed and recycled back into the treatment process.

Tertiary Treatment Process

The final step uses filtering and chemical treatment. This allows the water to be in better condition before it is put back into the water cycle system. The San Jose Creek Water Reclamation Plant has installed filters containing layers of anthracite coal, sand, and gravel which remove any remaining suspended materials from the water. The reclaimed water is then disinfected with chlorine.

After completion of all treatment processes, reclaimed water, is now free of harmful bacteria and viruses and is safe for human contact. Recycled water is then discharged to the San Jose creek destined to recharge groundwater supplies.

Any remaining chlorine in the purified water is removed prior discharge to protect aquatic life in the receiving environment. Water quality measurement and analysis are completed at laboratories located at the treatment plant to ensure reclaimed water meets all requirements of the Regional Quality Control Board.

The cleaning process from preliminary treatment to final disinfection prior reuse or discharge takes approximately ten (10) hours.

Information about the Sanitation Districts of Los Angeles County’s tours and facilities can be found at their website:
http://www.lacsd.org/about/wastewater_facilities/default.asp

The California Water Environment Association awards “best treatment plant of the year” to those facilities employing a state-of-the- art cleansing process, green technologies such as solar panels, and effluents meet stringent state quality standards. Check their website to know which wastewater treament plants have been awarded best in California. http://www.cwea.org/

Saturday, February 20, 2010

Sanitary pipe system design guidelines

The information and guidelines contained herein are to be used whenever applicable. All sanitary sewers shall be designed in accordance to City Standards and to accepted engineering principles. Always consult design guidelines with the City Engineer to ensure local regulations applied to the specific project and location.

Design submittals shall show all lines necessary for the development or improvement, including pipe size, material, appurtenant, manholes & laterals locations, all sewer profiles (slopes, invert elevations, and finished surfaced elevations), cleanouts, backflow devices, lots to be serviced, property lines, easements, etc.

Pipe Materials:

*Vitrified Clay Pipe (VCP): shall conform to the materials section of the current Clay Pipe Engineering Manual published by the National Clay Pipe Institute www.ncpi.org and shall conform to ASTM requirements, Designation C700, Class II. VCP shall have a dense wall and shall not leak through the barrel more than the allowable when tested in accordance with “Hydrostatic Pressure Test” as described in “Clay Pipe Engineering Manual”.

*Polyvinil Chloride (PVC) Pipe: shall conform to ASTM D3034 (SDR 35) for pipe diameter four (4) inches through fifteen (15) inches and ASTM F679 for pipe diameters from eighteen (18) inches through twenty-four (24) inches. PVC sewer pipe shall only be allowed for residential sewage flows. PVC standard laying length shall be 20 feet minimum, bell and spigot joints with elastomeric gaskets (watertight). www.plasticpipe.org ; www.uni-bell.org

*Reinforced Concrete Pipe (RCP): shall be Class II and conform to ASTM C76 for sewer pipe and lined with PVC T-lock sheets applied at the top 300 degrees of the pipe. RCP standard laying segments are 6 to 8 feet, bell and spigot with rubber gasket joints. www.concrete-pipe.org

*Ductile Iron Pipe (DIP): for sewers shall conform to ANSI A21.50 (AWWA C150) and shall be pressure class 150 minimum unless otherwise shown on plans. Asphaltic or polyethylene outside coating/film and interior ceramic epoxy or cement liner (40 mils) is required. DIP shall only be allowed from manhole to manhole when outside of roadways or sewer laterals, unless otherwise specified.
DIP and Cast Iron restraints calculations and other engineering information can be found on the DIP Research Association (DIPRA) www.dipra.org

