Here is a list of online books about Environmental Engineering in various formats available for free :

The 2010 Gulf Coast Oil Spill

by J.C. Jones, 2010, 38 pages, 2.5MB, PDF

Advanced Fluid Dynamics of the Environment

by Chiang Mei, 2002, PDF

Advances in Landscape Architecture

by Murat Ozyavuz (ed.), 2013, 924 pp, 70MB, PDF

Air Quality: New Perspective

edited by G.L. Badilla, B. Valdez, M. Schorr, 2012, 326 pp, 17MB, PDF

Atmospheric Pollution

by J.C. Jones, 2008, 109 pages, 4.1MB, PDF

Averting Catastrophe: Strategies for Regulating Risky Technologies

by J. Morone, E. Woodhouse, 1988

Biomass Properties and Fire Prediction Tools

by Miltiadis Boboulos, 2010, 61 pages, 3.5MB, PDF

Chemistry, Emission Control, Radioactive Pollution and Indoor Air Quality

edited by Nicolas Mazzeo, 2011, 680 pp, 26MB, PDF

Climate and Transportation Solutions

by Daniel Sperling, James S. Cannon, 2010

Concise Hydrology

by Dawei Han, 2010, 145 pages, 5MB, PDF

Data Analysis for Environmental Science and Management

by Bruce Kendall, Chris Costello, 2006, 136 pp, 800KB, PDF

Electrically Driven Membrane Processes

by Soren Prip Beier, 2006, 52 pages, 5.4MB, PDF

Energy Conversion

by Kenneth Weston, 1992, PDF

Energy Management

by Francisco Macia Perez, 2010, 254 pages, 16MB, PDF

Environmental Fluid Mechanics 1: Mixing and Transport Processes in the Environment

by Scott A. Socolofsky, Gerhard H. Jirka, 2005, 184 pages, 1.4MB, PDF

Environmental Land Use Planning

edited by Seth Appiah-Opoku, 2012, 232 pp, 12MB, PDF

Environmental Management in Practice

edited by Elzbieta Broniewicz, 2011, 448 pp, 22MB, PDF

Environmental Technologies

by E. Burcu Ozkaraova Gungor, 2008, 268 pages, 3.5MB, PDF

Fundamentals of Air Pollution Engineering

by Richard C. Flagan, John H. Seinfeld, 1988, 554 pages, 19MB, PDF

Geology for Engineers

by Robert Fox Sorsbie, 1911

Greening IT

by Adrian Thomas Sobotta, et al., 2010, 283 pp, 1.5MB, PDF

Groundwater Hydrology

by Charles Harvey, 2005, PDF

Hard Truths: Facing the Hard Truths About Energy

by National Petroleum Council, 2007, 380 pages, 15MB, PDF

Membrane Bioreactor for Wastewater Treatment

by Jixiang Yang, 2013, 125 pp, 5.5MB, PDF

Methods and Techniques in Urban Engineering

edited by A. C. de Pina Filho and A. C. de Pina, 2010, 270 pages, 9.7MB, PDF

Monitoring of Internal Moisture Loads in Residential Buildings

prepared by Lois Arena, Pallavi Mantha, 2010, 56 pages, 3.9MB, PDF

Natural Aerodynamics

by R.S. Scorer, 1958

Organic Pollutants: Monitoring, Risk and Treatment

by M. Nageeb Rashed (ed.), 2013, 229 pp, 8.8MB, PDF

Probability and Statistics in Engineering

by Daniele Veneziano, 2005, PDF

Recent Hurricane Research: Climate, Dynamics, and Societal Impacts

edited by Anthony Lupo, 2011, 616 pages, 58MB, PDF

Remote Sensing Tutorial

by Nicholas M. Short, 2005

Sediment Transport

edited by Silvia Susana Ginsberg, 2011, 334 pages, 31MB, PDF

Sun Power: The Global Solution for the Coming Energy Crisis

by Ralph Nansen, 1995

Sustainability: A Comprehensive Foundation

by Tom Theis, Jonathan Tomkin (eds), 2012, 643 pp, 92MB, PDF

Technical Guide to Managing Ground Water Resources

US Forest Service, 2007, 295 pages, 7.7MB, PDF

Thermal Processing of Waste

by J. C. Jones, 2010, 99 pages, 5.6MB, PDF

Transport Processes in the Environment

by Heidi Nepf, 2008, PDF

The Tsunami Threat: Research and Technology

edited by Nils-Axel Moerner, 2011, 714 pages, 173MB, PDF

Unsaturated Zone Hydrology for Scientists and Engineers

by James Tindall, James Kunkel, 1998, 624 pages, PDF

Waste Management

edited by Er Sunil Kumar, 2010, 240 pages, 19MB, PDF

Water Measurement Manual

Reclamation Bureau, 2001, 317 pages, 3.3MB, PDF

Water Pollution

edited by Nuray Balkis, 2012, 202 pp, 16MB, PDF

Wind Power

edited by S. M. Muyeen, 2010, 41MB, PDF