diff --git a/modules/turbsim/src/TS_FileIO.f90 b/modules/turbsim/src/TS_FileIO.f90
index d4a5814137..c9afe84b09 100644
--- a/modules/turbsim/src/TS_FileIO.f90
+++ b/modules/turbsim/src/TS_FileIO.f90
@@ -4868,7 +4868,9 @@ SUBROUTINE GetDefaultRS( p, OtherSt_RandNum, TmpUstarHub, ErrStat, ErrMsg )
    
    
    Z(2) = p%grid%HubHt + 0.5*p%grid%RotorDiameter    ! top of the grid
-   Z(1) = Z(2) - p%grid%GridHeight                   ! bottom of the grid
+   Z(1) = MAX( Tolerance, Z(2) - p%grid%GridHeight ) ! bottom of the grid
+   Z(2) = Z(1) + p%grid%GridHeight ! re-calculate just in case Z1 is set to Tolerance
+   
    CALL getVelocityProfile(p, p%UHub, p%grid%HubHt, Z, V, ErrStat2, ErrMsg2)
       CALL SetErrStat(ErrStat2, ErrMsg2, ErrStat, ErrMsg, 'GetDefaultRS')
 
diff --git a/modules/turbsim/src/TSsubs.f90 b/modules/turbsim/src/TSsubs.f90
index 173fd53f62..f869387b6e 100644
--- a/modules/turbsim/src/TSsubs.f90
+++ b/modules/turbsim/src/TSsubs.f90
@@ -1349,13 +1349,7 @@ SUBROUTINE CreateGrid( p_grid, p_usr, UHub, AddTower, ErrStat, ErrMsg )
 
    p_grid%Zbottom = p_grid%HubHt + 0.5*p_grid%RotorDiameter                                ! height of the highest grid points
    p_grid%Zbottom = p_grid%Zbottom - p_grid%GridRes_Z * REAL(p_grid%NumGrid_Z - 1, ReKi)   ! height of the lowest grid points
-
-   IF ( p_grid%Zbottom <= 0.0_ReKi ) THEN
-      CALL SetErrStat(ErrID_Fatal,'The lowest grid point ('//TRIM(Num2LStr(p_grid%Zbottom))// ' m) must be above the ground. '//&
-                      'Adjust the appropriate values in the input file.',ErrStat,ErrMsg,RoutineName)
-      RETURN
-   ENDIF   
-   
+   p_grid%Zbottom = MAX( Tolerance, p_grid%Zbottom) ! make sure it's above the ground
 
    ! (2) the tower points:   
    IF ( AddTower ) THEN