STL Engineers
STL Engineers is a Dallas-based, M/WBE and Texas HUB-certified engineering firm providing geotechnical investigation, construction materials testing, and QC/QA inspection services to government, transportation, education, and oil and gas clients across Texas.
- Company typePrivate
- Founded-
- HeadquartersDallas, United States
- Headcount51–100
- GTM typeB2B
- OfferingServices
What STL Engineers does
STL Engineers, operating as Southwestern Testing Laboratories dba STL Engineers, is a Dallas-based full-service engineering firm providing geotechnical investigation, construction materials testing (CMT), and quality control/quality assurance (QC/QA) inspection services. Founded by Arcilia Acosta, the company operates as a certified 100% Hispanic/Woman-Owned Business Enterprise (M/WBE) and Texas Historically Underutilized Business (HUB), serving public and private sector clients across Texas. The firm reports 51–100 employees, maintains offices in Dallas and Midland, and has over 20 years of operating history, with multi-decade relationships at marquee accounts including DFW International Airport, DART, and TxDOT.
The company's technical infrastructure is anchored by a 10,000 sq. ft. laboratory facility that is AASHTO R-18 compliant, CCRL accredited, and USACE verified, including a 1,400 sq. ft. climate-controlled curing room meeting ASTM D-3740, C1066, and E-329 standards. Field and laboratory work is delivered by technicians holding ICC, ACI, NICET, and TxDOT certifications. Core service lines include foundation design engineering, pile load testing, pavement design, soil and aggregate testing, concrete and masonry inspection, structural steel observation, bituminous paving inspection, and forensic failure investigation. The firm also operates state-of-the-art on-site laboratory capabilities demonstrated on large-scale projects such as the TxDOT I-35 Managed Lanes Project.
STL Engineers generates revenue through project-based professional services contracts secured via direct enterprise sales, RFPs, and contractor selection processes, with quote-based, project-specific pricing. The customer base spans government agencies (DFW International Airport, DART, TxDOT, Trinity Metro TEXRail, Dallas Love Field), educational institutions (Texas A&M, Tarleton State, TCC, Brookhaven College, North Lake College), and commercial construction clients. Major engagements include the $1B TxDOT I-35 Managed Lanes Project, multi-decade work at DFW Airport spanning terminal expansions and renovations, DART light rail extensions, and the 27-mile Trinity Metro TEXRail commuter rail line. Operations are concentrated in Texas, including the Dallas-Fort Worth Metroplex and West Texas/Panhandle oil and gas markets.
STL Engineers firmographics
Firmographics- Name
- STL Engineers
- Legal name
- Southwestern Testing Laboratories dba STL Engineers
- Website
- https://stlengineers.com
- Company type
- Private
- Operating status
- Operating
- Headcount range
- 51–100 employees
- Short description
- STL Engineers is a Dallas-based, M/WBE and Texas HUB-certified engineering firm providing geotechnical investigation, construction materials testing, and QC/QA inspection services to government, transportation, education, and oil and gas clients across Texas.
- Ownership category
- akta.pro rank
STL Engineers industry classification
Industry- Product category
- Geotechnical Engineering & Construction Materials Testing
- NAICS
- Testing Laboratories and Services (541380), Engineering Services (541330), Building Inspection Services (541350)
- SIC
- Services-Testing Laboratories (8734), Services-Engineering Services (8711)
- akta.pro primary industry
- Civil & Structural Engineering Consulting (BPAHAIAA)
- akta.pro secondary industries
- Commissioning, Testing & Closeout Services (Cx, TAB, Punchlist) (EDAEABAO), Structural & Civil Inspection (Steel, Concrete, Foundations) (EUAEAHAI)
Keywords
Where STL Engineers is headquartered
LocationHeadquarters
- HQ city
- Dallas
- HQ country
- United States
- HQ region
- North America
Offices2 records
Markets served
STL Engineers business model
Business model- GTM type
- B2B
- Offering type
- Services
- Cost components
- Personnel, Operations, Infrastructure, Technology or R&D, Marketing or Sales, Others
Revenue model
- Professional Services - Geotechnical Engineering: Geotechnical investigation services including foundation design engineering, pile load tests, dewatering systems, embankments, slope and erosion protection, dam inspections, retention structures, pavement design, and failure investigation and forensic studies.
