Zero Discharge for the Fourth Largest U.S. Army Base

Located on the banks of the Puget Sound, Joint Base Lewis McChord (JBLM), was faced with meeting the waste­water treat­ment needs of a growing pop­u­la­tion with a 60-year old waste­water treat­ment facility and more strin­gent dis­charge limits. The plan for the U.S. Army Corps of En­gi­neers (USACE) was to design-build a new 4.4 mgd waste­water treat­ment facility within two years on a green field site adjacent to the existing waste­water plant. The new facility would also support future zero liquid dis­charge goals through advanced treat­ment tech­nolo­gies.

The components to this advanced system include tertiary treatment with membrane filtration and ultraviolet (UV) disinfection for future groundwater recharge of 100% of the plant effluent. In addition, anaerobic digestion, producing a Class B biosolid, was employed with the future potential for energy production through combined heat and power.  The design also accommodated space on site and within buildings for a 50 percent facility expansion.

In addition to providing treatment technologies to remove nutrients, other challenges involved designing the plant to effectively operate over anticipated swings in seasonal flows and loads as well as significant variations in the base population; as well as managing industrial-like loads from the base operations. CDM Smith worked with the existing operations and maintenance (O&M) plant staff helping them transition to a new facility with higher operational complexity. 

Col­lab­o­rat­ing for Ef­fi­ciency
Because of the design-build approach, CDM Smith and the USACE were able to engage with stake­hold­ers early and col­lab­o­rate through­out the project to fast-track the schedule. Design-build also gave the team extra time to optimize the layout of the facility, while still main­tain­ing the po­ten­tial to expand in the future. The stream­lined site design involved co-locating the thick­en­ing and de­wa­ter­ing fa­cil­i­ties, po­si­tion­ing the main elec­tri­cal building near the largest elec­tri­cal loads, and sep­a­rat­ing the ad­min­is­tra­tion building from the main plant traffic. The end result was an ef­fi­cient and operator-friendly layout, which reduced the facility foot­print.

The new treat­ment facility includes:

• Influent pump station with self-cleaning wet well and au­to­mated de-ragging
• Influent screens, with screen­ings washer/com­pactor and aerated grit removal
• Rec­tan­gu­lar primary clar­i­fi­ca­tion – with controls to capture shock loadings
• Four-stage Bar­den­pho process with high-ef­fi­ciency turbo blowers and circular sec­ondary clar­i­fiers 
• Tertiary treat­ment uti­liz­ing pressure membrane fil­tra­tion and UV dis­in­fec­tion
• Gravity belt thick­en­ers for sludge thick­en­ing, anaer­o­bic di­ges­tion with use of biogas for process heating, followed by belt filter press de­wa­ter­ing and on-site storage of Class B biosolids 

The new ad­min­is­tra­tion building was also designed with a state-of-the-art lab­o­ra­tory and is on track to achieve LEED Silver cer­ti­fi­ca­tion.  Sus­tain­able features included the 45% water use re­duc­tion, op­ti­mized energy per­for­mance (minimum 40% re­duc­tion relative to baseline), use of locally sourced ma­te­ri­als, natural day-lighting, and water ef­fi­cient land­scap­ing and rain gardens for stormwa­ter man­age­ment. The plant was also designed to meet the security re­quire­ments of the USACE, and included a complete SCADA system for op­er­a­tions and control.

Reaching for Zero
The plant was suc­cess­fully started and com­mis­sioned with si­mul­ta­ne­ous de­com­mis­sion­ing of the old plant. The new plant has quickly achieved effluent quality in con­for­mance with Wash­ing­ton dis­charge limits and is capable of achiev­ing further nutrient removal and reuse water quality to fully support a “zero dis­charge” facility that will continue to serve JBLM’s needs well into the future as well as being a reliable en­vi­ron­men­tal steward in the north­west and the Puget Sound wa­ter­shed.