Horizontal Alignment: shall be preferably located at the center of street and never under the storm water system. Otherwise, sewer lines shall be located within the paved area of the road with not less than one (1) foot between the outside surface of the pipe and the nearest lip of the gutter or edge of improved road shoulder.
*In general, design public sewer mains in straight street sections to run parallel to the street centerline.
*In curved streets design them on one side of the center line to allow installation of other facilities such as water, storm drains, etc.
*Criteria for the separation water and sanitary sewer most conform to the State of California Department of Health Services (DOHS). The minimum separation required is ten (10) feet clearance between walls otherwise DOHS guidelines must be followed.
*Separation from other wet utilities (Storm drain, sewer, recycle water) will be a minimum of five feet (5) clear between pipes except at crossings.
*Separation from other dry utilities (Gas, electrical cable, etc) will be a minimum of four feet (4) clear between the pipes except at crossings.
*Separation from structures, building over-hangs, gutters, property lines, or edges of easement must be a minimum of five (5) feet clearance and three (3) feet from all monuments, and/or lips of gutters. The alignment will be designed so that any 48 inch manhole shall be centered a minimum of three (3) feet from the lip of gutter and any sixty (60) inch manhole shall be centered a minimum of four (4) feet from lip of gutter.
*Horizontal curves in gravity sewer mains are not allowed.

Vertical Alignment: shall conform to the State of California Department of Health Services (DOHS) “Criteria for separation of Water and Sanitary Sewer”.
*Generally provide a minimum of a foot (1) vertical separation from wet utilities and six (6) inches from dry utilities. When the minimum cannot be maintained other measures, such as concrete encasement or ductile iron pipe, may be submitted for approval of the Director of Utilities.
*Vertical curves in gravity sewer mains are not allowed.


Main Sizing Criteria: will be sized to serve the entire tributary area at build-out densities. Large developments may be required to provide trunk or collection system calculation or have a wastewater model run performed.
*Design Flow: is the average domestic flow, around 125 gallons per person per day, multiplied by the Peak Load Factor (may vary from 1.8 to 3.5). In addition, public sewers shall be designed to carry infiltrated water at the rate of 7% of the design flow. *Collection System Capacity Requires (Q) = Peak Factor (PF) x Average Daily Flow (QADF) + Rainfall Inflow and Infiltration (I/I) + Groundwater Infiltration (GWI)
* The minimum pipe size for main sanitary sewers is eight (8) inches inside diameter.

Hydraulic Calculations: Pipe size, flow rates, velocities, and depth for sanitary gravity flows are determined by solving the various parameters of Manning’s Equation.
Q= vA =(1.49/n)*A*{R^(2/3)}*{S^(1/2)}
Q = flow (ft3/sec)
n = Manning roughness coefficient (RCP-DIP-ABS-VCP n = 0.013; PVC n = 0.010)
R= Hydraulic radius (ft) = A/P
A= Area (ft2)
P= Wetted perimeter (ft)
S= Slope = {(∆E difference in Elev.) / (Horizontal distance)}
.v = velocity (ft/s)
D = Pipe diameter (ft)
.d= depth of flow (ft)
*Design all gravity sewers to achieve a minimum velocity of 2 fps when the pipe is flowing full (Qfull) and do not exceed a maximum velocity of 10 fps.
*Maximum depth of flow (at peak flow conditions) shall be 2/3 D; d/D=0.67 for pipe size ten (10) inch or smaller and 3/4 D; d/D= 0.75 for pipe size twelve (12) inch or larger.
*The preferred minimum slope (S) for gravity sewer is 0.005 (0.5%). Flatter slope conditions may be approved (City Standards)
*The maximum slope is 0.15 (15%), or 15 feet per 100 ft. Consideration to relevant factors such as steep terrain, steeper sewers may be allowed with the use of restrained joints.

Hydraulic Grade Line: The hydraulic grade line shall be determined from the design flows, based upon 100 percent development of the tributary area. Hydraulic grade line calculations must be submitted for the design of all lines 12 inches in diameter or larger.

Cover (Bedding): Minimum cover for all gravity sewers shall be 48 inch from top of the pipe to finish grade (City Standards). Per public works construction standard specifications (“Green book”), for cover less than four (4) feet or more than fifteen (15) feet special bedding is required.