- Construction Materials Testing (CMT): Testing and inspection services for soil, aggregate, concrete, reinforcing steel, masonry, structural steel, bituminous paving, roofing, and asphalt materials.
- Inspection Services: Full service Quality Control & Quality Assurance inspections including Transportation, Airfield, Roadway, Bridge, Vertical Building, and Civil and Facilities Construction inspections.
Go-to-market motion1 record
Distribution channels1 record
Marketing channels5 records
STL Engineers product offering
Product offeringCore offering
STL Engineers is a full-service geotechnical investigation, construction materials testing (CMT), and quality management & inspections firm. The company delivers foundation design engineering, soil, concrete, asphalt, masonry, and steel testing, and full-service Quality Control/Quality Assurance inspections for transportation, airfield, roadway, bridge, vertical building, and civil/facilities construction projects, supported by a 10,000 sq. ft. AASHTO-accredited, CCRL-accredited, and USACE-verified laboratory facility.
Product overview
STL Engineers is a full-service geotechnical investigation, construction materials testing, and quality management and inspections firm. The company operates as a single-service business model offering three integrated core service lines: Geotechnical Engineering Services (foundation design, pavement design, dam inspections, failure investigation), Construction Materials Testing Services (concrete, soil, asphalt, steel, masonry testing), and Quality Control & Quality Assurance Inspection Services (transportation, airfield, roadway, bridge, building inspections). These services work together to deliver comprehensive construction project support from initial site investigation through final quality verification.
Differentiator
Problem solved
Functional benefit
Products and services
- Geotechnical Engineering Services Engineering services using modern methodologies and accurate field exploration to develop improved foundation design, reduce construction delays, and increase awareness of construction risks. Includes foundation design engineering, pile load tests for expansive soils, dewatering systems, embankments, slope and erosion protection, dam inspections, retention structures, pavement design, and failure investigation and forensic studies. Targeted at transportation, infrastructure, government, and oil and gas clients across Texas.
- Construction Materials Testing (CMT) Services Specialized testing and inspection services covering observation and testing of soil type, compaction and stabilization, aggregate evaluation, concrete mix designs, drilled pier/pile foundation observation, concrete observation and testing, reinforcing steel/post tension observation, masonry testing, structural steel fabrication and erecting observation, welder qualifications and procedures, bituminous paving observation and testing, roofing inspection and testing, and asphalt testing. Delivered by ICC, ACI, NICET, and TxDOT-certified technicians.
- Quality Control & Quality Assurance Inspection Services Full-service Quality Control & Quality Assurance inspections covering Transportation, Airfield, Roadway, Bridge, Vertical Building, and Civil and Facilities Construction. Staff has extensive knowledge of ASTM, AASHTO, and ACI standards. Service roles include serving as Quality Acceptance Firm on multi-hundred-million-dollar infrastructure projects such as the $1B TxDOT I-35 Managed Lanes Project.
Quantifiable outcome
- Over 20 years of experience delivering professional geotechnical and materials testing services throughout Texas
- +2 more outcomes
Companies that use STL Engineers
Customer profileNamed customers9 records
Segments5 records
Ideal customer profiles4 records
STL Engineers technology and API
TechnologyTechnology focussed No
API detail
- Has API
- No
- API docs
- API detail
Core technology
AI maturity
App detail
Feature4 records
STL Engineers partnerships and signals
Strategic signalScale indicators4 records
Recent moves2 records
Expansion highlights3 records
STL Engineers competitors and assessment
Company assessmentBroad incumbents
- Terracon Consultants: Largest U.S. employee-owned geotechnical, environmental, and materials testing firm with a strong Texas presence. Direct overlap on CMT, geotechnical engineering, and inspection services for the same public-sector RFPs STL pursues (TxDOT, transit agencies, airports).
- Kleinfelder: National engineering, science, and construction services firm with deep transportation, water, and energy infrastructure testing practices. Competes with STL on large Texas DOT and transit projects and provides the same AASHTO/CCRL-accredited materials testing services.
