Scallop Risotto

4.5 cups chicken stock1/2 cup olive oil (divided)2.5 cups leeks (white and light green parts only, diced)2 cloves garlic (minced)1.5 cups arborio rice (uncooked)3 sprigs thyme.75 cup dry white wine2 tsp salt (divided)3 oz Parmesan cheese (grated)2 tsp fresh lemon...