Manholes:
*A manhole (MH) is required at every horizontal or vertical change in alignment (i.e. mains intersection).
*Spacing between manholes is 300 feet maximum (City Standards).
*A manhole is required at the end of every main in excess of 200 feet in length however a rodding inlet or cleanout may be installed in lieu if the main size is ten (10) inch or less.
*Mains eighteen (18) inch or larger in diameter and/or eight (8) feet in depth or more require sixty (60) inch diameter M.H.
*When a change of alignment is greater than 30 degrees allow a minimum drop of 0.1 foot (1.2 in) to compensate for energy loss caused by the change of alignment.
*When pipe sizes change at structures, design the inlet crown at least as high as the outlet crown.
*The change of direction at the manhole between the downstream and any incoming sewer shall be a minimum of 90 degrees.
*Drop manholes are not encouraged. They are typically required when the difference in elevation between the incoming and outgoing sewer is greater than two (2) feet. Upstream slope changes should be used to avoid the need for a drop manhole. If one (1) drop manhole can not be avoided at a connection, use a sixty (60) inch M.H., if two (2) or more are required, use a seventy two (72) inch diameter M.H.

Future sewer extension: when a sewer main extension ends at a manhole and the sewer will be extended further in the future, include in the design a three (3) feet long stub out of the MH with a plug or cap for future connection.

Sewer laterals: must be provide for each lot. The minimum sewer lateral size is four (4) inch and will be located on the property frontage.
*The minimum slop of sewer laterals is two (2 %) percent or ¼ inch per foot for four (4) inch diameter laterals and one (1%) percent or 1/8” per foot for six (6) inch laterals.
*Locate sewer laterals outside of driveway areas where possible. In general, sewer laterals will be in the center third of lots when driveway locations are unknown and a minimum of 10 feet from trees whenever possible. For hillside development, place sewer laterals on the low side of property frontages when not in proposed driveway.
*Laterals serving plumbing fixtures below the nearest upstream sewer manhole rim require an approved backflow overflow device.

Grease interceptors: shall be required for any business having the potential of producing grease. General commercial/retail buildings shall require dedicated grease line for future use.

Abandonment of sewer mains: Sewer mains that are to be abandoned will be securely closed at all pipe ends with a cap or at manholes with a concrete plug. Further, mains twelve (12) inch and larger must be filled with a sand slurry (City Standards).

Easements: When sewer cannot be located within the street, it shall be located in an approved easement. Sewer easement shall be a minimum 15 ft in width if it only contains a sewer main or 20 feet wide if it contains another facility. For deep pipe the easement shall be ((2 x depth) – OD) to a maximum 25 feet.
*No structures may encroach on, above, or below the surface of the ground in any public easement. This includes footings, eaves, decks, etc.
*No trees may be planted in a public sewer easement without first obtaining approval of the Director of Utilities.

Access roads: Clear access must be provided and maintained to all structures on the sewer system. Access roads must be a minimum of twelve (12) feet wide and its location must be approved by the streets and sanitation division.

Creek crossings: Advance approval of the Environmental Utilities Director, City Engineer, and other appropriate agencies is necessary to initiate design.
*Sanitary sewers crossing creeks shall be class 52 D.I.P. encased in reinforced concrete or 3/8 inch thick steel carrier pipe (Casing). The top of the encasement shall have a minimum four (4) feet of cover at the lowest point of the crossing.

Water well clearance: Sewer lines shall maintain a minimum 100 foot separation from all public or private wells (properly abandoned wells are not included). If a clearance of less than 100 feet is approved the pipe material shall be approved by the environmental Utilities Director. In no case shall a clearance of less than 50 feet be allowed.

Performance and testing: all sanitary sewers including laterals will be visually inspected prior backfill placement. Once backfill is completed all sanitary sewers will be air-tested for leakage using current ASTM standards prior to acceptance.

Pretreatment: Special pre-treatment may be required per City code for discharge of individual or commercial wastewater to the sewer at the Developer’s expense. Inquire with the City Water Pollution Control if an industrial wastewater discharge permit is required.

Permitting: Permits are required for all sewer work, including but not limited to the following – Excavation; Obstruction; Traffic control; other as necessary.

Save time and money by implementing Project Quality Management

The quality paradigm has assumed great importance in modern day business scenario. Management of quality in a project entails two different processes, quality assurance, and quality control.

