When you write your paragraph, try to set the scene as best you can. Describing what you observe and how you feel is a good way to go about this. You've already said it's a hot summer's day. How does that feel as you walk there? Can you feel the sweet on your body? Are your clothes sticking to you as you approach the sandpit? Are you thirsty? Did you bring anything to drink? Is there a breeze to help cool you down, or is the air still and humid?
Describe the sounds you might hear. Perhaps there is the hum of cicadas and the song of birds, wind rustling the leaves in the trees, or traffic from a nearby road. Maybe there's dead silence. You can describe the mood that this sound, or lack of sound, imparts on the scene.
A visual description is important as it will tell the reader what kind of sandpit this is. The context of the sandpit will inform the paragraph and can provide insight into what you are feeling as you approach it. Is it a sand trap on a golf course? If so, maybe you are embarrassed that you sliced right into it on the opening drive of a tournament. Is it a sandpit in a playground with children playing in it? If that's the case, maybe it evokes some sort of memory from your own childhood. What about a sandpit on a construction site? What might you feel about what is being built here versus what was previously in this place?
There are many possibilities for the paragraph you can write. Remember to do your best to add relevant details about what it feels like physically, mentally, and emotionally to set a complete and interesting scene.