Getting data from Arraylist within Arraylist

I'm sure the first response will be 'wtf, don't use arraylists!', but I'm really just trying to get this working in any way that I can.

It's basically the 'match looker' for a match 3 game. I'm having trouble getting access to the match data within the match list. See below..

     public void FindAndRemoveMatches() {
 
     ArrayList foundMatches = LookForMatches();
     
     //just checking if we're getting the right amount for now
     Debug.Log("We found " + foundMatches.Count + " 'Match 3's");
     
     foreach(Object el in foundMatches){
        //    Debug.Log(el.ToString());
     }
     
 }
 
 ArrayList LookForMatches(){
 
     //List<int> matchList = new List<int>();
     ArrayList matchList = new ArrayList();
     
     // search for horizontal matches
     // note that we're subtracting two rows here.
     // We don't need to check the last two rows because we're matching 3.
     for (int i = 0; i < BOARD_WIDTH; i++){
         for (int j = 0; j < BOARD_HEIGHT-2; j++){
             ArrayList match = GetMatchHoriz(i,j);
             if (match.Count > 2) {
                 matchList.Add(match);
                 i += match.Count-1;
             }
         }
     }
     
     // search for vertical matches
     for (int i = 0; i < BOARD_WIDTH; i++){
         for (int j = 0; j < BOARD_HEIGHT-2; j++){
             ArrayList match = GetMatchVert(i,j);
             if (match.Count > 2) {
                 matchList.Add(match);
                 j += match.Count-1;
             }
                 
         }
     }
     
     
     return matchList;
 }
 
 
 // look for horizontal matches starting at this point
 ArrayList GetMatchHoriz(int col,int row){
     ArrayList match = new ArrayList();
     match.Add(mBoard[col,row]);
     
     for(int i = 1; (col+i)<8; i++) {
         if (mBoard[col,row] == mBoard[col+i,row]) {
             if(mBoard[col+i,row] > mPieces.GetNumPieceTypes()) match.Add(mBoard[col+i,row]);
         } else {
             return match;
         }
     }
     return match;
 }    
 
 // look for horizontal matches starting at this point
 ArrayList GetMatchVert(int col,int row){
     ArrayList match = new ArrayList();
     match.Add(mBoard[col,row]);
     
     for(int i = 1; (row+i)<8; i++) {
         if (mBoard[col,row] == mBoard[col,row+i]) {
             if(mBoard[col,row+i] > mPieces.GetNumPieceTypes()) match.Add(mBoard[col,row+i]);
         } else {
             return match;
         }
     }
     return match;
 }    

Good news is, I know that it's finding the matches correctly. The number of matches it's finding using the debug log correlates with what's happening on the screen. Yay! But, I need to get access to that data so I can compare it to the board (mBoard[col,row]) and remove those objects from the game board.

The 'foreach' loop in findandremovematches gives an error about casting. Any help with this?

thanks!