- Atlas Technical Consultants: Publicly traded (ATCX) nationwide provider of materials testing, inspection, and engineering services competing for the same TxDOT, airport, and transit assignments as STL. Provides a public-markets multiple reference point for the CMT/inspection category.
- Professional Service Industries (PSI): National consulting engineering and testing firm (Intertek subsidiary) with full-service geotechnical, CMT, and special inspection practices. Competes with STL on large transportation and aviation projects across Texas.
Direct peers
- Raba Kistner Consultants: Texas-based (San Antonio / Houston) geotechnical engineering and construction materials testing firm comparable in scale and service mix to STL. Direct competitor on TxDOT, municipal, and private development projects across Texas.
- HVJ Associates: Texas-based geotechnical engineering and materials testing firm headquartered in Austin with offices statewide. Same core service mix as STL (geotechnical, CMT, special inspections) competing for public-sector infrastructure work.
- Paradigm Consultants: Houston-based geotechnical engineering and construction materials testing firm comparable in scale, service offering, and target market to STL. Direct competitor on Texas infrastructure, public, and private development projects.
- Wier & Associates: Texas-based engineering and inspection firm offering geotechnical, materials testing, and special inspection services for transportation, aviation, and government clients — the same core verticals STL serves.
Regional players
- Geotech Engineering and Testing: Texas-based geotechnical engineering and construction materials testing firm headquartered in the Houston area. Offers the same AASHTO-accredited lab and inspection services as STL, targeting TxDOT and Gulf Coast development.
- Alliance Geotechnical Group: Texas-based regional geotechnical and materials testing firm with comparable service mix and end-market focus. Direct competitor for mid-sized public and private construction projects in the state.
Market position
Strengths5 records
Weaknesses5 records
Competitive moat5 records
Key risks5 records
Key highlights7 records
Customer concentration
STL Engineers social profiles
Digital presenceSTL Engineers compliance and trust
Trust signalCompliance7 records
STL Engineers financial estimates
Financial estimateRevenue estimate
Valuation estimate
STL Engineers leadership team
Management profileNumber of profiles
Profiles1 record
STL Engineers funding detail
Funding detailFunding overview
Funding rounds
Investors
Funding detail is available on the Subscription and Enterprise plan.Contact sales →
STL Engineers M&A and investment
M&A and investmentM&A
Investments
M&A and investment is available on the Subscription and Enterprise plan.Contact sales →
Frequently asked questions about STL Engineers
What does STL Engineers do?
STL Engineers is a full-service geotechnical investigation, construction materials testing (CMT), and quality management & inspections firm. The company delivers foundation design engineering, soil, concrete, asphalt, masonry, and steel testing, and full-service Quality Control/Quality Assurance inspections for transportation, airfield, roadway, bridge, vertical building, and civil/facilities construction projects, supported by a 10,000 sq. ft. AASHTO-accredited, CCRL-accredited, and USACE-verified laboratory facility.
Is STL Engineers a public or private company?
STL Engineers is a private company. It is classified as founder individual operated bootstrapped and is currently operating.
When was STL Engineers founded?
STL Engineers was founded in -1. It employs 51 to 100 people.
Where is STL Engineers based?
STL Engineers is headquartered in Dallas, United States, in the North America region.
How does STL Engineers make money?
Three revenue lines are on record. Professional Services - Geotechnical Engineering is the primary driver. The others are construction Materials Testing (CMT) and inspection Services.
Who are STL Engineers's main competitors?
Broad incumbents on record are Terracon Consultants, Kleinfelder, Atlas Technical Consultants and Professional Service Industries (PSI). Direct peers are Raba Kistner Consultants, HVJ Associates, Paradigm Consultants and Wier & Associates. Regional players are Geotech Engineering and Testing and Alliance Geotechnical Group.
Does STL Engineers have an API?
No public API is recorded for STL Engineers.
What industry is STL Engineers in?
STL Engineers's product category is Geotechnical Engineering & Construction Materials Testing. Its primary akta.pro industry code is BPAHAIAA, Civil & Structural Engineering Consulting, with a secondary code of EDAEABAO, Commissioning, Testing & Closeout Services (Cx, TAB, Punchlist). Its NAICS code is 541380 and its SIC code is 8734.