Quality assurance is a dynamic, interactive process that monitors data collected and analyzes it such that meets project requirements. It refers to the overall management system which includes the organization, planning, documentation, evaluation of project activities and design. The purpose of quality assurance is to help producing data of known quality that states certain level of confidences and enhances the credibility a company in reporting monitoring results, ultimately saving time and money.

Quality assurance shall ensure:

*Data meets clients/project needs, goals and objectives.
*Effective presentation of results.
*Well-designed projects that are precise, accurate, represent the true conditions of the project and are complete.
*Projects are designed using standardized and acceptable techniques.
*Implementation of standards and requirements regulated by federal, state, and local laws.

Quality control refers to the routine technical activities whose purpose is, essentially, error control.

Wednesday, February 17, 2010

Where your drinking water comes from, L.A.?

Water Sources for Los Angeles, California

To reach many of us, water must travel long distances through complex delivery systems such as the:

**State Water Project: is a water storage and delivery system comprised of 34 storage facilities, reservoirs and lakes; 20 pumping plants; 4 pumping- generating plants; 5 hydroelectric power plants; and about 701 miles of open canals and pipelines. The project begins at Oroville Dam on the Feather River and ends at Lake Perris near Riverside. At the Tehachapi Mountains, giant pumps lift the water from the California Aqueduct some 2,000 feet over the mountains and into Southern California.
The project makes deliveries to two-thirds of California’s population (approximately 20 million Californians) and about 660,000 acres or irrigated farmland. It is maintained and operated by the California Department of Water Resources.

**Colorado River Aqueduct: The aqueduct impounds water from the Colorado River at Lake Havasu on the California-Arizona border to the east side of the Santa Ana Mountains. The system is a 242 miles water conveyance in Southern California composed of two reservoirs, five pumping stations, 63 miles of canals, 92 miles of tunnels, and 84 miles of buried conduit and siphons.
California is entitled to 4.4 million acre-feet of water annually from the river. Most of that water irrigates crops in the Palo Verde, imperial and Coachella valleys, located in the southeastern corner of the state, but the Colorado also is a vital source of water for urban southern California.
The aqueduct was constructed between 1933-1941 by the Metropolitan Water District of Southern California (MWD) to bring water to the 13 cities in the south coast basin that were founding member agencies of MWD however service area now extends from Ventura county to San Diego County.

**Los Angeles Aqueduct (Owens Valley Aqueduct): is a water conveyance operated by the Los Angeles Department of Water and Power (LADWP), the system delivers water from the Owens River in the Eastern Sierra Nevada Mountains into the City of Los Angeles, California. It consist of two sections, the first aqueduct completed in 1913 is 233 miles of 12-foot diameter steel pipe with a conveyance capacity of 520 (cu ft) per second which uses gravity two carry the water, so it is relatively autonomous and cost efficient.
The second Los Angeles Aqueduct, completed in 1970, added another 50 percent capacity to the water system (290 cu-ft per second). It starts at the Haiwee Reservoir, just south of Owens Lake and runs roughly in parallel to the first aqueduct, it carries water 137 miles and merges near the Antelope Valley Community Warm Springs.
The two aqueducts deliver an average of 430 million gallons a day to Los Angeles.

**Groundwater: About 30 percent of California’s total annual water supply comes from groundwater in normal years, and up to 60 percent in drought years. Local communities’ usage may be different; many areas rely exclusively on groundwater while others use only surface water supplies.
The Water Replenishment District (WRD) manages groundwater for nearly four million residents in 43 cities of Southern Los Angeles County. WRD is involved in groundwater monitoring, safe drinking water programs, combating seawater intrusion and groundwater replenishment operations throughout Southern Los Angeles County. http://www.wrd.org/
As part of a cooperative project with local water-management agencies to better understand the ground-water system and geology of the Los Angeles Basin, the U.S. Geological Survey (USGS) has drilled more than 30 monitoring wells throughout the basin, as deep as 1500 feet below city street, and has collected chemical, geologic, hydrologic, and geophysical data from these and other wells in the region. http://www.usgs.gov/