Proper use of Hydraulic Conductivity with a Sand Filter in WWHM3.
A conversion is required from the infiltration rate that is typically available. The conversion for modeling in WWHM can be approximated by:
HC = IR/ [(Distance from riser to swale invert+ filter material depth)/filter material depth]
Specifically, this case arises when modeling rain gardens with under drains (no native soil infiltration). The infiltration rate of the amended soils recommended to be 2 inches/hour. If there is a significant ponded depth above the material, the hydraulic conductivity is significantly reduced. Example:
HC = 2/(2.5/1.5)
HC = 1.2 in/hr
A special thanks to Mike Kooy

How do I install WWHM3. When you purchase WWHM3 you will receive a download link to WWHM3.msi from www.clearcreeksolutions.com. Download the program (about 60MB). After the download is finished, run WWHM3.msi. This will install WWHM3 to the default directory and create an icon on your desktop. WWHM3 requires that Allmaps.exe be downloaded and installed to function properly.

How do I uninstall WWHM3. WWHM3 includes an uninstall program.  Windows XP users will run Start / All Programs / WWHM3 / Uninstall WWHM3.  All others user can locate and run killwwhm3.exe to remove the program completely.

WWHM2-WWHM3 COMPARISON OF HSPF PARAMETER VALUES. There are some small differences between WWHM2 and WWHM3 HSPF parameters, but they are insignificant. We recommend the continued use of the current WWHM3 parameter values. WWHM2 users should upgrade to WWHM3 to take advantage of the currently recommended HSPF parameter values. Full article in pdf format.
BASINS CONFLICT WITH CCS SOFTWARE

The EPA program BASINS (which includes HSPF) includes a version of hass_ent.dll that is not compatible with WWHM3, BAHM, or SDHM.

The user has two solutions to this problem.  Use Solution 1 if you want to run BOTH BASINS software and CCS software (WWHM3, BAHM, SDHM).  Use Solution 2 if you want to run ONLY CCS software.

Solution 1:
Replace C:\Windows\System32\hass_ent.dll with a compatible version.
    1) Rename C:\Windows\System32\hass_ent.dll
    2) Uninstall CCS software - run the install program, select Remove
    3) Install WWHM3, BAHM, and/or SDHM
    4) To use BASINS rename CCS version of hass_ent.dll and change BASINS version back to original name

Solution 2:
Replace C:\Windows\System32\hass_ent.dll with a compatible version.
    1) Delete C:\Windows\System32\hass_ent.dll
    2) Uninstall CCS software - run the install program, select Remove
    3) Install WWHM3, BAHM, and/or SDHM


hass_ent.dll versions
Version         Date         Size     Notes
13.0.2.0      07/12/02   62MB     Distributed with WWHM3 - Compatible
13.0.12.0     08/26/04    9MB     Distributed with Basin 3.1  - Not compatible with WWHM3, BAHM, and SDHM
13.0.18.0     02/02/06    4MB     Distributed with Basin 4.0  - Not compatible with WWHM3, BAHM, and SDHM

We are working to eliminate this compatibility issue.