OSS Designer Professional List
The State of Washington requires that designers of septic systems be licensed by the State. This list represents licensed Wastewater System Designers and Professional Engineers (PE) who are qualified to perform design work in Washington, and have requested their names be added to our list. This list is not a recommendation, endorsement, or guaranty of workmanship by Cowlitz County. Questions, concerns, or comments concerning designers or engineers designing wastewater systems may be directed to the Washington State Department of Licensing (DOL) at 360-664-1568, or by accessing the DOL website at: https://www.dol.wa.gov/
Do Your Homework
As with any professional you hire, do your homework. The County is not able to give suggestions or references.
| Business Name | Name | Mail Address | City, State, Zip | Phone |
| ABC SEPTIC DESIGNS & MAINTENANCE | HAVILAND, DONALD L. | 664 DEEP CREEK RD. | CHEHALIS, WA 98532 | 360-520-1390 |
| ADVANCED ENGINEERING | ELSTROTT, CHRISTOPHER | 128 N RIVER ST | MONTESANO, WA 98563 | 360-249-8447 |
| ADVANCED SEPTIC CONSULTING | BUCK, TRAVIS | 220 HANSON RD | KALAMA, WA 98625 | 360-433-5476 |
| ASD2 INC - COLLIER SEPTIC CONSULTING & DESIGN | COLLIER, MARK | PO BOX 1476 | BRUSH PRAIRIE, WA 98606 | 360-798-6456 |
| BRIAN L. HEWITT ENGINEERING | HEWITT, BRIAN L. | 1928 BETHANY ST. | LONGVIEW, WA 98632 | 360-751-3751 |
| BRIAN L. HEWITT ENGINEERING | HEWITT, MARC | 1928 BETHANY ST. | LONGVIEW, WA 98632 | 360-751-3751 |
| EK ENGINEERING | EK, CHANE | PO BOX 3097 | BATTLE GROUND, WA 98604 | 360-687-7668 |
| EK ENGINEERING | EK, NATHAN | PO BOX 3097 | BATTLE GROUND, WA 98604 | 360-687-7668 |
| ENVIRONMENTAL DESIGN LLC | RIEGER, BECKY | 901 L ST | CENTRALIA, WA 98531 | 360-219-3343 |
| ENVIRONMENTAL MANAGEMENT SYSTEMS | SWEENEY, ROBERT | 4080 SE INTERNATIONAL WY #B112 | MILWAUKIE, OR 97222 | 360-735-1109 |
| EVERGREEN SEPTIC DESIGN INC. | WILLIAMS, MIKE | 7503 NE 219TH ST | BATTLE GROUND, WA 98604 | 360-687-9919 |
| H&H ENGINEERING, PLLC | BROWN, MATT | PO BOX 1220 | RAINIER, WA 98576 | 253-320-5397 |
| MCNAIR SEPTIC DESIGN | MCNAIR, CORY S | 18915 NE 164TH ST | BRUSH PRAIRIE, WA 98606 | 360-907-1576 |
| SWANCO CONSULTANTS | SWANSON, MATT | 1603 LARCH ST. #2603 | LONGVIEW, WA 98632 | 360-430-4965 |
| WHORTON ENGINEERING | WHORTON, DEAN | 426 SEARS RD | WINLOCK, WA 98596 | 360-785-4329 |